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- Newsgroups: rec.autos.tech
- Path: sparky!uunet!mcsun!sun4nl!dutrun!dutrun2!dutncp8!eur
- From: eur@dutncp2.tn.tudelft.nl (Eur van Andel)
- Subject: Re: Electrical Question: Multiple Batteries?
- Message-ID: <eur.714038738@dutncp8>
- Sender: news@dutrun2.tudelft.nl (UseNet News System)
- Nntp-Posting-Host: dutncp8.tn.tudelft.nl
- Organisation: TU Delft, The Netherlands
- Organization: Delft University of Technology
- References: <CMM.0.90.0.713813115.siegman@Sierra.Stanford.EDU>
- Date: Mon, 17 Aug 1992 08:05:38 GMT
- Lines: 53
-
- In <CMM.0.90.0.713813115.siegman@Sierra.Stanford.EDU> siegman@SIERRA.STANFORD.EDU ("Anthony E. Siegman") writes:
-
- >Anyone out there with experience on using, and recharging, multiple
- >batteries in a vehicle?
-
- >My son is a small contractor, one of whose vehicles is a big old parts
- >van. The van gets driven to a job site, then sits immobile for 3
- >weeks, holding job supplies and a communications radio for the job
- >crew which is left on 8 hours/day. This is too much for the regular
- >battery; after 3 weeks it's dead.
-
- >Proposal: Install a heavy-duty (marine?) battery for the radio, plus
- >an AB switch. Drive to the site on the regular battery, then switch
- >to the heavy-duty backup. When it's time to drive home, switch back
- >to the regular battery, start the truck, and drive home. Recharge the
- >heavy-duty battery either with a 110 V trickle charger at home, or by
- >switching back to it after the engine is started.
-
- >Any pitfalls in this? Will the truck's regular alternator and voltage
- >regular (12 V) be able to charge the heavy-duty battery also without
- >damage? Are there other ways to do this?
-
- >(We already know that just paralleling two batteries is a bad idea.)
- Not SO bad.
-
- I used to have an old Honda civic automatic (that is a rarity in Europe:
- virtually everyone has a gearbox here) and had a bad habit of leaving the lights
- on. Whith a gear-box that's no problem: you switch off the lights,
- wait a minute, and push-start.
-
- Alas, with an auto this doesn't work.
-
- So I put an extra battery in the trunk, and connected it to my regular one
- with a large diode: the spare could be charged, not discharged. When I left
- the lights on again, I got out my jumper cables, started the car with the
- other battery and drove off.
-
- So:
- |\ |
- + -----------| >|----------------- + ---------------------
- |/ | |
- Car battery Heavy Duty battery radio
- |
- - -------------------------------- - ---------------------
-
- This way, the heavy duty one is not used for the car, but does get charged,
- and the car battery is left to start the vehicle.
-
- The diode should be a large one: 15 Amps at least. Drill a hole in an aluminum
- plate, put the diode in so it can cool, and wrap the plate in tape, so it
- can't touch the metal of your car (sparks, roasted wire, blown out diode).
-
- eur
-