Charging Batteries with Chargeverter - Am I Doing it Right?

[AlaskanNoob]

So I've got my Honda 7000 powering an EG4 Chargeverter which is wired into my 48V bus bar. I have it set to charge my 8 x Pylontech US5000 batteries at 52V and 100A.

I started off with my bank showing 91% SOC and I started screen capping at around 50.7V. AC loads were about 300W. The battery was showing charging with about 4500W. Over more than thirty minutes, the battery voltage had climbed to 51.9V and the amps had dropped and the battery charge had dropped to about 1500W. I shut off the generator when the battery was showing 51.9V and about 24A.

But it showed 91% SOC the entire time. I was expecting the 38KW battery bank would have climbed in SOC by about 1% every ten minutes or so. Why did that not happen? I have frequently seen my SOC at 100% or 99% with the battery at 49.9V. Does the system just need time to balance the cells and get a correct average before it corrects the SOC?






Another question. The Pylontech ramps the MPPT down so that it only sends the power it needs. With me using the Chargeverter, I'm taking the Pylontech's ability to ramp the power down on the bus bar out of the equation. I worry that I might over voltage them or send them too much power as a result. However, it seems to me that by setting 52V on the Chargeverter, that shouldn't happen. And since the charge to the battery drops, that seems like it shouldn't happen, but I'm not sure. I've heard that power isn't SENT to batteries, it TAKES power. If that's the case, why does the Pylontech through the Victron VE.BUS ramp down what the MPPT sends to the bus bar?

Many thanks for helping me understand what is going on here.

 

[AlaskanNoob]

This morning the batteries were at 87%. So I fired up the generator (again with EG4 chargeverter supplying 52V and 100A) and I got the SOC to increase to 89% in about twenty minutes. But it didn't take long for the 4.5KW going into the batteries to drop to about 700W.

So it seems to me that if I want to get the batteries up to 95% SOC using the chargeverter, I'm going to need to increase the voltage. So I guess I'll increase it to 52.1V on the EG4 and see if that gets me to 90% SOC and I'll just keep ratcheting up the voltage until I get the 95% I'm looking for.

 

[Browse]

Not too familiar with those batteries, but I think you need to raise your charge voltage a bit.

 

[AlaskanNoob]

Not too familiar with those batteries, but I think you need to raise your charge voltage a bit.

I think you're right. I raised it up to 52.4V this morning (that's what Victron limits the charge voltage to even though Pylontech BMS will demand a bit more) and after twenty minutes or so the 87% raised up to 92%. I shut the generator off when the bank was only taking 4 amps (so half an amp per battery).

I'm not sure whether the chargeverter could charge the bank up to 100% or not, but the watts going in drop so low that it's not worth the gas of the Honda 7000 to charge that way. I'll be happy with 92% SOC for now, just trying to get the bank full before the welder gets here this morning since the sun won't be charging the panels until after he's done with the job. He's going to be pulling 240V and 50A so I want to make sure our 38KW of lithium has enough in it to make sure he has the power he needs. When he starts I'll probably kick the the chargeverter on with 52V to lessen the discharge.

Then I'll take the EG4 back to 52V and leave it on my auto-generator set up where it kicks on at 40% SOC and charges until the bank is at 50% SOC. I think 52V will be fine for that bulk charging just to keep the bank from going empty.

 

[MisterSandals]

I have it set to charge my 8 x Pylontech US5000 batteries at 52V and 100A.

I am also looking at your other thread. What does Pylontech recommend for charging voltage?

 

[AlaskanNoob]

I am also looking at your other thread. What does Pylontech recommend for charging voltage?

In the Victron compatibility guide it says that the Pylontech BMS will ask for 53.2V but Victron has opted to limit the charge to 52.4V because they have determine 53.2V is too high.

My system is setup through DVCC so the Pylontech tells the MPPT what charge it wants and Victron gives it up to 52.4V.

 

[Zapper77]

Why is the voltage so low? You must have the 15 cell pack batteries

 

[Zapper77]

 

[AlaskanNoob]

View attachment 174376

Interesting that this says charge voltage is as high as 53.5V yet Victron says the BMS will ask for 53.2V.

Victron says the higher voltages are more likely to result in over voltage (higher being above 52.4V). For me, Victron's MPPT over DVCC with Pylontech has been charging the bank up to 100% and cells have been balanced to within .002V each morning, so that works for me.

 

[MisterSandals]

Victron says the higher voltages are more likely to result in over voltage (higher being above 52.4V).

Where are you seeing this from Victron? The company docs or your charger? Or??

 

[AlaskanNoob]

Where are you seeing this from Victron? The company docs or your charger? Or??

Victron & Pylontech UP2500, US2000, US3000, US2000C, US3000C, US5000, US5000B, US5000C, Pelio-L, UP5000, Phantom-S, Force-L1 & L2 [Victron Energy]

www.victronenergy.com

My system only charges the battery to 52.4V​

When DVCC is enabled, the battery (via the CAN-bms) is responsible for the charge voltage. The Pylontech battery requests a charge voltage of 53.2V. We have however found that in practice this is too high.
The Pylontech battery has 15 cells in series, so 53.2V equates to 3.55V per cell. This is very highly charged and makes the system prone to go overvoltage.
It should also be noted that a LiFePO4 cell stores very little additional energy above 3.45V.
For this reason we opted to override the BMS and cap the voltage at 52.4V. This sacrifices almost none of the capacity and greatly improves the stability of the system.

 

[MisterSandals]

Ah, 15 cells. It all makes sense now.

Carry on.

 

[Islandlife]

This has been a really helpful discussion so thanks very much everyone. I’m trying to find a charging solution for my 8x pylontech usc3000 bank when the sun doesn’t shine. The inverter I have wants a >10kw pure sine wave ac input from a generator and there isn’t a generator on the market that meets this spec so I’m looking for a 5kw generator charging option for those odd days when we don’t have enough solar. Was looking at the eg4 chargeverter and very glad to hear someone is using it successfully with pylontech. That said, I can’t seem to buy it here in the uk. What I’d really appreciate is some guidance on some basic rules/parameters to apply to avoid damaging the batteries or worst burning my garage down!!

 

[Browse]

This has been a really helpful discussion so thanks very much everyone. I’m trying to find a charging solution for my 8x pylontech usc3000 bank when the sun doesn’t shine. The inverter I have wants a >10kw pure sine wave ac input from a generator and there isn’t a generator on the market that meets this spec so I’m looking for a 5kw generator charging option for those odd days when we don’t have enough solar. Was looking at the eg4 chargeverter and very glad to hear someone is using it successfully with pylontech. That said, I can’t seem to buy it here in the uk. What I’d really appreciate is some guidance on some basic rules/parameters to apply to avoid damaging the batteries or worst burning my garage down!!

When you say the inverter wants a >10kW input...wouldn't that depend on the max charge setting you decide on? If you lower this, then you can manage the load on the generator. Another option is to parallel two inverter generators to get the pure sine wave output power you need.

 

[Islandlife]

Thanks! Yes the parallel generator idea is possible. Unfortunately you can’t change the parameters in the inverter as it’s talking to the bms. I suspect by managing the load a smaller generator would work but I really don’t want to buy one to find out it doesn’t!