question

renne avatar image
renne asked

Multiplus II 48/5000/70 AGM battery settings?

I'm new to the Victron world. So a "Hello" to everyone!

I've connected 4 Accurat ST110 12V AGM batteries to the Multiplus II 48/5000/70.

A SmartSolar MPPT 150/45 with 2.4 kWp panels will be added in a week.

See the datasheet of the batteries.

I've selected "Gel/AGM" for the battery type and "Adaptive + BatterySafe" as charging algorithm. What values do I have to set for the following parameters to optimize battery life:

General -> Enable Battery Monitor

  • State of charge when Bulk finished?
  • Battery capacity = 110 Ah?
  • Charge efficiency?

Inverter

  • DC input low shut-down?
  • DC input low restart?
  • DC input low pre-alarm?
  • shut-down on SOC
    • SOC low shut-down?
    • SOC low restart?

Charger

  • Absorption voltage?
  • Float voltage?
  • Charge current?
  • Repeated absorption time?
  • Repeated absorption interval?
  • Maximum absorption time?
  • Temperature compensation = 0.97? room temperature between 15°C (winter) and up to 30°C (summer)


Thanx for any hint! :-)

Multiplus-IIAGM Battery
1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wkirby avatar image wkirby ♦♦ commented ·
That datasheet doesn't give any charge Voltage parameters.

Maybe best to contact the battery manufacturer and obtain the charging parameters from them.

0 Likes 0 ·
6 Answers
kevgermany avatar image
kevgermany answered ·

That datasheet is interesting. Took me a while...

From the graphs, you have the choice of charging to 2,27 or 2,4V/cell. Note the current limitations.

Configured at 48V nominal, you have 24 cells, so set absorption voltage to either 24 * 2.27 or 24*2.4. Your choice. What happens is the charger will push at it's max current until the absorption voltage is reached. Then it maintains that voltage. Their graphs correspond with this. What they also show is that charge times vary with DOD. Leaving your charger on adaptive should be OK. Max absorption time can be inferred from the graphs from the point of max voltage forwards. The default of 8 hours should fit well, but increasing won't be a bad thing. Usually it'll be a lot less in adaptive.

Repeated absorption I'd leave at defaults, unless you can get a clear statement from the makers.

They don't give a float voltage. I'd be tempted to charge at 2.27 to be safe, and set float a little lower, say 2.25.

If the current doesn't get too high, try charging at 2.4V and check the current.

I'd also watch the DOD/cycles. Quite a big improvement in life if you limit DOD to 30%.

On capacity, it's a touch misleading. We usually work from the C20 value as a starting point. IF you have very low current draw, you can set it higher.

Temp comp they only give for capacity. What's of interest here for charging is the Voltage change with temperature per degreee C. For now, leave at default. unless you get a better answer. Note that battery voltage decreases with temperature, for the same state of charge.


1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image kevgermany ♦♦ commented ·
Just realised I only commented on charging. SOC after bulk - from the graphs, 65% on 2.27 and 95% on 2.4 (solid black line)

I think charge efficiency is the 1.1/1.2 values. depending on charge voltage.

For the inverter alarm/shut down settings, decide on a discharge level, subtract from 100, find that on the right scale on the graph read back on the solid black line to the voltage at that level. But this is guesswork from voltage under charge, not discharge conditions. THere the voltage will be much lower. But I guess you don't want to be under 2.1/2.3V

Really like wkirby said, need more information.






0 Likes 0 ·
renne avatar image
renne answered ·

@kevgermany "accurat" is a home brand of "autobatterien-billiger" (batterium GmbH)

What specifically should I ask them to fill in the blanks?

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

95Ah (C10 discharged to 10,5V) at 48V is way to less for a 5000VA MultiPlus.

You will not get happy with that system.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image
kevgermany answered ·

Basically all the open questions.

Temp compensation, peukert, float, what's the real difference between charging at 2.4 and 2.27V, sustained discharge current. Matthias is right, I should have noticed the batteries are too small - 5KW is in the 100Amp region. Also rough indication of voltage under discharge conditions for your alarms. But if you don't have a BMV your alarms are very approximate.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

renne avatar image
renne answered ·

The OEM-vendor (batterium GmbH) cannot provide any other information :-(

We have a Raspberry Pi with Touchscreen, Venus OS and DVCC enabled. Do we really need a BMV or is Venus OS capable to aggregate the values of the SmartSolar MPPT and the Multiplus II to get correct voltage/currente/charge state readings of the battery?

Which configuration values do you suggest for a safe operation until I have found a suitable battery (probably LiFePo).


Thanx for any hint! :-)

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image
kevgermany answered ·

For the battery, as long as you stick to what you have, should be OK. But state of charge is going to be inaccurate. All the charging is voltage based.

So you're guessing the alarm level. As you probably know, when you put a load on a battery, voltage drops. When load goes off voltage climbs. Maybe warn at 12V, but no idea really, sorry.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources