to isolate or not to isolate (dual battery setup) ? (1 Viewer)

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mr_manny

mr_manny

Joined
Apr 10, 2004
Threads
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Location
san pancho, ca
I always thought isolators were for RVs so that you wouldn't have a problem starting your truck after watching TV and running the refrigerator all night. I don't really understand their need in a cruiser.

Back when I was younger and ignorant of FJ40s, I had a M38A1 (a Willys; not a J**P). It had been converted from 24V to 12 V, so I had two batteries hooked in parallel. It worked great and had a lot of power for running a winch, welding, forgetting your lights were on, etc. No wiring hastles and minimal cost.

I vote for not needing one. Of course, if you watch TV and run your refrigerator in your cruiser, you might consider it.
 
thanks for the info pin_head...

Hope you like your new bumper :D
manny
 
Thanks again Manny! :beer:

So I assume that Ian didn't have any trouble finding your shop?
 
It would have been better If we met at the shop, he could have checked out my 40....my house was closer.
He did mention Rubithon...maybe I'll see you there,
manny

some Isolator info:
The unit's solid-state switches are ideal for trucks using a standard battery to start the vehicle and a second battery to run auxiliary appliances in the cab or sleeper. These isolators direct charging current into the battery with the lower charge, allowing the starting battery to provide a strong burst of energy to start the engine, while running the equipment off the second battery.

These isolators are electronic sealed units that contain two diodes. Power supplied to the middle stud of the isolators flows to each of the other studs. As current can flow in only one direction, current cannot drain from one battery to the other, so each stays properly charged. The units are solid-state, protected against contaminants, and can withstand vibration and temperature extremes. They come in a range from 42 to 250 amps, for systems of 12 to 36 volts DC.
 
Geez, if that's all it is you could accomplish the same thing with a $5 100 amp diode for the second battery and a marine A, B, both switch.

I'm thinking about going to the Rubicon, but just the idea of driving up there in the 40 is giving me hemorrhoids. I got rid of the Suburban tow rig 8 years ago. I used to go up there in the 70s and 80s back when I was living in Sacratomato and the Bay Area. Back then, you could drive through the box on 31s and open diffs. You could also drive on a week day and not run into anyone. I guess things have changed a little?
 
one down, one to go...

manny
battery1.jpg
 
Mr. Manny the main function of the isolator is to prevent draw from both batteries. That allows you to run various equip. to whichever batt. and it won't draw down the other. I got my starter running off 1 optima and everything else off the other. so you can winch or listen to stereo or whatever till it is dead and not worry bout starting.
 
I had an old isolater which shorted out and was not functioning to isolate. My batteries were not both equal, one much older and I believe the good battery was being drawn down or effected by the bad battery. I just recently installed the marine switch to seperate them, and replaced the bad battery with a new red top. I'm set up to run winch and accessories off the second battery and starter off main. Not much experience with the new set up yet, but in theory it should work better.

troy
 
now just waiting for the isolator to arrive... :(

does anyone have a source for 2/0 cable?

thanks,
manny
battery3.jpg
 
the extra room is GREATLY appreciated :D

manny
battery4.jpg
 
120amp Isolator is installed, and working as advertised :D

I utilized 2/0 welding cable for entire system, much more flexible then battery cable.

Initially I had the voltage sensing line (from the alternator) attached to the stock cruiser/amp meter location, but found that attaching it directly to the primary battery was a better location.

The only thing that remains is to add a circuit breaker to the axillary battery, waiting for a 200amp unit to arrive (ebay).

I am running a chevy 12si alternator, wired as illustrated in attached jpg

thanks for all the input,
manny


200amp circuit breaker:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=32813&item=5763476971&rd=1&ssPageName=WDVW
alt2.jpg
isolator.jpg
 
mr manny, what are the broken black lines in your illustration?
 
The Illustration is from surepower...
The broken lines indicate a previous circuit, as in a previous alternator connection and an additional main battery which was connected in parallel.

I think the parallel batteries represent a non-isolated dual battery installation...

hope this helps,
manny
 
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