Second battery


frito

New member
Last year when I installed my aux battery I discovered that my LED panel would light up from the AUX even if the main battery was not in. I never really figured this out. My Bently is dated so my page numbers do not always match but it has 97.20 Camper Wiring which looks like the LED panel goes to number 30 on the relay "To Term 30 on Fuse/Relay Panel". Also my 1985 camper supplement to VW Vanagon owners manual says that the 8 amp fuse on the post behind the drivers seat is for "Water pump and lights in sink cabinet control panel."

My conclusion is that wherever the sink pump gets power, the LED panel measures that voltage. To check this I used a 9v battery with no main or AUX in the car. I put the 9v on the sink pump lead and measured the voltage going into the LED panel. No surprises, a little less than 9v.

As a last note on installing my AUX. I wired the batteries directly through the relay as Capt. Mike suggested. I am never happy about drilling into my westy so I put this job off for a while. But in the end a just fed an 8 gauge wire through and existing gromet in the main box -> under the car along original wires -> to front of the van -> up along existing harnesses -> through the gromet that the original power lead came into the fuse box-> under the carpet with wires that went to the relay under the drivers seat. No drilling :) harder job :( to each his own.

Oh yes while I was on a roll I installed a smart battery charger in the hidden cubby next to the water tank. It charges both main and AUX when I plug into AC. I did this more for when the van is sitting for extended periods. I killed both batterys last year during the winter. I tried to keep them up but it was a pain and they got the best of me and my free time. It is a nice two bank 10 amp smart charger (3 stages). Next year I hope I can maintain the batteries.
 
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Capt. Mike

Moderator
The wiring diagram for adding an auxiliary battery in a late model US Vanagon has been updated on the Tech Drawings site linked from the home page.

Two clarifications are in order.

Using terminal #87 of the relay for the input from the main battery was retained as was the original wiring of the sink pump to the other #87 as it also feeds the battery condition side of the LED panel. It was left this way since the condition of the main battery is the more important. If the sink lead is moved to the auxiliary battery, the LED panel will then read the auxiliary battery condition and the main could get low without knowing it. Sink pump use should not seriously affect the main battery charge.

The original red wire feeding relay terminal #87 from the power distribution panel under the dash is capped off and insulated since it was replaced by the heavier gauge wire from the main battery per Bentley diagram page 97.9a.

This installation schematic shows additional connections for an AC converter/charger and 2nd battery condition gauge. These would be optional.
 
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Capt. Mike

Moderator
Transferred to consolidate same topic.

Eartheyes Junior Member posted January 03, 2003 10:35 AM

Curious if anyone has done extensive research in different manufacturers of deep-cycle batteries that might fit into the driver's seat compartment.I had heard that an Optima battery for Hondas is very small, and can be laid on its side, though not sure if it is a deep-cycle type...and noticed they are all EXPENSIVE. Is there are any ingenious setups for installing perhaps larger types in other locations in the van? Might there be connectors to allow easy removal for helping other stranded motorists not close enough for a "jump".
Thanks Much!

Mike Robinson Member posted January 03, 2003 12:41 PM

Deep Cycle Batteries

My research on deep cycle batteries was quite interesting. Firstly they are too deep ie tall to fit into the space for a battery, and secondly not worth having. Somewhat inflamitory last statement. Let me explain.

I went all over trying to find a deep cycle battery that has the same dimentions that the standard VW battery has - good luck finding one. I finally found two that would work - both solid state. One that get used in a mobile wheelchair, and the second a 'franken-battery' custom made for CN rail. The CN battery was $130 CDN and had a similar (although lesser output) to the standard battery, the second was much smaller $80 with very low output, but it was small.

I also do not run my fridge on the second battery, the power was for interior lights, radio and fan for aux heater. Not huge pulls but when you have an old diesel that does not like starting in -20c ....

The sales assistant at the battery place - who had been doing batteries for a long time said that the best option was to put in another standard battery and he would guarantee it for 5 years rather than the customary 10 for 'normal use'

The reasons why -

1) Deep cycle batteries are not that much better at doing deep cycle than ordinary. They die if used in deep cycle mode constantly. I better decription for a deep cycle battery is a battery 'more tollerant to deep cycle work'

2) Having an identical battery allows you to do your own boost.

3) Having identical batteries allows you to swap the batteries over so they both have a similar wear pattern and will last longer.

4) Same batteries is easier for the charging system as - in theory - doing dual recharge should have the same batteries. I know, thousands of people do otherwise and are fine - I am just cautious.

5) Be kind to the normal battery and he careful of discharging it completely and it will last a long time. I camped in November of 3 nights - light, radio, fan and bearly made a dent on the battery!

6) Cheep and available $60.

7) Its like a glove in the battery compartment.


Hope this helps

Mike
 

Capt. Mike

Moderator
Chuck, I'm sorry but I can't really explain it any better than what is already posted. You needed the auxiliary battery positive cable, ground cable and the battery hold down. That's ALL you needed. Bus Depot sold you a bill of goods -- the relay is already there; the wiring is already there!

The diagram of how to hook it up is already posted on the site (Tech Drawings link). It's also in the Bentley.

The only thing we recommend is you use a heavy gauge wire to connect the two batteries -- also as shown in the Bentley! -- instead of the smaller wire going through the DC distribution panel.
 
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Capt. Mike

Moderator
;) See my experience and comments on Optima batteries in the TIPS forum, "Care & feeding of batteries." Since some have described using an Optima as the 2nd battery in a Westy, you might find it revealing. There is also updating of battery manufacturers and the supply chain.
 
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Capt. Mike

Moderator
Moved to consolidate same topic.

Mo Allen Junior Member Posted October 04, 2006 11:02 AM

Hi there,

I have a 92 Westfalia Claifornia (T4). All goes well, but I cannot find my leisure battery. I think I know where it is, but am not sure and would like confirmation before I go cutting anything.

My van has had an LPG conversion and the tank has been placed in the boot on the drivers side (LHD) against a quick release panel. I think the battery is behind this panel, but as I cannot move the LPG tank, I will need to cut from inside the large cupboard above where I need to get access to.

Mo
 

Capt. Mike

Moderator
The instruction for accessing the auxiliary batteries of the Eurovans is described in Bentley, sections Q72-2 and V27-16 for the under seat models and R76-5 & 6 for the dual-auxiliary battery models (Guideline #2). You should not have to CUT anything.

But if I read your post right, you have some non-VW approved aftermarket modifications. I can't picture anyone putting the LP tank INSIDE the car. Risky; lousy use of space. If so, I would very seriously consider moving or replacing the tank to something similar to the VW OE configuration. The loss of value from cutting up the cabinetry should pretty well pay for moving it.
 

Capt. Mike

Moderator
The current GVW-253-700AGM & -701AGM kits sold by GoWesty are overly complex and expensive. The older factory duplication kit is no longer in their listing. Replicating the original factory wiring is much cheaper. GoWesty's kits are also geared for a non-standard AGM (gel-cell) battery rather than the standard size 42 VW battery. [See the TIPS forum, "Care & feeding of batteries" topic for the advantages and disadvantages and safety considerations of mixing battery types.] The '84 came with the required relay and charge activation wiring. You need only a positive cable, std. ground strap & std. battery hold-down. We also suggest you use the heavier gauge wire for recharging per Bentley 97.9a but that's just a few feet of 8 gauge & a couple of wire ends. Go to the Auxiliary wiring diagram in the tech drawings folder. Don't make something more complex than it needs to be.
 
M

mrcmret

Guest
I installed a battery Isolator on my 91 Westy in 1994, and I am curious as to what would happen if I took out the relay between the batteries? I rewired the aux battery back then to handle my cabin lights, fridge, radio, and cigarette lighter. Since the batteries are both being charged from the Isolator I should not need the relay. Could I wire a cut-off switch between the wire from the main battery (Pos) and the wire (Pos) on the aux battery and remove the relay? Notification is off and I don't know how to turn it on email is echo9@wavecable.com
 

Capt. Mike

Moderator
The function of the original relay, when wired per VW and the diagram in the Tech Drawings link, IS THE ISOLATOR. Thus an additional or add-on isolator is redundant and a waste of money. Not knowing the isolator you have and its wiring, one can't comment on whether it is correct or functioning in the manner needed. The selling point of most aftermarket isolators is their ability to handle large banks of batteries (RV) and massive recharge currents from shore power converters, thus their inflated prices and size. This load is not present in the Westy which only carries the same current as the main, which it already did.

That you've switched the cabin lights & accessories circuit to the auxiliary battery is irrelevant to the function of the relay or isolator.
 

Snidge

New member
I've recently purchased a 74 westfalia and am trying to install an after market dual battery kit. I've read the other post and unfortunatly the tech drawing page is currently un-available (reading other posts I guess there is a bit of a frustration with flikr.)
The relay that I'm using uses the same number system as in other posts. I have the 87, 85 & 30 post hooked up okay, however do not know were to hook in the 86 into the existing wiring (the instructions that I received aren't the greatest). It says to connect with a 12V supply wich only becomes alive when either the ignition is switched on or when the engine is running.
Just starting to learn about the wiring so any help for a rookie would be greatly appreciated
 
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Capt. Mike

Moderator
Yes, the yahoos @ Yahoo are driving me crazy.

The purpose of the dual battery relay on a '74 is the same as a Vanagon -- to isolate the auxiliary battery when the engine is not running to prevent draining the main. In North America, only Type II's P27's with the AC/DC fridge were equipped with auxiliary batteries. The relay was located on the rear wall (closest to bumper) of the engine compartment, left side top. The "jumper" wire from the main battery ran above the engine opening.

Factory wiring used standardized DIN circuit labeling. #30 is the 12-gauge red lead from the + terminal of your main battery. #87 is the same gauge red to the + terminal of your auxiliary. This is the "switched" curcuit to put the batteries in parallel when the engine is running for recharge. Since both batteries are independendly grounded to chassis, wiring from the - terminals is not required.

#86 is a black 14-gauge wire from the alternator terminal #61 (D+). #85 is a 20-gauge brown wire to a convenient body ground. This is the circuit to operate the "switch", getting power ONLY when the engine is running and alternator is putting out power to close the switch, connecting the two batteries for recharging.

If you didn't have your email blocked (See Guideline #10 & Disappearing Posts links), I would have sent you the factory diagrams.
 

Snidge

New member
didn't realize email was blocked, I think that it's un-blocked now (still new at this), I appreciate the advice and would be greatful if you could send me the factory diagrams.

If I didn't figure out the email un-blocking it's craighol@yahoo.com (it's too bad that I have to use yahoo, sort of ironic that I need their email service to get the pictures that their server wont provide access to....)

Again all the adivice that you've provided in this post (and all over the forum) has helped me a great deal
Craig
 

icarus

Moderator
I would take out the aux battery, and bench charge to a know full charge, preferably with a hydrometer. It sounds as though you may have a aux battery with a weak cell.

Also, are you checking the running voltage with the fridge running on 12vdc?. I think you are correct that if the batteries are wired in parallel, they should read the same voltage under "running" condition assuming the relay has opened properly.

What many people miss is the difference between a battery voltage under load or charge, as well as surface charge. In order to get accurate volt meter readings on a battery it needs to be off charge/off load, and have sat for at least 3 hours. There are a number of good battery sites on line, (mostly from solar energy people) that explain more about lead acid batteries than you would ever want to know. In the case of my solar electric systems, the battery bank is over $1000 so taking care of it has been a priority.

Try this link http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

Or try http://www.rpc.com.au/products/batteries/car-deepcycle/carfaq4.htm#charge

Or this http://www.trojan-battery.com/Tech-Support/BatteryMaintenance.aspx

Or this http://www.xantrex.com/web/id/742/docserve.asp

Icarus
 

icarus

Moderator
I'm not too familiar with the Optimas battery. Different batterys require different charging modalities. Flooded lead acid cells reqire a higher float/absorbtion charge than do absorbed glass mat batterys. I think the Optimas may be an agm type battery. As such it may have a lower top/full charge voltage than the car battery. Most battery chargers do not do a good job of absorbtion charging batteries. To be considered fully charged most batteries need to be on a absorbtion charge for a good long while. While a battery can read 12.6 vdc it may only be very partially charged. (That's why batteries with openable caps are desired for good, easy testing). A hydrometer can quickly pinpoint a cell that is in trouble before it has time to affect the rest of a string. One bad cell can destroy a huge battery bank.

I have never been a fan of having a second battery in the Westy. I think that the weight/cost penalty is greater than the benifit. Unless you have great electrical needs and you park for days at a time, I found that having only one battery worked fine. (The catch is not to run the fridge on 12vdc when parked, but rather light the fridge instead).

I have also never been comfortable with a mix of battery sizes and types and ages in the same charging system. In solar applications it causes no end of aggrivation. The weakest battery in the string will determine the performance of the entire string. In solar service you should never place a new battery in the string that is more than 6 months newer than the rest, or you will degrade the entire string.

Bottom line for me was, save the money/weight/expense and gain a great storeage spot under the drivers seat.

Icarus

PS Sorry Capt. a bit off topic. Delete if needed.
 

icarus

Moderator
As Capt. Mike would say,,,do the math. If you calculate the amp/hour capacity of the battery, the amp/hour draw of the fridge, you should be able to get a rough idea of if it is line with what the battery should put out. (I don't know what these numbers are).

If memory serves +-12.24vdc is about 50% state of charge in a flooded battery. +-12.45 is about 75%s.o.c. If you can't get the battery to 12.6+- there is something wrong with the battery. If your battery was fully charged, my intuition says that it shouldn't be close to 50% s.o.c. with 20 minutes of fridge use. Remember, that to get the longest service out of "deep c and cycle" batteries, they should not routinly be discharged more than 20% and then recharged as quickly as possible. In solar service, I strive to keep my battery bank at least at 90%. I'm ten years into a battery bank that was warrented for 6. Still going strong.

Icarus
 

qbini

New member
Hi All.
I have a US 87 Westy Full Camper. She is aux battery ready. I have read thru the posts and question whether i need the second battery. I don't use the fridge on 12v much. But here's my question - i am paranoid about running the battery down using the lights, radio etc. while camping. We camp in alot of places where we're not like to find a jump. I'd rather not re-wire the beast to run accessories off the 2nd battery. So, now i'm thinking of installing the second battery and using it only for engine starts or to jump if i run down the main.

I'd install the aux(same batt as main), disconnect the relay for the fridge and sink. Rewire to act as main for starting. Does that make any sense at all? Is it a bad idea? Does it sound doable?
thanks,
kevin

btw, this site is awesome. I've had my westy for 5 years now and could not have survived without the information post here. Thanks!
 

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