Which trickle charger for 2 battery setup?

[nickR]

I just purchased a Schumacher battery charger from Performance Products to keep the batteries charged during prolonged garaging but the instructions advise against using it for a parallel battery setup. Does anyone have experience with this trickle charger with two batteries or suggest a better unit?

Thanks in advance
Nick

[Paul Schooley]

Since you already have that particular charger, why not disconnect the batteries and simply trickle charge one at a time, switching every couple of weeks between them. Makes more sense than spending more money on another one to me anyways.

[Chuck Miller]

Nick,

Never read the box... but couldn't recommend the Schumacher Mity Mite MORE

Been using it (them, I got one on my old Malibu as well) for over 5 years. I 'hard' mounted it to the right inner fender just above the left battery so just the AC plug sticks out of the top of the side trunk carpet....

As soon as I pull either car in the garage I automatically plug'm in ... they're plugged in all the time...

In fact the box DOES say you should NEVER start the car with the unit plugged in .... Well, after the years of use for both cars I'd say I 'SPACED' on that rule about 4 times... with NO adverse result....

My experience has been that these little things REALLY do a GREAT job....

Hope this helps,

[Grady Clay]

Nick,

The reason they offer that recommendation is every battery is ever-so-slightly different. In parallel (like ’69-’73) the battery with the lower internal voltage will receive the charging current. In normal operation of the car, this isn’t a significant issue. Depending on the “trickle charge” type of circuitry, this can become a big issue.

A way to tell if this is a problem is to track the specific gravity of the battery fluid (sulfuric acid and water).

Paul’s solution will work just fine.

Best,
Grady

[Gearbox]

I use a C-TEK charger on my 71 and it seems to work fine on a pair of Oddessy batteries. I like the C-TEK as it is one of those chargers that senses any drop in power and turns on automatically to reach max charge. So you can keep them plugged in for extended periods of time. It will also condition the batteries so they will accept a full charge by cycling them with pulses and draining them until the batteries hold the max charge.