Dual battery user question (1 Viewer)

CJF

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May 31, 2005
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Ok, so I try to help folks out around here when I can, but I'm still an electrical idiot. :eek:

My question: If I want/need to run without my backup battery, what do I do? Just remove it and make sure the cables can't contact anything? Or remove certain parts/cables? Or...?

TIA,

Curtis
 

80t0ylc

Hill & Gully Rider
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Ok, so I try to help folks out around here when I can, but I'm still an electrical idiot. :eek:

My question: If I want/need to run without my backup battery, what do I do? Just remove it and make sure the cables can't contact anything? Or remove certain parts/cables? Or...?

TIA,

Curtis
Are you just pulling it temporary or permanent? If temporary, I'd pull battery and also disconnect it's positive (red) cable at the source. Usually that's a post on your isolator or other device that separates you batteries. That should reduce the possibility of shorting out loose battery cables. Be careful about shorting out your wrenches to anything when loosening your red connections.
 
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Yep, what Tom said, definitely protect the red cable and separately protect any charge wires from your alternator or isolator associated with it.

One way to do this is to get a small plastic bottle that the clamp will slide fully into, then duct tape it onto the end of the hot cable(s). That way, a bounce or other movement when driving won't bring it in contact with ground.

What I'm not sure if is whether the lack of a load will affect your isolator running like this.
 

CJF

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Hmm..

More info: I sometimes go for a week or two at a time without driving this rig, and the backup appears to be dead, so I want to pull it and have it tested. (I don't *need* to drive it while it's out, so maybe I'll just let it sit.)

Also, even if I override the isolater, the system doesn't seem to "recognize" that the backup's there, and doesn't want to charge it. Is that normal operating procedure if the backup's dead?

Maybe I've got bigger issues? :meh:
 

Jacket

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I ran without mine for a while after short-circuiting my DB isolator and waiting for a replacement to arrive. I disconnected all the cables and pulled the battery. I pulled the ground wires down into the plastic battery box and zip-tied them to the box. For the power lead, I covered it in plastic and wrapped it with electrical tape and then I secured it to the battery box on the opposite end from the ground wire.

As long as you make sure you are not going to contact any metal with the power wire, you should be fine.
 

nakman

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When I've done this I've shoved the battery cables into some leather work gloves, then duct taped it up so they couldn't slide out of the gloves. Seemed to be ok for the few trips around town I needed to do until I could put my second battery back.. :meh:
 
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Hmm..

More info: I sometimes go for a week or two at a time without driving this rig, and the backup appears to be dead, so I want to pull it and have it tested. (I don't *need* to drive it while it's out, so maybe I'll just let it sit.)

Also, even if I override the isolater, the system doesn't seem to "recognize" that the backup's there, and doesn't want to charge it. Is that normal operating procedure if the backup's dead?

Maybe I've got bigger issues? :meh:
Only two reasons a backup is dead in a battery isolator system, if the wiring is intact.

Dead battery, due to age or abuse.

Fried isolator.

How old is the backup battery? Even a good battery with a longer guarantee may still be prone to failure after four years. This is especially so in a high electrical load vehicle like the average US-spec 80. Short trips in town that don't permit a full recharge after every start aggravate that tendency.

I know the Hellroaring instructions I used on my isolator install said to never ground the leads, but I'd guess this could be a problem for most of them, not just HR.

You may want to check the charge lead from the isolator to the backup battery as the most obvious place to check for damaged wire insulation or otherwise that may have gone to ground.
 

CJF

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How old is the backup battery? Even a good battery with a longer guarantee may still be prone to failure after four years. This is especially so in a high electrical load vehicle like the average US-spec 80. Short trips in town that don't permit a full recharge after every start aggravate that tendency.
Battery is ~3 years old. And yes, the rig often sits for a week or two, and then only gets driven around town for errands on a sat/sun. The main reason we own it is for expeditions and road trips; it's our 3rd vehicle.

Thanks for all the help, and I'll be sure to post up any updates. :)

Curtis
 

ppc

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With a direct connect systems (relay or manual switch) it's a good practice to replace both batteries at once so when connected together there will not be a surge current going from the good to bad battery. That will eventually kill both. I don't know what the isolated systems recommend or if they are capable of limiting the current.
 

CJF

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When I've done this I've shoved the battery cables into some leather work gloves, then duct taped it up so they couldn't slide out of the gloves. Seemed to be ok for the few trips around town I needed to do until I could put my second battery back.. :meh:
Cool.

Thanks. :)
 

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