Onboard charger questions

[hotrod53]

I have two batteries, starter battery way in the back, trolling in front of the console. The 2 bank chargers all seem to come with a 5 or 6 foot charging cable. If I centrally locate the charger up under the console, I can easily reach the trolling battery but the cable will not be long enough to reach the back. Is it OK to extend the Chargers cable? I'm getting pretty tired of pulling the trolling battery after each outing or going up into the boat in the driveway to connect the float chargers. I would also like to put a permanent AC plug port in the splash guard that I can easily hook up in the driveway. Any suggestions or comments?

 

[Grandad]

Hi hotrod. There?s no problem with extending the leads as long as they have sufficient current rating to carry the charging current. That said, if you?re connecting permanent wiring directly to the battery, you?ll also want to add an inline fuse in the positive lead where you connect to the battery. A short in those leads will allow all the stored current in the battery to melt the leads and set fire to your boat.

In regard to adding a permanent shore power plug, I wouldn?t unless an approved marine ground isolation method is used. That can add considerable expense. I understand that you only want to plug it in while it?s on the trailer, but you?re not likely to be the last owner of the boat. A boat in the water should not have any shore power connected via anything other than an approved wiring method. Adding a permanent plug could indicate to a future user that it?s OK to plug in while docked and any improper method could get somebody such as a swimmer killed. I'd leave the 120V cord from the charger hidden, but accessible for charging as you need it. Future users are less likely to assume it's a legitimate shore power installation for use at a slip. - Grandad

 

[hotrod53]

Good point grand dad, I guess climbing up to plug in the charger is still easier than lifting that 70# battery out every time. Currently I only charge my starter battery over the winter and never in the summer unless I'm going on a long trip. Every year my starter battery goes dead on a long trip since I haven't yet moved my live well and lights off of it. I'm hoping to solve that this year through wiring and a charger.

Having an electronics background I do understand your other point. Leaving the fuse at the battery connection is the only thing that protects that wire between the charger and the battery leaving all but 4" protected in the case of a short.

 

[gm280]

After reading these comments, your charger circuit presents an unusual situation that until now I never thought about before. I too understand electronics very well and the fuse at the battery itself is always a good thing to do. BUT, being how both sides of this circuit can produce a voltage and thereby current, it would almost seem that two fuses would be wise. One at the battery being charged and the other at the charger. If there were a shorted wires close to the battery, the fuse would open and stop and fire potential. But unless the charger is short circuit proof and shut itself down, the wires leading to that short would get hot and the fire potential is still there... Interesting to me, what do you all think? JMHO!

 

[Grandad]

After reading these comments, your charger circuit presents an unusual situation that until now I never thought about before. I too understand electronics very well and the fuse at the battery itself is always a good thing to do. BUT, being how both sides of this circuit can produce a voltage and thereby current, it would almost seem that two fuses would be wise. One at the battery being charged and the other at the charger. If there were a shorted wires close to the battery, the fuse would open and stop and fire potential. But unless the charger is short circuit proof and shut itself down, the wires leading to that short would get hot and the fire potential is still there... Interesting to me, what do you all think? JMHO!

Hi gm. I think it likely that all battery chargers now have some form of overcurrent/overload protection, otherwise there'd be a lot more "accidents" with chargers. I know that my C-Tek maintainer has such protection and it's not an expensive model. - Grandad