Dual Battery Relay

twinfalls · Post by **twinfalls** » Tue Feb 06, 2007 9:47 am

Isolator versus relay.
They do the same. Isolator is overkill.
Westfalia uses a relay. A few bucks 30A Bosch relay is just perfect.
Some use the ignition voltage to control the relay;
I like better the Westfalia way; The alternator/voltage regulator D+ voltage, controls the relay.
In the first way, batteries are connected together when you are going to start the engine.
In the second way, batteries are connected, a bit later, when the engine has started.

Post by **Sluggo** » Thu Feb 15, 2007 2:21 pm

Amskeptic wrote:If your aux battery is just an assist when car is parked,
get a big old Ford starter relay.
Hook one big terminal to the aux battery, hook the other to the starting battery. Hook an ignition power source to the relay's solenoid and ground the other. Every time the car is running the alternator can charge the aux battery. When ignition is off, your aux battery is free to do other things while keeping the starting battery fresh to start the engine.
Colin

Just got one. The two big posts are unmarked. The small posts are marked "S" & "I". Would the one marked "S" be the solenoid?

germansupplyscott · Post by **germansupplyscott** » Fri Feb 16, 2007 8:20 am

Sluggo wrote: I'm just wondering if this is like the "Hot Start Relay".

The relay we use in our kit:

http://germansupply.com/xcart/customer/ ... ctid=16766

is this one:

http://germansupply.com/xcart/customer/ ... ctid=17061

and is the exact same relay used in the genuine bosch WR-1 hot start relay kit.

The relays above are both 5 pole, however the dual battery kit needs only one switched pole. Bosch doesn't make a nice relay with the mounting tang that has 4 poles. Hella makes one but it costs 2x what the Bosch one does. So we use the Bosch 5-pole in our kits, one 87 pole stays empty.

Any 4-pole relay with terminals 30, 85, 86, 87 will work for the dual battery relay circuit. We use Bosch relays in our kit because they are better quality than generic ones, which are mostly made in Asia. Bosch relays are still German.

Our dual battery kits cost more than the others I have seen, for a reason. It has a custom-made wiring harness that is fitted exactly for the VW bus, with correct factory terminals and shrink-wrapped looms. The Hella kit that everyone else sells is just a relay and a bundle of wires, "cut to suit". Ours is designed for the application. It is a turnkey kit that you can install in under an hour and it is completely "reversible" in that you can install and remove it without making any permanent modifications to the vehicle wiring.

The typical cheap battery isolators do not, in fact, isolate very well. They "leak". The dual relay does not have this problem. I also do not like having to take large gauge wires to and from the isolator and alternator, something about having 8ga hot wires running all over the place makes me queasy.

Post by **Sluggo** » Fri Feb 16, 2007 5:46 pm

Scott,

Thanks for the excellent detailed reply. That's exactly the info I wanted. Yours does seem like the kit to get if someone was going for easy installation and a stock look. I've seen the other kits and they are exactly as you describe them. A standard 5 pin relay, bits of wire and terminals. Which is what prompted my question. I'm going with the Ford starter relay because I already have it and my Bus lost the stock look a long time ago.

skylermoon · Post by **skylermoon** » Fri Mar 30, 2007 9:16 pm

Hey I was thinking about getting a second battery and then I also found this SUNSEI SE400 6W Solar Trickle Charger. It's a solar charger for your car battery. I was thinking about getting one for my primary and one for my secondary battery and then mounting them on the pop-top.

There is a weblink here: http://store.sundancesolar.com/su6vsoch.html

-Josh

twinfalls · Post by **twinfalls** » Sat Mar 31, 2007 2:21 pm

skylermoon wrote:Hey I was thinking about getting a second battery and then I also found this SUNSEI SE400 6W Solar Trickle Charger. It's a solar charger for your car battery. I was thinking about getting one for my primary and one for my secondary battery and then mounting them on the pop-top.

There is a weblink here: http://store.sundancesolar.com/su6vsoch.html

-Josh

I think, it is a useless gimmick.
More stuff to maintain, for no real service.
About battery slow drain; A better investment is: A battery cut off. ( I simply disconnect the battery ground strap; keeping the post clamp bolt quite loose, makes it a two seconds work ).

Post by **Amskeptic** » Mon Apr 02, 2007 10:19 am

Sluggo wrote:Scott,

Thanks for the excellent detailed reply. That's exactly the info I wanted. Yours does seem like the kit to get if someone was going for easy installation and a stock look. I've seen the other kits and they are exactly as you describe them. A standard 5 pin relay, bits of wire and terminals. Which is what prompted my question. I'm going with the ford starter relay because I already have it and my Bus lost the stock look a long time ago.

The Ford relay is a solid chunk of engineering. "S" goes to the starter wire from the switch. "I" was for a wire that juiced the coil with some extra juice during starting since the coil runs through a resistor when in the on position.
Colin

boobtron · Post by **boobtron** » Fri May 18, 2007 10:58 am

I have no electrical experience. I came across this site last night and lost a night of sleep because of the goodness I've found. I need layman's terms, BIGTIME.

1. What exactly is the purpose of getting a second battery installed?

2. I was advised not to put one in because of cooling of the engine (Less room for cool air to flow?). Is it such a big deal?

3. And finally, how much should I pay for a procedure like this? I'm getting ready for the summer and I've never done this before.

P.S. Just recently got a beautiful Marigold Yellow '79 Westfalia, as clean as they come. I LOVE IT!!!! Time to use the heck out of it.

Post by **Sluggo** » Fri May 18, 2007 11:27 am

boobtron wrote:I have no electrical experience. I came across this site last night and lost a night of sleep because of the goodness I've found. I need layman's terms, BIGTIME.

1. What exactly is the purpose of getting a second battery installed?

To power items you use while the engine is not running (lights, stereo, fridge, etc...). That way you don't drain your starting battery.

2. I was advised not to put one in because of cooling of the engine (Less room for cool air to flow?). Is it such a big deal?

Complete crap. Never let that person work on your VW. Take a look at the battery that is in there. Does it restrict air flow?

3. And finally, how much should I pay for a procedure like this? I'm getting ready for the summer and I've never done this before.

Nothing. It is very easy to do on your own. Buy a Deep Cycle Battery, a relay and some wire. Follow instructions and ask questions. Shouldn't take more than 30 min - 1 hour for a novice. A mechanic will charge way more than this is worth and spend 20 min on it... and probably won't want to do it. Which is probably where that ridiculous blocking the cooling air story came from.

boobtron · Post by **boobtron** » Sat May 19, 2007 5:31 pm

YOU'RE THE MAN!!!!
Seriously, all the confidence I lacked in attempting to do this myself has vanished.
I hate the idea of someone else putting their greasy hands on my baby. Thank you so much.

P.S. This site is my new bible.

Birdibus · Post by **Birdibus** » Sat May 19, 2007 5:47 pm

Hey! Another southern Californian! Welcome. Congrats on the new bus.

If you have a Westfalia, you should already have the battery relay, unless it is broken of course. The aux battery goes into the left side of the engine compartment. Everything you need for mounting it should already be in there. Do you have the Westfalia owner's manual? Hmm... I was going to send you to another site, but they don't have the late Westy manuals. Anyone know if 76-79 Westfalia manuals are online anywhere?

Anyway, your westy should already be set up to use an aux battery. Good luck

Westy78 · Post by **Westy78** » Sat May 19, 2007 9:16 pm

Birdibus wrote:Anyone know if 76-79 Westfalia manuals are online anywhere?

http://type2.com/bartnik/csmanual.htm

http://type2.com/bartnik/

Birdibus · Post by **Birdibus** » Sun May 20, 2007 12:15 am

Westy78, thanks for the link to the manual. I'm not very familiar with that site.

Here is a photo of the dual battery relay in my 1974 Westfalia in case it is helpful to anyone. You can see that it is currently unconnected because the aux battery is dead. I'm not certain it is the OG relay. It might have been replaced at some point.
[albumimg]831[/albumimg]

twinfalls · Post by **twinfalls** » Sun May 20, 2007 2:24 pm

This is the location for the 1974 relay, but the original is much smaller ( like the 30Amp Bosch relay available everywhere ).
I see the original in line fuse ( a good source for bad contacts ).
I see a ground connection at the coil holder; This is overkill: Body is a fine ground for the Aux ( near it's - post ) and for the relay ( at one of it's holding screws ).
I think the PO had an overkill frenzy.

boobtron · Post by **boobtron** » Sun May 20, 2007 3:06 pm

There's nothing like this fricken site.
Thank you ALL!

Itinerant Air-Cooled

Itinerant Air-Cooled

Dual Battery Relay

Solar Charge

Re: Solar Charge

First timer. Aux battery install.

Re: First timer. Aux battery install.

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