Originally Posted by Stingo
I had a similar problem and someone that claims to know his way around electrickery, suggested that I fit a battery desulfator to my five year old bank of batteries. It's made a huge difference eg before fitting the desulfator, with the engine running, my link 2000 reported 13.2 volts while charging. It now charges at over 14 volts.
Apparently, these magic boxes send out a pulse that breaks down the sulphur build up on the battery plates and then dissolves it back into the battery water, where it should be. My desulfator cost $49, which is a whole lot cheaper than buying
a new bank of batteries.
I vote best answer on this one by Stingo
Lead-Acid batteries *hate* to be discharged below 50%. It causes sulfation on the plates and this reduces the batteries' overall capacity and the maximum voltage. A battery charging system that goes based on amps will register the battery as fully charged because the battery wont take any more amps, but sulfation on the plates mean that you will drop below the optimal voltage faster, hence, your batteries will appear to be dead.
I bought a 1.1A "smart charger" for $49 at Canadian Tire for my boat battery. It has a 7 step charging process one of which is "recovery" for below 50% charge where it does pulse a low amount of current to desulfate the battery. If you are regularly killing your batteries you'd probably want to get a much more powerful one so you can use it as your main battery charger
, say a 10-15 amp model, but my boat sits at the dock
connected to shore power
7 days a week in the offseason and usually 5 days a week in the sailing season so the amount of time it takes to fully charge doesn't matter to me.
When I first connected the smart charger to my battery my regular charger indicated that the battery was at 75% charge. The smart charger indicated under 25% and entered recovery mode.
Sympoms that my battery was sulfated and neeeded reconditioning on my boat were with the battery at full charge: Turning the stereo too loud when it would thump a deep bass kick would have the stereo turn itself off. Turning on multiple incandescent lights (I gotta get those replaced with LEDs this season) each successive light turned on would dim the others. Music
would cause the lights to fluctuate with the beat. The battery would seem to die quickly even after a full charge. My 8HP outboard
outputs a 1.5A charge and despite leaving the dock
with a full charge and running the motor
to get around it never seemed to have much effect at keeping the battery topped up ( I know a 1.5A current would take forever to actually charge the battery I did the math once ). The battery seemed to die quickly even when fully charged and the only current drain was maintaining the GPS's waypoints in memory with it turned off.
I bought two of the smart chargers, one for a truck that I dont drive much and one for the boat. Well worth the buy much cheaper than buying batteries after killing them from overdraining them.