Car battery charger/maintainers

JetMech

Solar car battery charger/maintainers...are any of them worth buying? Do they help AT ALL?

BB.

Re: Car battery charger/maintainers

I can verify the "cheap" battery maintainers will boil a battery dry in a few months... I have purchased a couple and they all can cook an 80 amp car battery (even with loads for GPS, On-Star, Lojack, etc.).

My trick is to purchase a cheap electronic or mechanical timer (like those used on lamps) and set them to charge for an hour a night (or what ever you believe the minor loads/self discharge require).

I did this on my In-Laws car which has a 0.185 amp drain (above electronics) for their car which sits for a month or more at a time:

24 hours * 0.185 maps / 1.0 amp "charger brick" = 4.4 hours per night on timer

No problems since (battery water stays OK--maintenance free battery, car starts first time, no jumping/charging). Only problem--trunk gets left unlatched (key fob unlock?) and nobody sees the trunk light on for a week -- kills battery. I should probably just take the trunk lights out of all of their cars and give them an LED flashlight.

-Bill

JetMech

Re: Car battery charger/maintainers

I'm thinking of the kind that sit on the dash and plug into the cigarette lighter, I don't think those put out enough to worry.

Come to think of it, it would have to be a "constant-on" lighter wouldn't it? Rather than those that only et power in ACC or ON.

Yeah those trunk lights have got me more than once too.

BB.

Re: Car battery charger/maintainers

The small chargers I used are just 1 amp. And a 1 amp charger running 24x7 is more than enough to destroy a couple 100 amphour batteries unless they are refilled with distilled water monthly (ask me how I know :roll: ). Actually, it was a battery maintainer which cycled on and off at a set voltage (this was before I came here and learned the details of battery maintenance).

-Bill

icarus

Re: Car battery charger/maintainers

I have a couple of 5 watt, 15 volt Pv panels sold by coleman. I got them from that weird site that sells just one thing every day. I paid ~$10 each for them. The trick is that it puts out less than 1 amp while the sun is out, and the voltage is limited to a max of 15 vdc. It never gets to that 15v so it doesn't need a controller of any sort. I have one on a genset that runs only rarely, another on a tractor and another I put on a bush truck that we rarely use.

It has kept these batteries fully charged for a couple of years. Pretty simple.

Tony

mike95490

Re: Car battery charger/maintainers

They should be OK, heck even VW uses them in the new cars shipping over on boats, they have a 10W panel on the dashboard. You can often find them on ebay.

BB.

Re: Car battery charger/maintainers

The thing is that a 1 amp solar panel only runs 2-5 hours a day... Its own automatic timer.

-Bill

RCinFLA

Re: Car battery charger/maintainers

Charger/maintainers like BatteryTender are okay.

They should be used for a battery that sits for more then a couple of months unused.

The only problem you can get into is when their maximum current won't get the battery past the initial bulk stage (14.4 vdc) and into their float voltage of 13.2vdc.

It is usually not a problem for a car battery, small boat battery, riding lawn mower, or electric start generator. I would rather they just do a current limited 13.2 vdc float.

They are definitely better then letting a battery sit and sulfate.

Now if you want 'snake oil' get a battery desulfator.

niel

Re: Car battery charger/maintainers

watch out that the current isn't going backwards during nights or cloudy times as some may skip the blocking diode. i prefer to use some kind of regulation, but the diode would be a must have if no controller is present to stop the back-flow of current.

JetMech

Re: Car battery charger/maintainers

Good point. Thanks for the info fellas.