Friday, October 09, 2009

Battery de-sulphuring device

So there have been a few questions about my de-sulphuring device, which I posted on some time ago.

Rob, how are you getting on with yours by the way?

Anyway, my battery refresher, or de-sulphuring device is still very much in use.

I see it's been over a year now and the batteries are still steadily improving. It has been a long, slow process. Longer than expected I suppose.

Please bear in mind here that the refresher needs at least 25.6 volts before it starts working. To get this voltage needs either a really strong wind for the wind generator to keep the voltage up or for me to run the generator. It is impractical for me to run the generator for more than say 10-15 hours a week, so the refresher does not get that much opportunity to actually work.

Obviously as time goes on and the battery improves, so the refresher works for progressively longer because of the wind generator.

Initially, the batteries took ages on the charger to get up to 25.6 volts. With the generator off, the wind generator could not keep this up at all, even in a stiff breeze.

Some time later, achieving above the magical 25.6 volts was faster, but as soon as the charger was turned off the voltage dropped - even with no load. The wind generator could still not keep up, except in a really strong wind.

Before the new inverter/charger, 25.6 became easy to hit and the voltage stayed above this for say half an hour or so, with no load, before dropping off again. The wind generator needed a really good breeze to keep up.

With the new inverter/charger the voltage stays above 25.6 with the fridge and a few small lights on for about half an hour. I suspect that's down to a combination of both the new charging regime and the inverters no load efficiency.

The wind generator is away getting serviced at the moment, more about that later, but on it's return I would expect it to now keep that voltage above the magical 25.6V relatively easily.

A new voltage trace would be both interesting and definitive. I'll have to see what I can come up with...


  1. Anonymous6:27 PM

    Your batteries are F-ing enormous. You have a nominal 920Ah x 24V = 22KWh.

    I am curious if you have worked out from the various current/SOC/voltage formulas what your actual capacity is in these cells.

    Some calcs might reveal if you are getting anywhere near the nominal 920Ah. You might find that replacing the lot with a set of 200Ah golf cart batteries would be economically advantageous.

  2. Hi Anonymous

    Yes, they are large, but very old.

    I don't know of any formulae for calculating the actual capacity, so would be interested to know more.

    In terms of replacing the existing set, while they still work ok I want to avoid spending the money on replacing them.

    Replacing those large batteries will be a logistical nightmare in terms of removing and disposing of the heavy old ones!