Date: Wed, 3 Aug 2016 20:46:52 -0400
Reply-To: Edward Maglott <emaglott3@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Edward Maglott <emaglott3@GMAIL.COM>
Subject: Re: testing capacity of house battery
In-Reply-To: <BAY405-EAS208E6588F21CBCAE6FB9F2DA0040@phx.gbl>
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Thanks for the info Dennis and Robert. Yes it is a group 41 battery. I
hooked the battery up to an "automatic" battery charger and let it do its
thing. It has a display that shows voltage but I find that it is more
informative to hook an ammeter between it and the battery to see what is
really going on. It starts out delivering 4A, then it drops to about 2A
and eventually down to 0.1A. there may be another step in there that I
missed seeing. Anyway, after about 24 hours it was down to the 0.1A rate
so I called that "charged." Ran the same test as above and got 35.5Ah, so
better than double the capacity of my first test which got 13Ah.
Now, I still need to go through my charging relay and wiring to make sure I
don't have a problem there. I've noticed for a long time though, that the
house battery doesn't really get that well charged by driving, and often
put it on a charger before I go on a trip. And I've read list wisdom about
the alternator charging voltage dropping by the time it gets to the house
battery. I've also been researching MPPT solar charge controllers. (
https://en.wikipedia.org/wiki/Maximum_power_point_tracking) This got me
wondering about something like this:
http://www.banggood.com/DC-DC-600W-10-60V-to-12-80V-Boost-Converter-Step-up-Module-Power-Supply-p-1041640.html
Could that or something similar be applied to the vanagon house battery
charging scenario? Do the fancy Sure Power battery separators that some
folks have do this?
Edward
On Mon, Aug 1, 2016 at 9:27 AM, Dennis Haynes <d23haynes57@hotmail.com>
wrote:
> Small (true) deep cycle batteries are rated at both a 5 and a 20 hour
> rate. These rates come up with somewhat different overall amp hour ratings
> due the batteries resistance to deliver higher currents over time. If you
> are using substantial loads such as lights and heaters along with stereo /
> inverters or what have you the 5 hour rate is the one that is important.
>
> The group 41 starting battery (if that is what you are using) as a
> starting-lighting-ignition battery also get rated for cold cranking amps,
> (0F), and reserve capacity. For an "SLI" battery the total amp hour rating
> is based on the 20 hour rate. For the group 41 battery ~60 A/H is typical.
> Reserve capacity is the time it can sustain a 25 amp load which is a factor
> when the a charging system fails or you need lighting during a break down.
> Again for the group 41 "SLI" battery a typical rating is 110 minutes.
>
> So based on your results below your battery is good for the core deposit
> or a door stop.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Edward Maglott
> Sent: Monday, August 1, 2016 8:56 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: testing capacity of house battery
>
> I have a few years old non-deep-cycle automotive starting battery I've
> been using as my house battery in the 86 Westy. it's been acting a little
> flaky so I pulled it out for some testing and possible replacement. I've
> had some other issues/symptoms with my house battery side of the electrical
> system so I wanted to take a possibly failing battery out of the equation.
>
> I last drove the van about a week ago for about 2 hours with not much load
> on the house battery. I hooked up the battery to one of these:
>
> http://www.banggood.com/ZB2L3-Battery-Capacity-Tester-External-Load-Discharge-Type-Module-p-1058571.html
> For the load I used a tail light bulb with both filaments burning. This
> put 2.55Amps load on the battery according to the display on the above
> device. I set the device to stop discharging at 10.5V and it came out to
> about 13Ah of capacity. That sounds low to me and like the battery was
> either not very well charged or it's toast. I've now got it on a charger
> and will check it again after it's recharged. comments? is discharging it
> to 10.5V more damaging than any info I gain from testing it?
>
> Edward
>
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