Second battery


peter

New member
This topic had become too large & cumbersome (7 pages). Much of the topic was covering individual errors in wiring or attempts to modify the wiring for unique circumstances. We have cut the forum down to deal with installation and wiring of the 2nd battery per VW's option.

Sorry, but we can't devote the amount of resources we were asked to totally unique topics . . . "I wanna wire my hot tub to the auxillary battery." The most common are trying to wire the interior lights or radio to the auxiliary (neither practical) and I'll try to leave those posts. The other unique wiring additions don't apply to sufficient members to continue them.

Occasionally, you will find a post that isn't clear because the answer refers to a post that has now been cut. Sorry for the confusion and you can email me direct for any requests to edit -- I'll do my best.
 
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Capt. Mike

Moderator
Dual batteries are common on Vanagons and were standard on some models. The Bentley shop manual Section 97.9a shows the layout for Canadian Westies where dual batteries were standard.

The well under the driver's seat will hold a 2nd size 42 battery. It is not sealed and outside vented like the main, but few have reported problems. VW sells the standard parts necessary -- a special camper dual lead positive cable, a ground strap, and the hold-down clamp. Most Vanagons were pre-drilled & tapped for the hold-down & ground bolts. Since the seat doesn't swivel 180º, you may remove it per Bentley 72.2 for working room.

In the US version the relay is wired "backwards" to allow the sink to operate without the engine running. The relay cut off the fridge when the engine stopped. You will have to rewire it so the relay now places both batteries in parallel when the engine is running to recharge it. When the engine stops, it will remove the main battery from the fridge circuit to prevent draining it. You may have to move the relay slightly to clear the battery box -- it's a tight fit. You MUST have a positive post guard (comes with new batteries) as the metal box lid is very close to the post.

There is a copy of dual battery wiring on my pic post site linked from the home page. Look in the technical diagrams folder. Note that I chose to add the heavier cable in picture 97.9a to cross-connect the two batteries rather than rely on the smaller gauge wire through the power panel that is stock.

Most put the sink pump on the new auxiliary battery. Replacing the 3x10W incandescents with an 8W flourescent is adviseable, but other than that, it is not practical to change the normal cabin lights.

Also on my pics post site are pictures of a 2nd battery monitor gauge, some additional interior lights and the use of DIN standard electrical accessory jacks instead of the inferior cigar lighter style sockets.

See the post under TIPS forum on Battery Care -- dual batteries add another set of considerations.
 

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Capt. Mike

Moderator
Sort of an add-on note: The purpose of the 2nd battery is to allow you to run the fridge on DC when stopped for a short while without changing over to LP. Shopping, lunch, a quick attraction sort of thing. It can also allow taking the sink pump off the main. But it is not some magic power source so you don't have to run the engine/recharge the main every so often. For example a 72Ah battery is just that -- 72 amps for one hour or 7.2 for 10. So don't count on a big load like a heater over several days. I always advise people on electrical items to "DO THE MATH!" V x A=W; A x Hrs=Ah.

I suppose you could wire a DIN accessory plug to it as well for some in-cabin accessories. I have a DIN plug mounted in my cabin (rear seat wall), though I didn't try to wire it back to the auxiliary battery. It's for things like a car vacuum or air compressor.

I've seen some put a cigar lighter or the DIN plug on the face of the sink cabinet near the indicator panel, which might be a solution with a shorter wire run along an existing path.
 
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Capt. Mike

Moderator
Transferred from another forum to keep similar topics together.

rickcrooks

Junior Member posted 09-25-2000 10:29 AM

My girlfriend and I are on the road for two months in my '86 syncro and I wired in a second battery as directed after reading through the archives. But my cabin light still seems wired to my regular battery. That is, it doesn't come on until I reconnect my main battery. The two wires from the fuse box behind the drivers seat seem to connect to the fridge and the indicator lights on the fridge/stove console--not the cabin light as said. Am I correct in assuming this? Do I need to find the wires to the cabin light and wire into my second battery directly? Confused and without the book. Trying to find one on the road.

thanx for any info
 

Capt. Mike

Moderator
Yes, your cabin lights still run off the main. Since a 2nd battery was not standard, all the electrics are set to run off the main.

The cabin lights run through the fuse box and would therefore be difficult to switch over. The 2nd battery is just for the fridge & water pump unless you re-wire other things. Probably not worth it. See the post under accessories -- some switch the main cabin light from the 3x10W bulb style to an 8W flourescent to save power yet better light.

You can get the Bentley shop manual at any dealer -- most still stock them.
 
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Capt. Mike

Moderator
There is an addition to the TIPS forum, "Care & feeding of batteries" thread concerning deep-cycle batteries that might be of interest to owners considering the auxiliary battery retrofit in Type II's & Vanagons.
 

frito

New member
I am adding and aux. battery and I am not sure were the normal ground location is. There is a hole for the hold down and another hole located behind the relay. Is this the correct hole? Also, I saw mention of a dual lead postive strap in this post. Does anyone have any idea of a part number. The parts guy at my dealer was tring to sell me parts for the battery in my engine compartment. Clueless.

Thanks
 

Capt. Mike

Moderator
What year & model? Read the Message Board Guidelines, especially #3.

I'm assuming, because of your comment about the battery not being in the engine compartment, you have a Vanagon. Tell your dealer to look at the fiche, plate #153-40, key #1. It should say Harness for 2nd battery, P/N 255 971-228A. This is from an '88> fiche, but probably the same for others.

My Vanagon has a threaded ground strap hole in the rear edge of the swivel seat platform. It doesn't really matter as long as it grounds to solid metal and doesn't short the relay. I moved my relay further to the right putting it behind the battery box frame instead of on it out into the box area.
 

frito

New member
Indeed, I have an 85 westy. I just slipped :(

The part 255 971-228A has two pigtails that are mounted to the terminal clamp. I have looked at the tech diagrams on your web page and I am not sure to which the lead are supposed to connect. It looks like one of the leads connects to #30 on the relay (alternator) and the other to the fridge. If this is the case do I leave the wire to the sink pump connected to the relay?
 
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Capt. Mike

Moderator
There's a wiring diagram on my pics site linked from the home page that should clear up the what-wire-goes-where. The harness is color coded and I've noted the numbers on the relay connections.

Understand how a relay works; 2 terminals, #85 & #86, trigger the relay. In this case activated by current from the alternator so that the relay closes only when the engine is running. #30 & #87 then connect the battery power (hot lead from main) to the appliance (in this case, 2nd battery).
 
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Capt. Mike

Moderator
Transferred from Archives.

Vent in battery compartment!

Bill, 4/6/00 (6:56 PM)

What's that vent in the battery compartment for and do I need to install one in my auxilliary battery compartment.

One more thing, can you use the battery guage in the control panel below the stove for the auxilliary battery, since the main battery now has little or no drain on it, and besides you could always jump it with the auxilliary battery! Thank-you!!

-- Bill

Capt. Mike Soehnlein (capt.mike@mindspring.com), 4/8/00 (2:00 PM)

Battery fumes are potentially hazardous, so the original compartment is sealed and then vented to the outside. Very few attempt to duplicate that in the auxilliary battery installation. You'd have to replace the left lid with a sealed one, come up with air-tight wiring pass-through, and install an external vent.

Since the battery only recharges (period of highest gassing) while the vehicle is running, and there is usually good ventilation while underway, most take the calculated risk. Not a recommendation -- each to their own comfort level. Many vehicles, including VW Bugs, had the battery unders the seat or other interior locations for many years without any special venting, but times, batteries and regulations change. The last battery I bought came with a remote venting kit to vent via a hose to the outside. Might be something to look for when you purchase the battery.

The battery condition indicator is a solid-state circuit board; theoretically possible to install a change-over switch to read either, but not practical or cost effective. See my picture site from the home page link under Westy Accessories. You'll see my installation of a 2nd condition gauge for the auxiliary battery. Much easier & cheaper, plus gives you both. Mine even has a momentary on switch so it's not reading all the time. Even cheaper, install a cigarette lighter accessory plug and use one of the little plug-in voltmeters from the auto & RV stores.

Don't underestimate camping drain on the main battery -- all the lights, radio, sink pump, etc., still run off the main. Usually not a problem on overnighters, but can show up over a couple days -- or high drain items like Cassette & CD stereos.

Jumping from the auxiliary is easy; you only need one jumper cable since they are mutually grounded. The short distance between batteries allows a fairly small gauge, say 8 or 10, thus a compact unit to store.

Capt. Mike
 

Capt. Mike

Moderator
You are aware that there is no battery charger standard or built in to the '85 Westy? So you can't recharge your aux or main just by plugging into AC.

You can install an AC converter -- I did -- and the necessary timer. The converter fits in the void under the side cabinet behind the AC outlet. I put the timer up into the cabinet above so it could be reached easily. The unit used in the late Type II P27's was still available. However, I've found this pretty much a waste as I doubt I've needed to recharge the aux from AC twice in the 10 years.

I just keep a small jumper cable in the rear cubby. You only need one since they're grounded common.
 

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Geoff Barnes

New member
I am working on installing one of the Optima sealed batteries as my auxilliary on my 85 Westy. Of course, it's a bit deeper than the Type 42, so getting it in is going to be a chore.

When I remove the driver's seat, I'm faced with the swivel platform. I need to remove that to gain extra space to insert the battery. Bently manual doesn't cover this, and I can see no 'obvious' way to remove the swivel platform.

Anybody had experience with this? Would appreciate some tips.

Also, it looks, from the Bently diagram, that both Pos and Neg wires go from the 1st Battery, down through the 1st Battery well, and across and up to the Aux Battery well, and attach to the Relay inside the Aux Battery well. Correct?

Thanks :)

Geoff
 
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Capt. Mike

Moderator
A complete description of R&R and adjustment of the swivel seats is contained in the INTERIOR forum under the Seats thread.

The wire you describe in Bentley 97.9a allows you to run a much heavier wire (I'd opt for 8 or 10 gauge) for recharging purposes than the original light gauge wire that ran through the solid-state distribution module. Tie off & insulate the end of the no longer used orginal.

The negative ground strap does NOT go between batteries; each has its own going to chassis ground near the battery.
 

Capt. Mike

Moderator
In response to a question on placing the two batteries in parallel permanently.

No. You can permanently tie the two batteries together in parallel by runing a single large -- I'd suggest 1-4 gauge wire -- between positive terminals. Obviously, you could install a straight on-off switch in the jumper cable but only a relay system can isolate one battery from the other automatically when the engine is not running.

:confused: Ask yourself what you are trying to achieve by tying them permanently together. The double power only occurs during starting; they are immediately placed in parallel for charging while the engine is running in the recommended relay system.
 
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Capt. Mike

Moderator
Aux battery for '93 Eurovan fridge drawer

fred from seattle Junior Member # 1469 posted 07-09-2001 03:20 PM

I recently bought a '93 Eurovan MV w/ Westfalia poptop and fridge drawer. Great vehicle, but the fridge only runs a couple hours before quitting, after drawing battery voltage down to ~11.5 V (measured w/ fridge off). Should I expect more cooling time than that? IE is the aux battery about dead?

Aux batt specs say I need 720 CCA; installed aux is 510 CCA rated, unknown age. So far, I am not able to find a battery for sale that meets spec (Group 41, 720 CCA). Any suggestions for alternatives?

Thanks!

Capt. Mike Moderator Member # 11 posted 07-09-2001 05:37 PM

Per Message Board Guidelines #3:

"Do some preliminary checking first. For example, don't post 'battery died' until you have checked charge, voltage, had a load test performed on the battery and checked the alternator output. The more information others have, the more likely they can pinpoint your problem."
Discussion of battery state of life is discussed under the "Care & Feeding of Batteries" topic. I'd also suggest you read and understand the "Calculating loads & capacity" thread. The CCA numbers, though impressive advertising material, are less important than the Ah (amp-hour)rating.

Measure your original battery, including such things as post height, and discuss your needs with a competent battery dealer, or preferably, a distributor. They can often guide you to a better choice than blindly following some CCA rating. For example, my Interstate Distributor suggested a lower power but heavier duty industrial battery for my diesel tractor as it had high load (start pre-heat) but then use involved a lot of idle and steady-state time. The fanciest Megatrons, expecting high charge rates, didn't do as well as this 'lesser' battery.

"Where can I get?" questions are deleted as 'wanted'. Bargain hunting is outside the scope of the technical boards. Please patronize our site sponsors when shopping aftermarket.
 
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Capt. Mike

Moderator
The LED panel does NOT measure the auxiliary battery; it measures only the main. It's that battery that is not getting/holding charge.

I've always recommended that owners installing the 2nd battery do so per the original VW factory wiring with a separate, heavy gauge wire routed as per Bentley 97.9a and as posted above on 16 June 01.

Since changing the LED over to the auxiliary battery is near impossible because it's solid state, I suggest a 2nd battery condition gauge. My installation is shown on my pic site linked from the home page. There are other alternatives for 2nd battery condition gauge posted elsewhere on the site.
 

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ChrisGeo

New member
Hello all, I have a 76 Westy that has the second battery set-up already wired in. Once upon a time, I had used the set-up to charge a dead battery as well as used shore power to run the fridge and small accessories via the sockets on the lower bench panel. Today, I installed a deep cycle battery in prepration for a trip, and I got nothing out of it. I plugged into shore power as well, and still got nothing.
have checked little things like fuses and connections look good. Any clues what else I can look for? I'm not overally electrically inclined, but what is the lil "relay" looking box that allt he battery wires connect to? Could that be the culprit for the apparent lack of power? Anything y'all can suggest would be greatly appreciated!

Chris George
 

Capt. Mike

Moderator
Per the 6-29-01 post above, there is a full wiring diagram of the P27 Type IIs on the tech drawings site linked from the home page. That will not only show all the wiring for the relays, but also the wiring for the shore power system. The AC/DC converter has its own internal fuses; there is a circuit breaker for the AC outlets; and there is an inline fuse for the aux. battery system.

I'd suggest you also read the topic on batteries (TIPS forum) to understand the ramifications of mismatched batteries in a dual battery system.

Last, I'd suggest you read the owners manual about using the built-in charge system for the aux. battery. It does NOT charge the main battery and attempting to 'jump' by misusing the relay can cause problems. If you want to recharge both, carry a single jumper cable to connect the two positive terminals (the negatives posts are already common grounded.) But also understand the factory AC converter is not intended for both, so you will want to use it sparingly for limited time periods so it doesn't overheat or blow its fuses. Or alternate charging batteries by disconnecting the ground strap on the auxiliary while charging the main.
 

Capt. Mike

Moderator
On a US Westy, the Driver's side battery is an aftermarket installation -- they were not standard. See the 6-15-01 11:47 PM post above regarding removing/installing that battery which requires seat & swivel removal.

Access to the Passenger side battery is described in the "Main Battery . . ." topic in the 12-23-00 4:01 PM post.
 

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