VANAGON archives -- April 2010, week 3 (#727)

Date: Wed, 21 Apr 2010 18:17:04 -0400 Reply-To: Phil Zimmerman <philzimm1@SHAW.CA> Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com> From: Phil Zimmerman <philzimm1@SHAW.CA> Subject: Re: charging aux battery: too much of a good thing?

On Tue, 20 Apr 2010 15:11:51 -0700, mark drillock <mdrillock@COX.NET> wrote:

>Today I was able to fire up my 3 battery system for the first time. A >dedicated 125 amp hour deep cycle was added...

..... I was surprised to see the meter reading over 60 amps going into the battery when I first started the engine even though the battery was fairly full. This quickly tapered down over a few minutes to a steady 25 amps. I wonder if maybe I have too much charging?

.....I am measuring 14.5+ volts at the alternator which I believe is pretty common with modern vehicles but I wonder how good it will be for the battery >long term..... That seems too high for a "float charge" but >I don't know how it will be in practice. Anybody know? Suggestions? -----------------

Hi Mark,

Wow... now thats a dedicated aux battery for a Italian Gelato Refer.... darn near the size of Karls D4 Battery under his rear seat! I now have a serious case of Battery envy!

Which side of the engine is the Battery mounted and how did you hang that 80 lbs monster in there?

What type of Cell... Wet, AGM or Gel?

The previous posters have hit most the salient stuff I know, other than operating a Battery at elevated temps in the engine compartment... Higher than ambient (meaning room temp) temperatures can kill a battery by 50% to 75% of its expected life-time. Anything to keep the battery cool(er) will help.... IMHO

Alternator Charging is pretty much limited to 'Bulk' charging. A float charge is really never reached while running on the Alternator... With the Fridge running... that 14.5 volts will be somewhat dissipated as heat and in line-losses... keeping your battery safe from overcharging. I would be more concerned with over-heating than overcharging... but, the devil is in the details in battery charging.

Might be worth the time and effort to put a temperature probe on the battery to measure its temperature while Underway and Charging. See what the temps are?

regards

Phil Z. Campbell River, BC -----------------------

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