Trickle Charging While on Vacation?

Each time I leave my 1995 854T in a cold garage (~ 6C) while on a winter vacation, I return to find the battery dead. My Volvo dealer says it's normal due to the drain from the security system. This year, I'm thinking about setting up a charger to come on daily for an hour or so, charging it at the low setting of 2 amps.

Is this better for the battery than allowing it to discharge fully? Is

1 hour per day at 2 amps likely to be too much or too little over a 3 week period?

Java

Reply to
Espressopithecus (Java Man)
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Use a battery Tender Jr. It will switch on and off automatically and keep the battery up to charge with no hassle.

Reply to
Leftie

Even deep cycle batteries suffer from a full discharge unless they are NiCads. The Battery Tender Jr. seems like a great battery maintainer, and will also charge batteries if given enough time. You can find them for $30 on Ebay.

Reply to
Leftie

Thanks to all who have responded. It sounds as though the Jr. is the ticket.

Java

Reply to
Espressopithecus (Java Man)

You're welcome. The Tender also comes with two sets of plug-in leads: alligator clips and a separate set of ring terminal leads that you can install on the car, so you can just plug it into the Tender when you leave it sitting.

Reply to
Leftie

Aside from purpose chargers, is it a Relly Bad Thing(tm) to just hook up a regulated power supply to the battery or will that also do the trick? I have the same problem with my oldtimer convertible which does not see the light of winter.

Maarten

Reply to
Maarten Deen

I'm thinking of a laboratory power supply, set so 12 or 13 V. It will not give more than that voltage and the current will drop to almost 0 when the battery is full. I'm wondering if that is bad for the battery or not.

Oh, and I'm Dutch ;)

Maarten

Reply to
Maarten Deen

That depends on what you mean by "regulated." If it switches off when the battery voltage hits 13.6 or so, and doesn't try to charge at

10 amps, it may be ok. But seriously, why not spend $35 for a real battery maintainer?
Reply to
Leftie

Is the power supply happy connected to a 13V unlimited current supply if the mains fails?? Many are not.

Steve H

Reply to
steve H

There are standing recommendations to use only chargers and not power supplies for charging batteries, however, the failure mode that Steve mentions above, which is probably the reason for such recommendations, is easy to protect against. Just fit a blocking diode of a large enough amperage rating on the +ve lead, and crank up the output voltage by .2V to take account of the voltage drop across the diode. This prevents the battery supplying voltage to the output terminals of the power supply if the mains fails, or, if someone 'helpfully' turns the PSU output down.

Ken P.

Reply to
Ken Phillips

A battery charger is just a regulated power supply with the voltage preset and a high current capability. A trickle charger is just a regulated power supply with the voltage preset and a low current capability.

The problem with using a normal regulated power supply is if you make an error in setting the voltage. If it is too low you won't get a full charge and if it is too high you will burn off the electrolyte and ruin the battery. I think the power supply should be set at 13.6 volts or slightly less, not 12 or 13 volts. That makes a big difference.

Battery manufacturers should have a spec sheet which lists the optimum trickle charge voltage.

Also, never set a battery on a concrete floor. That shortens the life. I am not sure exactly why except the floor is a huge thermal sink and causes condensation in humid weather. It also causes a thermal gradient in the battery.

Reply to
Stephen Henning

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