Chevy Astro and GMC Safari Forum banner

Dual Battery Noob questions

2K views 8 replies 6 participants last post by  Roger Ramjet 
#1 ·
Sorry if I'm repeating stuff but couldn't find clear answers to some questions in the other topics on this - I want to set up a dual battery system and use the house battery to power a smallish Amp and invertor for Laptop or DVD player

House battery will be housed behind drivers seat

Do the 2 batteries have to be the same kind/make ? - I was going to install an AGM battery as the house battery due to the spills/fumes issue - have a lead acid duralast as the Main

If my proposed isolator is 160AMp can I wire up a 240 AMP (told you they were Noob questions)

Was going with a Dr Battery 160 isolator - anyone used that kind ?

I saw in a previosu post a member was going to install 2 batteries under the hood by using a custom tray - I know you can buy dual trays on Amazon but presume these aren't strong enough unless sitting on a flat surface

http://www.amazon.com/Dual-Group-27-Bat ... B000NKGZU6

Thanks
 
See less See more
#2 ·
Neb127 said:
Do the 2 batteries have to be the same kind/make ? - I was going to install an AGM battery as the house battery due to the spills/fumes issue - have a lead acid duralast as the Main
They absolutely DO NOT need to be the same kind/make batteries! They merely need to be rechargable 12v batteries. An AGM battery for inside use is a good choice.

If however, you were going to "parallel" the batteries (without isolator)... then you would want identical matching batteries for best performance and longevity.

If my proposed isolator is 160AMp can I wire up a 240 AMP
The amperage simply means how much "maximum" current the isolator is rated for, or how much it can actually handle. It will not pass any more than what the alternator puts out under "full" load. If the alternator (for example) puts out a maximum of 100 amps, then it won't make any difference whether you use a 160 or 240 amp isolator... either one would never see more than the 100 amps the alternator supplies.
 
#4 ·
In fact you do NOT want the same type of battery for START and HOUSE. A starting battery has porous plates and is designed to handle a huge current pass for a short period of time. You will notice a starting battery weighs less than the same sized deep cycle battery.

A deep cycle battery (AGM, flooded lead acid, whatever) has thick non-porous plates to deliver high current but over longer periods of time..like hours. They weigh a ton. Each battery is suited to its purpose.

I don't know if those isolators have a combine battery function, but that feature is really awesome when the start battery is dead.
 
#5 ·
One thing to be aware of, some battery isolators use a large diode to send charge current in one direction. The problem is that all diodes have a forward voltage drop of .6 volts; this means if your alternator is charging your main battery at 14.4 volts the house battery is only getting 13.8 volts, which will top off the house battery but will never fully recharge it, and that is hard on a batteries lifespan.

Try to select a battery isolator that is relay/solenoid based and not diode based. I just used a cheapo eBay solenoid that's good for like 160 amps, it's wired to come on with the ignition.


Since this picture I have beefed up the wire gauge to and from the solenoid. It's fed from an 80 amp fused lug in the relay center, the "upfitters" feed.
 
#6 ·
Thanks for advice, I was looking at the diode versions to avoid the 'complication' of connecting to the ignition, that's the duffer in me ..might have to rethink it again :think:

I like the look of your Astro, what are your tires and rims if you don't mind me asking

]
 
#8 ·
So Finally Got my Dual power set-up
I used a Stinger Battery Isolator in the corner of the engine bay and ran it to a Kinect Power cell that fitted neatly in the pocket thingy of the passenger bay

because I don't need my Astro to bump (as my teenager would say) its fited to a modest Amp and sub-woofer that more than fills the cab.

 
#9 ·
I put a second battery in mine , I put it where the jack should be . I ran 8 gauge cables from the front battery ( both side post and top post ) I ran it to a nascar style on and off switch , It was a cheaper alternative to a isolater , and works perfectly fine . It runs my 2000 watt power invertor .

If I leave the key in the altenator charges both , remove the key and it shuts flow off from the under hood . And runs my fridge and stuff
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top