Battery charging question

Hey guys. I know it’s early…but I took my boat batteries out to top them off/charge them the other day and the Schumaker battery charger (about 2 years old) I used started to make a very high pitched noise when I tried using it. I called Schumaker and they said not to use it at the low 2 amp setting to charge the batteries (I’m charging standard deep cycle group 29 batteries; never had any issues before). I always thought the 2 amp ‘trickle’ charge was considered the best approach for charging up/topping off deep cycle batteries, but this person from Schumaker said to instead use 10 amp setting. Does that sound right to you?

I’ve always heard the 2 amp change was the best too but todays batteries might be a little diffrent and a 10 amp charge is ok too. The noise might simply be a sound you hear so it redirrects you to a diffrent amp charge. From past experience it doesen’t hurt to charge at a 10 amp. because thats not much more like a 50 or 100 amp charge is. Id say your safe and Id charge at a 10 amp rate.

Is it a plastic cased charger? I have one that squeals right away, but it is just the fan that makes the noise. I just whack it a couple times and it usually stops.

Mine does it also. Helps to keep it where it’s warm. Mine usually don’t do it in summer

Most on-board chargers do a 10amp until they are 75 to 80%, then step down the amperage from there to a milli-amp charge. Your 10 amp should be fine. If you have a battery tester, check the voltage. A battery in good shape should be about 13.1V

Great tips, guys! To answer the questions. Yes, it’s a blue plastic cased charger. And I was trying to charge the battery in my garage, so obviously colder than when I typically used it in the summer. Maybe it’s a temperature thing. I did try smacking it a couple times and the sound stopped briefly. Might be something on the fan, too I guess. I’ll try it again tonight inside/the basement where it’s warmer. But also good to know a 10 amp setting is probably fine for deep cycle charging, too.

Lol, with your hand or a hammer because I’ve been known to use a hammer once or twice.