TheSamba.com :: View topic - Adding a second battery..how to...with photos FAQ

Mon Jul 15, 2013 10:49 am

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.

Mon Jul 15, 2013 11:42 am

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.

Mon Jul 15, 2013 12:23 pm

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

Mon Jul 15, 2013 1:02 pm

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

Wed Jul 17, 2013 11:16 pm

grandpa pete wrote: AEROMECH; I put the fuse block next to the battery for the tutorial ,it isn't even hooked up. I didn't wan't to confuse the issue by showing how i ran 3/4 inch flexible conduit through the rear tire wheelwell to a custom made box inside with the inverter and the fuse pannel. The inverter is hard wired direct to a double outlet box in the wall with the faceplate painted orange so you know it is inverter voltage and not shore power like the unpainted one next to it. The pump for the sink works now too

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

Thu Sep 19, 2013 11:33 am

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

Thu Sep 19, 2013 3:41 pm

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.

Thu Sep 19, 2013 5:34 pm

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

Tue Jul 01, 2014 7:38 am

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!

Tue Jul 01, 2014 11:20 am

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.

Wed Jul 02, 2014 6:31 am

Desertbusman wrote:
6) A low drain evaporative cooler

i am looking for something like that. do you have a little more information on the one pictured?

Fri Sep 05, 2014 9:18 am

Hey DBM !! are you gonna answer this guys question ?? :P :D

Fri Sep 05, 2014 9:28 am

Pete,
Mikes been MIA for a bit

Fri Sep 05, 2014 5:02 pm

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 :D :D

Fri Sep 05, 2014 5:30 pm

Fixed it for ya

quitting cigaretts after 74 years is making him grouchyer

Fri Sep 05, 2014 5:37 pm

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. :D

Fri Sep 05, 2014 5:37 pm

aeromech wrote: Fixed it for ya

quitting cigaretts after 74 years is making him grouchyer

:lol: good for him though.

Fri Sep 05, 2014 5:38 pm

It's no diss. Just stating fact. I'll be there soon myself since I'm 57.

Fri Sep 05, 2014 5:41 pm

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

Fri Sep 05, 2014 6:04 pm

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

You're making me grumpy