Charging TM batteries while its connected

[nater]

I recently had two deep cycle batteries that drained to 3 volts after one day. They are about 4 years old so they need to be replaced. When I plugged in my on board 2 bank 10 am charger it made my trolling motor begin turning on its own.

From talking to friends it is recommended anyway to disconnect your TM while charging. One had it fry a part in his TM. $300 fix. How many of you guys disconnect your TM before charging?

[bobbymalone]

I don't.

I doubt anybody with an onboard charger does either.

[SkunkedAgain]

I've never disconnected anything while charging the battery with my onboard charger

[delcecchi]

I almost always disconnect the TM. And recently I have had another mysterious electrical problem. I have a 522 Lowrance on the bow. I had a string of blown fuses first thing in the day, that when replaced seem to last all day. It took me a while to notice it was just first thing that they blew. I thought something was wrong with the wiring. Then I tried unplugging the 522 while charging and no more blown fuses.

I can't figure out what is happening. Something weird in onboard charger?

Nothing about setup is new.

[sheephead2]

I have a 3 bank charger 24v TM and one hooked up to starter battery.I thought I read you are suppose to unplug the TM before charging.

Also my starter battery is hooked up to all my electronics and my TM battery's were charged before starter Battery.This is after about 8 hours. Weird because I ran about five miles WOT. So I shut off charger took off power cord to electronics plugged charger back on and Starter Battery was was on Full maintenance mode. So I just wired up a on off light switch that feeds my electronics thinking that there is a load always going to electronics even though they are not on.

[Kyhl]

I always unplug electronics when charging.

The DC waveform generated from cheap AC conversion looks like a saw blade and is generally tough on electronics unless they are designed for it.

I'll try linking to wiki picture. If they delete it, just search wiki for a picture of a DC wave form.

[JohnMickish]

I've never disconnected anything while charging the battery with my onboard charger

Same here.

[Hookmaster]

I disconnect my TM when charging with an on-board charger.

[CaptainMusky]

I unplug my TM when not in use. ALWAYS. Its never plugged in when being charged PERIOD.

All it takes is someone to hit the remote button or step on a footpedal and your kids have fingers sawed off.

[EBass]

I don't unplug mine, but I do have a 60AMP circut breaker.

[TruthWalleyes]

I have never disconnected my TM while charging.

[harvey lee]

Only time my TM is plugged in is when I am using it. Don't know whyy, just what I have always done. I use an 2 bank onboard charger also.

[JohnMickish]

A Terrova will not turn on while it is in it's docked position.

[delcecchi]

kyle, are you saying that onboard chargers produce those waveforms? Do you have any information about the technology used in those chargers?

I would be very interested in schematics, actual waveforms, etc. I'm not sure those waveforms have much significance in this discussion.

[Kyhl]

I don't have a scope to try it. I would bet that onboard chargers are a little smoother but I doubt that they are pure DC.

The buzzing sound you hear from an external charger probably looks very similar to that saw tooth.

[delcecchi]

fer sure they aren't just the output of a transformer run through a rectifier. Modern on board chargers move the current around, charge at various voltages at various times, and switch modes.

My bet would be that they are a lot closer to DC than you might think. Even a newer external charger is fairly sophisticated. The one I just bought is fan cooled and reads the percent charge.

[delmuts]

I've always unplug mine as soon as I'm done fishing, but for safety.( I manage to bump the foot pedal as I was leaning over the nose to hook the boat to the trailer! I think it was recommended before charging with the older chargers.

[SkunkedAgain]

I've never disconnected anything while charging the battery with my onboard charger

I should clarify because what I wrote is inaccurate. I unplug my trolling motor from the on-board electrical socket before it goes on the trailer. The wiring from that outlet to the batteries is still connected when I hook up the onboard chargers, so I'm actually in the group that disconnects. However, I disconnect it more for safety and to keep that outlet cover free of moisture more than anything

[Kyhl]

That would be great.

[Capt. H (Ret.)]

Me Too!!!!

[nater]

Thanks guys, I never considered disconnecting my TM while charging until it started acting up. Pretty unnerving when your $800 TM is operating on its own! Its an older cabelas charger so I better start.

[Whoaru99]

I unplug my TM when it's not being used...not spot to spot, but when I'm done fishing for the day it gets unplugged.