Logging-machine and inverter?

[Huru-ukko]

Hi all, I'm new here and would like to know your opinion about using logging machine with solar power.

I have an off-grid system in summer cottage. Cottage is used only in summertime during weeks and from april to oct on weekends. I have 5x285w polypanels , 4x200ah (c10) agm batteries and victron 3000/24 inverter. There is one fridge ( 165kwh/year a+++), which is on from april to oct. Nothing else consuming ( only led lights ). Normally on sunnu day the mppt goes to float at 11.50 am. About.

I have been using a logging machine which is rated 1500w, but it takes much more when u start it ( so with every log) , the inverter handels it and i only use it when sun is shining. I haven't connected my generator yet. I'm curious am I doing some harm for the batteries with short but high power peaks that the machine takes when it starts? It did not work with 3kva hinda eu30i generator...

and be free to comment if any ideas how to make the system even Better, thanks in advance

t.Huru-ukko

[Huru-ukko]

So what i'm trying to ask is that does several hundred high current peaks per day destroy my batteries in no time? The peak is more than 3kw since honda generator could not handle it. When using the machine sun is always shining and the wattage from panels is normally about 700+ watts.

should I connect honda generator to the inverter and switch it on while using the logging machine - so that the current from
batteries would be smaller?

[DavidH]

I think you'll have to provide everyone here with the start-up surge of the logging machine and how long it runs for (you'll find this in the online manual) and probably the link to the datasheet of your batteries. If you have that Victron Inverter and have the low voltage disconnect set up correctly to protect your batteries then the inverter should cut out to protect the batteries. I found this topic that might interest you:

https://www.solarpaneltalk.com/forum/off-grid-solar/batteries-energy-storage/22042-battery-sizing-for-surge-loads

[Huru-ukko]

Hi, thank you for your reply and good link.
The machine manual did not provide any information about start-up surge - however I managed to use it once before honda went to overload mode so I would guess 3-3,5kw surge. The machine is rated 1500w.
the machine shuts down after every log, so the use is something like 10 seconds use , then picking up the wooden peaces and taking a new log and starting again . The use is about 10 sec use 10-30 sec pause and so on.
Inverter has proper settings and while using the machine solarcharger shows quite often still float even when using ( guess the pauses are so long that panels have time to charge between using) battery voltage never went below 24,97 volts.

so the batteries should not get empty - but is the high short current harmful? ( those agm batteries are not car start batteries )
this might be a stupid question but it would be great to know 😊.

[Huru-ukko]

All battery wires are 95mm2 lines - short ones with professional terminations.

[DavidH]

What AGM battery are you using? Some AGMs can support high Cold Crank Amps (CCA). Check this Rolls AGM 100Ah 12V battery datasheet and you'll see the cold crank amps are 1300. http://www.rollsbattery.com/battery/r12-200agm/ So that AGM battery is designed in a way to support surges of that amount. Post the link to the datasheet of your AGM batteries to see what it says the CCA are.
If you use the battery outside of the manufacturer's specifications I understand that, in general, you are asking for a shorter lifespan.

[Huru-ukko]

Hi thank you again , I found the link to probably right battery ( cant check now) . My iphone says there might be some malware on the site but i was able to open pdf correctly. It says for one battery max 4200w for 15 min ( i had 4 batteries ) so there should not be too much problem aguess.

https://www.monbat.com/modules/downloadResource.php?resource=806&hash=5ed79056eee38b0cecbb50bbffb49f49

[DavidH]

Yeah I don't see the CCA anywhere, but I do see that about the 4200W for 15 minutes. Beyond that I don't really have an answer as to the effect on lifespan. I'm learning as much as I can as I go along too. Maybe someone else with more experience will be able to let you know.

[Huru-ukko]

Thank you alot for taking time and effort. I would guess batteries should handle the short spike well , but if anyone has other opinions or knowledge please let me know. I will continue to use them and if it fails I'll let u all know 😊. Fortunately the system did not cost too much.

[Huru-ukko]

Hi all,

after winter the main system works properly. However one installation pole which had 3 panels mounted had cracked in high wind. Panels were intact but the pole broke. So now the panels will go to roof.

System will be 6x285w poly panels. And same batteries. there will be a professional istaller to the roof so lets hope they will be there next year too...

just thinking of connecting my old honda 3 kva generator to the inverter as an gen assist. Any opinions, I already have it...

[Mike90250]

If your inverter supports Generator Support mode, than I'd say use it that way.

You should not connect an inverter output with a generator output. The more expensive device will be damaged from un-synchronized power phases

[Huru-ukko]

Yes , it should be able to use generator support. Victron multiplus 3000/24/70.
now there will be a fully licenced elecrician to do the connections who is familiar with the products.

so with that I should be able to live fully normal living in there from march to early december.

( from dec-march there is ice so i’m unable to go there unless I buy a hydrocopter or such...

[Huru-ukko]

Now everything works.

Generator support works . 6 panels give +1400-1500w and after 4-5 hours of woodwork the batteries were floating. Could use only under 4 kwh a day... ( did not use generator )...

Thank for all of u for your help.