Getting High voltage alarms on Victron SCC and LiFePO4 battery bank.

[backwash]

so this summer I've gotten several high voltage alarms (14.6v) with my pair of LiFePO4 batteries (280a EVE cells). so investigating the victron SCC profile; the full charge voltage is 14.2 (looks correct) and the float charge is 13.5 (also correct) but then I noticed a little blip in the manual (yes; I read it) that LiFePO4 has a default absorption time of 2 hours and does NOT use adaptive tail current to end the absorption time similar to the other profiles. My thoughts right now is that the absorption time is way too long. so as an experiment I re-configured the custom charge profile to be:
charge voltage: 14.2, float voltage: 13.5, adaptive absorption time enabled, adaptive current 3amps, max absorption time: 15min.

I was wondering if anyone had any thoughts or experience with the Victron SCC charge profile for LiFePO4 as well and has seen this ?
(oh yes; the cells are all balanced. they typically show about 10-20mv across).

 

[John Frum]

What component is issuing the high voltage alarms?
If your the max voltage your solar charge controller can produce is 14.2 volts then the battery should not be being overcharged.
14.2 volts is less than 14.6 volts.
Is there any other charge source?

 

[gnubie]

Yes, Victron's default absorption time is long but it's also what they have tested with their own batteries and found to be OK and other SCCs do long times here too.

That said I run my own batteries at 12 mins because that's what my observation has shown to be long enough to bring the batteries to charged and allow time for cell balancing. My advice has been that if you aren't happy with Victron's absorption time and can't have tail current monitoring in the particular setup, the way would be to observe how long it takes for the current to fall to a level you find acceptable and set the time there.

I would turn adaptive absorption off as this is more of a lead acid strategy where you have the long slow march up to fully charged. Fixed time or tail is IMO what you want with lifepo4.

I can't see how an extended absorption charge stage at 14.2V would cause your battery to go to 14.6V though.

 

[backwash]

The BMV-712 has a high voltage alarm at 14.6 and I've had 4 of them so far this summer.
I agree that if the charge stage ends at 14.2 that it can't get to 14.6 but it is. (there is no other charge source)
I was thinking that the alarm was occurring during the absorption period but maybe it's not. it could be occurring at the very end or near
the end of the bulk charge cycle when it's pushing current. ie: maybe the battery spikes up to 14.6 for a brief moment before the SCC catches it and switches in to absorption ? I went and moved the charge voltage to 14.0 just now to see what that does for today.
thank you for the input !

 

[gnubie]

Is your SCC and BMV in a network, ie the SCC is listening to what the BMV is saying or are they separate with the SCC only using what it senses at its own terminals?

 

[backwash]

the two 100/50 SCCs are networked in to the BMV-712.

 

[John Frum]

The BMV-712 has a high voltage alarm at 14.6 and I've had 4 of them so far this summer.
I agree that if the charge stage ends at 14.2 that it can't get to 14.6 but it is. (there is no other charge source)
I was thinking that the alarm was occurring during the absorption period but maybe it's not. it could be occurring at the very end or near
the end of the bulk charge cycle when it's pushing current. ie: maybe the battery spikes up to 14.6 for a brief moment before the SCC catches it and switches in to absorption ? I went and moved the charge voltage to 14.0 just now to see what that does for today.
thank you for the input !

The bulk phase is the constant current part.
The charger limits the current by limiting the voltage differential between itself and the battery.
The absorption phase starts when the battery no longer draws the max allowed current from the charge source.
That means the bulk phase voltage should effectively be equal to or less than the absorption phase voltage.
Also it should not be a big deal to leave your batteries at absorption voltage for a couple of hours.
Some/many charge controllers use the sundown as their charge termination logic.

 

[gnubie]

Anything else we have to guess at here? You've gone from notionally one Victron SCC to a Victron SCC and a BMV and now 2 SCCs and a BMV.

 

[nebster]

Yes, draw your (entire) circuit please.

 

[Pappion]

I heard the SCC and the Remote Sense voltage don't agree. SCC was lower, maybe compensating for some nominal resistance.
Do you have the Smart Sense or Smart Shunt (with voltage sense)?

 

[backwash]

good day; I have the BMV-712. (I'm not sure if the smart shunt is any different) It's fully integrated with the smartsolar SCCs. I know that they get the temperature from the BMV-712. Once I modified the charge profile to only go to 14V and not 14.2 the high voltage alarms stopped. so I'm happy with that.