Batteries not charging fully

[bajarick]

My neighbor has had a couple 24V 200 amp hour batteries for a couple years. He just added two more and told me they weren't getting over 26.6 volts and goes down to about 26.3 overnight. We've had plenty of sun. 1650 watts of solar from four panels and his outback cc says 27 amps and 80 volts coming in. Settings on the Outback are 28.8 absorb and 27.4 float. He's going to unhook two batteries tomorrow to check but it seems like he should have enough coming in to get him to at least float voltage. Anything else he should check?

 

[Supervstech]

At 27v, 1650W is 61A, so hes not getting half the rated wattage.

 

[bajarick]

Thanks. Sound like a panel connection?

 

[Engr. Boye]

The batteries need to be checked.Try Old and new batteries charged and drained ( connection to inverter) separately. You may need extra charge controller and change over / knife switch. Enough power is coming from panel.

 

[DIYrich]

At 27v, 1650W is 61A, so hes not getting half the rated wattage.

27a @ 80v is 2.160 kW from the panels.
24v x 400ah is 9.6 kWh.
4.5 hours to charge batteries plus whatever load is using.

 

[MisterSandals]

1650 watts of solar from four panels and his outback cc says 27 amps and 80 volts coming in.

27A x 80V = 2160W

Sumpin not adding up. Is that 27A from the array or charging at 27A?

 

[DIYrich]

27A x 80V = 2160W

Sumpin not adding up. Is that 27A from the array or charging at 27A?

At 1650 watts it is 6 hours to charge plus load. I was thinking he had really strong sun to exceed the panels rating.

 

[MisterSandals]

At 1650 watts it is 6 hours to charge plus load.

Understood.

I was thinking he had really strong sun to exceed the panels rating.

2160W / 1650W = 130% of spec? Call me VERY skeptical.

 

[Supervstech]

27a @ 80v is 2.160 kW from the panels.
24v x 400ah is 9.6 kWh.
4.5 hours to charge batteries plus whatever load is using.

... the amps reading in a charge controller is at battery voltage...

 

[bajarick]

Just back from fishing. Thanks for the replies. I was looking at his outback 80 charge controller screen. Volts was 80 and amps out was 27. Didn't go on the roof to look at the panels but he had a pic of the label. Don't remember exact numbers but it was around 45volts and 12 amps per panel. And, he had 4 200amp hour batteries. I'll check later because he was going to unhook the two older batteries.

 

[bajarick]

Ok. Here's the label off the back of one of the (4) panels. They must be connected 2 parallel 2 series to get 80 volts. He's disconnected the older two batteries. Newer ones (24V 200 amp hour) still are not going over 26.6. High noon sunny all morning. Outback says 80 volts, 27 amps out. Charger settings 28.6 absorb and 27.2 float. Pretty much all the same even with the 2 year old 200 amp hour batteries connected yesterday.

 

[MisterSandals]

They must be connected 2 parallel 2 series to get 80 volts.

Looks like only one of the 2S strings is producing. Can you SAFELY disconnect one of the strings?

 

[bajarick]

I get him to try that tomorrow. He's a neighbor but not right next door!