dead battery?

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answer3

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Hi guys
I have a 1 year old 122amp h marine deep cycle battery that I use for my trolling motor and a minn kota MK105P portable charger and have been using this setup for 1 year with no issue at all. But when I wanted to charge my battery about month ago the charger was charging for 5 seconds and stopped for 5 seconds and so on until I unplug it. I measured the voltage it is 12.4v so probably ~70% charged, but I cannot charge it further to 12.7v... I tested another 12v deep cycle marine battery which is charging perfectly fine up to 12.7v and the charger does not do this weird on-off cycles at all, so I assume that the charger is ok and the issue comes from the battery. I checked the electrolytes levels by opening the caps and they all seem ok. Does anyone know what is wrong with the battery? did this happen to anyone before?
Thanks
Damien
 
So the charging led is going on and off every 5 seconds. Are any other led's coming on? Is the battery disconnected from the trolling motor and everything else? This may also be a desulfate mode operation on the battery. You might want to try a different charger on the battery or take it somewhere else for a quick charge. Some auto parts places do this for free and will load test it for you too.

Tim
 
there 3 leds on the charger: "charging", "charged" and "check connections". The "charging" led in on for 5sec then the "charged" led is on and so on... no other leds. I disconnected the battery from the trolling motor and even tried without the fuse and the circuit breaker, it is the same thing.
 
My bet is, its charged.

Try hooking up the battery and running something on it to discharge the battery. Once drained, try recharging it.
 
:twisted: More than likely you have a sulfated battery. Nothing you can do but replace it. Never let a Deep Cycle battery wear down. You must keep it charged.
 
Most batteries have a 1 year warranty. If you still have your receipt, you may get a free replacement.
 
huntinfool said:
My bet is, its charged.

Try hooking up the battery and running something on it to discharge the battery. Once drained, try recharging it.


It worked! I run a trolling motor for 3 hours on the battery to discharge it and charged it back and the charging cycle went perfectly well. It is now fully charged.
Thanks for the tip!
 
try testing each cell of battery with a battery hydrometer. if you don't have one , they are cheep at any auto parts store. it floats a bunch of colored balls in its tube and this tells you % of charge on each cell. if one is a lot less than others it the problem. but befor replacing battery , turn something and draw the battery charge down some and then try to charge it again and re test. if still bad replace the battery. hope this helps.
 

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