Classic 250 switches rapidly from Bulk to Absorb

[erikven]

My Classic 250 switches rapidly from Bulk to Absorb and back about every 3-4 seconds. My battery voltage is at 24.3 V my float voltage setting is 27.2 the absorb is 28.6 which are the recommended voltage settings for a the two inline 12 V marine batteries I have. (EverStart 29DC) It does this even when sunlight conditions are consistent.
Can you please advise what's wrong, what can I do? Thank you.

 

[400bird]

Midnite has great support. You could try giving them a call.

It sounds to me like you have resistance between the charge controller and battery. Or maybe a heavy load that is pulling battery voltage down that quickly.

 

[time2roll]

Is this a new install? Change anything lately? Any significant load on the battery?
At this voltage Bulk and Absorb should be about the same thing. What is indicating the change?
What is the input and output voltage of the controller?

All I can suggest right now is a re-boot. Disconnect solar, disconnect battery and give it a minute then reconnect battery then solar.

Voltages are fine. I assume the two batteries individually have about the same voltage.

 

[timselectric]

This suggests a quick voltage drop.
Are the batteries equally charged?
Are the batteries new?
Are all connections good?

 

[erikven]

Here is what I found. I had a 150A auto disconnect switch between the Classic and the batteries, that I was going to use as a battery disconnect switch. Both the classic and the switch were new installs in a system that had been running for four years. (After my other classic took a dump - I addressed it in a separate post). Just to see what happens I have removed the disconnect switch and now everything is great. But I have no disconnect.

 

[400bird]

What disconnect switch/breaker were you using? I've got a Midnite breaker between the SCC and battery. Should last a long time.

 

[erikven]

@time2roll, no load on the batteries at all at the time of testing.
The change is indicated by the classic on its display and also the fluctuation in charging and discharging Amps on an independent system monitor.
Input voltage 110-120 V, output voltage 27 V
I have done the reboot, it did not do anything until I removed the disconnect switch.

 

[erikven]

What disconnect switch/breaker were you using? I've got a Midnite breaker between the SCC and battery. Should last a long time.

https://www.amazon.com/dp/B078XQW8BL?ref=ppx_yo2ov_dt_b_product_details&th=1

 

[erikven]

This suggests a quick voltage drop.
Are the batteries equally charged?
Are the batteries new?
Are all connections good?

Yes
Yes
Yes

 

[erikven]

Midnite has great support. You could try giving them a call.

It sounds to me like you have resistance between the charge controller and battery. Or maybe a heavy load that is pulling battery voltage down that quickly.

Yeah, I'll do that tomorrow. Today they closed.

 

[time2roll]

Bad switch

 

[sunshine_eggo]

Get some quality hardware. Blue Sea Systems or Littlefuse breaker. You just discovered a common issue with cheap Amazon shit.

 

[erikven]

Thank you guys to all of you. You all were quite helpful!