I'm finishing up my first trip out and about to put the trailer into storage for the next 4-5 months. I have indoor climate controlled storage with power available. My question is how bad will a modern 3 stage converter really be to a marine battery over that period of time. Do I really need to go out and buy a charger that costs half as much as a new battery (I can't imagine the cheap Chinese junk is any better than the converter) or will I still have a working battery come Spring? Also what is the failure mode for overcharged lead acid batteries? Any chance for fire or flames?

I always left my converter ON when in storage. No damage done.

A good converter isn't "bad" at all.

A modern multistage converter should be not hard on the battery at all for that length of time. It would be a good idea to check and top up if needed the battery electrolyte at the start if that hasn't been done recently.Since this is winter in a relatively cold climate, you could also charge the battery fully and disconnect it for the few months of winter and it wouldn't self-discharge too much. But with power available it hardly makes sense to do that.

It is the older converters that do not have a three stage charging cycle that are hard on batteries. The continuous charge on older units can boil the battery dry if not checked on regularly as far as I understand.

If that modern converter is a WFCO all bets are off. Measure the voltage after a week and see if you actually see storage mode at 13.2 volts.Regardless you still need to check the water level periodically.

How bad are converters on batteries? | Good Sam Community

Mandalay_Parr
Explorer
Dec 31, 2016
I always left my converter ON when in storage. No damage done.
ScottG
Nomad
Dec 31, 2016
A good converter isn't "bad" at all.
DrewE
Explorer II
Dec 31, 2016
A modern multistage converter should be not hard on the battery at all for that length of time. It would be a good idea to check and top up if needed the battery electrolyte at the start if that hasn't been done recently.

Since this is winter in a relatively cold climate, you could also charge the battery fully and disconnect it for the few months of winter and it wouldn't self-discharge too much. But with power available it hardly makes sense to do that.
Ava
Explorer
Dec 31, 2016
It is the older converters that do not have a three stage charging cycle that are hard on batteries. The continuous charge on older units can boil the battery dry if not checked on regularly as far as I understand.
time2roll
Nomad
Dec 31, 2016
If that modern converter is a WFCO all bets are off. Measure the voltage after a week and see if you actually see storage mode at 13.2 volts.

Regardless you still need to check the water level periodically.
theoldwizard1
Explorer II
Dec 31, 2016
If you are concerned about overcharging, buy a cheap mechanical lamp timer and install it between the power source and the charger. Set it to run for a couple hours per day.

Next time you are shopping for a house battery make sure to get a TRUE deep discharge battery. Most "marine" batteries are dual purpose and therefore are a compromise between starting and powering things.
SoundGuy
Explorer
Dec 31, 2016
afidel wrote:
I have indoor climate controlled storage with power available. My question is how bad will a modern 3 stage converter really be to a marine battery over that period of time. Do I really need to go out and buy a charger that costs half as much as a new battery ...

Lucky you with indoor heated storage with power! :B If I had that luxury I'd just make sure the battery was properly watered and plug the trailer into power so the converter can maintain battery charge. If that doesn't suit you remove the battery, take it home, and invest in a good stand alone charger ... so what if it costs "half as much as a new battery"? ... it's cost amortized over the many years you'll use it will amount to pennies a day.
afidel
Explorer II
Dec 31, 2016
time2roll wrote:
If that modern converter is a WFCO all bets are off. Measure the voltage after a week and see if you actually see storage mode at 13.2 volts.

Regardless you still need to check the water level periodically.

See, that was my worry. It's a two hour round trip (during good weather) to my storage so the chances of me going during the next few months are pretty much nill. I think I'll pick up a timer and just set it to go for an hour or two a day which should be plenty to keep up with the small parasitic loss from the CO/LP detector and the stereo (or should I pull the stereo fuse?).
sonora
Explorer
Dec 31, 2016
Ava wrote:
It is the older converters that do not have a three stage charging cycle that are hard on batteries. The continuous charge on older units can boil the battery dry if not checked on regularly as far as I understand.

Would a mid 90's converter be an "older" one?
prichardson
Explorer
Dec 31, 2016
I would charge fully, ensure proper water level, make sure the top is clean and dry and disconnect the battery. With any charging system, the water level needs to be monitored.