Advice on batteries--I am accused of being paranoid but!!!
I have a 43 two years old french built, sailed in Solent and south coast/channel Uk and had the lead acid service batteries replaced after 6 months under warrenty as they were not holding charge. replacement are Exide EF1453 proffessional lead acid 145 amp hr and two off. On investigation the Dolphin charger had not been set up for lead acid.
I am on a mooring and have a Rutland 413 wind generator which delivers 2amp in 20knots of wind. I also have a sonic anti fouling device (built from kit obtained from Austarlia) which draws 300 milli amps ie about 8 amp hr per day. Usually the wind generator keeps up with it but I am down at least once a week and run the engine if necessary. Have an Adverc voltage regulator with an 80amp Hitachi alternator. battery has never been below 11.9v or 60% capacity as measured by NASA Clipper battery monitor.
Last week the charge when topping up after a day at anchor with the fridge on --approx 70 amp hr--I noticed the charging current was only 60 amp for approx 10 min and then dropped off fairly quickly. Usually the charging current os 75 amp for up to an hour before it starts to drop off as the regulator cycles.
checked all connections etc and took specific gravity of cells. It transpired that the cells had stratified with 1.2 sg at top and 1.3 at bottom. can't get any reason for why they should have stratified and have been adviced to run charge at 14.8 volts (can do this by removing voltage sensing lead from regulator) and to gas the batteries for 30-45 mins which I am told will stir up electrolite and restore the return the batteryies to their normal capacity. All the normal precautions re gassing cells and removing tops and ventilating.
Any ideas on what could have caused stratification and whether gassing for a period will resolve and restore condition.
Don't really want the expense of fitting AGMs as these batteries are only 18 month old. Had thought of upgrading batteries after about 4 years not two.
Any advice or solutions gratefully received.
Michael Boyle--Barti Blue
The Exide EF1453 batteries are listed as starting batteries in the manufacturers literature. If you're using them as your house bank that might be the root of your problem.
If your wind turbine is only making 2 DC amps at 20 knots and the boat is out on a mooring thats not helping the batteries either. Especially if theres a constant albeit small load. As far as overcharging them for 45 minutes to help stir up the batteries I don't think thats going to be of any use. Most guides to equalizing batteries recommend an 8 hour time period.
I'm sorry to be so negative but I think you're going to have to change the batteries to deep cycle batteries. A wind turbine that actually puts out some amps would be a big help as well.
is the ventilation good where the batteries are ? when toping batteries off are you using sulfuric acid .......lead acid batteries come back to life [so to speak ] when drained and refilled with sulfuric acid