[upandgo]

Hi Steve,
I have 2 200ah Lithium Valley batteries purchased from Benson only 10 weeks ago. He set up my epever controller for me using the MT50 but i assume the settings will still be the same for you so here is what mine is set too.
Using the MT50 to set it up the sequence is as follows (the laptop may be different)
Select 'control parameters'
"Type' is user
'Battery' is the ah rating of your battery pack (in your case 100ah)

Over Volt. Disconnect Volt. 32.00v
Over Volt. Reconnect Volt. 30.00v
Equalisation Charging Volt. 29.2v
Boost Charging Volt. 28.8v
Float Charging Volt. 27.6v
Boost Recon.Charg.Volt. 26.4v
Charging Limit Voltage. 30.0v
Discharging Limit Volt. 21.2v
Low Volt. Disconnect Volt. 22.2v
Low Volt. Reconnect Volt. 25.2v
Under Vol. Warning Volt. 24.0v
Under Volt. Warn. Reco.Volt. 24.4v

Do you have a battery monitor like the Juntek to monitor these batteries, highly recommended to the point of being essential. Check out Neddys posting about battery monitors.
Hope this helps
Gary

[CatholicKiwi]

Thanks for taking the time to hunt out your settings Gary - much appreciated!

I decided to use the Solar Station Software from Epever and set the parameters from the laptop. Benson emailed me a photo of the required settings, so that part of it is now fine.

However, there is something else going on. I'm now at the stage where Benson has arranged to courier the batteries back to Sunny Tech to test them. Even with the new settings they are spiking. I've tested them as 12v and as 24v. 24V spikes up to 35V and 12v was spiking to 17V.

But---- a user would not know they were spiking in voltage like this -- Unless the user has something that will 'trip' if it goes over voltage. The spike lasts for perhaps 1 second. and then it's back to normal.... However, this was tripping my inverter and alerted me to the issue. If a user only had appliances etc such as lights, water pump, thetford oven ignition, suburban water heater ignition, stereo, cigarette 12v lighter sockets, etc - it's possible they would not know their batteries are spiking like this.

So I'm really interested to find out who else has Lithium Valley batteries, and whether they can test the voltage, which would be done by waiting until the inbuilt BMS says they are at 100%SOC, with the sun out to provide charge, using a voltmeter to watch the battery voltage. This needs to be watched for up to half an hour? Within that time they would sit at a normal voltage, but then maybe after a few minutes fluctuate and spike to 35V. - Trip the BMS?, and go back to 27V or there abouts, until the BMS resets and it happens again?

Hopefully I can get to the bottom of this.....

[davef]

35Volts / 8 cells = 4.375V. 4.2V is the recommended max voltage https://www.powerstream.com/LLLF.htm. When cells get above, say 3.6V are they still going to track each other? If they don't track perfectly then at 35V one or more could be well above 4.375V.

The recommendation is not to equalise or float LiFePO4. A guy who knows a thing or two about LiFePO4 is www.electrodacus.com

At the bottom of page one ... the LVD and HVD are built-in. So, when you try to over-charge the battery the battery is disconnected from the charging source and the voltage to everything will rise to whatever no-load voltage the charging system can deliver, ie 33-35V or more for PV panels.

[johnny]

A similar spike event as you call it happened to me when my lifepo4 BMS locked out the battery on over voltage.
I believe the solar controller was faulty.

[Nut17]

Are you able to easily open the battery case with these Lithium Valley Batteries? It would be quite a revelation to be able to monitor the individual cell voltages through the charging and discharging cycles.
My eight years working with prismatic LiFePO4 cells has proven to me that charging to a higher voltage than 3.5 volts per cell provides a minuscule extra capacity, but does enter the area where cell balance and cell voltage runaway can take place. 3.45 - 3.5 volts / cell has been my default charge regime for the last five years, with float set at 3.3 v / cell (never activated) My currently used controllers have a dedicated lithium setting which has bulk charging only with no absorption or float charge which suits these cells perfectly. The bulk charge voltage is however 14.4 volts (3.6 v / cell) but with the fitment of the active HA02 cell balancer all cells stay in perfect sync right through the charge - discharge cycles.

[scubadoo]

CatholicKiwi

Were those 35/17V peaks measured with an inbuilt voltmeter? If so I wonder if that voltmeter measures the terminal voltage even if the BMS has disconnected the internal cells.
I would use a multimeter and monitor the terminal voltage for a while and compare the readings.

Even a brief 17V (4.25V /cell) at the battery would be a real concern for me with mild panic well and truly setting in. Thankfully my last resort HV cutoff would have alarmed and triggered well before that ever occurred.

As Chris mentioned the top end knee voltage readings relate to very little capacity change.
My 300Ah battery capacity increases by about 1Ah when charging at 30A from 13.85 to 14.30V with no load over the less than 2 minute timeframe required. 14.6V would take about another 5-10 seconds. Hardly worth the effort or any top end cell voltage drift concerns.

[CatholicKiwi]

Johnny - That's interesting regarding the similar spike you were seeing., and it then being a faulty charge controller. I tried my Epever charge controller on AGM batteries that I have and it is working fine. - I also tested the batteries individually (12V system) on a different controller, a 10 Amp Epever Tracer 1210A and saw the same spiking occurring. (However I was later told that the 1210A is too old to support Lithium, so possibly negates that test?) But I'm not going to rule out the problem being with my charge controller, - it just seems very unlikely at this stage, - it's charging AGM's perfectly, and spiking is occurring using two different controllers. As far as I know my charge controller is fine, but....?

Chris - (Are you able to easily open the battery case with these Lithium Valley Batteries?) At the moment the batteries are back in the courier to Sunny Tech for testing, but from memory the plastic cases look pretty sealed.

Scubadoo - The spike readings of 35V (24V system) and 17V (12V system) were readings that I took with my multimeter. The batterys have an inbuilt LED display showing SOC and Volts. When I saw the brief (1 second) spike on my multimeter I don't recall seeing any change in the voltage on the inbuilt LED display on the battery. But that may simply because staring at the multimeter for half an hour meant my focus was not on the LED display on the battery at the time of spiking.

I agree with you Scubadoo, the brief spike is a worry. What is also a worry is that if I had a system using lighting, stereo, TV, water pump, oven ignition spark, water heater ignition spark, cigarette lighters for phone charging, - I would NOT know that this spiking was happening. The only reason I knew is that I tried to run an inverter which has over voltage cut out. This over voltage on inverter was triggering, but only when batteries were fully charged and it was daylight. --- I see the value in having, as you mention Scubadoo, a high voltage cut off in ones system, and I might look into this ......

In the meantime the batteries are on the way back to Auckland to be tested....

[Nut17]

We await the outcome of the testing with interest