# Onboard Battery Charger Questions



## Maryland Mitzi (Jul 11, 2016)

1. Do you leave the charger plugged in when storing the boat, even when the green (charged/maintain) light comes on? When I unplug after green light comes on and leave for a few days and then plug back in the on board charger and extra amp bank needs recharging. Could this be due to a short?

- I have one on/off battery switch for the starter/accessory battery. Should I install another on/off switch separately for the trolling motor battery?

2. I had the boat out last week, the first time after installing a Minn Kota 55lb 12v co pilot trolling motor. The motor worked fine for a while then just shut off. Afterwards I found I had blown a fuse. It was the fuse from the trolling motor battery to the flush bow mount plug. It was a 30v Fuse, I assumed this is plenty, but I must have had a short somewhere? Most likely after the battery?


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## csnaspuck (Apr 2, 2013)

@Whiskey Angler seems to be the resident electrician so I will let him respond to the possible short. 

As for the charger unless its a trickle charger its probably not a good idea to leave it plugged in all the time. There are stories on this site about boats catching on fire. I just plug mine in the night before going out. I also noticed my onboard charger has a fan on it that helps it from over heating so I feel better about leaving it charging over night while i dream about fishys


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## Whiskey Angler (Mar 20, 2015)

Maryland Mitzi said:


> 1. Do you leave the charger plugged in when storing the boat, even when the green (charged/maintain) light comes on? When I unplug after green light comes on and leave for a few days and then plug back in the on board charger and extra amp bank needs recharging. Could this be due to a short?
> 
> - I have one on/off battery switch for the starter/accessory battery. Should I install another on/off switch separately for the trolling motor battery?
> 
> 2. I had the boat out last week, the first time after installing a Minn Kota 55lb 12v co pilot trolling motor. The motor worked fine for a while then just shut off. Afterwards I found I had blown a fuse. It was the fuse from the trolling motor battery to the flush bow mount plug. It was a 30v Fuse, I assumed this is plenty, but I must have had a short somewhere? Most likely after the battery?


With regards to the charger question, it really depends on what kind of charger you have. But generally, you do not need to leave it plugged in. Once your charger says its charged, you can unplug it, and if its a few weeks before you get out on the water again, just plug it back in the night before to make sure. Even on the most expensive Minn Kota chargers, if you unplug the charger after the green/charged light is on, and plug it back in the green lights will turn off while the computer is sensing the charges, and sometimes it takes 5-10 minutes for the light to go back to green. If your deep cycle gets charged it will stay charged for a quite a while if you disconnect any circuits hooked up to it. If your trolling motor is the only think hooked to it, unplug/disconnect the trolling motor to prevent any voltage leak (which could partially drain your batter over a long period of time). For your other batteries, install a master perko cuttoff switch. That will keep all your other boat crap from draining your starting/house battery.

With regards to your fuse question: your 30amp fuse did just what its supposed to...fry at 30 amps. The 12V 55# Minn Kota's draw some serious current and NEED a 60 amp breaker (I'd recommend either the Minn Kota 60 amp or Blue Seas 60 Amp). You blew the 30 amp because you were probably drawing well over 30 amps.

Also, you NEED to follow Minn Kotas wiring size guide for the trolling motor leads - usually 6ga or 8ga for a 55# 12V. Where is your TM batter placed an how long are the cable going from the battery to the TM?

If your wire are undersized, and that fuse doesn't blow...you've got yourself a hell of boat fire.

Lastly, USE GOOD & PROPERLY CRIMPED CONNECTIONS for trolling motor wiring. When they corrode, you get voltage drop, which means your motor will draw more amperage to compensate....which could heat your wires/terminations and ....fire.

One time I had a 101# 36V minn Kota running at 100% for about 5 minutes (i was bouncing a lot a reef marking high points) and my plug burst into flames...The plug connection was badly corroded, and created an electrical bottle neck...fire.


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## Maryland Mitzi (Jul 11, 2016)

Thanks guys, I ordered the mini kota 60 amp breaker!! The onboard charger I have is the ProMar recreational series with a 5amp and 3amp storage bank. I'm pretty sure all connections are good as I just set it up, but once I get the breaker from amazon I will check the other connections as well. I have a perko cutoff for my starter battery and all other accessories.

The connections from the trolling motor from the battery is in the bow of the skiff through a Marinco 70a trolling motor plug and receptacle. So the breaker will replace the current fuse between the battery and the receptacle. length is probably 3 feet or less from receptacle to battery and less that 2 feet from motor to plug.


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## not2shabby (Sep 14, 2016)

Whiskey Angler said:


> Lastly, USE GOOD & PROPERLY CRIMPED CONNECTIONS


Whiskey. I've been looking around for a good recommendation on connectors. Molex Perma-Seal? Other brands?? Where do you buy them? Any feedback is appreciated!


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## Whiskey Angler (Mar 20, 2015)

not2shabby said:


> Whiskey. I've been looking around for a good recommendation on connectors. Molex Perma-Seal? Other brands?? Where do you buy them? Any feedback is appreciated!


https://tinnedmarinewire.com/wire/
It's crazy how much better there weatherproof/heatshrink terminals are compared to home depot or auto zone....night and day.
They also have nice tinned lugs for cable (like 0 awg - 8 awg). I bought this crimper from amazon a few years ago, and it gets the job done for cheap.https://www.amazon.com/gp/product/B00MVE48Z6/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
If you have a bunch of wiring to do, spend a few bucks on standard crimper/snipper for all your smaller terminals (10 awg - 22 awg)....like this https://www.amazon.com/GS-388-Crimp...8&qid=1492798740&sr=1-8&keywords=wire+crimper


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## TheFrequentFlier (Feb 17, 2016)

great info, thanks man. 

Currently on month 4 of an 8 month deployment. I have the fiancee plug in the boat and deep cycle trolling motor battery every few weeks. She lets it charge for a day or two, then have her unplug it again so everything isn't connected to power for weeks straight. I'm certainly no electrician like Whiskey Angler, so don't take this as gospel, but I've done this several times for long periods of time where my boat sits for a month or more, I come home and she starts the first time every time. (knock on wood)


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## Whiskey Angler (Mar 20, 2015)

tgjohnso said:


> great info, thanks man.
> 
> Currently on month 4 of an 8 month deployment. I have the fiancee plug in the boat and deep cycle trolling motor battery every few weeks. She lets it charge for a day or two, then have her unplug it again so everything isn't connected to power for weeks straight. I'm certainly no electrician like Whiskey Angler, so don't take this as gospel, but I've done this several times for long periods of time where my boat sits for a month or more, I come home and she starts the first time every time. (knock on wood)


"Electrician" - you use that term loosely. I'm in the structural steel business...they don't let ironworkers touch copper out in the real world.
May God Watch Over You during your deployment.


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## topnative2 (Feb 22, 2009)

the tinned wire link is a tremendous help...I will be able to light myself up with a professional flash!


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