Battery question

[Peter]

Hi all,

I have been running a solar panel to keep my battery charged. It is a 75 W Coleman model and it came with a charge control unit.

This fall the battery started to get weak. I pulled it today and took it to my garage. They tested it with a load and it did not recover.

The water was low so I topped it up and put it on my home charger and it is pulling about 7 amps. All cells were low on fluid.

Two cells are bubbling but the others are doing nothing.

I suspect that charge controller is not too good and maybe it boiled off a lot of water?

When I first starting using the solar panel it always indicated the battery was charged when I would go to the boat after a period of non-use. However, later in the summer it always indicated it was still charging when I went to the boat.

Next season I plan to get a better charge controller.

Questions:

1) does it sound like the battery is toast?
2) any recommendations for a charge controller

I cannot attest to the provenance of the battery as I was given it by a friend so I really do not know old it is.

Appreciate your thoughts,

Peter

[Peter]

additional data point

charge rate is now down to 6 amps and all cells are bubbling equally

Peter

[GregH]

With your 75W panel on a perfect day, it may operate at 75% efficiency. Most panels I've come across are more like 50-60%. I'm conjecturing that at 75% and 18V you'll be getting wee bit over 3 amps. With a basic pwm controller (I'm assuming) that'll be the highest amps you could push into the battery with that system.

With the fluid being so low in the battery, any amount of charging isn't going to do much to bring the battery to full. Topping up and make sure specific gravity is good may help for the short term. I suggest get it fully charged and have them do a load test. My guess is it's time for a new battery. And then you know it's quality and state.

See what's up with the battery before worrying about the charge controller.

With the basic pwm charge controller, most often there is no battery temp sensor option and it may be over heating the battery and adding to the evaporation. Do you happen to know what it's pushing for charge voltage? 14.3V?

[Peter]

new battery is probably best option.

i will measure the panel output next time i am at boat.

thanks,

Peter

[jbsoukup]

the portion of the plates in the battery which have dried out will not recover.
the battery is toast.
why the electrolyte level became low is anybody guess. could be it was never checked for years and just dried up from normal charging.
the level should be checked annually at least and replenished with DISTILLED WATER ONLY.

[edwardc]

Even a 5 watt panel can cook a battery dry over time if used either without a charge controller, or with a "dumb" one that does not have "float" mode.