The Care & Feeding of Batteries


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The Care & Feeding of Batteries

Capt. Mike Soehnlein
5/8/00 (7:21 AM)

There are so many rumors, stories, old tales & misconceptions about batteries, I thought I would try to consolidate the many resources I have into some semblance of order. First, there is no perfect, right answer for every battery condition & usage. This is a very general discussion. I’m not going to get into deep-cycle and gel-cell on this page.

First, an explanation of how a battery works. It doesn’t STORE electricity -- it makes it on demand. There are positive lead peroxide plates and negative spongy lead plates. An electrolyte (sulfuric acid) diluted with water attacks the metal lead peroxide plates, turning them into lead sulphate. Electrons flow – current. As it does so, the proportion of acid drops in the electrolyte, getting it closer to water (low SG), and the battery loses its ability to convert more into electric current. It’s “discharged.”

Reversing the current causes the lead sulphate to give up its sulphates back to the electrolyte, turning it from water back to acid and converting the plates back to lead peroxide and spongy lead, allowing the process to start over. It “recharges.” The specific gravity (SG) increases again and is thus the indicator of percent of charge. Full charge is 1.285, dead 1.120. This wasn’t meant to get that technical, but it’s important later to the care and use of batteries.

Let’s throw in two other misconceptions. There are no maintenance free batteries. There are sealed (vent recovery system, glued cap and enough electrolyte to not need adding over average life), and old-fashioned with caps. Cute multiple cap covers that require special tools or pry bars to open doesn’t make it maintenance free! They both need checking, testing and cycling.

One of the controversies around maintenance free batteries is charge rate. Most modern chargers have a higher amp rate for “maintenance free” based on the ability to charge faster without boil over due to vent & cap design. But true maintenance free sealed batteries have to charge at a LOWER rate due to limited venting and not wanting to lose excess electrolyte due to gassing. Use the low rate -- it will have less gassing & chance of boilover, thus is safer.

Lead-acid batteries do not have a memory, like NiCads, but should be discharged and recharged on a regular basis. Daily use is actually easier on them then any storage. Continuous trickle chargers may do more harm than good in the long run. If you use your Westy regular – weekly, there’s not much more you can do besides keep the terminals clean & tight, and check the electrolyte during your 3,000-mile oil changes. Top off only with distilled water; DO NOT OVERFILL. Different batteries have different fill marks, but if in doubt, fill to ¼” above the plates. Too full and you will have the dreaded “leaker” or boil-over during charging. No need to remind you what a leaking battery does to your battery box!

Different manufacturers recommend different storage techniques, but most have you remove the battery and recharge every so often. Porsche = 3-4 months; VW = 6-8 weeks; New Castle (biggest manufacturer of antique car batteries) = 2 months. Many also recommend you discharge the battery some before recharging, while others say ‘not necessary.’ Back up to the chemical reaction and you can see it doesn’t hurt, and probably helps. Continuous high state of charge (trickle chargers) may not allow the charge/discharge cycle to complete and the plates may build up lead sulphate too much to recover. They can warp or short out the plates. Only discharging batteries can complete that desired duty cycle. That’s not a problem with batteries in daily use.

Although everybody cautions against complete discharge, I’m going out on a limb and recommending you discharge the battery down to around 10 volts (5 on 6v systems) by running a MODERATE load such as the headlights. Then do a slow recharge at 4-6 amps, preferable with a charger that shuts off when fully charged. Repeat this every 4-6 weeks, checking electrolyte levels each time. Try to avoid fast charging if you let it get down too low. On 12v systems, the normal recharge is about 13.5 – 14.5v, 7 - 8v on 6v systems. Once recharged, remove the charger until next cycle. When a quicker recharge is necessary, start on low amperage to get the process started and electrolyte back to a more normal SG, then after 10-15 minutes, boost to the higher rate. Return to the slow or trickle charge as you approach full charge.

Other tricks to extend battery life include disconnect switches or removing them to controlled climates (avoid storing in extreme heat or cold). If storing out of the vehicle, store on wood or plastic strips. Do not allow moisture or dirt to collect on the case or terminals. Cap the plus terminal to avoid accidental shorts. There are acid-neutralizing pads available to set the battery on (in & out of the car), and I recommend both the felt treated terminal washers and the special non-conductive protective sprays for the terminals. Go to your auto parts store and get a good terminal cleaning brush and a pair of those inexpensive battery pliers that will spread the cable end clamps back open. Finally, use the right size wrench, but don’t over tighten. Battery carriers are the safe and smart way to carry a battery, whether the ice-tong style clamp or the straps that fit on the terminals. Keep a can of the battery spill neutralizing spray around in case of a spill.

There are truly automatic battery tenders that supposedly draw the battery down and then recharge. But that complexity means they won’t be cheap. Most, despite their advertising claims, are not much more than an automatic trickle charger that shuts of at full voltage and then restarts when voltage drops below a certain point. The ones I’ve seen, including my own, do so in such a tight range, they approach full-time charge and do not have enough drawdown to cycle the system at anything approaching the ideal daily use.

Auto or trickle charges are fine on systems that drain a battery quickly, such as those with high draw accessories that remain on with ignition off (clocks, alarms, modern car sensors & computers) AND will get normal use shortly. But for your Westy, sitting up over the winter, remove or at least disconnect and do the monthly draw down/recharge. You won’t hurt it and will probably help extend life. We’re all look for the easy way out, but these trickle chargers and auto-charge systems have a price. At the cost of today’s good batteries, especially the premium we often have to pay for the Westy’s off sizes, even an extra season should be worth the effort of doing the old-fashioned storage method. But it’s your money & takes your choice! (Editorial note: What a waste of automotive resources! Westies are great winter cars.)

A final word about battery testing: Get a SG tester; the cheap floating ball one at the discount store is fine. A battery load tester is more expensive -- $US 40-60bucks – but the only way to truly test a battery. By testing with a large load, you can observe draw-down and recovery. Even a dead battery can be charged up to read its surface charge of 12v with a voltmeter, but that doesn’t tell you its condition. Since you are usually dealing with a questionable battery or have it out of the car when test time rolls around, it’s a wise investment for your tool chest. Oh, and whenever you're working on a battery, charging or just checking electrolyte, Use Safety Goggles!!

More later!

Capt. Mike

6/21/05: Prices for a battery load tester describe above have dropped; I've seen them on sale at the discounters below $20. There is no excuse not to have one.
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Capt. Mike

Dual battery Westies:

Whether factory OE or added auxilliary battery, duals require an additional consideration. Although most dual systems are set so the auxiliary battery does not drain the main while the engine is shut down, this is defeated as soon as the engine restarts and recharging begins. When the relay kicks the batteries into parallel mode to recharge both, the batteries will try to equalize. i.e. the weaker battery will attempt to draw current from the stronger.

This is not a big problem with a good charging system and if both batteries are in relatively equal condition. The charging system will put out enough to feed both batteries their required amperage for recharge.

Where it becomes a concern is when one battery will no longer hold a load test, or has an internal short. It will never take a full charge, so it will continue to try to equalize its better brother. There is a continuous high drain on the remaining good battery.

My own experiences confirm that a bad battery will quickly deteriorate the good one. Therefore most of my battery sources recommend replacing paired batteries together.

Since the main and auxilliary battery do NOT receive the same use and loads, I actually "rotate" my main and auxilliary at least once during their estimated life. Maybe at the 2-year interval along with coolant and brake fluid?!


New member
My Eurovan Westy has two auxillary batteries in the bank and they are connected to each other with a heavy guage wire.

Is there something that could be installed to avoid the balancing act between the batteries?


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I love this website. Finaly... someone who has a clue about batteries (I'm an electrical engineer).

Yes, I've always bought my batteries in pairs. And I too rotate them... every 6 months (first day of spring, and first day of fall). I buy my batteries at PepBoys ($39 ea now). They always last over 6 years. Been doing this since 1982.

If you're hooking up a dual battery system, get the biggest solenoid you can and be sure to use #4 cable with good crimp-on or solder-on lugs. Stay away from #6 or #8 cable it does make a difference. Especially when you have a long run (10 ft or more).
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Capt. Mike

John B: maybe "filmcan" can concur, but my electrical engineer contact said yes, but then rattled off so much mumbo-jumbo I lost him.

What I gathered was that it was complex and I'm not sure solved your problem. How would you get the lower battery up to level to trip a device that would then allow it to receive the power that it needs to get there? Sort of a Catch-22.

In reality, most of the time when one battery is failing and the other tests OK; that's a short term condition. The good battery probably isn't that far behind.

Exactly what I ran into on the dual-battery Cummins diesel this past winter. One battery tested great so I bought a refurbished to carry me through until the 2nd one failed. It did -- about a month later. I then bought two new matchings and yanked the refurbished. Actually cost me more that buying the 2 new ones the first time.

If you are rotating batteries, they should give relatively close service life.


New member
John B: Yes, I'll concur. The device you want may work well on the space shuttle, but a little too complex for a Westy. Sorry, I'm not familiar with the dual aux battery system in a Eurovan. So does this mean you have 3 batteries total?

In any case the most important thing to consider is that you are charging all the batteries in parallel, so they should all have the same internal resistance, and thus receive the same charging current (ideally). This means that all the batteries should be used in the same way at the same time. This never happens, and this is why I rotate my batteries every 6 months.

I've seen many campers set up with a deep cycle marine battery for the aux and a normal automobile battery for the main. This is the best way to get short battery life and waste a lot of money. Even Wesfalia has non-matching batteries (that stupid little aux battery under the drivers seat!)

I don't know enough details about what a deep cycle battery really is, or how it should be charged, but if you think it's better, then get two (or three in your case)matching deep cycle batteries - if they will fit in thier spots.

The main thing is that the batteries match. But if you batteries are fine now, keep using them. Just 'cause they don't match on the outside doesn't mean they don't still have matching electrical characteristics.

Capt. Mike

Deep cycle batteries: OK, here's my PERSONAL take on deep-cycle batteries, supported by a techie from Interstate.

Deep cycle batteries use some minor changes in technology to change their performance characteristics. There is a misconception that it's perfectly OK to discharge a deep-cycle until it's dead-dead again & again with no effect. Wrong! The things that happen to a regular battery can happen to a deep-cycle, they are just built to minimize that effect and reduce the chances of instant, permanent damage.

The main difference in a deep-cycle performance curve is the time/rate sequence of generation. (Remember, batteries GENERATE power, not store it?) A fresh regular battery is designed to put out high amps (starting) for short periods and then run the low-draw accessories. It puts out a little above its rated voltage, usually 12.8v. This slowly reduces as the electrolyte weakens from the chemical reaction. Picture a soft hill. The power starts to decrease almost immediately, and then picks up steepness (speed) towards the bottom. But because of construction, the bottom is like hitting the rocks -- it can damage the battery if allowed to bottom out.

A deep-cycle does not put out more power. It is designed to put out a lower draw for a longer period. It will hold that low draw level longer. At the end, though, it drops very rapidly. A TRUE deep-cycle can discharge to about 20% of capacity without harm. Unfortunately, many batteries sold as 'deep cycle' are in reality hybrids and can only be safely discharged to about 50%. Thus are likely to suffer damage in our Westy, forgot-the-fridge-was-on, use.

In practice where deep cycles are intended (Which isn't cars!) the drop in performance is so marked, that people are forced to pull the battery from service right away. If you are trolling in the boat, and it drops to the power of a swizzle stick, you dig out the paddle or crank up the Johnson. You didn't leave it on to dead-dead.

But in the VW, chances are you will put it on the fridge, and next time you check is when the green stuff starts growing on your cheese. It's been dead-dead for a LONG time. Ruin a true deep-cycle the first time, probably not. But repeating daily? Yep, eventually.

I guess the question to ask is not are deep-cycles better for the auxiliary battery in a Westy -- that's a given. But is it worth their significantly higher cost and the subsequent changes in interaction between the two batteries? Particularly taken in light of the lack of proper size in a Vanagon application?

The question becomes a pays-your-money, takes-your-choice. But please, don't do something stupid like cutting off posts, blocking vents and improper charging methods. Batteries are still dangerous if mishandled.
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New member
Yea! Ask yourself if it's worth the higher cost? Not just the higher cost of the battery itself, but the fact that you will be replacing batteries more often.

If you properly care for your batteries, you'll get at least twice the service life compared to someone who never even checks the electolite level in the so called "maintanance Free" battery.

I've seen "maintanence free" batteries that say "do not remove" right on the cap block that you need to remove to add water! I guess we can assume that the battery companies are in the business of SELLING batteries.

I've recently seen "deep cycle" batteries for only $10 more than "regular" batteries. Are they really Deep Cycle? You got me!?!?


New member
Having read here something to the effect that normal and deep-cycle batteries should NEVER be mixed, I would like to state my case to the contrary. I've been using a deep-cycle 2nd battery in my 71 Westy for about a month now and have had absolutely no problems. What's important in this case is the use of a suitable battery isolator/combiner to insure that both batteries are on the same circuit ONLY during charging, ie when the engine is running and the primary (starting) battery isn't hopelessly discharged.

The isolator/combiner I'm using is from Hellroaring Technologies ( and is a bit pricey but very well designed and suitable for pretty much any battery situation. As I have it installed, the secondary battery is connected when the positive bus reaches 13.4V and disconnects at 13.2V. I'm not running huge loads on the secondary battery; just lights and a small sound system, occasionally a blender. With liberal use of these and normal driving, I've never come even close to deeply discharging the secondary battery, and the primary hasn't even "noticed" the addition of the secondary system.

The deep-cycle type battery is suitable for RV-style power. A standard battery is better for cranking a starter motor (Cold Cranking Amps rating is higher). There's no reason not to take advantage of this in your camping setup.

Capt. Mike

The cautions about mixing battery sizes & types lie in electrical characteristics. Nobody said it CAN'T be done; what they've said is that it can have undesireable side-effects. We don't doubt that complex isolators can minimize some of those effects.

When two batteries of difference capacity and state of discharge are placed in parallel, they will attempt to equalize. It doesn't matter what type of batteries and really doesn't matter what type of isolator.

These effects are minimal when both batteries are in good condition and within normal states of charges. Where they show up is at the end of the battery life. You're 1 month is NOT a valid test. When one battery dies and the other is faced with the equalization phenomena, THEN you may find, as our members have, that the bad battery took the good one with it.

Also, Message Board Guidelines #7 indicates responses are usually based on OE & OEM configurations. The average Westy owner putting in dual batteries will retain the OE relay and VW's suggested wiring configuration so answers are geared along those lines. I certainly wish you well and thanks for your input. I hope this special isolator works for you, assuming you are well versed in the differences between deep-cycle and standard batteries and your use reflects them.
OE and OEM aside, I suggest disconnecting the aux. batt. from the starting battery altogether and charging the aux. batt. with a good solar (PV) module and charge controller. Many PV charge controllers also have a load controller built in with a low voltage disconnect which will prevent dangerously low discharges. The size of PV module you select will depend on how much power you need and can be determined with the help of a good PV technician (or a good book), but a good system can be installed for under $500 CDN (which is like about $12 USD these days ;), is much more versatile than relying on starting the engine every time your cheese goes green. On my 74, the module fits discretely in the luggage rack.
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Capt. Mike

Not yet available for Westies, there are several new battery technologies out. Optima started the trend towards 'gel cel' style batteries in automotive use. Before you run out & buy one for your Westy, look at some differences and long-term effects. In particlar, read the "Main Batteries . . ." and the "2nd Battery . . ." topics under the BATTERIES & CHARGE SYSTEM forum.

Some of the new technologies are Ni-Cad; Lithium; Nickel-hydroxide and probably a couple of more. I spent some time with the techies at Batteries Plus and here's a few general comments.

Most are designed for electronics or industrial applications. Ones large enough for applicatation to a Westy (probably as the aux. battery) are really expansions of the technology for cell phones & the like. The larger ones are usually for very intermittent use like computer power back-ups, those new 'jump start' power packs and some larger electronic equipment in industry. Yes, they produce volts & amps that can fit into a Westy application. Designed for that applicate, NO!

Their strengths -- size, spill-proof, leak resistant (notice I did not say leak-proof as I've seen many bulge or corrode through), longer shelf life and longer charge state when not in use. Weaknesses: cost, cost and well, cost. They also produce a LOT more heat -- you've probably heard about the multi-million lithium battery recall by Sony for their batteries causing fires from overheating. Not available in a nice drop-in size & capacity for the Westy. And you'll be hard pressed to find one that has the ultimate power of a lead-acid between charges. Think about rechargeable Ni-cads in a flashlight -- they don't come anywhere close to an old-fashioned Alkaline's life before needing a long charge.

Some technologies are more resistant to the battery memory problem of Ni-Cads. If kept at a constant state of charge, they develop memory and lose their ability to discharge through the design range. But, according to Batteries Plus, NONE are completely memory-free and they still recommend charging all types, discharge to a 'low battery' level, then single recharge. NOT leaving it on the charger.

Think about a Westy -- the auxiliary is usually idle, then put back on charge everytime you drive, only to sit idle again. On the rare times it is used, it's discharged heavily, which the memory may have cut to a very short period. In a Westy, it's almost like leaving it on the charger -- not the low-power discharge of a cell phone for long periods and then single recharge. Note, this applies to the above battery types; Optima claims their gell cels are not susceptible.

The same comments about trickle charging apply. They charge the battery, then shut off VERY briefly until the battery drops a 10th volt or so, then recharge again. In effect cycle on & off rapidly around full charge -- not the recommended discharge and recharge.

If you've got a cordless phone in the house, you've got a good idea of how pitifully short battery life really is. I'm trying to remember the last time I got 2 years out of one. I get 6 years out a quality auto battery in my Westy. They cost (my last-- $120 for two at Batteries Plus) pro-rated PER YEAR doesn't come close to the cost of a sufficiently powerful enough Ni-Cad style. What's $20 a year for a pair of high-quality batteries that have few compromises for the Westy's real needs & use pattern?

Capt. Mike


This is an update on Optima, the gell-cell technology discussed above.

My first experience with an Optima was a disaster. AACA requires an original battery -- at least style & type -- on show cars. My show truck has been using a Ford 2HF 6v battery that is physically identical to the old 1950 style, although they had slightly updated technology inside. They served well.

I'm getting older and more concerned (paranoid?) about leaks in a show truck and decided to try one of the Optima's. Antique Auto Battery in Hudson OH makes replica antique batteries and will put an Optima inside a reproduction case so the battery LOOKS like an original 1950 Ford, right down to the molded-in logo and Ford script lead connector bars between cells, but inside is the appropriate Optima, in my case a #8810-044 6v.

It didn't work! They tout it comes fully charged and ready to install -- no finding acid and filling locally; no overnight charge. It wouldn't even make the headlights glow! A voltmeter would read 6v, but drop off as fast as you could count down the seconds. In a couple hours, it would be down around 4v without a single item connected. It wouldn't even activate the starter solenoid, never mind the starter. It wouldn't take any form of charging current.

Do remember, this was a $300 battery! $150 for the antique battery case and shipping plus another $150 for the Optima installed inside. A regular lead-acid, original case antique w/ shipping would run ~$150.

I had to get a return authorization and then send the battery back at my expense. They promised 'resolution' within a week. 3 weeks later, nothing. I emailed -- no reponse. I called and got shuffled to several people until a service dept. employee said yes, they had tested the Optima and it did the same thing for them. No output; voltage dropped off rapidly.

I asked for a new regular battery and refund of the difference. "No. We'll get you a new conversion out next week. I raised a little more Cain about the broken time line promises, and that got it to me 4 days later. This one appears to work -- at least it started the truck. Total time down = 12 weeks! I'm not happy -- with Optima or Antique Battery Battery.

When this happened, I started checking around. One of Raleigh's biggest radiator & welding shop has been through 9 Optimas in their fleet with several leakers and not one lasting 2 years. The Optima dealer I do unrelated starter/generator business with says pretty much the same. Lots of problems. They "may" last a little longer (when they do work), but aren't worth the money -- the only reason he carries them at all is for special applications.

Fool me once, shame on you; fool me twice, shame on me. I won't be buying any more Optimas.

9/6/06 Update: I voiced my displeasure to Optima and got a nice reply from Cam Douglas, Dir. of Sales. He was both concerned and a little ticked off at Antique Auto Batteries as well. First AAB is NOT an Optima dealer so he wonders where they are getting Optimas for the conversions and the age/condition/treatment before they go out the door. He was also quite concerned as to the ventilation of the concealed battery and how they made their connections. 'Welding' or heat soldering connections to the terminals can ruin the Optima inside.

We had a long discussion on batteries and applications. I was pleased with his concern and the things he plans to do to 'make right,' as AAB's conduct also reflects, at least indirectly, on Optima. Optima is not adverse to what AAB was doing, but wants to be sure they do so correctly and will offer their technical expertise to do so.

My discussion with him confirmed there are NO Optima's for the Vanagon Westy (or Beetle) due to size. I'll be trying a 12v version in my tractor to at least get an idea of their quality/life expectancy for down the road. The 12v arrived with a 'spacer' to sit the battery on if necessary (it's shorter than what it was replacing) and two types of hold down brackets to adapt to some types of trays. I'm pleased with Optima's response -- appropriate and customer oriented.

11/2/10 Upsate: I put a winch in my antique car hauler should I ever have to load a dead car. I switched the Optima to the winch and then put a Johnson Controls manufactured battery in the tractor. Both are working well. The Optima does retain its full charge much better that average for the long periods between use. It is not hooked up to the vehicle charging system so must be checked before any big trips, but in a trailer that's not used regularly, it is no problem. I have needed it, mostly for other people's cars, but it's nice to have.
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Capt. Mike

Who's your (battery's) Daddy?

Seems batteries fail in batches. No sooner than I got the antique truck resolved, the battery in my wife's old MBenz 190D gave up the ghost. Not complaining, it was 70 months into a 72 month battery. Still takes a full charge, but the load reserve has gone. If misery comes in threes, I have one more ready to go somewhere. [It turned out to be the old VW Bug battery.]

One thing I've always advocated is doing a load test. Here's a caveat. A battery can pass the load test, but still be failing. The load tests the ability to generate the high amps for a short period. My tester is 100 amps 10 seconds. Then it shows recovery. A 750 CCA battery can still do that even when partially sulfated or old. But a starter may be 2-300 amps. That may be one reason VW still uses the old carbon-pile adjustable resistance testers. Usually much more expensive and larger in size, thus why most of us opt for the fixed resistance testors.

The load test is just one part of a comprehensive battery check -- the other half is measuring the SG of the electrolyte before & after charging & tests. In this case, although the battery passed the load test and took a full charge, the SG still only showed about 25% capacity. The reversal of the process during charging had weakened significantly. When a battery is fully charged and in good condition, the ctual Specific Gravity measuring testers (hydrometers) will read about 1.285. My best cell was 1.19, ≈50%; most were below 1.15, ≈25%. The inexpensive, floating-ball type will have at least 3 and preferable 4 balls floating in all cells.

Now the real surprise. I hadn't had cause to research batteries in some time. Things have sure changed! Consolidation has brought us down to 3 major manufacturers. Johnson Controls is the dominate one. (Also makes Optima.) Exide is probably 2nd. Even respected old brands are now supplied by these manufacturers. Douglas has sold out to East Penn Mfg. There are a number of smaller manufacturers and some overseas manufacturers, but they either don't focus primarily on the automotive market, or their products aren't generally found in the auto battery replacement market.

This makes an interesting dilemma -- IF you can figure out who supplies the batteries, is there a significant difference between them? Assuming same specs? We know the warranty is a numbers game determined by dealer marketing, not the manufacturer. So, specs equal, do we go for the cheapest with a reasonable major brand? What is going to be the difference between an Advance for my wife's 190D at $66 and the MBenz factory at $106, if both are made by Johnson Controls with the same dimensions, & specs? The brands can specify certain manufacturing standards like number of plates, etc., but at what point do minor changes in internals increase cost of manufacturing beyond what it would cost to supply the same higher quality battery that meets all?

Here's some of the branding I've been able to track down. Besides Optima, Johnson Controls makes for almost everybody else, including the Interstate, AC Delco and Sears Diehard brands. Wal-Mart, Advance, Pep Boys, Motorcraft & Autozone are all Johnson's. Plus they've bought or sub-contract the battery operations of even European OEM suppliers like Varta & Bosch and most US supply of Asian OE including Mitsubishi, Mazda, Honda & Toyota. Exide makes NAPA, Nat'l Tire & Battery, NASCAR, Sam's & Champion brands. Douglas has spun off their automotive division to East Penn Mfg., whose in-house brand is Deka and supplies Batteries Plus and Ray-O-Vac. The rest of the manufacturers that even offer an automotive battery are more likely to be specialty batteries not sold by the usual replacement vendors. And even less likely to offer a size that can be used in the Westy.

There are often a couple of capacities and tech difference between brands from the same manufacturer so these might be worth pursuing. I found warranties on the size I was looking at varied between 24 (MBenz OE) & 84 months.

Consumer Reports recently did another battery comparison. In one size batch, a NAPA (by Exide mfg) was rated top but Johnson Controls had 6 of the top 10 including "best buy" Duralast (AutoZone). The next size batch had an EverStart (WalMart by Johnson mfg) and a NASCAR (by Exide) as best buys. 3rd & 4th groups -- EverStart (WalMart by Johnson); 5th group a Duralast (AutoZone by Johnson). But in all groups, the top third rated out overall as VG to excellent. Interstate copped 2 worst in group, Kirkland (Costco by Johnson), EverStart & NASCAR one each. CR heavily weights their 'best buys' on warranty length. I'm not sure that should be the dominate factor.

Consumer Reports showed free replacement warranties varied from 6 months (Interstate) to 50 months (AC Delco). Pro-rata remainder ran from zero (MBenz OE) to 108 months (NASCAR by Exide & EverStart by Johnson).

So if you're not confused by now, you're not trying! I would suggest you first analyze your history with batteries. Do you get long life or are you plagued by leakers, early deaths and poor performance? If you're not getting 5 years plus, the problem might be you -- your use &/or system maintenance. Then analyze your needs -- capacity, whether maintenance free, deep cycle or leak-resistant. Examine your warranty expectations, and especially look at your cost-per-year or cost-per-mile. If a $60 battery lasts 5 years and a $100 battery 6, which comes out ahead and which provides the fresher battery most of the time? Everything is a compromise and sometimes supposed longevity is at the expense of capacity.

I once had trouble with a top-of-the-line Interstate (1995) that failed in 2 years in my diesel tractor -- terrible use conditions. Stored outside from 2°F to 100+°F, idle for weeks, heavy start-up load (preheat & high compression). Lousy maintenance, maybe service once a year. My Interstate distributor back then (1997) -- very knowledgeable factory trained -- suggested we go to a cheaper line because it was actually heavier construction inside despite lower specs and warranty. That battery is now 9 years old and still passes EVERY test -- load, charge, SG.

Also, bear in mind that most warranties become pro-rata exchange after the first year or two, born by the vendor, thus you will typically get a credit on the same-brand replacement -- not a free new battery or refund. For example, the Interstate in question was $102.95 for 72 months. I'd be due a 24/72 pro-rata warranty or $38.65 towards another Interstate listing for $115.95. Shopping around found an Autocraft (Autozone) that brought my replacement cost down to $65.50 for an 84-month warranty. Both made by Johnson, same CCA. Go figure.

[An interesting side note -- dealers will always take your old battery for recycle/disposal, usually without charge. Advance requires your old or pay a $10 core charge. I don't know if this is a true recycle value to them, or a civic duty ploy to keep batteries out of the landfill, but I approve. I didn't ask if it is a same-size requirement.]
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Some random toughts on batteries

It has always been my policy, (born out by intuition rather than exaustive testing!) to buy the cheapest battery that fits the use. I tend to get 6-8 years out of any battery in any use. The biggest issue is (in my mind) the useage. In normal useage I have found that any battery will do. I suppose that in constant start/stop usage one might surpass another, but that is not the way I drive.

I have never installed a 2nd battery in my syncro Westy on the therory that I don't need to carry the weight day in and day out, I don't have a big need for a large draw down when I'm camped or stopped (Light the fridge!)and I like having the room in the second battery box for more storeage.

Having said all this, in my bush cabin, where we live for 6 months at a time, we live with a solar/battery system for 99% of our electricity. I have 6 huge Trojan 90lbs deep cycle batteries in series/parallel, that I take very good care of, as the system is very expensive. Understanding that they are "permitted" to draw down to 20% of capacity for thousands of cycles, I never draw them down to less than 80% od capacity if at all possible. I has been clearly demonstrated that continual draw down below 50% of will significantly shorten the life of the battery, even if it is speced to do so. As a result I have better than 10 years on the current set of batteries and they show little sign of deterioration.

As this relates to Westy owners. People get caught up using battery capacity for extranious uses because they can. As a result the life of both batteries is compromised As is stated other places on this site, the biggest factors in determining the life of the Westy batteries are, keeping matched set (age and capacity) and limiting draw down to a minimum.

I consider the life cost of only one battery, using it for reading lights and radio while parked, (charge the cell/laptop/dvd while you drive!) driving almost every day while on the road to keep it charged. This way, I only have to replace one battery instead of two. If I shorten the life of the one by a small percentage as a result so what? It is still cheaper(life cycle cost) than replacing two. I have 7 years on my current interstate and it seems to be fine.

Sometimes we search out solutions to problems that really don't exist.


New member
1984 Vanagon Westfalia

After typical battery frustration for the Westfalia's second battery, I did something that has rarely paid off for me in the past -- bought the most expensive versionI could find. GoWesty has this battery, as well as other places. It is the Odessey Extreme Battery, model PC 1200. It fits nicely in the compartment behind the drifver's seat. I used a old rectangular rubber muffler hanger (what I had) against the rear compartment wall and the GoWesty battery clamp and it sits in there tight. It doesn't have posts, so it actually makes it easier to mount electical items to it.

I bought this battery for a couple of reasons. First, I have sleep apnea and need a CPAP machine at night. This means I have a need for a constant electical source to run the CPAP for eight hours. Whereas this battery's specs for things like Cold Cranking Amps isn't as high as the Optima batteries, Odessey claims that charging and recharging this battery has no affect on it. They claim 400 recharge cycles is normal. For me, that's 15+ years. So, theoretically, discharging it each night won't hurt it. More importantly, though, is its ability to have have small or medium size trickle draw from it and have it last twice as long as a standard battery OR an Optima batter. For the CPAP, that's critical. The Exide battery I had for three years, couldn't run the CPAP for a whole night. That's actually so pathetic, the battery should be taken out and shot. But more importantly, for people who rely on the 12-volt draw for the refrigerator -- a medium draw -- it should be a major improvement. And considering I no longer bother to light the fridge unless I plan to stay some place for days, this is a big plus.

Anyway, the battery went in today (April 28, 2007) and I will be reporting how the battery is working. I have no connection to GoWesty or the manufacturer, so I will report whether or not this thing is worth its $150-$180 price tag honestly.

Capt. Mike

The Odyssey is an Absorbed Glass Mat (AGM) technology battery. Odyssey is an EnerSys brand. I did not include EnerSys in my earlier manufacturer post because they do not make batteries designed for the auto market. They produce for applications in deep-cycle, RV and boat markets, and thus the cross-over, but EnerSys's primary focus is on Reserve Power, Motive Power and Military use.

AGM was designed in the '80's to handle extreme vibration in military and industrial applications. They are an advancement over the Gel-cell technolgy. They use a glass mat to absorb & hold the electrolyte, thus making it 'leak-proof'.

The Big 3 battery producers all have AGM batteries. The best known is the Optima from Johnson Controls. East Penn's Deka Intimidator is an AGM line. Exide has their Exide Extreme. I have found AGM's in some of their respective sub-brands.

There are some consideration you should research carefully before purchase. Obviously, do you need one? jerepowers does; but does the average Westy owner? Only you can answer that question, so don't ask the site -- "Do the math."

After you've sorted through all the marketing BS and specs to determined if the claimed long-life/maintenance-free/gel-cell/leak-proof/deep-cylce/macho-named battery is really an AGM, then fitment becomes the most difficult hurdle -- finding one that properly & safely fits and mounting it can be frustrating. Having mixed battery types (if you don't put in both in a dual-battery system) still creates equalization effect. Their ability to discharge deeper will put additional load on the alternator. Older buses with generators and small alternators may not be up to the task.
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New member
Odessey Extreme Battery follow-up

1984 Westfalia full camper

Two years ago I bought an Odyssey Extreme Battery for the second battery. I rely on a CPAP machine to sleep and need a constant small draw for eight hours. I had a regular cheap battery in the second spot for a while and it was always disappointing. So I bought the expensive battery. I think the battery is fine, however I think my initial problem had more to do with wiring the second battery than the quality of that battery. (See second battery wiring and pay attention up upgraded wiring.) Initially I had the same problem with the expensive battery as I did the cheap one until I upgraded wiring. I also added a hard-wired battery maintainer that kicks in any time the Westy is plugged in -- an easy upgrade.

Having said all that and made the wiring changes, this battery does work very well in that I can now go several days of using the CPAP without starting the Westy. I think this is because this battery is doing what is claims to do -- provide a low to medium draw for longer that a standard battery. Whether that is really worth three times the price of a cheap battery greatly depends on your needs.


New member
Battery care tips.

- Firstly, it is important to keep the battery clean and free from dust. To do so you can use baking soda and a non-metallic brush to get rid of any corrosion from the cables.
- Then, disconnect the cables and clean the area surrounding the battery terminals and cables.
- To remove the battery cables first disconnect the negative cables and then the positive.
- Remove the battery cover and check the level of electrolyte/ it should be about half an inch deep. If the level is not maintained add clean distilled water and let it mix with the electrolyte.
- Inspect the battery case for any kind of leakage and cracks. If in case there is any crack replace the battery case.
- Make sure the car battery is well secured inside insulated case because the vibrations caused while driving may damage the battery. Ensure that to protect the battery from vibrations, you don’t over tighten the clamps.
- To replace the car battery carefully lift the battery because the acid inside can be dangerous.
- To reinstall the cables, first connect the positive cables and then the negative.
- Smear a little petroleum jelly onto the battery terminal before fastening the cable clamps to the posts. This jelly like substance will help slow down corrosion and enhance life of the battery.

Capt. Mike

Do you want to feel dumb? A couple of weeks ago I bought new batteries for my Porsche. My model takes 2 special sized 12v units in parallel. Now available ONLY from Porsche, and they had to be ordered from Germany. They were only used on 4 years of the 911 models. Anyway, they arrived and for my well over $300, looked cute in their special packaging. I pulled them, installed and discovered I had no juice and they would not take a charge. What I had not done, spoiled by the ready-to-go batteries locally, was to check for electrolyte. They were bone dry. Now I have to find electrolyte, no longer as easy as days gone by. Dealers no longer service their own battery stock so they don't stock it. Batteries Plus says they have it, but it will cost me $10-15 per battery. Nice to know and next time, I'll check the electrolyte level when I buy new batteries.

10/31/2010 Update: About the only place I found that carried electrolyte & would 'charge' them for me was Batteries Plus. I'm told Car Quest sells packets for lawn & garden batteries, but couldn't confirm. Anyway, two batteries cost me an additional $30 + tax. They did the labor incuding unloading & loading from my car, so I can't complain too much. Installed, hooked up, and they started the car fine. I also put in permanent terminals for a Battery Minder. The cost of these batteries still boggles my mind. List = $229 + tax each. :eek:
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