battery charging question

McLovin · Post by **McLovin** » Tue Nov 11, 2014 6:38 am

I have a battery that just took about 12 hrs longer to charge than the other batteries. Is this the first sign of a week battery ? I feel like my batteries are fading at the end of the day. It's a 36 volt set up. Thanks.

Gene Buchholz · Post by **Gene Buchholz** » Tue Nov 11, 2014 8:15 am

first how old is it ,is a maintenance free or do you have to add water? If it is fully charged now have a load test put on it. That will give you an idea if it is going bad or if you might have a batter charger poroblem

McLovin · Post by **McLovin** » Tue Nov 11, 2014 8:26 am

It's 2yrs old and the water level is good. I don't think it's the charger as it is brand new. I will load test it and see what happens. My first set of Trojan batteries lasted 4yrs now I can't get two yrs out of them. By the way gene, what brand of batteries do you guys have the best luck with?

scottsweet · Post by **scottsweet** » Tue Nov 11, 2014 10:31 am

McLovin wrote:I have a battery that just took about 12 hrs longer to charge than the other batteries. Is this the first sign of a week battery ? I feel like my batteries are fading at the end of the day. It's a 36 volt set up. Thanks.

For your trolling motor batteries, the batteries work as a unit, not 3 individual batteries. If one battery is bad, the other two are getting worked harder.

How old are your batteries as a whole? Did you buy them all at the same time? Are they all the same brand/model? Do you charge your batteries up within a day of when you use them? It is possible that the one battery has a bad cell. Each battery has 6 cells, producing 2 V each. If you test the battery and it has a resting voltage of ~10 V, then you have a bad cell.

To really understand the state of your batteries properly, you should charge them all up, let stand for 12 hours to cool and then test them individually to see if they match each other. As Gene mentioned, doing an individual battery load test is the ideal approach. They should be almost the same...within .2 V resting voltage. The load testers will tell you the Amp capacity...they should be within 10% of the MCA of each other. In other words, if your batteries are 1000 Amp batteries, then they all should be within 100Amps of each other.

Hope this helps,

TCS · Post by **TCS** » Tue Nov 11, 2014 12:17 pm

Since were on the battery topic. I have three batteries in my boat. Two are deep cycle trolling motor batteries and a crank-fishfinders battery. The trolling motor is 36 volt and is wired to the two deep cycle batteries then a jumper wire to the crank battery to make it a 36 volt system. Is this normal? It seems like I should have three deep cycle batteries dedicated to the trolling motor and the crank battery should stand alone. Also, if the three batteries are connected in unison should they all be the same brand and output. Ive had my boat for years now and seem to get 3-5 years out of the batteries so im not sure if its a problem.

Gene Buchholz · Post by **Gene Buchholz** » Tue Nov 11, 2014 1:27 pm

We sell AC Delco. I feel Trojan's and AC Delco Batteries are the best two batteries on the market for trolling motors. Before you do anything get them load tested. IK do load testing at the HOOK If you are in the area call me and I can do it for you.

Gene Buchholz · Post by **Gene Buchholz** » Tue Nov 11, 2014 1:32 pm

As far as the other question it used to be the norm having your cranking battery as part of your 36 volt system.
It is not suggested anymore. Your depth finders are pulling more power and you may run your batteries down so low they may shut off on you. I would put in a 4th battery

scubaman · Post by **scubaman** » Tue Nov 11, 2014 5:09 pm

Get them load tested at Pep Boys....My Trolling motor batteries all would charge to 13.7 Volts but when load testing them all 3 where bad...

McLovin · Post by **McLovin** » Tue Nov 11, 2014 5:44 pm

Thanks for the help guys. It showed bad after I load tested it, so I bought a new one. Went with interstate this time because of the price and ease of getting one. Will see if it last longer than the Trojans.