12V Home lighting - Lithium battery charging

[Mikey B]

I have set up a system using a single 240W panel with two parallel connected 50Ah Lithium batteries and a PWM controller, I have short 12V LED strip lights switched in every room of the house. As winter approaches there is not enough power from the single panel so I will be adding an additional 300W panel with its own MPPT controller (the new panel will be at a different angle to my existing one) research on YouTube shows this to be an acceptable solution.
For reference - currently (October 2023) the setup is using around 15Ah per day and the panel is replacing around 7 - 14Ah per day.

My question is - This setup will not be enough to cover December/January requirements. I am considering if I can use the wall mounted Mains (240V) charger that came with the battery (there were two chargers as I bought the batteries separately) but where do I connect it into my system?

Direct to the each end of the battery "pack" (charger +ve to battery #1 +ve, charger -ve to battery #2 -ve)
Should I disconnect my solar panel feed(s) to the controller when I need to use the mains charger?
Should I disconnect the battery "pack" whilst I use the mains charger?

Thanks in advance for any help. Also is this in the correct section?

 

[sunshine_eggo]

My question is - This setup will not be enough to cover December/January requirements. I am considering if I can use the wall mounted Mains (240V) charger that came with the battery (there were two chargers as I bought the batteries separately) but where do I connect it into my system?

To the battery bank as you describe in the next line:

Direct to the each end of the battery "pack" (charger +ve to battery #1 +ve, charger -ve to battery #2 -ve)
Should I disconnect my solar panel feed(s) to the controller when I need to use the mains charger?

no.

Should I disconnect the battery "pack" whilst I use the mains charger?

no.

Charging from multiple sources

One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank. Examples (some or all at once, even multiples of a single type, different brands, etc.): Solar PV via MPPT Solar PV via PWM AC-DC...

diysolarforum.com

 

[Mikey B]

Thanks Sunshine_eggo, I will go for it.

 

[Mikey B]

I left the setup untouched and connected the battery charger to my two 50Ah Lithium batteries (which are connected in parallel)
charger +ve to battery #1 +ve
charger -ve to battery #2 -ve
The light on the charger was green, and it did not appear to have charged the batteries.
Any further ideas?
The only thing I can think of is to reconnect the system to one of the batteries and charge the other one "off line" and keep repeating this as required.

 

[sunshine_eggo]

I left the setup untouched and connected the battery charger to my two 50Ah Lithium batteries (which are connected in parallel)
charger +ve to battery #1 +ve
charger -ve to battery #2 -ve
The light on the charger was green, and it did not appear to have charged the batteries.
Any further ideas?
The only thing I can think of is to reconnect the system to one of the batteries and charge the other one "off line" and keep repeating this as required.

Battery voltage when you connected charger? May not run unless it's below a certain voltage.

 

[Mikey B]

Thanks, I will consider this.

 

[Mikey B]

I left the mains charger connected across the battery and left it for several hours. The output from the charger showed 14.6V and when connected and switched on the power light changed to red. I left the solar system running and the battery monitor connected through a shunt on the -ve cable showed the current increased by a couple of Amps. I expected when I powered the mains charger this figure to rise, but it did not.

There are are videos on YouTube showing two controllers connected to the battery and also using a controller in place of solar panels. I could not find anything about combining a charger and panels though.

In my simplistic view it should be straightforward to setup, but obviously for some reason (am I connecting to the correct places?) it is not working.

Any further ideas?

 

[sunshine_eggo]

You didn't indicate you had a battery monitor. The charger output (-) must be connected to the battery monitor system side, i.e., where the solar charger is presumably connected.



The only thing connected to the main (-) should be the shunt. Current must pass through the shunt to be seen.

 

[Mikey B]

Thanks for your quick response, I will try that tomorrow and let you know. A very clear picture there.

 

[Mikey B]

Tried connecting as shown above. Nothing happened.
Had a thought and changed the charger to the one which came with the other battery - instant charge which went from 1.5A from the just the panel to 6.5A with the charger.
Thanks for your help it is much appreciated.
Cheers Mike