Bad SCC or battery?

[Sandrat]

So im running a midnite classic 250. I have an 8 battery 12v parallel bank. I have 4x 350w panels.


My question is... On the scc I can see the panels in V and A. On the right i can see battery V and A. My batteries will build up to 13.4 or so.l, then the amps on the panel in side goes from 24ish to 000 and the battery V drops to 12.9... Why is this happening? Scc bad or a battery?


Thanks in advance

 

[MisterSandals]

What is the Voc of your panels, how are they configured, and what is your SCC's max input voltage?

Can you describe your 8 batteries? All alike in Ah, age and all 12V? Lead acid i assume or you would have surely mentioned a BMS.

 

[Texas-Mark]

Does the charge controller have configurable settings for bulk and float charge?
And as asked above what type of batteries?

 

[740GLE]

8 - 12v batteries in parallel?

 

[Sandrat]

I have 8 deep cycle batteries. 4 are SLA and 4 are FLA. They are hooked together POS to POS and NEG to NEG. Which is parallel I believe.

 

[Sandrat]

Does the charge controller have configurable settings for bulk and float charge?
And as asked above what type of batteries?

Yes it does my float is 13.4 and absorb at 13.6 volts.

 

[Sandrat]

scc can handle 60a. Each panel is 9a and Voc is...46.7v

 

[MisterSandals]

scc can handle 60a.

What SCC do you have? Is it a secret? What is the max input voltage?

If your panels are 9A, it is mighty strange that your SCC is seeing 24V. Even if your panels were producing 8A (to make the math work), that would just be 3 of the 4 panels. How is your array wired? All parallel?

 

[Sandrat]

What SCC do you have? Is it a secret? What is the max input voltage?

If your panels are 9A, it is mighty strange that your SCC is seeing 24V. Even if your panels were producing 8A (to make the math work), that would just be 3 of the 4 panels. How is your array wired? All parallel?

I said in the first line of the op...midnite classic 250. Yes array is all parallel. The scc doesn't have a problem with it because it never jumps above 60a.

 

[Sandrat]

Here are pictures of my set up and panel stats.

 

[Texas-Mark]

IMO you may have a bad battery. I would disconnect them all and measure each one individually. I had something similar happen when I had one battery that had a dead cell.

 

[MisterSandals]

I said in the first line of the op...midnite classic 250.

Oops, sorry.
Why are you running all in parallel? With 3 or more panels in parallel (edit, not series) you would need to fuse all the panels. A 2S2P array seems like a no-brainer if not working around extreme shading issues.

BUT! Looking at how you have your batteries wired, its not surprising that you are having issues. The wiring is improper and is wired extremely unbalanced... all from one end of the battery bank.
You NEED to wire positive from one end of the bank (lower left in your pic) and the negative to the other end (upper left in your pic).

This will make a huge difference. Not sure your cells are all good or not but this is a big problem how you have them wired.

 

[MisterSandals]

Looking at your SCC display, your input numbers are way way way too low. Since all your panels are in parallel, you should try disconnecting some to see if your numbers change. I am thinking you have a bad connection or 3 in your array. I wonder if running without fuses backfed too many amps and damaged a panel(s)?

If it were me, I'd try running 2 panels in series first. Your volts should be 60-70, your amps should be around 9. Try this with the other 2 panels. If these are all good, connect the 2 series strings in parallel and see if you're getting double the amps in.

 

[Texas-Mark]

I agree with the above to move that main negative to the negative of the upper left battery. But I still think all the batteries need to be checked individually. A shorted cell in one will cause that bank voltage to drop quickly like is being seen. It may also be confusing the charge controller.

 

[Sandrat]

Oops, sorry.
Why are you running all in parallel? With 3 or more panels in series you would need to fuse all the panels. A 2S2P array seems like a no-brainer if not working around extreme shading issues.

BUT! Looking at how you have your batteries wired, its not surprising that you are having issues. The wiring is improperly and is wired extremely unbalanced... all from one end of the battery bank.
You NEED to wire positive from one end of the bank (lower left in your pic) and the negative to the other end (upper left in your pic).

This will make a huge difference. Not sure your cells are all good or not but this is a big problem how you have them wired.

Okay that was how i had it before was drawing POS from the engine and NEG grom the caboose. Im running everything in parallel because that's what i knew would work. If i use all 4 panels at once though its too many amps for the scc

 

[MisterSandals]

If i use all 4 panels at once though its too many amps for the scc

No. The SCC pulls the amps it needs.
The max input voltage is the number that matters. All 4 in series is likely too much. But 2S2P sounds perfect size-wise.

 

[Sandrat]

No. The SCC pulls the amps it needs.
The max input voltage is the number that matters. All 4 in series is likely too much. But 2S2P sounds perfect size-wise.

Ok. So I need to fix my battery draw points and redo my panels 2s2p?

 

[rmaddy]

With 3 or more panels in series you would need to fuse all the panels.

parallel, not series.

 

[Texas-Mark]

Ok. So I need to fix my battery draw points and redo my panels 2s2p?

Yes. But I still think you need to check those batteries. I have a similar setup of 9 batteries in parallel. 4 of them are sealed. The other 5 I can check the specific gravity easily enough, but the only way to check the sealed ones is to disconnect them. One bad battery will harm the rest of the bank quickly.

 

[MisterSandals]

.

parallel, not series

oops, yes. 3 or more in parallel they need fuses. Thanks!
Fixing my post.