On Sun, 24 Dec 2006 12:15:20 -0000, "rigdent" <[EMAIL PROTECTED]> wrote:
>Richard thanks for your interest , you asked >> >> What type of batteries are they? > >dont know thw brand but they are four off 6V deep discharge wet cell >lead acid batteries of 200 Ah each in as series parrallel arrangement >to give 12V 400 AH. > >> How long were they left at a discharged state? > >I dont think they were left discharged but rather they were >insufficiently charged but a faulty alternator whch was only getting up >to about 13.8V and putting out a few amps. I beleive that were taken >from say 75% to 50%. We monitor the batteries with a volt watch and >should stp discharge when the 11.5V light comes on > >> How many batteries in the house bank? > >four batteries 6V in series parrallel > >> You say 14.6v under charge did you leave them long enough to get to >> float ? >No I shut off the engine after a few minutes once the 14.6V light came >up on the voltwatch. But they had been on a 4A mains charger for a >week. the charger was at 14.6V and was putting in about an amp. > >Nb Maximus is run by a syndicate so i dont know exactly what has been >going on but from reports the battery capacity has been declining over >tha past 3 months or so. I'm guessing that the alternator has been >faulty for about that long. >> > >Hope that gives you some clue to help diagnosis > >Regards > >Terry Ok if it was me I would 1 mark them as series pair A and B 2 Get them off the boat and on the bench. Ensure acid is over all plates. 3 Charge pair A at 14.4v with a 10amp plus charger until the current falls to less than 5amps (14.4 at the battery). Top up all cells to correct level with distilled water. 4 Increase charge voltage to 15 or 15.5v and continue to charge until current dropped again to less than 5 amps then leave on charge for another 10 hours 6 Take off charge top up all cells and leave for a day 7 Discharge with a 120w load (say 6 off 20W 12v halogen lamps in parallel) and monitor time to about 11.5v. Note time for the pair 8 Repeat from 3 9 Compare first time to second, was there an increase? if yes repeat from 3 until no appreciable increase in time. 10 Repeat 3 to 6 to ensure bank left charged 11 Do the same with bank B Warning. Monitor the bank temperature through charging or discharging and stop if any battery gets hot Warning. Ensure charger is OFF before connecting or disconnecting. Make connection to battery before connection to charger or load. Make this connection AWAY from battery - NO sparks near battery top!!!! Assuming that your load is about 10A then the hours from "Charged" to 11.5v should be approx 16.4 hours (205 * 0.8)/10 If it is say 10 hours then the bank capacity is very approximately (Hours * 10)/0.8 = 125Ah Manufacturers suggest binning batteries less than 80% of original capacity. (164Ah or 13 hours in your case) After reading all of the above you may decide that it is simpler to just sort out your alternator and fit new batteries!!!! E & O E Richard Nb "Pound Eater" Parkend G+S
