on board chargers

[knoppers]

OK I will bite, do you leave your on board charger running through winter? I have a minnkota on board charger and was thinking of leaving it plugged in through winter. does it charge to hard? or does it work like a battery tender.

[huntnfish]

I store my boat in an Unheated shop for the winter. I pull all batteries and keep them in my heated garage and periodically charge them throughout the winter. I try to put my digital float charger on each one once every few weeks. I did store my boat in the garage the first winter I had it because I wanted to add and make a bunch of changes. That winter I would plug the onboard charger in every so often. I don’t know if this is the best way or not but it’s what I do. 

[delcecchi]

My boat is stored in unheated space over winter, batteries not plugged in.   In spring they seem to still be at like 2/3 charge.   No major problems.   Been doing it that way for 20 years.   

[knoppers]

thanks for the reply's, I know heat is the battery's worst condition, and cold is better. I think I will leave the battery's in the boat, and plug the on-board charger in every now and then. I have been removing the battery's for years, and placing them in my basement, which has worked well. I do keep the starting battery in the boat since its very difficult to remove, but putting a battery tender on it all winter.

[BobT]

On 10/10/2020 at 8:10 PM, knoppers said:

thanks for the reply's, I know heat is the battery's worst condition, and cold is better. I think I will leave the battery's in the boat, and plug the on-board charger in every now and then. I have been removing the battery's for years, and placing them in my basement, which has worked well. I do keep the starting battery in the boat since its very difficult to remove, but putting a battery tender on it all winter.

I check the electrolyte to make sure it is optimum (add distilled water if it is low), make sure the boat key is turned off, and leave my batteries in the boat stored in unheated lean-to. I just plug the charger in about once a month for about a day to make sure they are topped off. As an added safety precaution, you can disconnect the boat wires from the starting battery because some boats have electronics that may use a small amount of power from the battery even when the key is off. 

 

Even so, batteries will lose some charge over time and as they do they become more susceptible to freezing. Please note that a battery at 50% charge can freeze at temperatures right about -10 F give or take. Keeping them topped off will protect them. Here's a chart showing the freezing points of batteries at various charge levels that I found from Trojan Batteries. 

 

[h8go4s]

There's no need to worry about good batteries stored over the winter. You don't need to take them out of the boat and lug them down to the basement. Make sure the water level is full and they're fully charged. Then disconnect ALL the leads. Tie-wrap the positives together and the negatives together. That way, next spring, you'll be sure to clean all the terminals. Attached are voltage readings from my batteries before and after storage and a chart of charge percentage at different voltage levels.

[knoppers]

I did get 10 years out of my batterys from new, I put in 3 new batterys last year, not sure if my on-board charger is working correct. I checked my 24v system batterys and one was at 30% and the other at 40%. I plugged in on-board charger in friday, and unplugged saturday, I will do a check next weekend to see were they are at.

[Wanderer]

Thanks for posting the good info guys.  

[knoppers]

after one week, the batterys were at 60% and 40%, still not what I was expecting. I need to look into my tester, that may the problem.