Joe really nailed it with the trickle charge approach. This is similar
to a method that I prescribed in accordance with National Agency
standards (IEEE, ANSI, DOE, NETA, etc.) for maintenance of batteries
that were required for use in critical safety applications at a DOE
nuclear facility; so, I'd say it's good advice!
The only thing that I'll constructively add is that I recommend building
a storage shelf that helps the charging and keeps you safe. Absolutely
do not leave your charging batteries or other batteries in storage on a
concrete floor - concrete will guarantee that they will fully discharge
over a short period even with a small flow. Also, there is some
inherent danger with storing batteries with a trickle charge (fire,
shock, etc.) - just use common sense about where you do this and with
what materials and you'll be fine.
1979 TR7 BRG DHC
>From: Joe Worsley[SMTP:email@example.com]
>Sent: Tuesday, November 04, 1997 3:07 PM
>Cc: firstname.lastname@example.org; email@example.com
>Subject: Re: Battery Chargers ('Maintainers')
>> I'm considering keeping a couple of batteries from my three season vehicles
>> on a battery charger (or maintainer) through the winter. Several
>> questions: (1) is is worth the trouble in terms of preserving the overall
>> health of the battery? (2) any units out there that you would, or would not
>> recommend? (3) is it possible to keep more than one battery at a time
>> hooked up to it? (4) do you run them continuously, or periodically?
>> Thanks in advance for any info.
>> Ned Corcoran
>> 1971 TR6
>You only need enough charge going in to the batteries to compensate for
>the internal leakage of the batteries.
>If you paralled two batteries you will have current circulating between
>the two until one discharges enough to match the voltage of the other.
>The only proper way to parallel batteries is to use a isolator diode in
>series with each battery as is done in motorhomes and other similar
>situations where more than one battery is charged from one source.
>Automotive batteries are designed for high current drain and short life
>compared to a battery that is designed for standby power and kept on a
>trickle charge all the time and only used for light long term discharge
>loads. We have standby power batteries on electronic systems that are
>over 20 years old and still perform like new. They are warentied for 20
>Without the isolator paralleled batteries will charge charge up to the
>value of the charging voltage and one will discharge slightly into the
>weaker (one with lower terminal voltage) one when it is off . If the
>charger is a automatic (one that shuts off or comes on once in awhile to
>compensate for losses) charger you will have the discharge cycles each
>time it goes off. Some taper off the charge but keep a continous small
>charge on the battery all the time. The maintenamce current needed is
>probably only around 100 ma. This would be the better type to use as it
>keeps the constant maintenace charge on all the time and would eliminate
>the discharge cycle.
>Small steady output chargers that put out less than a amp or just a
>maintenace charge are available pretty cheap at Wallmart or autoparts
>stores. With a steady low charge you can do without the isolators.
>Kinda long soapbox speech huh! You'd never guess I like to talk.
>Tupelo, MS USA