Date: Thu, 4 Sep 2008 07:42:50 -0700
Reply-To: Mike Elliott <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike Elliott <camping.elliott@GMAIL.COM>
Subject: Re: Did I hurt my Aux Battery?
In-Reply-To: <c4e7c5f90809032135s34277066g988ec13920376c83@mail.gmail.com>
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On 9/3/2008 9:35 PM neil N wrote:
"[DVD player's]AC charger says 1.3 amps on it. Maybe I could measure the
draw with my VOM."
(Obligatory warning ON)
You may need to measure this. Take care when measuring anything connected
to 120 vac household current. Make sure you know what you're doing.
(Obligatory warning OFF)
Were the DVD player's AC charger/power supply 100% efficient, then it
would take in 120 vac @ 1.3 amps from your house's wall outlet when it's
working hard. If you're running that charger off an inverter, then that
inverter (were it 100% efficient, which it isn't) will be pulling 13 amps
from the battery's 12 vdc and outputting the needed 120 vac @ 1.3 amps to
run the DVD charger. Roughly.
One hour @ 13 amps is 13 amp-hours taken from the battery. Your two-hour
movie would have required 26-ish Ah.
--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR
On 9/3/2008 9:35 PM neil N wrote:
> Hi all.
>
> 2-3 years ago, I installed a smallish, sealed, 40-ish amp house
> battery in my Westy. At time of purchase, I didn't note the battery
> type. (deep cycle or AGM). I *think* it's a deep cycle, but am not
> certain.
>
> My new "intelligent" battery charger: http://tinyurl.com/6jryzn
> tops up the battery quite quickly at the 8 amp/deep cycle setting.
> Coupled with the fact that the incandescant interior light and
> portable DVD player drained it down to ~ 20% fairly quickly, I thought
> it might only be "surface" charging. I charged it a second time. It
> still charged back up quickly. (1/2 hour - 45 minutes).
>
> Is the fast charging a bad sign? I hope that using a standard charger
> or vehicles alternator all this time, hasn't damaged the batteries
> ability to hold a charge.
>
> Would it help the battery to hold a charge longer if I drain it down a
> few more times and do a slow 2 amp charge?
>
> Is there an easy way to tell if the battery is deep cycle or AGM?
> (that way I could knowingly use the right setting)
>
> FWIW, after the second charge, running ONLY the DVD player for 2
> hours, drained it down to 60% or 12.3 volts (says the charger). I
> don't know how many amps the DVD player draws. Nothing in the manual
> or online. AC charger says 1.3 amps on it. Maybe I could measure the
> draw with my VOM.
>
>
> Thanks for any help,
>
> Neil.
>
>
>
> --
> Neil Nicholson '81 JettaWesty "Jaco
> http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines
> http://web.mac.com/tubaneil
> http://tubaneil.googlepages.com/
>