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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) asked

MultiPlus Compact 12/1600/70-16 Absorption Phase and Float Voltage?

Hi guys,

Left my boat last year in her winter storage end of September with service batteries (4x110Ah Victron AGM in parallel) fully charged. Open voltage was 13.10V. Then checked batteries end of November. Open voltage at 12.93V. Battery main switch always turned off > means no loads at all.

Today I made a short visit to my boat to check again. According to the battery display (has its own shunt and measured at the battery pole) voltage was down to 12,71V. Confirmed measurement with a DMM and the BMV 702 (also with its own shunt). Battery temperature at 6.2°C.

Decided to put shore power on to charge with the MultiPlus. Charge current in bulk was around 40A and decreasing. Charger went into absorption phase about 15 minutes later at 14.7V. Now I would expect the absorption phase to last for at least 2 hours if not longer. But charger decided to switch into float in less than 30 minutes while still charging at about 13A. The second before switching into float, current was at 17A. That doesn't look ok to me or is it normal that absorption only lasts for that short duration while battery is still sucking lots of amps?

Second problem as you can see from the image is float voltage. It stays at 14.08V (again confirmed with a DMM). Float voltage is set to 13.80V and max charge current fixed at 40A with VE.Configure when I bought it as a new device. And so far for the last two seasons it has worked simply fine. No issues at all. How come that float voltage gets that high and why is the absorption phase so short?

Hopefully there's someone who can enlighten me.

Cheers

Stefanie





MultiPlus Quattro Inverter Charger
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2 Answers
boekel avatar image
boekel answered ·

Well it sounds like your batteries were fully charged...13A absorbtion current for a 440Ah bank is pretty much charged.

the float voltage: keep an eye on it or check settings.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

Thanks Boekel,

yes maybe fully charged with just 3%. But still would have expected absorption phase to last longer. It is set for 4 hours (which probably implies a fully discharged battery) and I cannot figure out why it went that short. Maybe it has to do with time of bulk phase.

Float/Absorption voltage is set to 13.80/14.40V. But reading the manual again I think I found what I was looking for. Absorption and Float voltage has temperature compensation (Multi has a temp sensor connected). Not sure what "adjust mode" means but looking at the chart I guess the multi is not in adjust mode.

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boekel avatar image boekel ♦ Stefanie (Victron Energy Staff) ♦♦ commented ·

Ah yes if it's cold the voltage goes up :)

And just be happy it doesn't stay in absorption too long ;)

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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Boat is back in the water. Now the situation is completely different with the MultiPlus Compact 12/1600/70-16. Suspect battery bank fully charged with absorption current less than 6A. The Multi goes from Bulk into Absorption after a few minutes but keeps staying in Absorption for hours and doesn't want to switch to float. After 3 hours I had to take precaution and switched the Multi off to protect batterie bank.

Batterie temperature was at about 15°C with Absorption voltage at around 14.4V due to temperature compensation. Before switching the Multi on for the first time yesterday I updated firmware to 459 and changed the charging profile to adapt better with my MPPTs. Settings are 14.2V absorption, 13.6V float, 4h max absorption time and checked adaptive + battery safe.


Should I be worried?



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boekel avatar image boekel ♦ commented ·

I'd just keep an eye on it for a couple of days, battery bank has temperature sensor I read?

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ boekel ♦ commented ·

Yes, will do. I‘m checking again settings just in case I missed something.

No external temp sensor attached yet as I need to install BMV again.

Temp reading is coming from a Pico with sensor attached to battery bank. But AFAIK the Multi has internal temp sensor. At least I can read out temperature from the Venus Pi. Multi and batteries are in the same location.

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boekel avatar image boekel ♦ Stefanie (Victron Energy Staff) ♦♦ commented ·

I would advice to install the temperature sensor for the Multi, didn't it come with it? (not sure if all models do come with it) this will make it use the correct voltage for the battery temperaturs.


also see the datasheet of your batteries about this.

https://www.victronenergy.com/upload/documents/Datasheet-GEL-and-AGM-Batteries-EN.pdf

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ boekel ♦ commented ·

I just checked. Been a long time since I installed the multi. I had the temperature sensor installed. Sorry for the confusion.

Also checked settings for the charger again. Everything looks fine to my eyes. But what do I know. Since 30 minutes Multi keeps staying in Absorption again. Bulk lasted for only few seconds when I switched the Multi on this morning with full batteries.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ Stefanie (Victron Energy Staff) ♦♦ commented ·

It still doesn’t want to switch into float. For the moment I reduced absorption voltage to a safe level of 13.8V.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ Stefanie (Victron Energy Staff) ♦♦ commented ·

Flashed to 2606159 and Multi goes quickly into float mode. Just like it should be.

Flashed again to 2606459 and Multi stays forever in absorption mode.

I‘d say a firmware problem with 459 together with my multi compact and reproduceable.


@mvader (Victron Energy Staff)

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boekel avatar image boekel ♦ Stefanie (Victron Energy Staff) ♦♦ commented ·

Hi @Stefanie

I've asked a developer to look at it, can you share the settings file from the multi?

Can you tell what other components are in the system?

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ boekel ♦ commented ·

Hi Boekel,

Have your address saved. So you may delete it.

Since I flashed to 159 and not having saved the settings, it will not be possible. Unless you want me to flash to 459 again, which is no problem at all as I wanted to try 433 also (for the Assistant).

But have used default settings. Only changed Absorption Voltage, Float Voltage and Max. Absorption Time in a custom battery setting. No Assistant. Virtual Switch at default value.


Amongst the Multi, there is a BMV-702, DMC and a Blue Solar MPPT 150/35. All connected to a Raspberry Pi via Ve.Bus Mk3 or Ve.Direct to USB interface.

Batteries are 4x110 Victron AGM in parallel.

Pi is runnning Venus OS v2.30~43.






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