DC electric

[czechmate]

I run a 24v DC pump for water from a well.
To power it I have two (old) 12v batteries with a 12v solar panel to each - then a link from + to minus the ne the pump connected to the 24v result.
Now, I had this one time last year and now again today. Pump not working so I investigate with a volt meter. Across from he 24 v is a volt. Check each battery separately… 1 is 9v; the other has turned to minus 9 volt. Disconnect the minus battery solar panel and check, when disconnected the panel is the correct polarity.
Puzzled

 

[Timbo]

Have you got a charge controller on each panel?

The battery will discharge through the panel in low light / night time otherwise.

 

[yoki]

So your two 12v batteries in series create a 24v circuit.

How do you charge that with 12v solar panels?

 

[czechmate]

Have you got a charge controller on each panel?

The battery will discharge through the panel in low light / night time otherwise.

How do you know? I assume when you buy a panel it is complete for use. I will say, I bought them separately and one registers voltage when disconnected (just like the several little panels on electric fences we have) and the other doesn’t register voltage when it is disconnected

 

[czechmate]

So your two 12v batteries in series create a 24v circuit.

How do you charge that with 12v solar panels?

Two panels and two batteries

 

[yoki]

But your batteries are in series therefore effectively behaving like one 24v battery.

How else would they run a 24v pump?

Can the panels be run in series to produce a 24v+ charge?

I know about electricity but have no experience of solar panels so I'm addressing the problem from basics.

 

[Paddington]

Should be getting around 20V ish with no load in daylight, sounds like one is U/S.

 

[czechmate]

But your batteries are in series therefore effectively behaving like one 24v battery.

How else would they run a 24v pump?

Can the panels be run in series to produce a 24v+ charge?

I know about electricity but have no experience of solar panels so I'm addressing the problem from basics.

 

[czechmate]

Should be getting around 20V ish with no load in daylight, sounds like one is U/S.

Battery or panel?

 

[czechmate]

But your batteries are in series therefore effectively behaving like one 24v battery.

How else would they run a 24v pump?

Can the panels be run in series to produce a 24v+ charge?

I know about electricity but have no experience of solar panels so I'm addressing the problem from basics.

I do wonder about running the panels in series too

 

[czechmate]

Have you got a charge controller on each panel?

The battery will discharge through the panel in low light / night time otherwise.

This year and last, the problem arrives in September

I flat battery I can understand… it’s the reversal that baffles me

 

[Bury the Trash]

just an example of a simple charge controller ,

 

[czechmate]

just an example of a simple charge controller ,

I used to be 10 miles from an RS components

 

[czechmate]

just an example of a simple charge controller ,

We run several electric fencers off solar panels without such a thing. The panels do have a little box though

 

[yoki]

This is what you need.

Or if your panels are designed to do such a thing, connected in series (plus to minus) like so.

But don't do that unless you know the panels are capable of it!

 

[Paddington]

Battery or panel?

Panel. Are the batteries car or leisure batteries, as 9v seems low for car type.

 

[czechmate]

This is what you need.

Or if your panels are designed to do such a thing, connected in series (plus to minus) like so.

But don't do that unless you know the panels are capable of it!

I will try this

 

[e5c0rt.mk1]

This is what you need.

Or if your panels are designed to do such a thing, connected in series (plus to minus) like so.

But don't do that unless you know the panels are capable of it!

This !

They way you have it wired at the moment is like putting 2, 12v battery chargers on a 24v vehicle and expecting it to charge to 24v, putting two on is only upping the amperage not the volts.

 

[yoki]

Panel. Are the batteries car or leisure batteries, as 9v seems low for car type.

They will drop if the load continues.

I've a couple of 12v fencers powered by automotive batteries a bit past their best.

Occasionally I've missed swapping one in time and seen them as low as 5 or 6 before going on the charger.

Very naughty discharging them as low as that I know but they're never left discharged and always pick up again. I'm surprised how well they're taking the abuse to be honest.

 

[yoki]

I will try this

I'm not sure it will work.

At the end of the day their circuitry is designed to work at 12v not 24v.

You could connect them in series off the battery first and put a voltmeter across the combined unit to see if you at least get 24v?