Date: Sat, 9 Oct 2004 07:55:11 -0400
Reply-To: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Subject: Re: Monitoring aux battery charging?
In-Reply-To: <415CD951.6040708@adelphia.net>
Content-Type: text/plain; charset="us-ascii"; format=flowed
I don't think you're going to see much on the 60 amp scale of the typical
ammeter. Let us know if you have this in place and how it works...
I once had a dream of monitoring the following: Aux battery amperage going
in or out, voltage of main battery, voltage of aux battery. I was going to
do this buy cannibalizing a cheap digital multimeter that had a 10amp DC
current scale. I was going to mount it somewhere and then have a selector
switch of some sort that would switch the setting on the meter and the
routing of the wiring between the van's electrical system and the inputs on
the meter (simultaneously). I would also have an "off" setting that would
take the ammeter out of the circuit in case I needed to draw more than 10
amps from the aux battery for any amount of time. I took the multimeter
apart and started figuring what I would need to do in terms of wiring and
switching. Then my head started hurting, and I think I eventually hit a
problem that I couldn't figure a way around. I think it may have been when
I came up with the requirements for the selector switch I would
need. Someone more clever than I could probably come up with an elegant
way to do this.
Edward
At 12:13 AM 10/1/2004, you wrote:
>Fortunately Mellow Yellow and I are not at sea for months at a time, and
>a failed battery will not sink us. So a first-order approximation of
>battery charge should suffice, I reckon. Today I picked up an good old
>school round analog ammeter with a +60-0--60 scale. Wired it in series
>with the aux battery's (+) terminal. Negative readings big enough to
>deflect the meter will indicate that I am pulling a lot of current out
>of the battery, so I should back off on the power consumption. And
>during charging, high positive current will show that the battery is
>absorbing a lot of current while it charges up from a partially
>discharged condition. The current should taper off as the battery
>reaches full charge. All I need to do is make sure that the engine is
>revved enough to make the alternator's voltage regulator regulate and
>watch the meter. A digital voltmeter connected to the aux battery will
>let me monitor alternator voltage when the engine is running and the aux
>battery is connected to the main battery. And when the engine is off and
>the aux battery disconnects from the main, the voltmeter will let me
>keep an eye on how much reserve the aux battery has. Optima does not
>recommend letting this Yellow Top discharge below 10.5 volts.
>
>That's my plan, it's a good one, and I'm sticking to it.
>
>--
>Mike "Rocket J Squirrel" Elliott
>71 Type 2: the Wonderbus
>84 Westphalia: "Mellow Yellow (The Electrical Banana)"
>KG6RCR
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