Minimum battery capacity for Victron Multiplus II 12/3000

[Rumbledethumps]

Hi All,

After looking through the literature for the 12v Victron Multiplus II 3000VA, it states a minimum requirement of 400Ah battery capacity.

This system is a bit overkill for my present needs (small shed/cabin home office) but I purchased it to allow for future additions/upgrades.

The max load I’ll be drawing at any time will be well below the capability of the unit (likely no more than 150w on average with around 1400w peak/surge when including the momentary startup load of a small fridge/freezer unit), I had intended to use 3x 100Ah Victron high current superpacks with the following specs:

Nominal Capacity – 100Ah

Charging Current – 50Amp

Max Charging Current – 100Amp

Max Discharging Current – 200Amp

Max Continuous Current – 100Amp

Max Charging Voltage – 14.0 ~ 14.6V

3 of these batteries would be under Victrons recommended Ah capacity but wouldn’t the loads be comfortably within the limits for the continuous discharge current for 3 of these batteries, especially considering the max discharge rating of 200A per battery?

In truth at one point I was wondering whether I could get away with using just 2 of them?

Should this be OK or if not, what else do I need to take into account?

The rest of the system comprises 3x200w panels, a 100/50 Charge controller, 12/3000 Multiplus II Inverter, lynx distibutor and shunt and a Cerbo GX.

Many thanks.

 

[time2roll]

As long as the limitations are acceptable, the battery will drive the victron at the limited level just fine.
I would adjust the charging current to 50% to 80% of the maximum.

If the usage increases the battery will need to be expanded.

Victron would never recommend a limited use install. Your call.

 

[Rumbledethumps]

As long as the limitations are acceptable, the battery will drive the victron at the limited level just fine.
I would adjust the charging current to 50% to 80% of the maximum.

If the usage increases the battery will need to be expanded.

Victron would never recommend a limited use install. Your call.

Thanks,

Just so I'm clear, can you clarify what you mean by limited use install and driving the victron at a limited level?

How is using a smaller battery bank detrimental if the load being used is well under the spec of the units and batteries capacities? Or do you mean that it's best to build the system to handle all likely future demands to avoid unnecessary upgrades later on?

 

[time2roll]

The description said the expected limit was 1400 watts. That is a limitation compared to the 3000 available.

As long as no extra load is encountered all will be fine. If there is additional load and the system shuts down don't call Victron. Not a big deal.

I believe the 400ah rating is primarily for voltage drop at high load when using lead-acid batteries. If the undersized LFP can provide full power, less than 400ah is fine.

 

[Rumbledethumps]

The description said the expected limit was 1400 watts. That is a limitation compared to the 3000 available.

As long as no extra load is encountered all will be fine. If there is additional load and the system shuts down don't call Victron. Not a big deal.

I believe the 400ah rating is primarily for voltage drop at high load when using lead-acid batteries. If the undersized LFP can provide full power, less than 400ah is fine.

Got it, thanks.

 

[John Frum]

After looking through the literature for the 12v Victron Multiplus II 3000VA, it states a minimum requirement of 400Ah battery capacity.
<snip>
I had intended to use 3x 100Ah Victron high current superpacks with the following specs:
<snip>
Max Continuous Current – 100Amp

3000 volt amps ~= 2400 ac watts
2400 ac watts / .85 inverter efficiency / 12 volts low cutoff = 235.294117647 service amps
235.294117647 service amps / .8 fuse headroom = 294.117647059 fault amps

Those 3 batteries can cover the max continuous draw of your inverter, but they can only do it for ~80 minutes.
IMO, buying batteries from Victron is like buying gasoline from Ferrari.

 

[Bud Martin]

BTW, the inverter is rated at 3000VA 2400W, not 3000W due to Power Factor, see spec sheet.

 

[Rumbledethumps]

3000 volt amps ~= 2400 ac watts
2400 ac watts / .85 inverter efficiency / 12 volts low cutoff = 235.294117647 service amps
235.294117647 service amps / .8 fuse headroom = 294.117647059 fault amps

Those 3 batteries can cover the max continuous draw of your inverter, but they can only do it for ~80 minutes.
IMO, buying batteries from Victron is like buying gasoline from Ferrari.

? Fair point on the batteries.

Thanks for the calculations; that's really useful.

Going to keep thinking about this before spending unnecessary money; feeling a bit skint as it is after buying the other bits!

 

[Rumbledethumps]

BTW, the inverter is rated at 3000VA 2400W, not 3000W due to Power Factor, see spec sheet.

Got it, cheers.

 

[HRTKD]

Have you purchased all the components? The Multiplus II may not be the best fit for your use case. A regular Multiplus would work and is slightly less expensive. The Multiplus II is marketed towards an RV with a 50 amp split phase system. I doubt you have that in a cabin.

 

[Rumbledethumps]

Have you purchased all the components? The Multiplus II may not be the best fit for your use case. A regular Multiplus would work and is slightly less expensive. The Multiplus II is marketed towards an RV with a 50 amp split phase system. I doubt you have that in a cabin.

Hi,

No, not yet; I've got the panels, charge controller, distributor, cerbo GX and lynx shunt; just the inverter and batteries to buy.

I've actually been debating about whether to go with a 24v system as it looks like it might be a better fit, so I will definitely check out the standard multiplus.

Thanks.

 

[Bluedog225]

Since no one has said plainly, the victron batteries seem like a big mistake. Way too expensive. Much better options available.

The other possible mistake is not going straight to 48v.

Good arguments for 12v and for 48v. Few for 24v.

 

[Rumbledethumps]

Since no one has said plainly, the victron batteries seem like a big mistake. Way too expensive. Much better options available.

The other possible mistake is not going straight to 48v.

Good arguments for 12v and for 48v. Few for 24v.

I think Joey was pretty plain about it ? but yes, after looking the prices do seem very very high.

48v; perhaps, I just wonder if this will be in excess of my needs at the moment...

If we do go for a whole house system at a later date it will be for a different house and that will definitely be 48V.

 

[Lilikoi_Heavy_Industries]

I think Joey was pretty plain about it ? but yes, after looking the prices do seem very very high.

48v; perhaps, I just wonder if this will be in excess of my needs at the moment...

If we do go for a whole house system at a later date it will be for a different house and that will definitely be 48V.

48v isn't "in excess of your needs". A 48v MultiplusII costs less than a 12v one last I checked.

It would allow smaller wire sizes, lower amp circuit breakers, and allow you to quadruple your solar array size in the future if you get the chance. Where is the downside, if you don't have major 12v loads?

Why are you asking detailed questions for a system that wouldn't be a reasonable price to buy? Who buys victron batteries and why, are you trying to send them to space or something?

What made you start thinking you need to buy lynx distributors and shunts? We run our MultiplusII/48/3000 up to 2000watts all the time, or even higher with generator powerassist, and we just use an old BMV712 shunt. We also run a raspberry pi4 instead of buying a cerbogx, but you do need to buy a couple extra victron cables to use raspberry pi instead.

 

[Rumbledethumps]

48v isn't "in excess of your needs". A 48v MultiplusII costs less than a 12v one last I checked.

It would allow smaller wire sizes, lower amp circuit breakers, and allow you to quadruple your solar array size in the future if you get the chance. Where is the downside, if you don't have major 12v loads?

Why are you asking detailed questions for a system that wouldn't be a reasonable price to buy? Who buys victron batteries and why, are you trying to send them to space or something?

What made you start thinking you need to buy lynx distributors and shunts? We run our MultiplusII/48/3000 up to 2000watts all the time, or even higher with generator powerassist, and we just use an old BMV712 shunt. We also run a raspberry pi4 instead of buying a cerbogx, but you do need to buy a couple extra victron cables to use raspberry pi instead.

Cheers for your opinion but thanks to the help I received from members of this forum, everything is up and running and working perfectly for my needs.