Victron Multiplus II 3000 Charging Question

[OTRwSolar]

I'm used to using standard RV converters. Their charging curves are very linear from 0 to 100%.

Just installed a 12v Victron Multiplus II 3000 (charging 304ah 4s EVE cells via a JBD 200a BMS). Set the battery type to lithium, fixed mode, absorption 14.25v, and float 13.5v. Charging is very linear as battery voltage approaches 14.25v. The LED charge indicator goes from bulk to absorption.

However, when charge current drops to approx. 2-4a, charge voltage suddenly spikes causing the charge current to increase to 10-12a. You can hear the Multiplus hum slightly louder at the same time. This current spike subsides within a few min. leaving the battery at a final voltage of 14.50v.

Thinking this was a fluke, I discharged the battery approx. 2-3% and charged it back to 100% 3 times. Did the same thing every time.

Is this normal charge behavior for the Multiplus 3000?

 

[sunshine_eggo]

1. What does the BMS report during this time?
2. Is it enabling charge protection?
3. Did you top balance your pack within the last 7 days?
4. Does the issue occur if you lower the absorption voltage to 13.8V and increase the absorption time to 2 hours?

 

[OTRwSolar]

1. JBD 200a BMS (via the bluetooth app) reported similar voltage and current as the Victron windows app (MK3 USB) throughout the charge process.
2. No BMS HVD's (battery HVD 14.60v, cell HVD 3.65v). If the BMS were activating HVD's I could see it causing charge voltage/current spikes. However, none occurred, the Multiplus did all this on its own.
3. Cells were parallel balanced to 3.650v several days ago. Since the 4 cells charged to 14.50v and didn't hit the HVD, I believe this shows the cells were reasonably well balanced.
4. I'll give this a try.

I get the impression this is not normal charging behavior for the Multiplus II. Is there anyway to reload the firmware?

Thanks!

 

[sunshine_eggo]

1. JBD 200a BMS (via the bluetooth app) reported similar voltage and current as the Victron windows app (MK3 USB) throughout the charge process.
2. No BMS HVD's (battery HVD 14.60v, cell HVD 3.65v). If the BMS were activating HVD's I could see it causing charge voltage/current spikes. However, none occurred, the Multiplus did all this on its own.
3. Cells were parallel balanced to 3.650v several days ago. Since the 4 cells charged to 14.50v and didn't hit the HVD, I believe this shows the cells were reasonably well balanced.
4. I'll give this a try.

I get the impression this is not normal charging behavior for the Multiplus II.

No. They follow a traditional 3 phase charging scheme, and they should not exceed programmed absorption voltage.

If nothing is feeding the MP OCV like a shunt, you might get better results connecting sensing wires to the V-sense terminal so the MP can base its operations on OCV.

Also worth triple checking all connections and BMS sense leads. Confirm all voltage readings with a separate meter.

Is there anyway to reload the firmware?

I'm not aware of a method for this.

 

[sunshine_eggo]

MPPT Firmware Downgrade - Victron Community

community.victronenergy.com

 

[OTRwSolar]

OP here. In addition to the voltage/current spike issue previously mentioned, our Victron Multiplus II 3000 2x120 also hummed and buzzed loudly while pulling an excessive 3-4a 120vac while under zero charge load. Clearly a number of things weren't quite right. After spending the weekend trying a number of different charging scenarios, changing various presets and double/triple checking wiring/connections, I finally gave up and tried contacting currentconnected.com today (where I purchased my Multiplus). I had completely forgotten it was Labor Day---my bad. Even so, Dexter at cc was still willing to give me a hand. Very impressive customer service to say the least! He suggested I make a few checks along with a firmware update. As it turned out, the firmware update corrected nearly all my problems. Ordinarily cc updates the firmware before shipment, but I had also ordered an MK3 USB---plus, I was trying to beat a shipping deadline last week, so I declined programming---again, my bad. Huge shout-out to Dexter at currentconnected (@HighTechLab)!! All is now well with our new Multiplus!

 

[sunshine_eggo]

I'll say it again... @HighTechLab doesn't suck.