Graham Nash Posted April 4, 2012 Report Posted April 4, 2012 I have recently fitted one of the new batteries to my project and before spending my remaining leg on another I wondered how would I know whether my old batteries (that I have lying around all over the place) are dead or just flat?? I have one that is giving just over 8 volts one about 9 volts and a couple around 11volts. All of them are a little low on fluid. Do I just stick some distilled water in them and charge away only to find that it is beyond repair or is there some magic way of telling for sure whether they are worth charging or chucking? Thanks. Quote
duncan Posted April 4, 2012 Report Posted April 4, 2012 they all sound dead to me - unless they have been recently left attached to a load and 'just gone down that low' I wouldn't personally trust them on a boat for anything beyond the cabin reading light. as to testing - you need to top-up, fully charge with a proper charger then - 1. leave 24 hours and re-check the voltage should hold 12.8 2. if the above it good then maintain a voltage test under load for a few seconds, and re-check voltage afterwards. Shouldn't drop too much under load and should recover to previous voltage reasonably quickly. if you have a hydrometer you can test the SG after trying to charge instead. Quote
Graham Nash Posted April 4, 2012 Author Report Posted April 4, 2012 Bin it is then Duncan. I dont want any problems while out there, certainly not for the sake of Quote
Mike Fox Posted April 4, 2012 Report Posted April 4, 2012 I've got a pair of 110 amp "domestic" batteries on Frisky that have been charged regularly for 10 years and are now holding 12.6V at rest...Sounds like despite the care, they might be on their way, mind, I guess 10 years is good. The starter battery is about 12.8V, but is only a year old. Good idea about discharging and then trying voltage check again. Will try that over the weekend Mike Quote
great white Posted April 4, 2012 Report Posted April 4, 2012 Best way to know is to charge them up and put a discharge tester on them I did that at Christmas to mine to find out which one of the three was weak, answer was all three That hurt financially, but at least in the coldest of weather I knew that my engine would go. Charlie Quote
niggle Posted April 4, 2012 Report Posted April 4, 2012 If anybody wants them tested after they have been charged,I have a discharge tester. So pop in to Nuffield Motors and I'll test them FOC Nige Quote
duncan Posted April 4, 2012 Report Posted April 4, 2012 I've got a pair of 110 amp "domestic" batteries on Frisky that have been charged regularly for 10 years and are now holding 12.6V at rest...Sounds like despite the care, they might be on their way, mind, I guess 10 years is good. The starter battery is about 12.8V, but is only a year old. Good idea about discharging and then trying voltage check again. Will try that over the weekend Mike mike, if they are holding 12.6 over a reasonable time, say a week, then they sound pretty good; your charging system may not be getting 'everything' into them as well (but I suspect that yours will be smart and matched). Quote
mw Posted April 4, 2012 Report Posted April 4, 2012 Mike look on you tube for lead acid battery recharging they say adding epson salts and distilled water mark w Quote
Coddy Posted April 5, 2012 Report Posted April 5, 2012 Graham If you need to check your batteries I too have an electronic tester that I use all the time. It soon tells you what its state is. Give me a call and I can pop over most times. Dave Quote
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