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DBJones
DBJones

Posted: Thu Mar 13, 2014 10:16am

Post Subject: Both Starter Battery and Leisure Batteries have failed

Hi Tony, Just over a year ago I installed a new starter battery and a Stirling Pro charge U 20amp battery charger. About 2 and 1/2 years ago I also installed a new set of 4 x 110 amp leisure batteries. About a month ago the starter battery failed due to a cell failure which was replaced under guarantee . We have now set off on a 3 week trip and the leisure batteries would seem to be failing. They seem to charge up ok but as soon as we switch the heating after about 10 minutes the battery voltage drops from about 12.2volts to 10.3 volts. I do not like coincidences and wonder if the charger has in some way damaged the batteries. The charger does have a De-sulphation / equalization cycle of 15.5 volts. Is this causing the batteries to fail. As regards the 4 leisure batteries, could they have all failed or is it perhaps just one which would need replacing. Al always many thanks for your help and advice

Tony-B
Tony-B

Posted: Thu Mar 13, 2014 12:24pm

Post Subject: Both Starter Battery and Leisure Batteries have failed

First of all you only identify the batteries as “leisure” and that is far too general to allow me to identify the exact type. If they are in anyway sealed then the charger should have been set so it does not carry out any equalisation charging. In fact ideally equalisation should only be done on wet open cell batteries under manual control where the battery temperature and cell specific gravity are tested each half hour and the equalisation stopped when either measurement indicates it is necessary. As a fully charged battery should have a rested voltage of about 12.7 to 12.8 your figures do suggest either a faulty cell or extreme sulphation. That sulphation could well have taken place between the time you fitted the batteries and the time you fitted the charger. Something prompted you to buy the charger – was it loss of battery capacity by any chance? Once sulphation has hardened even 15.5 volts will not be enough to reconvert it to lead oxide. In fact 2 ½ years for domestic batteries with no external charging is a fair life when one considers the lack of care and charging many boaters apply to their batteries, especially at the cheaper end of the market. You need to take each battery out of the bank in turn (or all at once if you can take them home) and charge it until the charger deems it is fully charged. Leave it to stand for 24 hours and measure the voltage. If it is less than about 12.7 then you can assume the battery is faulty. Let it stand for about another week and retest the voltage. If it has dropped then again it indicates a faulty battery. If they all pass this test then its sulphation so the bank needs changing. This does not test the remaining battery capacity, only the condition of the cells. If they are wet open cells then you can use a hydrometer at any state of charge as long as you have not recently topped the cells up. If any cell differs by more then 0.03 from any other that cell is faulty as it will be if the liquid is coloured or an individual cell gasses when on charge. Only then use the coloured bands to assess the state of charge. Please be aware that in general leaving batteries on charge with a PROPERLY SET multi-stage charge is a good thing but once they start to fail it can speed up the process. I trust that this helps you understand what may be going on but I can not help more without knowing the battery type and how you have looked after them from new. Tony Brooks

DBJones
DBJones

Posted: Tue Mar 18, 2014 10:10am

Post Subject: Both Starter Battery and Leisure Batteries have failed

Hi Tony, As always many thanks for such a comprehensive reply. The batteries are standard wet flooded . The reason we got the charger was that as we are selling the house there is a high probability that we would be moving full time onto the boat. Generally speaking for most of the time the batteries have been charged of the engine when we have been travelling (12 weeks per year) altohough for the least few months they have been charged off the mains. On the battery charger it would seem that the De-Sulphation / equalization cycle is selected automaticlly as per the battery type. On a new set of batteries which now seems likely do you think it is ok to leave the set up as is or should we try to switch off this part of the charging process. Many thanks again for your help.

Tony-B
Tony-B

Posted: Tue Mar 18, 2014 2:02pm

Post Subject: Both Starter Battery and Leisure Batteries have failed

First of all please do not take De-sulphation cycle to be any more effective that what charging at a higher voltage would be. If that cycle or even normal charges superimposes a high frequency pulse onto the normal charging current then there is some evidence that in some cases it may help break down sulphation but in other cases it seem it may destroy elderly batteries. As far as I can see the main thing it may do is to reduce the size of the chemical crystals within the plates but to what end I have no idea. As an elevated voltage will in itself convert more lead sulphate to lead oxide than a lower one so marketeers imply an equalisation charge has special characteristics that reduce sulphation. This is misleading because any high voltage will do it. Charging a wet open cell battery at anything much above 14.4 volts for lead-antinomy plates or 14.7 to 14.8 volts for lead-calcium plates will cause the cells to gas so they need regular checking and topping up as required. If you do not do this then one or more cells will dry out and fail very quickly. I would prefer it of you can manually trigger the equalisation charge every four weeks or so and check the electrolyte before and a day later. If not you may be able to set it for every 30 days or some such, in fact it may already be set like that. Otherwise I would be very reluctant to let it equalise every few days. Remember I warned you about leaving faulty/worn batteries on permanent charge and please take heed. If there is any doubt about battery condition simply turn the charge off when you leave the boat. Certainly turn off the equalisation setting. Its not so bad if you are on the boat because normally before a cell explodes it produces a hydrogen sulphide gas that tarnishes all the brass and copper on the boat. It also smells of rotten eggs. As long as you check the batteries regularly you can leave equalisation enabled unless you suspect cells are beginning to fail. I would not leave it enabled if I was away from the boat for months on end but with good batteries I would leave the charger turned on.

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