All summer I had 4 car batteries (in parallel) charged by solar panels, now the sun has reduced I tried to charge them with a charger but it tells me the batteries are no good now. I thought the deep cycle batteries would be ok. The system is only used to power 12v water pump to water my plants in the greenhouse. The charge control(s) are supposed to make the batteries more efficient Do I need to use special solar batteries?

  • \$\begingroup\$ Your question lacks any serious research done by you. You thought deep cycling batteries is OK. Why? Charge controllers making batteries more effcient, uhm the name is Charge controller so they control the charging. How would that make things more efficient? Solar batteries I've never heard of those. <some Googling> OK, they're basically ordinary Lead-Acid batteries with a "solar battery" sticker on them and an increased price. If you want to do/be/talk technical, fine but then know what you're talking about. If not, educate yourself instead on relying on (wrong) assumptions. \$\endgroup\$ – Bimpelrekkie Nov 7 '17 at 9:32
  • \$\begingroup\$ Are the four batteries simply connected in parallel? Are you actually trying to charge all four at once in parallel from a single charger? \$\endgroup\$ – Finbarr Nov 7 '17 at 11:08
  • \$\begingroup\$ Those poor batteries... \$\endgroup\$ – Voltage Spike Nov 8 '17 at 23:10
  • \$\begingroup\$ Thank you for your comments, yes I have only just started researching this, you have helped me a lot. \$\endgroup\$ – Philip Holden Nov 10 '17 at 9:28

The charge controller optimises the way the batteries are charged from the solar panels. It doesn't actually make the batteries more efficient.

Did you disconnect the charge controller before connecting the charger? If not, that may have confused it.

Deep cycle batteries are more forgiving of being discharged than normal car batteries, but if they have been left flat, or almost flat, for several days then they may have been permanently damaged.

You might have some luck using a dumb, old-fashioned battery charger - one that won't tell you the batteries are no good. If possible, set it to trickle charge and leave it for day or so. But if the batteries are dead, that won't magically fix them.

Is there actually such a thing as a "solar battery", or is it just a deep cycle battery with a different label stuck on it?

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  • \$\begingroup\$ Thank you, yes I will try the older type of charger, your comments have helped me greatly. \$\endgroup\$ – Philip Holden Nov 10 '17 at 9:29
  • \$\begingroup\$ I have only just joined this blogg so bear with mek if there is anything I should do to give you credits \$\endgroup\$ – Philip Holden Nov 10 '17 at 9:30

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