Hi all, hope you are all well.
I have a (now aging) off-grid system that comprises of 24 lead-acid batteries, a solar system and backup generator.
Not completely unusual, but I have noticed that the voltage dropping (from 48v) more quickly in the last few days.
As I say, not completely unusual as when there are periods of prolonged colder weather, this does seem to happen. But I have noticed the generator kicking in much more in the last2-3 weeks.
As I say the batteries are aging but up to this point have been fine for my needs.
Is there a way of testing each battery? Presumably each will produce around 2v. I’m not that inept that I can’t use a volt meter, but the terminals on the batteries seem to have covers on them.
If your weather is anything like Southern England then you’ve probably not been charging the batteries how they want. They may just need a long absorption charge and then an equalisation, making sure the water is topped up. When fully charged you could check each cells SG with a hydrometer and see if any cells are weaker.
But I see you have a mish mash of random cells, so it could just be all a bit unhealthy and irrecoverable if they have all been thrown together like that for a long time. I don’t look back at my old 2v Pb cells since moving over to LFP!
Thanks for this. You have opened up a whole new world of learning thinking about the SG of the batteries. Never occurred to me.
And yes, they are as I say, aging. The 3 lighter coloured ones have been in for at least 7 years and the others 10. I inherited the system when I bought this place (in the Peak District) and I am in the process of scoping out upgrading it all.
It was originally installed by Off F=Grid Energy but they seem to have disappeared off the face of the earth, and finding someone trustworthy around here isn’t easy. I have had a couple of ‘start-ups’ look at it but they didn’t have the depth of experience (they seem ok as long as it is a pre-packaged thing they can put together, but have not ability for lateral thinking).
Any recommendations for who might be good around here would be welcomed too.
I have ordered myself a hydrometer – so I guess the question is, what sort of level of pH am I looking for in each one?
And yes, I have been looking at LFP. I have the money to invest in a new system and now is the time to do it, but I am still wholly reliant on the old until the new is installed.
Hopefully you’ll be measuring the Specific Gravity, pH should be 5-7 but not as important for seeing cell health as the SG. Just remember PPE, acid will corrode your skin and clothes!
If you can’t find the original data sheets for your cells, have a search for Hoppekke, Bater, Zvei etc 2v lead acid data sheets and battery care instructions.
TBH you can probably nurse your cells for now with a decent full day (12h) charge with 4h+ absorption and then 1-2h equalise charge, start the genny before the sun gets going on a day you know will have some sun, then let solar finish off, but you probably will need a good equalise charge if they haven’t had one in a while, (once a month or so) but I’d be looking to save up and build some LFP batteries or buy a DIY cell kit from Alibaba if you can’t afford off the shelf rack batteries etc. Look on diysolar forum for research or just go to Fogstar in the UK for their Seplos etc kits, not perfect but a good and cost effective way of going LFP and closed loop communications with Victron.
