PL20 Solar Controller -Low Battery Disconnect feature

[carlyai]

Son has a campervan with a solar panel and batteries setup.

The batteries are 2 x 12V AGM 12V/100Ah/20H deep cycle, second hand batteries in parallel.

The solar controller is a Plasmatronics PL20.

The problem is there is no load current.

The batteries have been left standing and discharged for a long period.

At the moment the batteries are charging at 3.8A from the solar panel and the battery voltage has climbed from 9.25v to 11v.

The PL20 has a Low Battery Disconnect feature but I can't find and info. on what voltage the load is disconnected. 

I think this could be the problem as the batt. Volts are only 11V.

What do you think?

Should I get the electronic charger and recharge the batteries separately to full charge?

In future should the batteries be kept on float charge if not used for a long period?

Thanks.

[BritManToo]

Try charging 1 battery at a time.

You might have a dead battery.

[sezze]

If the battery isn't dead , that low of a voltage isn't a good sign for a long life .

[LA8RAT]

I also run a solar setup in my campervan.  Myself I'm using lithium lifepo4 cells because I'm able to fully discharge them. Or use 100% of their capacity. 

 

With lead chemistry batteries you are limited too 50% discharge. I fear your sons leasure batteries are now <deleted> or at least greatly diminished in capacity. 

 

Sorry. 

[carlyai]

21 hours ago, BritManToo said:

Try charging 1 battery at a time.

You might have a dead battery.

Put 1 battery on the electronic charger this morning. 

From an other comment it would seem that these are the wrong type of batteries for a intermittently used campervan.

Also 11V is a low voltage? 

So should the batt. Volts be about 14.2v for 12v batteries?

Thanks.

[carlyai]

Just checked the batteries again and seems like 1 is no good. (Charger very hot and LED indicator not moved).

So better to buy LIFPO4 cell batteries?

Seems they will only be using 12v lights and 12v fridge. Maybe when it works they may use more.

So if I recommend LIFPO4 batteries, and use the same 20A controller, should I still recommend 2 12v 100Ah batteries in parallel?

Thanks

 

[carlyai]

3 minutes ago, carlyai said:

Just checked the batteries again and seems like 1 is no good. (Charger very hot and LED indicator not moved).

So better to buy LIFPO4 cell batteries?

Seems they will only be using 12v lights and 12v fridge. Maybe when it works they may use more.

So if I recommend LIFPO4 batteries, and use the same 20A controller, should I still recommend 2 12v 100Ah batteries in parallel?

Thanks

 

Correction    LIFePO4

[Crossy]

Check out the used LiFePO4 golf cart cells in my Car Port thread, you just need 4 of them and a 4S BMS. 

 

The ones on our solar are going just fine.

 

The DALY Smart BMSs work pretty well, have BlueTooth and aren't silly money. 

 

EDIT Do you have the charger manual? pl20.pdf

[carlyai]

2 hours ago, Crossy said:

Check out the used LiFePO4 golf cart cells in my Car Port thread, you just need 4 of them and a 4S BMS. 

 

The ones on our solar are going just fine.

 

The DALY Smart BMSs work pretty well, have BlueTooth and aren't silly money. 

 

EDIT Do you have the charger manual? pl20.pdf

Hi crossy. I'm still in the convict colony getting a new back.

No charger manual but can probably download one.

What am I looking for in the charger manual?

When I get back I'll be setting up one of your suggestions and get one of our 3 phases that supply the aquaponics and hydroponics set up onto solar, so good to learn a bit now.

 

 

 

[carlyai]

Sorry, I do have the PL20 manual...I thought you meant the battery charger I'm using ti charge the batteries.

 

[carlyai]

The camper trailer circuit doesn't have the diode installed like it shows in the manual.

[carlyai]

One battery has charged to 14.2 v, so I'll try and charge the other one.

[Crossy]

14 hours ago, carlyai said:

The camper trailer circuit doesn't have the diode installed like it shows in the manual.

 

Where's the diode shown in the PL20 manual?

 

The only mention of a diode in my copy of the manual is to say that it doesn't need a "catch diode" across the relay coil (although I'd probably install one anyway).

 

[Crossy]

14 hours ago, carlyai said:

Sorry, I do have the PL20 manual...I thought you meant the battery charger I'm using ti charge the batteries.

 

Yeah, my bad there, not being clear, sorry about that.

 

It's also just filtered through my addled brain that the camper is in Aus, so getting cells from Lazada probably won't be on the cards ???? 

[carlyai]

2 hours ago, Crossy said:

 

Where's the diode shown in the PL20 manual?

 

The only mention of a diode in my copy of the manual is to say that it doesn't need a "catch diode" across the relay coil (although I'd probably install one anyway).

 

 

[carlyai]

The first battery taken off charge has dropped to 12.4v. 

Long time since I played with batteries...should I discharge and recharge the battery? Or just connect it on it's own to the PL20 and plug in a LED light as a load? See what happens.

[Crossy]

1 hour ago, carlyai said:

The first battery taken off charge has dropped to 12.4v. 

Long time since I played with batteries...should I discharge and recharge the battery? Or just connect it on it's own to the PL20 and plug in a LED light as a load? See what happens.

 

I'd just give it a go and see what occurs.

 

Not sure what that diode is for, but I doubt it's the cause of your issues.

[Muhendis]

Any lead acid battery left idle for a long time with no trickle charge will become sulfated which will reduce its capacity. If you can do a desulfation cycle that may make it a bit more useable but since the battery terminal voltage has sunk to below 10.5v I would think it is a waste of effort. Charging the battery and finding you have over 12v is nice but either a capacity test or a CCA/internal resistance measurement will tell you how far gone the battery really is. Like Crossy say's "give it a go" but don't expect too much.

[carlyai]

So I disconnected 1 battery and found on the web site they have a better manual. 

This gave a low voltage cutout that could be adjusted from 11 to 15v. It was set at 14.2v so i set it to 11v as family said they only wanted to use the LED lights.

Now load O/P working. 

I'm not to sure if disconnecting the suspect battery (wouldn't charge) or changing the low voltage cut out fixed the problem as at the end I checked the 12v output connector, which I'd checked before, and now had 12v. 

The LED lamp and portable fridge I was using to test were both faulty. Now new LED lamp and other fridge worked.

So It's all working....now they want to use the fridge as well. ????

Thanks for the help.