lead battery maintainers

[torqueon]

I have a customer who is constantly having batteries go dead from infrequent use, A T V s, lawn equipment the list is long. I have a bunch of 12 volt wall warts
200 to 500 ma that I would like to use, to keep all these batteries healthy. However the open voltage on these units are 15 to 17 volts, on the battery over time will push the volts to 14.5, even the 200 ma unit will make the battery gas. I will try 100 ohm resister to limit current. What would you suggest ?

2nd Question is do S L As have a higher resting voltage than F L As , after a full charge ?

Thanks to all here i have learned much from you guy's

Happy Holidays

Pete

 

[amberwolf]

What you're after is a float charger meant for SLA, for those that are SLA, and FLA for FLA. But because theyr'e usually cheap, I wouldn't leave them plugge din all the time, but only use them periodically to top them up.

Powerchair chargers are typically capable of this, and can be found used (soemtiems for nothing if you make friends with your local repair shop, when they trash old stuff). But they are usually for 24V, so you'd have to series two SLA at once.

I wouldn't use the wall warts for that. Cant' rely on any particular voltage from most of them, as they don't usually have a regulator in there to limit output voltage or current.

SLA voltages vary depending on brand/size/etc., but typically 14.4V is what I see max charge voltage on the labels of mine, 15V on some. 14.1V on one 12Ah. 13.6V for final resting voltage once disconnected is common.

 

[torqueon]

hey amberwolf thanks for your replies, you have been quick to answer, questions. This project has to be a turn key . I will try to build a circuit to limit voltage/amp etc. surly there's a way to do this cheap. Thanks again

Pete

 

[Dave_S]

This project has to be a turn key . I will try to build a circuit to limit voltage/amp etc. surly there's a way to do this cheap.

I have been using one of these on a vehicle that only gets use 3 months out of 12. It does the job for $10.
http://www.harborfreight.com/automotive-motorcycle/battery/automatic-battery-float-charger-42292.html