Flogging Dead Batteries.

[LDVV]

I have a decent Epever Charge Controller, and some spare panels.

I'm wanting to try grow some food at the back of our house (there is a room which is a lot like a greenhouse, but sun is limited).

As I'll be using 12v devices (water pump, LED lighting), I won't need an inverter.

Is there some way that I can use one of my old "retired" batteries that no longer holds a charge (it was run flat too many times)? Can I just use it as I would a healthy battery? It's liable to combust, vent excessively, or something else, is it?

I only care for running these devices while the sun is up anyway, I don't care for power at night.

 

[Rednecktek]

As long as the battery will hold enough charge to keep the SCC active you'll basically get as much power as your panels can produce. I've had batteries that dropped to less than 8v as soon as the charger was taken off regardless of how long it sat charging, so that battery wouldn't work. Charge your battery and see how much charge it holds after being fully charged for a couple days, then let it sit for 24 hours and see what's still in the tank.

 

[LDVV]

As long as the battery will hold enough charge to keep the SCC active you'll basically get as much power as your panels can produce. I've had batteries that dropped to less than 8v as soon as the charger was taken off regardless of how long it sat charging, so that battery wouldn't work. Charge your battery and see how much charge it holds after being fully charged for a couple days, then let it sit for 24 hours and see what's still in the tank.

Right, I'll try that.

I was using this battery (attached image) as a second battery in my Van. However, I noticed too late, that one of the audio amplifiers must've been draining it even while not in use.

Now it will go to full charge, but ~24 hours later it's down to around 10.6v.

Even though it won't hold charge, could it still be used for my specific purposes? It's only needed during sunlight anyway.

 

[Rednecktek]

Ooohh... that is rrriiiggghhhttt on the line of maybe. You can throw your SCC on there and see if the screen stays lit for 24 hours or not. If it does you can probably milk it a bit longer, but for certain connect up your sprinklers and lights to the LOAD port on the SCC so it shuts them off BEFORE the battery is completely dead.

That battery is a 50Ah lead acid which is about the same usable energy as a 25ah LFP battery. You can get a 20Ah for about $40 which is probably cheaper than a 50Ah lead replacement if it doesn't work. Or you can roll your own with a cheap Daly BMS and some grade-B cells from Siriko for a little less.

 

[KITROBASKIN]

AGM lead acid batteries are not going to hurt anything trying what you are suggesting given you performing best practices regarding wiring, placement and such, Right?

 

[Rednecktek]

No, worst that will happen is the little bit of draw from the SCC will drop the voltage down below what the battery can provide and it'll shut off.

 

[LDVV]

Thanks for the replies.

Ideally I'd be able to carry this out without batteries, but I don't think I can run my Epever that way.

...and no Load port on this model.

Duoracer MPPT solar controller 20amp

An MPPT type solar controller focuses on charging mainly the house battery, but does a maintenance charge on the start battery as well. this controller is lithium capable for the house battery and lead acid for the start battery System voltage 12/24 VDC Auto, Rated charge current 20A, Rated...

www.vantagerv.co.nz

 

[pollenface]

Is there some way that I can use one of my old "retired" batteries that no longer holds a charge (it was run flat too many times)? Can I just use it as I would a healthy battery? It's liable to combust, vent excessively, or something else, is it?

I only care for running these devices while the sun is up anyway, I don't care for power at night.

absolutely

Connect it all up and crack a beer

 

[Rednecktek]

No load port? Probably not gonna work then. As soon as a cloud rolls by the loads are probably going to drain the battery below the minimum voltage for the SCC to work.