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Lead acid... it's dead isn't it?

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tszaboo:

--- Quote from: paulca on February 24, 2021, 02:31:01 pm ---Enersys Cyclon batteries

Ouch!  12V 25Ah is £400+

--- End quote ---

That is more than what I remember. Maybe I had bulk pricing.
I am genuinely sorry.

bdunham7:

--- Quote from: paulca on February 24, 2021, 01:13:17 pm ---Sorry, to be clear, I was considering fully charged to be when the charge controller switches from boost, 14.40V to 13.60V float. 

Heres is the chart for 2 days.  The min value 12.11V occured when the 15W load was occuring.  The left side shows what I considered the battery getting somewhere close to fully charged.

--- End quote ---

Your battery needs a good boil.  It's probably sulfated and has an internal impedance that is now way too high--you're just getting a 'surface charge' on it.  If you have the means, connect it to a charger or power supply that can supply 10 amps and force it to take 10 amps up to a limit of about 16 volts.  If it won't take a full 10 amps, just leave it at 16 volts.  You should see the current ramp up to 10 amps (if it wasn't there already) then you'll see the voltage start to go down.  Or, you'll see just one cell start to boil, in which case you battery is likely done.   If that works, give it 10 amps for 16-20 hours starting from the time that it actually takes the 10 amps.  If this works, you won't be able to raise the battery voltage back up beyond 15 volts with a 10 amp charge.  You probably want to do this outside and not near flammable objects, sources of ignition or things that would be excessively bothered by acid fumes.

tautech:

--- Quote from: bdunham7 on February 24, 2021, 11:35:24 pm ---
--- Quote from: paulca on February 24, 2021, 01:13:17 pm ---Sorry, to be clear, I was considering fully charged to be when the charge controller switches from boost, 14.40V to 13.60V float. 

Heres is the chart for 2 days.  The min value 12.11V occured when the 15W load was occuring.  The left side shows what I considered the battery getting somewhere close to fully charged.

--- End quote ---

Your battery needs a good boil.  It's probably sulfated and has an internal impedance that is now way too high--you're just getting a 'surface charge' on it.  If you have the means, connect it to a charger or power supply that can supply 10 amps and force it to take 10 amps up to a limit of about 16 volts.  If it won't take a full 10 amps, just leave it at 16 volts.  You should see the current ramp up to 10 amps (if it wasn't there already) then you'll see the voltage start to go down.  Or, you'll see just one cell start to boil, in which case you battery is likely done.   If that works, give it 10 amps for 16-20 hours starting from the time that it actually takes the 10 amps.  If this works, you won't be able to raise the battery voltage back up beyond 15 volts with a 10 amp charge.  You probably want to do this outside and not near flammable objects, sources of ignition or things that would be excessively bothered by acid fumes.

--- End quote ---
This ^
Decent solar controllers have an Equalise function that you would normally set to automatically run once per month.
RTFM to see if your controller has such a function and engage it.

paulca:

--- Quote from: tautech on February 24, 2021, 11:55:11 pm ---
--- Quote from: bdunham7 on February 24, 2021, 11:35:24 pm ---
--- Quote from: paulca on February 24, 2021, 01:13:17 pm ---Sorry, to be clear, I was considering fully charged to be when the charge controller switches from boost, 14.40V to 13.60V float. 

Heres is the chart for 2 days.  The min value 12.11V occured when the 15W load was occuring.  The left side shows what I considered the battery getting somewhere close to fully charged.

--- End quote ---

Your battery needs a good boil.  It's probably sulfated and has an internal impedance that is now way too high--you're just getting a 'surface charge' on it.  If you have the means, connect it to a charger or power supply that can supply 10 amps and force it to take 10 amps up to a limit of about 16 volts.  If it won't take a full 10 amps, just leave it at 16 volts.  You should see the current ramp up to 10 amps (if it wasn't there already) then you'll see the voltage start to go down.  Or, you'll see just one cell start to boil, in which case you battery is likely done.   If that works, give it 10 amps for 16-20 hours starting from the time that it actually takes the 10 amps.  If this works, you won't be able to raise the battery voltage back up beyond 15 volts with a 10 amp charge.  You probably want to do this outside and not near flammable objects, sources of ignition or things that would be excessively bothered by acid fumes.

--- End quote ---
This ^
Decent solar controllers have an Equalise function that you would normally set to automatically run once per month.
RTFM to see if your controller has such a function and engage it.

--- End quote ---

It does have an equalising mode and I believe it's set to default.  I have seen it charging the battery to just over 15V but only rarely.

If I try this 16V 10Amp thing on a sealed battery, surely it's just going to force it to vent... assuming it has a suitable vent.

Ian.M:
As a fellow pessimist, "What could possibly go wrong?"

If the vent is restricted, (it *shouldn't* be but do you care to bet?) there's a risk of gas pressure buildup causing the casing to warp, which has a tiny risk of one of the links breaking loose, sparking and *BANG*!

Equalize it outside with the battery in an open weave cloth sack (not mesh or plastic film coated) to contain any explosion but still let gas freely escape, in a catch-tray for any acid escape on a surface you either don't care about or that is acid resistant.  Wear appropriate PPE, have a large pack of Bicarbonate of Soda handy for neutralizing any acid spills, and have clean water (e.g. several 2L bottles of still water) immediately available for personal washdown!

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