I bought a new to me truck that replaces my S10..Astounded to find dual batterys under the hood..I have RPO code 8bo.From what I can find this is for the camper. There is a relay that seperates the one batt from the starting batt.Upon testing, the spare batt read 9 volts so I removed it. Also during my tests all 7 pin connections work normal without this battery. All this battery does is it acts like an additional battery on top of the two that I have for the camper. So I assume this will allow me to have a third battery..Im thinking to put a 12 volt duracell deep cylcle 75 AH batt like the camper has.. Does this sound right?I should be able to boon dock with added power longer and get through the fall night with heater going, without waking up to batts that are under 50% discharge..Ill have 225 AH then if I do this..They had an AC delco 600 CCA batt in there. Funny the starting batt is the same but a 770 cca batt. Both these batts state 63 ah on the label which is weird...

What is the new truck? Years back I've seen trucks with a dual battery option, usually as part of snow plow package. I think the extra battery helps run the electric hydraulic pump and extra safety lights, rather than bog down the alternator. I had an 06 1500 Sierra with room for two batteries, but only wiring for one.

GordonThree wrote:What is the new truck? Years back I've seen trucks with a dual battery option, usually as part of snow plow package. I think the extra battery helps run the electric hydraulic pump and extra safety lights, rather than bog down the alternator. I had an 06 1500 Sierra with room for two batteries, but only wiring for one.Its an 06 silverado 1500 as the pic below shows..There is a terminal block that I can hook accessories to..Ill take pics and post back in a few...

Here is tha batt I took out.. And pics of the other batt tray and the starting batt..Extra battStarting battExtra batt tray on passenger side truck near firewall.Overview..

I'd check fuses and wiring to find out why that second battery wasn't charging. 9v is ruined.As far as adding to your power reserve for camping, it's possible but you'll need extra wiring. The factory wiring isn't setup for powering much of a load on the 7way connector.I'd go this route:A 4 gauge wire running from that accessory terminal back to the hitch will help move that extra power. A similar wire on the trailer into the batteries will link them together. Use a heavy duty connector like the Anderson power pole. Use a 4 gauge wire for ground on both sides too, doesn't need to be long, any easy to get to screw or bolt you can put a wiring terminal under.

GordonThree wrote:I'd check fuses and wiring to find out why that second battery wasn't charging. 9v is ruined.As far as adding to your power reserve for camping, it's possible but you'll need extra wiring. The factory wiring isn't setup for powering much of a load on the 7way connector.I'd go this route:A 4 gauge wire running from that accessory terminal back to the hitch will help move that extra power. A similar wire on the trailer into the batteries will link them together. Use a heavy duty connector like the Anderson power pole. Use a 4 gauge wire for ground on both sides too, doesn't need to be long, any easy to get to screw or bolt you can put a wiring terminal under.The battery was charging... Before I removed the batt it was charging and showing 14 volts or so. but with ignition off it was 9 volts... starting batt showed the same but with ign off stayed at 12.7...I understand the 7 way has a small wire to the charging circuit. Thats no worries.

RPO 8BO Duel Batterys on silverado | Good Sam Community

17 Replies

lawrosa
Explorer
Sep 24, 2016
MEXICOWANDERER wrote:
A 78 has the same amp hours as a 22 or 22F. Pathetic. The setup you have was also used for the 6.2 diesel engine option where both batteries were paralleled on a good day blowing snot they might equal the same CCA as a good group 31.

Only one battery starts the truck.. The other battery is for the camper. This is a different option then the dual battery diesels.

70ah is good IMO as my two 12 volt duracells from sams club are only 75 ah...

so this in turn should give me 220 AH or 110 AH of usuable power
MEXICOWANDERER
Explorer
Sep 24, 2016
A 78 has the same amp hours as a 22 or 22F. Pathetic. The setup you have was also used for the 6.2 diesel engine option where both batteries were paralleled on a good day blowing snot they might equal the same CCA as a good group 31.
lawrosa
Explorer
Sep 24, 2016
well I found an exide battery that has side terminals. Its 70AH at the 20 hour rate...

So Ill give it a try when boondocking. It should allow me to extend my time between charges and let me use more power hungry stuff loonger.

exide 78s.. Only 99 bucks at tractor supply.

http://www.tractorsupply.com/tsc/product/exide-nascar-select-auto-truck-suv-battery-78s
lawrosa
Explorer
Aug 28, 2016
free radical wrote:
Fwiw
On my 08 Silverado the starting battery is on right passenger side,
Tray on left is for extra batt,in my case its empty now..
Probably makes no difference,just thought I should mention it..

Yes I read on some trucks its the opposite.. But my starting batt is drivers front. Alternate batt is pass by firewall.

Its empty now until I decide what to do.
free_radical
Explorer
Aug 28, 2016
Fwiw
On my 08 Silverado the starting battery is on right passenger side,
Tray on left is for extra batt,in my case its empty now..
Probably makes no difference,just thought I should mention it..
lawrosa
Explorer
Aug 28, 2016
GordonThree wrote:
Read about ohms law. Then it will make sense.

I doubt that the truck battery will not drain down as equal at the camper batterys.

Im not pulling 50 amps ya know...
PaulJ2
Explorer
Aug 28, 2016
You have what is called the camper package option from the factory. It includes a second battery, a charging circuit and a wireing harness that goes to the rear 7 pin connector as well as a harness behind your cab (drivers side)that connects to the left front of your truck camper. Is #10 wire by the way.
Your battery reading 9 volts has a dead cell BTW.
GordonThree
Explorer
Aug 27, 2016
Read about ohms law. Then it will make sense.
lawrosa
Explorer
Aug 27, 2016
To use the batter(ies) mounted in the truck, you'll need to upgrade the wiring, otherwise you will drain your trailer batteries but hardly put a dent in the truck batteries.

That statement dont make sense.....
GordonThree
Explorer
Aug 27, 2016
lawrosa wrote:
The factory setup is -was-and will temain- a joke. The RV batteey will discharge the 2nd battery will yawn and you'll wonder what went wrong.

What do you mean??? The + at the 7 pin supplys the TT from the aux batt.

Your post dont make sense

The factory wiring is so long and such a narrow gauge, hardly any current can flow. It's designed that way, so if something screws up at the 7-way or in the trailer it won't kill the vehicle's electrical system.

To use the batter(ies) mounted in the truck, you'll need to upgrade the wiring, otherwise you will drain your trailer batteries but hardly put a dent in the truck batteries.

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RPO 8BO Duel Batterys on silverado

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