[Shop-talk] Solar car battery chargers - Now battery tenders

[Scott Hall]

  Well that brings up a new tack--I'm about to buy two new batteries for 
the truck and I'd like them to last.  Is this sulphating an issue that 
comes from sitting or being charged on a charger, or...?

Basically, will sticking a solar charger on the truck for weeks at a 
time kill the batteries prematurely, and if so, what should I do to 
counteract that?

Thanks.

On 10/11/2010 8:24 PM, Karl Vacek wrote:
> And not to hijack the thread, but the HF unit does NOT desulphate - only a
> very few chargers do.  For me that's as important as maintaining a charge.
> Batteries are expensive - it's nice to take good care of them painlessly.
>
> Karl
>
>> I've bought a few of the Harbor Freight Battery tenders ($12 or $8 on
>> sale) and they seem to check out very well according to my Fluke VOM.
> I've had a few of those myself, and was not impressed.  For one thing, they
> just regulate a constant voltage, rather than using a fallback like the
> BatteryMinder does.  Over time, that will shorten the life of the battery.
> It also doesn't keep the battery fully charged.
>
> But more importantly, they have no current regulation.  If you connect them
> to a discharged battery (in violation of the instructions), the wall wart
> overheats and fails.  If you then replace the wall wart with one that will
> handle the increased current and repeat the experiment, the electronics
> module overheats, melts and fails.
>
> I see they do now offer a "3 stage" charger/maintainer, but it's somewhat
> more expensive. ($30 list/$15 sale)
>
> Randall