Victron Multiplus numbers just don't add up

[The Brockerts]

I'm running multiplus and started a bulk charge last night, expecting a full charge over night. Instead I ended up with these numbers. So I rebooted PC and power cycled multiplus several times and the numbers didn't change. A volt meter reading at the terminals shows 12.9V not 12.13v that the multiplus shows, so it did charge the bank. Bulk charge 1 A? Is this unit dead?

Joe

 

[DDW]

Something definitely wrong. Is there a shunt in the system, and where is it wired? Both absorb voltage and float seem set pretty high - what kind of batteries?

 

[The Brockerts]

Something definitely wrong. Is there a shunt in the system, and where is it wired? Both absorb voltage and float seem set pretty high - what kind of batteries?

No Shunt in the system, just the SOC that the Multiplus provides, The batteries are AGM.

Update:
Shut everything down, connected up a secodary battery charger, powered the systems back up with the Multiplus battery charger off. The Multiplus when into Passthru, as it should, and it's Voltage is now reading correctly. SOC at 100%. I'll let the system stabilize for a day and then bring the Multiplus Charger back online.

 

[rslifkin]

The Multiplus won't be able to track SOC even remotely accurately if there is ANYTHING other than the Multiplus that provides power to, or draws power from the batteries.

 

[JackConnick]

A shunt will give you much better information.

 

[tpbrady]

Whenever you power off the Multiplus, it resets everything meaning when the charger switches on it’s in bulk. Bulk with 1 amp would tell me the battery bank is full.

 

[Bmarler]

Those voltage numbers look pretty close to me. I float mine at 13.6, as it’s what full river recommends.
It’s the bulk output of 1 amp and voltage at 12.13 that’s concerning.
Bulk should run at 70 amps according to the screen shot, until you reach the 14.7 volt setting. Then it looks at amps output to taper off till you go to float. It sure if you can set the absorption amps/float threshold on that, but it seems like Victron would give you access to that.
Is there something else buried in the menu that might limit the output? Something about breaker size or similar? I don’t have any experience with multiplus so don’t know the menu structure.

 

[Bmarler]

The Multiplus won't be able to track SOC even remotely accurately if there is ANYTHING other than the Multiplus that provides power to, or draws power from the batteries.

Really? What about the engine alternator? Surely there’s a way for a multiplus to handle that. Am I missing something, or is a multiplus designed for inverter duty only?

 

[Delta Riverat]

Nope.

The multiplus is a inverter / charger. It inverts and it charges. Doesn't know anything about your batteries except the voltage. Charges to what you set it for and outputs AC as needed.

Yeah, you need a shunt if you want to know how many AH are left in your batts.

 

[SteveK]

No Shunt in the system, just the SOC that the Multiplus provides, The batteries are AGM.

Update:
Shut everything down, connected up a secodary battery charger, powered the systems back up with the Multiplus battery charger off. The Multiplus when into Passthru, as it should, and it's Voltage is now reading correctly. SOC at 100%. I'll let the system stabilize for a day and then bring the Multiplus Charger back online.

Is the multiplus reading correct voltage "while" the other charger is running? I also would like to know how a SOC can be accurate without a shunt measuring in/out current.

 

[Bmarler]

The old balmar smart gauge used to do some sort of calculation without a shunt, but I think they dropped it in favor of the smart shunt available now.
I guess soc on the multiplus is just an approximation based on voltage. I wouldn’t consider it even remotely accurate.
Back to the original problem, do you input the battery bank size in the multiplus?
Still wondering why it didn’t charge right.

 

[twistedtree]

Only the Multiplus SOC calculations will be messed up with other DC chargers and loads on the batteries. All other aspects of charging should work correctly, but definitely ignore the SOC reported by the Multi.

Do you have the Multi remote voltage sense wires hooked up?

The Multi's won't go back into bulk until the battery voltage drops a certain amount below either the float or the absorb voltage. I don't recall which, nor how much of a drop is required. But if you turn them off and back on again it should go into bulk.

 

[rslifkin]

Rebulk on a Multi is float voltage minus 1.3V for a 12V system unless the Lithium option is enabled, then it's float minus 0.2V. No ability to adjust that and the inability to end absorb based on amps (for lead systems) bugs me on the Multiplus. Those features are all adjustable and work great on the MPPTs, but the Multiplus charge algorithm is much more rigid and not as good. Mine often stays in absorb too long with their "smart" algorithm, other times it seems to drop to float too soon.

Really? What about the engine alternator? Surely there’s a way for a multiplus to handle that. Am I missing something, or is a multiplus designed for inverter duty only?

With other charging sources and power consumers, you either ignore or turn off the SOC calculation in the Multiplus and need to use a BMV or Smartshunt or other shunt based battery monitor to track SOC.

 

[The Brockerts]

Not much change, with a secondary charger I was able to get the battery voltage up to 13.20 but once the Multiplus 12/3000 charger was turned back on the low battery alert comes on, bulk charge starts and at 0-1Amp.

All these problems started after a firmware update and now I believe that has caused these problem. I've downloaded VE.Configure and will start looking at the configuration file that it is using in detail

 

[rslifkin]

Firmware updates typically reset a lot of the settings in the Multiplus, so definitely go through the configuration and see what you've got. It's possible settings didn't get re-loaded properly after the update.

 

[The Brockerts]

I didn't seem anything that looked out of reason.
I’ve fired up VE.config, loaded the default setting config file, and then pushed that to the Multiplus 12/3000/120. I can see that the pushed worked because the Charger setting went to 90Amp, and it was set to 70 before the push.
There was no change , went into bulk charge at 12.62V 0 amps

I then switched to Charger only, no change,

Seems the charger is dead from the firmware update

 

[rslifkin]

Did you confirm the charge voltage settings? I remember some kind of update saying they'd be reset to 12V so it wouldn't actually charge.

 

[The Brockerts]

Did you confirm the charge voltage settings? I remember some kind of update saying they'd be reset to 12V so it wouldn't actually charge.

yes, did check that and the voltages for different ranges were ok

I've SOLVED the problem !?, the following fixed it

powered unit down,
removed and reconnect all battery related cables
Tested the ANL FUSE, It passed a continuity test, but showed signs of burning or heat, replaced
powered unit up to ON via front switch, low battery light came on
loaded default config from VE.Config, changed one setting, Lowered charging rate from 90 amp to 70 amp
Front switch moved to Charger Only and the charger fired up and the low battery light went off
Front switch changed to ON, the unit seem to be running normal and battery charge went to float at 13.79V