Date: Thu, 11 Nov 2004 15:39:34 -0700
Reply-To: jimt <wetwesty@TACTICAL-BUS.INFO>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: jimt <wetwesty@TACTICAL-BUS.INFO>
Subject: Re: aux battery + jump starting
In-Reply-To: <d338c996041111124053f98111@mail.gmail.com>
Content-type: text/plain; charset="ISO-8859-1"
If the main battery is drained way down and is weak in the first place,
another battery in parallel may not do the trick if it is not large enough
to over come the load of the dead battery as well as start the vehicle. In
this case a volt meter is a good tool to have. Check the voltage of each
battery right at the terminals with the wires disconnected. You want at
least 12.3v for a charged battery and no less than 10.5v on a dead one.
Lead acid starting batteries that have been dropped below the lower level
too often will not charge back up properly and also will act as a major load
when trying to jump start from a battery alone. The other problem is what
gauge of wire do you have connecting your batteries together. The smaller
the gauge the bigger the drop in voltage trying to get to the starter.
On my own system I use relays not isolators. I also use the same massive
gauge as my main starter line to connect my batteries to the charging
circuit. I have intentionally drained my starting battery down to 11.5v
which is to low to start, and then jumped successfully. A test with a bad
battery put in for the starting battery (this battery was only good for
about 11v when charged) and no jump start could be done. However I picked
up the aux battery and moved it to the start position and started just fine.
After those tests, I look at my aux being a jumper when my main is "weak"
not dead. And the aux as a replacement when the main is "dead".
••••••••••••••••••••••••••••••••••••••••
jimt
Planned insanity is best.
Remember that sanity is optional.
http://www.tactical-bus.info (tech info)
http://www.westydriver.com
On 11/11/04 1:40 PM, "Joel VanderKwaak" <joelvanderkwaak@GMAIL.COM> wrote:
> Howdy,
>
> I have an aux battery, isolated from my main using a Hellroaring
> isolator. I run an amp, cd changer, and a 45L Engel fridge off the
> aux, and have everything else (lights, radio, etc) running off the
> main.
>
> Hellroaring has a nicely designed product (remote module) that allows
> one to connect the aux to the main with the flip of a switch, allowing
> you to jump-start the van off the aux. I installed this setup several
> years ago for my trips to Mexico so that I'd only drain the aux
> running the fridge, and, if the main was discharged, I'd get some help
> from a (hopefully charged) aux.
>
> Yesterday I left my lights on at work, and my main battery was dead at
> the end of day. No sweat, I thought, as I'm boyscout-prepared for just
> this scenario: I'll just 'jump' the van using the aux. I flipped the
> switch, the lights came on, the fuel pump started humming, but... not
> enough juice to turn the engine over. Dang, I was glad I wasn't on
> some remote beach.
>
> So, now I'm thinking this aux setup doesn't add the safety factor I'd
> envisioned, and was wondering if anyone else out there has a setup
> that actually works in this scenario. I'm considering adding an
> additional battery to the aux side of the circuit, for example.
>
> For the record, the Hellroaring isolator is setup in the 'basic'
> method, meaning I've run a wire from the main battery to the aux,
> routing power through isolator. The aux battery is an Optima
> Yellowtop, and the main is what came with the van when I bought it
> (std starting battery). I may replace the main in any case, as I don't
> know how old it is or how often it's been drained.
>
> Thanks in advance,
>
> Joel
>
>
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