charging system question...

rick lester · 07-07-2009, 12:55 AM

i am adding a second battery to my 88 chevy suburban. 350 motor. i will be using second battery to power two inverters (400 watt under center console, second up to 2500 watt in back) and stereo system. stereo will only be aftermarket unit with small amp and up to 6 or 8 speakers, not a booming, anoying everybody on the road stereo, just a nice sounding system. i plan on using suburban to tow with an open trailer and sleep in at the track so very little room for things like generator or big battery charger. how do i hook up second battery to charging system? do i just add a second wire from alt. post to battery pos. terminal? i will be running 2 gauge wire to a junction box under suburban, then run 8 gauge to front inverter, and 4 gauge to back inverter. i know it sounds like overkill, but when i go tailgating and racing, i have all the power i need, and if i run the second battery down to nothing, i still have the main battery to start the suburban up with no problems. i have not thrown out the idea of running cable from first to second battery with a diconnect switch, just in case first battery goes out and i do need second battery to start. i hate going to any place, racing or tailgating, and not being prepared. rick.

B Aceves · 07-07-2009, 01:14 AM

You will need a battery Isolator to make this happen, Go to any Parts store or RV supply and they have them. It allows you to not have the two batteries in series and achieve what your looking for. Good luck

henrys57wagon · 07-07-2009, 08:29 AM

You want to keep both batteries separate. The second battery would feed your stereo etc. You would wire in the isolator as you would wire in a relay( which does the same job as an isolator). A 12ga wire from the truck battery(alt would do) to the isolator then to the spare battery, (for recharging only) this is the part of the relay that is not energized when the key is off. Then a signal wire(16ga) from a run circuit to the coil of the relay then to a ground. This is the same as wiring a fan relay, hope this make sense, Henry. PS you want the batteries in parallel.

Harry 6674 · 07-07-2009, 09:22 AM

I personally don't trust isolators. I like to use a 200 amp continous duty solenoid to charge the spare batteries with its own switch. That way I control when I'm chargeing the extra batteries. Also which ever way you go use 8 or 10ga. wire, I prefer 8ga with a large (100 amp+) alternator.

magnumv8 · 07-07-2009, 03:07 PM

All the isolator is for is to allow your dual batteries to be charged from a single source plus keep them "isolated" from each others circuitry...in your case you would just need to follow the instructions that come with them to do the proper install....there are a couple different types of isolaters so let the RV supplier direct you to the one that best suits your needs...the main thing is to fuse protect your invertor feeds from your secondary battery, depending on how large a battery you use you have the potential for full battery power to both inverters, without the fuses you could have a very large fire if for some reason an inverter feed shorts out....also depending on how far you have to go from your battery to the 2500 watt inverter you may need to go larger than 2ga.....for our installs we usually end up running dual 2ga feeds for a 2500 watt inverter because you have a power need of more than 200 amps at max output on that size inverter....you will need around a 50A fuse for the small inverter and around 250A fuse for the 2500 unit...DO NOT USE BREAKERS...these will give you around the 125% safety factor required for a good install.....remember to always keep your fuses as close to your battery as possible......

D L RAMBO....

07-07-2009, 12:55 AM	#1
rick lester Member Join Date: Oct 2004 Location: Littlestown PA Posts: 163 Likes: 9 Liked 4 Times in 1 Post	charging system question... i am adding a second battery to my 88 chevy suburban. 350 motor. i will be using second battery to power two inverters (400 watt under center console, second up to 2500 watt in back) and stereo system. stereo will only be aftermarket unit with small amp and up to 6 or 8 speakers, not a booming, anoying everybody on the road stereo, just a nice sounding system. i plan on using suburban to tow with an open trailer and sleep in at the track so very little room for things like generator or big battery charger. how do i hook up second battery to charging system? do i just add a second wire from alt. post to battery pos. terminal? i will be running 2 gauge wire to a junction box under suburban, then run 8 gauge to front inverter, and 4 gauge to back inverter. i know it sounds like overkill, but when i go tailgating and racing, i have all the power i need, and if i run the second battery down to nothing, i still have the main battery to start the suburban up with no problems. i have not thrown out the idea of running cable from first to second battery with a diconnect switch, just in case first battery goes out and i do need second battery to start. i hate going to any place, racing or tailgating, and not being prepared. rick.

07-07-2009, 01:14 AM	#2
B Aceves Member Join Date: Nov 2008 Posts: 457 Likes: 1 Liked 7 Times in 4 Posts	Re: charging system question... You will need a battery Isolator to make this happen, Go to any Parts store or RV supply and they have them. It allows you to not have the two batteries in series and achieve what your looking for. Good luck __________________ Bob Aceves, 746 E/SA A&M motorsports

07-07-2009, 08:29 AM	#3
henrys57wagon Member Join Date: Jan 2009 Location: Carleton Place, On. Canada Posts: 107 Likes: 5 Liked 0 Times in 0 Posts	Re: charging system question... You want to keep both batteries separate. The second battery would feed your stereo etc. You would wire in the isolator as you would wire in a relay( which does the same job as an isolator). A 12ga wire from the truck battery(alt would do) to the isolator then to the spare battery, (for recharging only) this is the part of the relay that is not energized when the key is off. Then a signal wire(16ga) from a run circuit to the coil of the relay then to a ground. This is the same as wiring a fan relay, hope this make sense, Henry. PS you want the batteries in parallel. __________________ old 1608 stock racer

07-07-2009, 09:22 AM	#4
Harry 6674 Senior Member Join Date: Dec 2006 Posts: 589 Likes: 0 Liked 0 Times in 0 Posts	Re: charging system question... I personally don't trust isolators. I like to use a 200 amp continous duty solenoid to charge the spare batteries with its own switch. That way I control when I'm chargeing the extra batteries. Also which ever way you go use 8 or 10ga. wire, I prefer 8ga with a large (100 amp+) alternator.

07-07-2009, 03:07 PM	#5
magnumv8 Member Join Date: Feb 2009 Location: Coraopolis, Pa. Posts: 172 Likes: 0 Liked 0 Times in 0 Posts	Re: charging system question... All the isolator is for is to allow your dual batteries to be charged from a single source plus keep them "isolated" from each others circuitry...in your case you would just need to follow the instructions that come with them to do the proper install....there are a couple different types of isolaters so let the RV supplier direct you to the one that best suits your needs...the main thing is to fuse protect your invertor feeds from your secondary battery, depending on how large a battery you use you have the potential for full battery power to both inverters, without the fuses you could have a very large fire if for some reason an inverter feed shorts out....also depending on how far you have to go from your battery to the 2500 watt inverter you may need to go larger than 2ga.....for our installs we usually end up running dual 2ga feeds for a 2500 watt inverter because you have a power need of more than 200 amps at max output on that size inverter....you will need around a 50A fuse for the small inverter and around 250A fuse for the 2500 unit...DO NOT USE BREAKERS...these will give you around the 125% safety factor required for a good install.....remember to always keep your fuses as close to your battery as possible...... D L RAMBO....