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Renogy question

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Nol

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Oct 27, 2020
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I have no problem but I am looking for an explanation.
I have a LFP of 280Ah in combination with a Renogy DCDC 40A and a Renogy AC charger 20A
When I drive with my RV the DCDC booster charge my LFP perfectly, no errors or what ever
When I charge the LFP with the AC charger I always get an alarm that one or more cells are overloaded
Maximum delta of the cells is 0,015mv
Can someone give me an explanation why it happen with the AC charger and not with the DCDC charger ?
TIA
 
The JBD should report why the alarm is triggered. In addition to the cell overvoltage protection, there is a pack overvoltage protection. Is it possible you have the pack voltage set lower than what the AC charger provides?
 
Since I can´t change that AC charger I have to change the setup of the BMS but how and would it not change the charge of the DCDC charger ?
 
Nol said:
Since I can´t change that AC charger I have to change the setup of the BMS but how and would it not change the charge of the DCDC charger ?
Click to expand...

Nothing you said above is related like you think it is. We'll get to that later. You may find that you shouldn't use your AC charger with this battery.

What is your cell overvoltage protection value?
What is your pack overvoltage protection value?
Have you ever charged with the AC charger while watching the BMS app when the alarm occurred?
 
sunshine_eggo said:
You may find that you shouldn't use your AC charger with this battery.

What is your cell overvoltage protection value?
What is your pack overvoltage protection value?
Have you ever charged with the AC charger while watching the BMS app when the alarm occurred?
Click to expand...

I hope I did not spent that money for nothing ?
And I try to watch untill the alarm came up but ... I try it again

Look at my setup maybe that explain and you can advice me
 

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Your battery must be PERFECTLY top balanced to reliably charge to 14.6V. The charger might not be perfectly at 14.6V. It could even be a little over 14.6V.

I suspect one of your cells is SLIGHTLY out of balance, and it triggers over voltage protection (OVP) and triggers an alarm.

If your cells are all over 3.55V when you get the alarm, the battery is full and cells are SLIGHTLY out of balance. No worries.

What are your balance parameters?

These should be on:

1663371990302.png

These should be:

1663372043247.png

.005 is a little aggressive, but it might be necessary for that charger.
 
Thank you for the advice, I will set it up tomorrow and went to bed because I travel all day and it is 2AM here
By the way, could this be the "problem" that the AC charger trigger one or more cells ?
 
Nol said:
Thank you for the advice, I will set it up tomorrow and went to bed because I travel all day and it is 2AM here
By the way, could this be the "problem" that the AC charger trigger one or more cells ?
Click to expand...

Nothing is wrong with the BMS.
The changes to the BMS MIGHT improve any slight imbalance.
The charger is probably just charging at slightly too high of a voltage triggering OVP.

Example: If you're charging to 14.6V, all 4 cells must be perfectly at 3.65V at the same time. At 14.6V, if 3 are at 3.64V, then one must be at 3.68V - which will trigger OVP and shut down.

The DC-DC charger likely charges at a lower voltage than the AC charger, so it doesn't trigger OVP.
 
I change the setup and this is how it is now :
 

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