MPP solar not accurately detecting appliance

[AbbzBeast]

hey everyone! New to solar set ups and inverters and would really appreciate some help for my camper van set up!

I have 440 W of solar on the roof connected to a 1000 W MPP solar inverter/charger with 200 AH 12 V of lithium ion batteries (Litime). I am also currently connected to the grid.

i have just installed a Nekpokka 12 V mini split air conditioner on my rig and it’s supposed to pull up to 900 W at first and slowly go down to around 300 W once it gets rolling. Weird thing is is whenever I turn on the mini split it shows 0 watts are being pulled and the load is at 0% too, but it’s bringing my battery from 13.4 V (which according to LiTime manual is fully charged) to 12.7 V within 5 minutes and then the battery dies within a couple of hours. But then I turn on my mini kettle is rated to pull 600 W and on the inverter it shows it fluctuates between 585 W to 610 W and the load goes up to 60%, which obviously is accurate. Basically, it’s like the mini split is only pulling energy from the battery and not being charged thru my solar or utility power.
Any ideas as to what could be happening?

 

[Mattb4]

Is your mini kettle also DC? If AC perhaps your unit does not measure DC wattage. Thus you would only see battery with that DC air con. (Off the DC common bus) at that so you would need to look at Bat amps in and Bat amps out which your unit may not measure.

I would expect an Air con unit to deplete your 200ah 12vDC batteries rather fast unless you have a high charge amperage from AC set.

 

[meetyg]

As you mentioned your mini split is 12v, that means its a DC load directly connected to the battery, I assume.
If so, the inverter cannot measure that, as it's not an AC load that is provided by the inverter.
Your kettle is probably powered by AC coming out of the inverter, so it's able to measure the load.

The mini split will be drawing around 75 amps at startup. But since you don't have (or didn't mention) other means of measuring the current going out of the battery, you really don't know how much it's pulling from the battery. It sounds logical that the battery would only last a few hours with the mini split on. It may be pulling more than 300w continuously.
If you had a shunt on the battery, or if your battery supports a Bluetooth app, that would help you understand exactly how much it's pulling.

BTW, while 13.4v is considered fully charged, the cells in the battery might not be well balanced if you only charge to that voltage.
I would recommend charging a bit higher (at least 14v) to allow some balancing to occur.
If cells are indeed unbalanced, the BMS might stop discharge because one (or more) cells have reach their lower limit.

 

[AbbzBeast]

Thank you so much for reading my post and trying to help. I appreciate you!

Yes the mini kettle is AC powered, so that does make sense. I just plugged in an apple MacBook charger which is rated at 45 W into AC outlet and a heating pad at 65 W at the same time but the inverter is showing 0% load and 0 W output. I have the inverter set to my the Sd5 setting which says “no matter connected load is low or high, the on/off status of inverter output will not be effected”, so even if I was only using 100 W on AC power it should still show up on the output correct? Maybe it’s just so low it doesn’t read it… but yes it does not read an DC appliances I have a fan and a fridge running currently and it shows 0 output.

I just figured out the issue. I basically do not have enough batteries, plus my inverter does not recognize DC power as an output and therefore will not power any DC appliances through my house but only thru the battery. The inverter can only charge 50 amps at a time and my AC unit is pulling 75 amps at first and slowly decreasing down to 300 W. So that is why it is dying. I would add more solar but it says in the manual it can only handle up to 500 W of solar.

Are there any beginner friendly inverters that can be charged with more solar?

Thanks so much

 

[AbbzBeast]

As you mentioned your mini split is 12v, that means its a DC load directly connected to the battery, I assume.
If so, the inverter cannot measure that, as it's not an AC load that is provided by the inverter.
Your kettle is probably powered by AC coming out of the inverter, so it's able to measure the load.

The mini split will be drawing around 75 amps at startup. But since you don't have (or didn't mention) other means of measuring the current going out of the battery, you really don't know how much it's pulling from the battery. It sounds logical that the battery would only last a few hours with the mini split on. It may be pulling more than 300w continuously.
If you had a shunt on the battery, or if your battery supports a Bluetooth app, that would help you understand exactly how much it's pulling.

BTW, while 13.4v is considered fully charged, the cells in the battery might not be well balanced if you only charge to that voltage.
I would recommend charging a bit higher (at least 14v) to allow some balancing to occur.
If cells are indeed unbalanced, the BMS might stop discharge because one (or more) cells have reach their lower limit.

Thank you so much for getting back. I appreciate you.

Thats a great idea, I’m going to look into battery monitors today, it seems that it does not measure any DC output. I ran about 100 W of AC energy thru the inverter and that didn’t show any load either, but it maybe was too small for it to show.

I’m a little confused though because I’m connected to shore power through my house and I’m pulling about 200 W of solar right now which isn’t a lot but it’s something and connected to utility power that I know can handle high wattage because I have ran a heater on a separate AC power outlet before with no issues. So any ideas as to why the battery continues to die although it is connected to it? I know for sure I definitely need to buy another 200 AH battery though and more solar before I go on any vacations in the camper.

Also, I charged my battery separately for 24 hours a week ago and it would only go as high as 13.4 V. Do you believe my battery is no longer able to function properly?

Thank you very much for your advice!

 

[meetyg]

Also, I charged my battery separately for 24 hours a week ago and it would only go as high as 13.4 V. Do you believe my battery is no longer able to function properly?

This is a strong indication that the cells are unbalanced. Probably one cell is at a higher SOC and therefore reaching its voltage limit (BMS will block charging at this point), while others are lagging behind.
I suggest you charge to 14v, but with very little current/amperage. This should allow some balancing. Then, when 14v is achieved, you could go a bit higher (14.2-14.4v).

 

[AbbzBeast]

Thank you so much for reading my post and trying to help. I appreciate you.

Yes the mini kettle is AC powered, so that does make sense. I just plugged in an apple MacBook charger which is rated at 45 W into AC outlet and a heating pad at 65 W at the same time but the inverter is showing 0% load and 0 W output. I have the inverter set to my the Sd5 setting which says “no matter connected load is low or high, the on/off status of inverter output will not be effected”, so even if I was only using 100 W on AC power it should still show up on the output correct? Maybe it’s just so low it doesn’t read it… but yes it does not read an DC appliances I have a fan and a fridge running currently and it shows 0 output.

What is confusing me is I have it set for the utility to be the main power and solar as a backup, I’m pulling about 220 W of solar according to PV and I’m connected to the grid, so is there any reason why it should not work? Do I need to install more batteries?

This is a strong indication that the cells are unbalanced. Probably one cell is at a higher SOC and therefore reaching its voltage limit (BMS will block charging at this point), while others are lagging behind.
I suggest you charge to 14v, but with very little current/amperage. This should allow some balancing. Then, when 14v is achieved, you could go a bit higher (14.2-14.4v

This is a strong indication that the cells are unbalanced. Probably one cell is at a higher SOC and therefore reaching its voltage limit (BMS will block charging at this point), while others are lagging behind.
I suggest you charge to 14v, but with very little current/amperage. This should allow some balancing. Then, when 14v is achieved, you could go a bit higher (14.2-14.4v).

Thanks for getting back again! When I charged it for that 24 hours, it says it was fully charged at 13.4 V and it wouldn't charge anymore. Perhaps I need to call Litime and see if I can get a replacement. But this definitely tells me my battery is not working right. Thanks again!

 

[AbbzBeast]

Also, I have figured out that I need to get a different inverter, one that can handle more solar. Do you have any recommendations for a good inverter that could handle 800 W of solar and is beginner friendly?

 

[meetyg]

Also, I have figured out that I need to get a different inverter, one that can handle more solar. Do you have any recommendations for a good inverter that could handle 800 W of solar and is beginner friendly?

Which model do you have and how much solar are you planning? Most MPPT solar charge controllers can be over-paneled, as long as you don't exceed maximum voltage on the PV input. As for current, the SCC will pull whatever it can (up to its maximum current) for the solar panels. So it's safe to slightly over-panel.

 

[AbbzBeast]

Thanks again for getting back with me. I have the MPP solar PIP1012LV-MS Inverter/Charger (PF1). I just looked at the manual, it says not to exceed 102Vdc for the max PV array open circuit. I have 2 220 W Newpowa panels rated at a max voltage of 17.52 V and current at 12.60 A. So even though it says max 500 W, it’s okay to over panel because the max voltage of both panels is way below the max PV array open circuit. That helps a lot thanks so much!