question

rithym1964 avatar image
rithym1964 Suspended asked

multiplus with built in AVR

I have a pair of 48v 5KVA Multi II in parallel and they have been working great for a couple years now supplying 230V all day every day. Due to my limited battery reserves the inverters switch to grid every night at 10pm to make use of cheaper night rate electric and give the battery bank a rest. Unfortunately I am a long way from the local 230v transformer so my grid voltage drops as low as 170V causing shut downs with my PC. To combat this problem I bought an APC UPS 1000KVA which has built in AVR so when it senses the voltage drop below 210V it 'boosts' the current up instantly and still delivers 230V to the PC. This has also worked great since installing almost two years ago, my PC has not rebooted once since installing the UPS.

My question is if Victron could incorporate this same UPS AVR feature into a Multiplus III unit it would possibly be a total game changer as the unit would clean up dirty or low/ high AC (from grid or genset) Interested to hear from Victron technical staff who understand how important this feature could be

Multiplus-II
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

2 Answers
Michelle Konzack avatar image
Michelle Konzack answered ·

The current and only solution is a very big charger from Victron with wide input voltage and charge your batteries at night.


I have installed the same at a customer using two Skylla-TG 24/100 (120-240V) to get the Batteries over night full and support the load (tree MultiPlus-II 24/5000) because they failed horrible with 3x42mm² over a distance of more then 800m where the Voltage should drop only 18V @32A, but the reality looked different.

3 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

rithym1964 avatar image rithym1964 commented ·
I have no idea how your input is related to my suggestion? Why would I want to charge my batteries at night?? not only would this cost me money but I would then be cycling my batteries twice every day thus shortening their life by 50%.
0 Likes 0 ·
Michelle Konzack avatar image Michelle Konzack rithym1964 commented ·
If your ACin drop to 170V, then you have a little bit more problems.


Maybe you should ask your Energy provider to increase the Voltage?


Here in Estonia Country side the Voltage can drop easily under 200V because some houses require more then 600m cables, hence it is possible, to request EestiEnergia/Elektrilevi to increase the Voltage at the Transformator up to 252V.


I think, you should first contact your Energy Provider, because it is mostly in HIS responsibility, if the cable to your house is owned by him.


Otherwise it is your responsibility, if you own the cable from the Transformator to the House and it is sized to small for the lenght and current transfered


0 Likes 0 ·
rithym1964 avatar image rithym1964 Michelle Konzack commented ·

Yes you are correct to contact the EDP who supply my power. I did this many years back and they said they could not boost the voltage any higher as it would cause problems for the people living next to the transformer 3KM away.


Another option would be to invert power from the battery bank 24/7 (so not switch to grid at 10pm) and use a small 3 phase 48V forklift charger powered from my grid timed to come on at 10pm to supply enough power to cover night time loads which are about 1KW average. Not exactly efficient but I think it would work and maintain the voltage to all the loads at 230V.

0 Likes 0 ·
nickdb avatar image
nickdb answered ·

The inverters are designed for ESS which requires it to sync with the grid, thus input and output voltage/frequency will track to the grid. Best solution is a small secondary UPS on the output for sensitive gear.

You can try set a higher Voltage cut-off limit on the inverter, that sometimes helps.

2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

rithym1964 avatar image rithym1964 commented ·
I already have a UPS as stated above, you obviously never read the whole post.


You state 'setting a higher voltage cut-off limit on the inverter' will you please explain in more detail how that will help my grid voltage being so low?

0 Likes 0 ·
nickdb avatar image nickdb ♦♦ rithym1964 commented ·
I did read your whole post, no need to be sarky, I just stated that it is the best option.

Equipment dips because the inverter tracks the grid voltage downwards, if you set a higher cut-off voltage you may be able to prevent passing a lower voltage to sensitive gear, which is what causes systems to reset/reboot.

If your batteries are low, the transient that an inverter can put on them during cutover can also be sufficient to cause instability on AC OUT.

These two factors of the ability of the battery to cope with a momentary surge as well as grid "browning out" is usually what will result in voltage problems on AC out.

The hardware is not designed to provide clean output power like a proper UPS, that is not the purpose of an inverter.

My grid is not as poor as yours (only drops down to 198V) but we have numerous outages on a daily basis.

In 3 years I have only had two occurrences where equipment restarted.

The UPS function is perfect for the majority of use cases, but in very poor grid conditions, you are going to be stuck with an external UPS to bridge the gap.


0 Likes 0 ·