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Old June 4th, 2006, 05:10 PM
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Bryan Tate
Join Date: Aug 2004
Location: Wilmington, NC
Posts: 479
Dual Optima connection options

I had dual optimas connected together in my 110, but couldn't isolate them to keep power in reserve.

Now I am going to put them in the 90.
I thought about the painless wiring dual battery kit that seems to give alot of control over battery management, it costs about $100. But seems like alot to mess with.

Is there a reason I can not simply have a battery on/off switch on the positive cable between the first and second battery? (I bought the part, its a small Hella switch that looks easy to install and have it poke threw the seatbox)

I thought I would run both batteries most all the time, if I went to a remote area or planned to leave the stereo/amps/lights on I could switch off one battery and hold it in reserve till I cranked up again.

I planned to have all connection for radio/lights/winch run to a terminal off the primary battery.
The second battery would be connected + to + and - to -..........trying not to make it a 24 volt truck.

Is there a reason this will not be effective?


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Old June 4th, 2006, 05:18 PM
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East Coast Rover Co.
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D-90 Source Vendor
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Location: Rockland, ME, USA
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It'll work... it just means more work for you as a driver (where the battery minder/ Painless things do all this automatically for you).
You'll need to make sure you connect it to charge the "spare" battery when you are running and then remember to disconnect it when you want the "reserve" etc etc but if you can remember... it will work without issue. I'd switch the negative side of the second battery though.

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Old June 4th, 2006, 07:32 PM
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Robert Dassler
1994 D90
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Join Date: Apr 2004
Location: Albuquerque, NM, USA
Posts: 987
I installed a similar setup about 5 years ago. I have a yellow top Optima that I run on most of the time. I have an ARB fridge that is run off of it as well as some work lights. I have a red top wired in parallel through a switch that I can put into the circuit to start the truck if the fridge runs the battery down or if I need it during winching. I usually charge the red top on long drives but keep it switched in reserve most of the time. I've had no problems. Previously I had a voltage sensitive automatic relay for an RV that would do the job but it worried me because it was always extremely hot to the touch. I replaced it with the manual system. I think I will have to replace the Yellow top next year as it runs down pretty far at night with the fridge running.
Rob Dassler
SWR Automotive
505-872-7818 (shop)
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Old June 4th, 2006, 09:37 PM
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Randy Black
'95 D 90 SW
Join Date: Nov 2003
Location: Tulsa Ok USA
Posts: 753
I have a dual battery setup made by Wrangler I think. It uses a three position switch and a solenoid to control the way you use the batteries. It probably cost me about $100.

If I could do it over I would use the setup that Rob uses. It's simpler and much less expensive, but like Mike said, you just have to remember to use it correctly.
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Old June 5th, 2006, 05:01 AM
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jimmy salmon
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jimmy salmon
94 D90 AA Yellow
Join Date: Jun 2004
Location: Methuen MA USA
Posts: 1,343
On my 110 i had a short which would flatten the battery within seconds, couldn't find where it was shorting so had dual batteries fitted. I could run it on the main battery and if that went flat, switch the cut off key and start it on the reserve one, once started switch back over. The alternator would charge the main battery and keep the spare topped up but only the main would disscharge.As to how it was wired i havn't got a clue waas fitted at frogsisland
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