So I went overvoltage today....

[bagmaker]

14.2v
Dont know why. Which bothers me.
Hasn't happened before (over 12 months of use)
We are hooked up to shore power, unusually, 50a Projecta charger + the solar array input, both set to 13.8 max. 3rd day hooked up. Occured in the morning with a bright blue sky, perhaps 0830.
Alarms went off, like they should, and disconnected solar feed. Voltages returned to normal with some manual hi-current drainage (inverter powered microwave), no sign of cellular level damage but incident not logged -bummer. All cells within 25mv.

System is 600Ah LiFePo Winstons with Rainbow / T1 style Dingo charging.

Anyone got ideas?

[jon_d]

Incorrect temperature compensation set.

Interactive voltage sensing and a device sensing no effect on its control lines

Electrical noise in the system. (I have this and have been eliminating it source by source - it's surprising how much is there. Plays havoc with the shunt.)

[BruceS]

Any idea what each cell was at the time?
Charger got an equalize set in it for once a month?

[bagmaker]

Incorrect temperature compensation set.

Interactive voltage sensing and a device sensing no effect on its control lines

Electrical noise in the system. (I have this and have been eliminating it source by source - it's surprising how much is there. Plays havoc with the shunt.)

No temperature compensation on Lithiums Jon,
Noise -maybe? we were all still in bed, there wouldnt be any unusual noise, typically only inverter powered fridge action.
Certainly I would expect noise to be an issue at some stage but not for .4 of a volt..... ( I had to silence the alarm)

[bagmaker]

Any idea what each cell was at the time?
Charger got an equalize set in it for once a month?

Unfortunately I wasnt logging the cells at the time , lessons learned.
Will check if the charger has this feature, never noticed it in the past (IQ5000)

Cheers

[jon_d]

No temperature compensation on Lithiums Jon,

I know that; but is it set or did it influence the problem? And may have previously turned it off, but is it on now?

Certainly I would expect noise to be an issue at some stage but not for .4 of a volt.

It depends where the noise is; and what is interpreting the noise. I've got 3 noise sources. The one that had the worst effect was a relay which has a little transistor control circuit. It was putting noise into the shunt which triggered the solar controller to read a much higher AH usage. This then screwed up my charging regime. (cause and effect)

[bagmaker]

Ahh I see!
I will have to check that too, never looked at the dingo or projecta regarding temp compensation.
Back to the manuals I guess.

Not a particularly different day from the last few hundred though.

Worth a look, thanks

[T1 Terry]

Was the over voltage a single cell or the whole battery? Single cell out of balance is the most likely event, caused by holding the battery @ 13.8v 24/7 with the Projecta IC5000 in power supply mode.
The cause, lithium cells are full when they are full, they can be a little bit over full and this will cause the voltage to rise, as long as the control stops the cell voltage climbing over 3.6v by cutting the charging sources, there isn't really a problem as far as damage at that point, but it will develop over time into an out of balance problem that will require further attention.
Once a cell is fully charged it takes very little to make the cell voltage climb back up to 3.6v, if all the cells reach this voltage at the same time then the total battery voltage would be 14.4v and generally the charger would have dropped into float mode well before that happened. The problem occurs when one cell is ever so slightly ahead of the others. Once the cell has hit 3.6v a few times yet there was no load to drain the cells, it takes only maybe 1 amp for 1 minute to bring it back up to 3.6v, once it is saturation charged, seconds at 1 amp will return that cell to 3.6v. The other 3 cells are not fully charged so they haven't reached 3.6v and 1 amp for 1 minute is unlikely to get them there before the already saturated cell reaches 3.6v again until it becomes so saturated it only takes seconds to hit 3.6v again.

If the mains charger is not controlled by this BMS that stops the charging when a cell hits 3.6v but rather it is trying to reach 13.8v when set to power supply mode, or much higher if set to another battery chemistry, the saturated cell voltage will climb rapidly till it is damaged or killed.
In this case, the cell voltage was monitored and set off an over voltage alarm letting the operator know that charging control had been lost and damage would occur if something was done.

The fix, turn the mains charger off and only turn it on when it is needed. let the solar do its thing and let the battery pack work, drained a bit over night and refilled the next day. If the Victron BMV says you do not have enough battery capacity to make it to the next morning without the 20% SOC alarm going off, then turn the charger on over night, but turn it off again the next morning so the solar can do its thing the way it was designed.

T1 Terry

[bagmaker]

It must have been the pack voltage, not a single cell.
I recall seeing 14.2v through the wake up alarm and it was from the BVM700.
Might have to rig up a remote switch for the charger, its too hard to reach and the remote interface doesnt have a cutoff (silly sausages at Projecta, what were they thinking?)

There is a slight unknown that the IC5000 was set to trickle 2A on AGM setting, this would account for an overvoltage. As would Terry's explanation above, thanks.
Unfortunately I just started pushing buttons and disconnecting things in my naked, half sleep state, I am only wondering in retrospect if the setting was wrong.

Cannot find any reasons for a thermal issue JD, nice sideways thinking though

I will advise the forum should anything interesting occur again, for the general good of mankind.

[Busman]

Put some clothes on, for the general good of mankind............