ColinB

I'm away from home a lot and I sometimes leave the battery maintainer on for up to 2 months. I find this will boil off a little of the electrolite so I am very careful to top it up after each long absence.
Anybody else experience this?

Colin 89GT

dr bob

Colin--

My car often sees the same duty, unfortunately. I have a hard-wired connector by the fan controller at the front apron, dedicated to the maintainer.

The maintainer I use is a Schumacher, and it charges when terminal voltage drops below 13, stay on until terminal voltage exceeds 14. Considering that the nominal charging voltage from the alternator is 13.8, this isn't a bad way to maintain the battery.

Meanwhile, many inexpensive 'float' chargers are nothing more thatn transformers and a couple diodes. The saturation voltage on the transformer and the voltage drop through the diodes provide the only charge limiting in these sophisticated devices. They may settle out at 14.5 volts or greater sometimes, depending on the impedance of the battery. 14.5 Volts continuous will definitely boil out a little water from the battery.

You can find out how well your charger is working by checking the terminal voltage after the charger has been attached for a while. Use a good external meter, and don't rely on that dash gauge for anything other than a yardstick number.

ColinB

Thanks for that Bob. I'll check it, but my battery maintainer is a really good one. An 'Optimate', Belgian-made. It's a 'float' charger that charges, stops for an hour, measures the state of charge then charges again as necessary. I have another on my bike which also boils off the electrolyte but it happens even faster on the small bike battery.

Kind regards. Colin. 89GT