charging a deep cycle

How many amps does the charger seem to be supplying - does it have a guage? Take it off charge and let it "rest" for an hour or so. Take a voltage reading then....

Mine reads 13.2 when charged. Are you using a smart charger?

75 a/h is a lot for a normal charger to charge, it will take ages. As a rule of thumb, the longer a battery takes to charge, the better condition it is in becuause it is accepting more charge. I have had 4amp chargers take more than overnight to fill a large battery in good condition. One more thing, if the battery is stuffed it may never get to the voltage the charger is set to cut off at say 14v. This means the charger will never stop, i had a battery left to charge over a weekend in a factory fill the whole place with hydrogen gas, bubble the battery to bits and almost knock us out on the way in monday morning. This is becuase the battery was damaged, and the charger just kept filling it up.

hi mark do a lot of beach camping with deep cycle batteries and found the best way to gauge batteries is with a muti meter you will get a spot on read no mistakes 11.5 dead flat 13 to 13.5 fully charged depending on how good your battery is . buy a good cheap muti meter one from tandy or dick smith or even super cheap auto.but a good one will last you forever. dags

thanks for the responses,

my battery charger is only 4 amps so didnt seem to have the grunt, went to Bunnigns and there chargers same size as mine were not rated to charge a 75Ah battery. This was the same brand as mine, but a few years newer.

Borrowed my mates charger that can go all the way to 7 amps and it seems to have charged it up pretty quick.

Am currently runnign the fridges to see how long it lasts to get an idea of whether the battery is stuffed or not.

Then i will recharge it again.

Mark

omn
i have had a brand new 75a/h deep cycle for several weeks went for a trip checked the battery every morning after use [ fridge etc] sometimes down to 12v , 11.8, 11.4 after recharging from alternator went to 13.4v every time (exide) hope this helps

cheers

Mark, if the battery was at 11.1V for any length of time before you started charging it it is truly dead. Yes, it would take ages to charge and you may be able to resurrect it, it also may need desulphation before it regains a decent capacity.
You really won't know its present charge state until you take it off the charger, let it first rest over night then connect the 12V fridge or a light, then measure at the terminals. If it measures 12.6V it has come good.
Do youself a favour and NEVER let deep cycle batteries drop below 12V before recharging, they will reward you with a much longer life.
Klaus