Lead Acid Batteries
Lead acids. Have you checked to see it they come up with a reverse charge?
This is something that is quite safe to do to a Lead acid (but never a Nicad as they explode), as this is how the original batteries were made.
There are 2 types of lead (Pb) sulphate that is formed on flat batteries, the first type is conductive and allows normal recharging, the 2nd type is hard lead sulphate that just insulates the cell plate and inhibits normal re-charging unless very high voltages (>5V/Cell) are applied. But reverse charging (with a suitable current limiting lamp in series) will break down the hard sulphate immediately. A couple of charge/discharge cycles will then bring back a heavily sulphated battery to near normal capacity.
DRY?? The so called dryfit batteries are actually wet types with a clever seal. They are just as susceptible to loss of water by over-charging and warm temperatures as wet batteries are, but you're supposed to throw this type away instead of topping them up!
However, closer examination of the top of dryfits will show a glued cover over a set of 6 rubber cup caps that, if removed, will let the cells be topped up as normal. Only some success is possible with this method, as over-charging usually destroys the lead frame in the +ve plate as well and it falls apart.
Cycle charging up to 14.5V (6 cells), 13.8V standard infinite float charge, but 13.5V MAX on sealed cells.
Tony, G8TBF says there is another way to recover batteries that have gone high
resistance due to being left idle for long periods. Connect a bridge rectifier across the battery, + to +, and supply this from a 240V AC source in series with a 15W or 40W light bulb. The supply should preferably be from an isolating transformer..... 73, Tony, G8TBF.
73 De John, G8MNY @ GB7CIP
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