Swapped from GEL to Lithium, now getting Battery OVD

[thecampulanceman]

You've helped me in the past with my questions and I'm hoping I can get some advice on what's happening...
I just swapped from 12v GEL to 12v Lithium batteries in my camper (converted ambulance). I'm using an Epever Tracer AN 100a controller with a custom profile. My Tracer doesn't have a Lithium profile- I originally bought it 2.5yrs ago and it never had Lithium charging designed in.
The batteries I added is (2) 200Ahr Chins. I charged each separately using a standalone 14.6v 15a charger until the charger turned off. Then I installed them in parallel and set the Epever with settings provided by Chins.
I watched the voltage on the MT50 as the solar charged and saw it jump over 14 6v, showed 15v momentarily, then went into Battery OVD. This happened 3x on day 1. Yesterday, day 2, after several hours of solar charging, I watched the voltage climb and the same OVD happened. At that point, I turned on my inverter and the charge voltage then stayed at 14.4v (set point) for the remainder of the day until the sun faded.
I've never had this OVD and I'm admittedly a little lost. I'll paste my controller settings here but there's nothing I see in them that looks incorrect:

Over Volt Disconnect 15v
Charge Limit 14.6v
Over Volt Reconnect 14.2v
Equalize Charge 14.4v (set to 0 mins)
Boost Charge 14.4v
Float Charge 13.8v
Boost Reconnect 13.7v

From watching the MT50, the voltage seems to climb rapidly once it reaches about 14v - it then goes up through to 14.6 in a matter of minutes after taking hours to climb the lower voltages.

Is there anything I have wrong in my charge settings that stands out? Should I have connected the 2 batteries in parallel and charged them before installing? Should I uninstall and do that? I'm floundering as these are my first lithium batteries and I don't feel comfortable with them yet...

 

[lexio]

i use some thing like this


Over Volt Disconnect 14.6v
Charge Limit 14v
Over Volt Reconnect 13.9v
Equalize Charge 13.9v (set to 0 mins)
Boost Charge 13.8v
Float Charge 13.4v
Boost Reconnect 13.5v

 

[12VoltInstalls]

use some thing like this

Is there anything I have wrong in my charge settings that stands out?

I’m no expert and I’m not that lithium knowledgeable but those parameters suggested may be good for your setup.
Better is that the batteries should have instructions that will tell you what their designed charging parameters are, and the bms specifications. I’d use those published parameters.

 

[HRTKD]

I would go with the more conservative settings that @lexio posted. If you don't get the high voltage disconnect then try 14.2v for the boost.

 

[thecampulanceman]

I would go with the more conservative settings that @lexio posted. If you don't get the high voltage disconnect then try 14.2v for the boost.

Thank you all for commenting - I've changed the settings to a more conservative set and I'll be watching to see if things go better.

 

[HRTKD]

Be sure to post pictures of your rig and setup. From your user name it sounds like you have a converted ambulance?

 

[Supervstech]

The HVD is triggering because the bms is disconnecting charging, and the charger is still sending voltage, so it momentarily spikes. Lowering the charge voltage a few points will stop the issue. But it isn't a big deal, it just means the cells aren't perfectly balanced at the top of the range.

 

[fafrd]

The HVD is triggering because the bms is disconnecting charging, and the charger is still sending voltage, so it momentarily spikes. Lowering the charge voltage a few points will stop the issue. But it isn't a big deal, it just means the cells aren't perfectly balanced at the top of the range.

Yes, and the cells may be poorly top-balanced internally.

Tough to top-balance a finished battery, but by lowering boost voltage until OVD stops happening and setting Float Voltage at that same voltage (until Boost Voltage has increased past desired Float Voltage), you should be able to get the runner cell or cells to balance down closer to the average after enough cycles/hours.

But Boost Voltage of 14.4 is too high for any but a perfectly top-balanced battery (3.6V per cell means and cell 50mV above the others will trigger HVD).

50mV above 3.65V is a little as +0.125% SOC meaning as little as 0.25Ah of additional charge in the runner cell of the OP’s 200Ah battery…

I have no idea what the passive balance current of the BMS used in those Chins batteries is, but the battery would probably need to be held above 14.2V for over 4 hours total to burn off 250mAh of excess charge in a runner cell…

 

[thecampulanceman]

Be sure to post pictures of your rig and setup. From your user name it sounds like you have a converted ambulance?

 

[HRTKD]

Sweet! Does it have the 6.0 or 6.4 diesel?

 

[thecampulanceman]

Sweet! Does it have the 6.0 or 6.4 diesel?

No, I have the 7.3 turbo diesel. It's an '02...

 

[thecampulanceman]

The HVD is triggering because the bms is disconnecting charging, and the charger is still sending voltage, so it momentarily spikes. Lowering the charge voltage a few points will stop the issue. But it isn't a big deal, it just means the cells aren't perfectly balanced at the top of the range.

Thank you for that - I understand... never had a battery that could turn itself off. I've been at 14.2v boost for 2 days now and haven't had the OVD again.

 

[HRTKD]

No, I have the 7.3 turbo diesel. It's an '02...

Ah, it looked newer than that. 7.3L is a heck of an engine.

 

[corn18]

Ah, it looked newer than that. 7.3L is a heck of an engine.

And none of that emission crap to deal with.

 

[HRTKD]

And none of that emission crap to deal with.

Exactly. But I do like the clean smell of my 6.7L. I just wish that the emissions equipment was a lot more reliable.