Battery Question

[huntervasili]

Hey all Just wondering what the deal is with my trolling motor battery... I can charge it all the way to 100% but after an hour or so it goes down to 85% and it has done this a couple of times... any idea whats up? thanks in advance

[irishfield]

Sulphated plate! Try cranking the charge up so it boils for a bit.. then trickle again.

[cranks bait]

If it's a charger like mine, that is normal. Or at least that's what the instructions said (yes I read them). It gives an initial surface charge and then stabilizes itself and will go into the deep cycle charge.

[huntervasili]

So Wayne... ya mean stick it in a pot and wait for it to begin boiling? how long So charge at 12 A/hr till it goes all the way up and leave it? Its an auto charger so it'll turn off on its own to a trickle... Thanks!

[Mark Kulik]

How old is your battery Bill? also if you run the motor at high it will suck-up power pretty quick, a lot of the higher end motors have built in electronic energy saving system which prolong the use, make sure your terminals aren't corroded and tight, and always charge the battery as quick as possible after the fishing day, a disharged battery deteriorates quicker that a charged one-also make sure you us a deep cycle battery -they are built for this purpose, I use 3 large Interstates in my Triton, and power has never been an issue. hope this helps. Mark

[irishfield]

I was reading it as you charge your battery 100% and then once off charge it quickly drops to 85% charged (this generally shows a cell problem)....not a read out on an auto charger while still powered up. As Cranks points out may be normal for your charger... on high it first hits 100%.. then drops to trickle and slowly works it's way up again with the lower current now showing 85% as it works the last bit to top the battery.

[huntervasili]

Fairly new Deep-cycle battery... hasn't used up battery too fast on the minn... Just been sitting in the basement except for one top off (stored at 100%)

[huntervasili]

Used to show that it was at 100% I believe... basically I hook it up to the charger and it charges the last 15% in all of 3 or 5 mins... then after being off the charger for maybe 30 mins its back at 85%... should I drain the battery and recharge it maybe?

[irishfield]

Have you got a volt meter Bill ? Should show about 12.8 to 14.2 volts if it's fully charged. I know my on board... even if the batteries are fully charged... if I unplug and plug back in it will go thru the full sequence. Mine shows 5 green lights and then a red when fully charged. If I unplug, and then plug back in... even after fully charged they start all over again with 5 greens...working their way down to none and the red light to show fully charged.

Edited March 4, 2008 by irishfield

[huntervasili]

Only shows 14.2 when charging... my charger will measure the volts... only shows 12.7 when at a resting state... But i believe that is normal...

[irishfield]

I actually meant to put 12.8 to 14.2 volts.... differernt styles of batteries give different charged outputs. Odysey sealed batteries = higher voltage static. The only true battery test is a load test, but a bad cell will quickly have it showing about 10.5 to 11 volts. Maybe a local garage or marina will do a load test for you in hopes they can sell you a battery. Probably about the only tool I don't have in my arsenal here.

[Mark Kulik]

You can get a load test at a garage, .

[huntervasili]

Thanks guys... If I cant figure it out Thats what I will do...

[huntervasili]

now it holds at 90% lol what gives?

[danbouck]

You can buy a tester that puts a load on the battery from Princess Auto and I believe TSC. They run around 20 bucks. They always work great for me!

[bigbuck]

Canadian Tire will load test your battery for free. Just take it to the parts counter and they will check it.

[huntervasili]

Thanks guys... I guess thats the plan for today

[corvette1]

hey bill i run a four bank on board charger i have 4 31series batt 2 for the trolling motor 24v i only get two years good running when they act up i buy new

[boatman]

charge your battery fully and then disconnect it. Let sit for 24 hours and then take a reading with a volt meter. if its over 12.6V its at 100% charge. Don't go by the battery charger. That display is not accurate.

 

Also, deep cycle batteries need to be broken in. Its common for them to have a shorter life at first. They can develop a memory so recharge them after every use. However, its better to run them down low the first few times out.

 

Wayne is right about boiling your battery, but I doubt your auto-charger will allow that. If it has a manual setting then charge it manually and allow it to over-charge (bubble) for an hour. This will remove sulphation from the plates.

 

You should also be using a marine charger and not a standard automotive charger, but someone will probably argue that point. Deep cycle batteries are meant to be charged at a high rate (10A) up to about 90% charge and then slowly drop down the charge to about 2A until at 100%. Automotive chargers do not precisely charge above 90% and may actually shorten the life span of a battery. Again someone will dispute this, but I've seen it dozens of times in our battery charging lab where someone has destroyed an expensive battery with the wrong charger.

Edited March 5, 2008 by boatman

[huntervasili]

Thanks guys... I will do that, and after resting for a couple days it stays at 12.7V... Maybe it is good to go still... So I should charge at the 12A setting till almost full then switch to 2A if I can remember? Also is it bad to use the battery to start up my car when the Battery is dead? It works life a charm but don't want to use it if it'll mess ir right up. Thanks

[boatman]

12.7V is 100% charge on a flooded battery, which is likely what you've got. Its best to charge on auto, but you should recharge manually at least once a year to boil the plates a little. Just don't do it for too long. I do it once in the spring.

 

For interest sake. The relative state of charge (SOC) of a flooded battery is as follows.

 

100% 12.65V (can be as high as +13V)

75% 12.45V

50% 12.24V

25% 12.06V

0% 11.89V

 

The SOC test is a good reference point, but not as definative as a load test.

 

PS. It is not recommended to use your deep cycle battery for starting, but lots of people do it with no ill effects.

Edited March 5, 2008 by boatman