Adding a second battery..how to...with photos FAQ

[Vince Waldon]

My suggestion: make a list of what you want your house battery to be for... and then wire accordingly.

IE: What things do you want to run when parked for the night? Stereo? Dome light? tach? oil pressure gauge?

Whatever the list is... those are the things that are wired to your house battery (thru a fuse panel, of course) and will be able to draw power when the ignition is off and the engine is not running... by design.

When the engine is running both batteries are essentially in parallel with all of the loads. It's when you turn the key off that the magic happens...hence the importance of the list.

[DougB]

I'd love to do the same, but my aux battery wiring kit has been on order from German Supply for 2 months. I need to call them and find out what's up...I'd love to get that and the other pieces I ordered sooner rather than later. At this point it's almost difficult to even remember what I ordered.

[locky]

Thanks for the replies guys. I am clear on all of it now. If I were to install one of these http://www.bluesea.com/products/category/Manual_Battery_Switches/m-Series
In line with the ACR
http://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A,
could I switch off power to my second battery when I didn't need it. ie: when I had it parked in shop not driving for days? This way all power to accessories is off until I need it.
This is the fuse block I bought
http://www.bluesea.com/products/5026/ST_Blade_Fuse_Block_-_12_Circuits_with_Negative_Bus_and_Cover

[Westy Steve]

Interesting stuff. Assuming I get my bus running pretty soon, I'm going to be working on my interior. I was just going to put a marine battery in the back and wire the two batteries together, but then wire up a disconnect switch like they use for boats so that I could isolate the marine battery manually by turning a key. Then I was going to run a bunch of cigarette lighters through my "walls" that connect to the marine battery only. I was also thinking of mounting a plug in trickle charger into my Westy's wiring that would route a trickle charge from the Westy's shore power to the battery. So when I'm on shore power, it would keep the marine battery topped off. Lastly, I was thinking that I'd have a solar cell that would power a trickle charger to the marine battery. I don't think any of these would conflict with each other, but I don't know if it's bad for a marine battery to apply a constant trickle charge to it...will it get a memory?

I'm guessing the auxillary fuse near the ignition switch would do the same thing, but I was hoping to minimize wire length by essentially keeping the key turn/isolator in the back of the bus where the power is.

Steve
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Have nice 914, want nice Bug

[Tristan79]

[Brian]

Wouldn't having two batteries on one alternator just be terrible for a 55amp alternator's lifespan?
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Wash your hands

'69 Bug
'68 Baja Truck
'71 Bug
'68 Camper

Only losers litter

[telford dorr]

Theoretically, no.

An alternator is inherently current-limited by nature (that's why there's no current detection in the regulator, unlike with a generator). Assuming it has sufficient cooling air, it should be OK.

But, like they say, "In theory, theory works in practice; in practice, it doesn't." I suspect that if you ran an alternator continually at full rated current, its lifespan would be substantially shorter than under a normal automotive load. That said, I suspect that a typical dual battery setup is no harder on an alternator than a single battery - if you don't continually (like everyday) run the second battery low or dead.
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Same thing happens when you're stupid. - Philippe Geluck
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[grandpa pete]

How did you wire the wall outlet? Could you also just explain what the two different ones are for, thanks[/quote]

The all white outlet is wired directly to the external "shore power "...The outlet with the orange paint on it is hooked to the inverter and provides limited 110 volts off the camping battery
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63 two fold rag
66 sedan delivery Type 6

http://www.thesamba.com/vw/forum/viewtopic.php?t=569619&highlight=sedan+delivery

[JQ1492]

Interesting post. I have a 77 camper, but the wiring for the 2nd battery is messed up. I think I can fix that based on this post, but have a couple questions:
1) I have an Edgestar 630 high efficiency fridge. Can I run it off the 2nd battery indefinitely while I am driving, since the batteries are being recharged as I drive?
2) I have a Goal Zero solar panel with inverter and wonder if there is a way to use that to help recharge the 2nd battery while parked.
3) The manual says that while the primary battery will not be drawn down by tapping the second, when you start the bus, it will split the ignition draw between the two batteries and may not have sufficient power to start the engine. Will this issue be fixed by rewiring as directed above? I'm assuming it will be, (why else go to the trouble), but wanted to make sure.

Thanks for helping a newbie!

[aeromech]

Can I run it off the 2nd battery indefinitely while I am driving

I think so. The way it SHOULD work is that when parked, the batteries are separated. You can wire the fridge to run off the house battery. When you start the engine and voltage increases about 13 volts, that should cause the ACR to close and connect both batteries to the bus charging system (alternator). In transit, the aux battery feeds the fridge but is also being charged at the same time by your engine.

I have a Goal Zero solar panel with inverter and wonder if there is a way to use that to help recharge the 2nd battery while parked.

Of course. Here's a picture of a charging panel sold by GoWesty. One of my customers has this and it's pretty cool. Not sure if you need to buy the whole package that includes the solar panels to get this or not.

http://www.gowesty.com/ec_view_details.php?id=23897&category_id=&category_parent_id=

it will split the ignition draw between the two batteries and may not have sufficient power to start the engine

The systems I install using the Blue Sea ACR keep the batteries separated for roughly the first minute when the engine starts. All the power for the ignition and starter comes from the start battery. Most of the systems include the battery switch which allows you to easily COMBINE both batteries for engine start if the start battery gets low.

I really can't imagine why anyone would want to install a dual battery system any other way. The Blue Sea "add a battery" kit is available for less than $150. Most guys would spend way more than that on their stereo.
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Licensed Airframe and Powerplant Mechanic
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Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
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Fokker F28/F100
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[chachi]

[grandpa pete]

Hey DBM !! are you gonna answer this guys question ??
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63 two fold rag
66 sedan delivery Type 6

http://www.thesamba.com/vw/forum/viewtopic.php?t=569619&highlight=sedan+delivery

[aeromech]

Pete,
Mikes been MIA for a bit
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[grandpa pete]

Chachi ; Just talked to DBM.. that unit is no longer produced anywhere

Aeromech : Hi! thks for jumping in....I called Mike ; The old faht is doing fine ; just taking a break from Samba.....quitting cigaretts after 74 years is making him grouchy
_________________
63 two fold rag
66 sedan delivery Type 6

http://www.thesamba.com/vw/forum/viewtopic.php?t=569619&highlight=sedan+delivery

[aeromech]

Fixed it for ya

quitting cigaretts after 74 years is making him grouchyer
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[babysnakes]

Hey! Don't diss DBM, I had a great lunch and a good time with him a few weeks back. He's not grumpy, he's..................DBM.

[Brian]

[aeromech]

It's no diss. Just stating fact. I'll be there soon myself since I'm 57.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[babysnakes]

I'm six years behind ya, so watch out!

[aeromech]