Battery Not Accepting A Full Charge

[papajoe222]

I have a 24V system set up for my trolling motor along with the cranking battery.  One of the three is not accepting a full charge from my three bank charger.  My volt meter only registers 12.7V  the other two batteries are drawing the full 13.2 Volts.  It's the newest of the three batteries and if there were a dead cell, it wouldn't register more than 11 Volts.

Anyone have an idea what may be going on?  I switched the leads from the charger around with the same results, so I know it isn't the charger.

[retiredbosn]

Is there a reason you think it should read 13.2 volts when fully charged? If it's the cranking battery I wouldn't give it a second thought, idk if I would care if it's one of the TM batteries it is only half a volt. Does your volt meter have a way of checking amps? I would be concerned if the amps were way off. Half a volt I wouldn't worry about. I bet it's the cranking battery that shows less voltage, not a problem. Besides that your cranking battery gets charged by the motor anyway. I have a 36 volt TM, my onboard charging system only charges the TM batteries, the cranking battery doesn't require re-charging after every outing

[GPtimes2]

It can be tricky to figure out what voltage your battery should be at any given time. I just checked mine that have been charged for a week (onboard chargers). My cranking battery on a cabela's charger is reading 17 volts. The charger may be in a  mode that boosts voltage temporarily. My two trolling motor batteries (on a minn kota charger) is reading 25.3 volts ( divided by two would be 12.65 volts each). This charger is in a maintain mode. Looking at charts on the internet, 12.7 at rest, shows 100% charge. Hope this helps.

[Wayne P.]

A FULLY charged battery is 12.6-12.7 volts or 2.1V per cell AFTER it cools down/stabilizes from charging.

A battery charger outputs over 14 V depending on the charger.

[papajoe222]

My concern is that the battery in question is only drawing a trickle charge from the automatic charger even when first connected. I would expect it to draw a full 6amps @ 13+ volts. I guess it could be holding a charge well enough that it doesn't require more. I just thought there might be a problem.

[retiredbosn]

My concern is that the battery in question is only drawing a trickle charge from the automatic charger even when first connected. I would expect it to draw a full 6amps @ 13+ volts. I guess it could be holding a charge well enough that it doesn't require more. I just thought there might be a problem.

Deep cycle marine batteries should not be charged using 6amps, you'll shorten the life of the battery. Deep cycle batteries require a long slow charging cycle, I always used the 2 amp setting on the portable unit I used to use. Marine batteries hold a large amount of amps but discharge then very slowly, the same goes when charging them a longer slow charge will result in more useable power and will provide a longer life.

Just out of curiosity which battery is not charging to the point that you would like? Cranking? TM?

[papajoe222]

It's one of the two TM batteries. The other battery pulls 13.2 volts when first plugged in. 

[slonezp]

Deep cycle marine batteries should not be charged using 6amps, you'll shorten the life of the battery. Deep cycle batteries require a long slow charging cycle, I always used the 2 amp setting on the portable unit I used to use. Marine batteries hold a large amount of amps but discharge then very slowly, the same goes when charging them a longer slow charge will result in more useable power and will provide a longer life.

Just out of curiosity which battery is not charging to the point that you would like? Cranking? TM?

Some beg to differ with your opinion. The "smart" chargers available will quick charge your batteries to 80%, gradually slow down the charge until it hits 100% and then go into float mode. The "Pro" series chargers are 15 amps per bank

[Comfortably Numb]

As Wayne said, they will show 13.2v hot off the charger. They will settle at around 12.7 after resting a few hours.

[retiredbosn]

The "Pro" series chargers are 15 amps per bank

I respect your right to disagree with me. As I tell people all the time "you have the right to be wrong" Yes smart chargers and bank chargers are labeled as 15 amps, but that is their maximum output for the entire bank, not each battery. I've had as many as a thousand batteries in the field all charging utilizing solar panels. The largest charger utilized 4amps. We had to inspect them annually and replace any faulty battery within 24 hours. So naturally we used the technology that provided the maximum charge while maintaining the maximum life of each battery. Quick charging a deep cycle battery will shorten it's life. Just did a quick Google search, Interstate, optima and charger manufacturer Waeco all recommend long and slow on their deep cycle batteries. Smart chargers that quick charge to 80% of the battery are referring to voltage not amp hour. Some volt meters have an amp hour setting, use it to check your boat's onboard charger. I think you'll be surprised at how slow the charger is recharging amp hours.

[papajoe222]

Thanks for the info guys. Old dog here. I just always assumed that a charger charged at a set voltage, never considered that them and the amps varied. Auto charge to me meant the charger would shut down on its own. Glad to learn something AND know there isn't a problem with my system.

[Jig Man]

Some beg to differ with your opinion. The "smart" chargers available will quick charge your batteries to 80%, gradually slow down the charge until it hits 100% and then go into float mode. The "Pro" series chargers are 15 amps per bank

 

That is what Dual Pro told me and on their web site www.dualpro.com it lists the 15 amp 3 bank like I have as 3 banks (15) amp per bank total (45) amps.

[retiredbosn]

That is what Dual Pro told me and on their web site www.dualpro.com it lists the 15 amp 3 bank like I have as 3 banks (15) amp per bank total (45) amps.

Are you saying your charger uses 45 amps? You do know that's not possible right? A standard circuit breaker is rated at 20 amps a gfi normally 10-15 which is any outside outlet garage included, so unless you have a special circuit dedicated to charging your boat the aforementioned example is impossible. Besides that your extension cord would melt trying to conduct that many amps, standard 14ga extension cords are rated at 15 amps. Like already stated automatic chargers list the maximum output they do not operate or charge deep cycle batteries at those amps. It would literally blow your battery apart.

[Jig Man]

I'm not saying anything.  I'm quoting Dual Pro.  Check the link.

[GPtimes2]

I read somewhere once that 1 AC amp = 10 DC amps. That's probably how chargers can get 45 amps from a 120 volt 15 amp service. It would only pull 4.5 amps. But there may be an efficiency loss that would bump that up a little. I could be wrong, just something I read somewhere.

[Wayne P.]

Are you saying your charger uses 45 amps? You do know that's not possible right? A standard circuit breaker is rated at 20 amps a gfi normally 10-15 which is any outside outlet garage included, so unless you have a special circuit dedicated to charging your boat the aforementioned example is impossible. Besides that your extension cord would melt trying to conduct that many amps, standard 14ga extension cords are rated at 15 amps. Like already stated automatic chargers list the maximum output they do not operate or charge deep cycle batteries at those amps. It would literally blow your battery apart.

You are getting input voltage/amps confused with output voltage/amps. There are NOT the same.

 

His charger OUTPUTS 45 total amps (15A per bank) at about 14V.

The Dual Pro chargers are separate chargers in a single cabinet.

 

My three bank Dual Pro does 10A per bank or a total of 30A 

 

I have a booster 12V charger that outputs 60A on the high setting.

 

These are examples of a multi-purpose chargers--no special circuit needed to use them;

 

http://www.walmart.com/ip/Diehard-80-20-10-2-Amp-Fully-Automatic-Battery-Charger-with-Emergency-Engine-Start/15140190

 

http://www.walmart.com/ip/Schumacher-SE-4020-200-100-40-10-Amp-Manual-Starter-and-Charger/15160138

 

 

This is the Dual Pro website.

 

http://www.dualpro.com/project/professional-series/

 

I guess the 4 bank 60A total version that boaters with 4 batteries use is way beyond your comprehension.

[retiredbosn]

That makes more sense, I was thinking 45 amps being drawn as a circuit. I was thinking input not output. Electricity is one of those things we take for granted without ever considering the science behind it. Its always amazed me that .2 Amp will kill you but .4 won't if someone is there to administer cpr.