New Victron MPPT Firmware

[rslifkin]

Originally Posted by noelex 77

Unfortunately, tail current will not terminate the absorption cycle accurately. For example: if there is a load greater than the tail current setting, the absorption phase will never be terminated.

I've got a Smartshunt and a Cerbo GX in the system, so with DVCC shared current sense enabled, it avoids that problem. It uses the current sensed by the shunt to end absorb (rather than output current from the MPPTs), so with my tail current set to 5 amps, once the batteries are accepting less than 5 amps (regardless of load) both MPPTs drop to float. Now if only the Multiplus inverter could end absorption this way (and had an adjustable re-bulk voltage).

[noelex 77]

Originally Posted by rslifkin

I've got a Smartshunt and a Cerbo GX in the system, so with DVCC shared current sense enabled, it avoids that problem. It uses the current sensed by the shunt to end absorb (rather than output current from the MPPTs), so with my tail current set to 5 amps, once the batteries are accepting less than 5 amps (regardless of load) both MPPTs drop to float. Now if only the Multiplus inverter could end absorption this way (and had an adjustable re-bulk voltage).

Using battery return amps from a shunt rather than the tail current from the solar controller is the ideal system to terminate the absorb cycle at the correct point. The advantage over a simple algorithim using the solar controller is that the absorption cycle is terminated correctly every cycle. It is, however, complex, requiring comunication betweeen the battery monitor and the solar controller, so it is not for every system.

[cofc]

Originally Posted by cofc

Hmm, I must be doing something wrong. I have float voltage set to 13.02v (per US Battery specs) and my rebulk offset to 0.12v. So theoretically once the battery voltage drops below 12.9v for one minute it should initiate a new bulk cycle, correct? However it’s not. I’ve come back to the boat at 2:00pm, in full sun, with the batteries at 12.7v and the charge controllers in float.

I do have my starting battery connected to the BMV-712, which is networked with the charge controllers. But surely they’re not taking the starting battery voltage into account when deciding when to rebulk, right? It’s on a relay so it always stays at 13v.

Following up on this. After speaking to my sales rep, and him talking to Victron, we realized that having Temperature Compensation enabled was for some reason causing this problem. After disabling this setting, the charge controllers re enter bulk charging as they should after meeting the threshold voltage for a period of one minute. My temperature compensation setting was set to the default of 9mV per degree Fahrenheit.

I didn’t find out why it was causing the problem, but disabling temperature compensation seems to have fixed it for now.

[GILow]

Originally Posted by cofc

I didn’t find out why it was causing the problem, but disabling temperature compensation seems to have fixed it for now.

That’s kind of a poor compromise, don’t you think? Temperature compensation is there for a good reason and one of the reasons to buy these sorts of regulators. I’d be getting back on the phone to Victron until the issue was fixed.