PowMr 10,2kW Inverter with 4x12V 300Ah PowMr Battery question

[Mitsu2]

Hi Everyone, New Member here.

I am in Thailand, at the moment I am using a 5kW Sofar On-Grid inverter which works great, but we are going to change to an Hybrid system with at first 4x12V 300Ah LFP Batteries (more coming soon as budget allows.

The inverter *PowMr* and the Batteries *also PowMr* are on back order at the moment, so hopefully they will arrive early next month.

My Questions:

I will be using a PowMr 10.2kW Inverter which will be connected to 4 LFP PowMr x 12V 300Ah batteries connected in Series to create a 48V system. The batteries will have a HC02 balancer. Now as the Batteries do not have a way to connect a RS cable to the inverter I will need to set to Battery as User Defined in the PowMr. The System will be set in Hybrid mode and still have a connection to the grid but Battery charging will be done by Solar only.

I need the voltages to set in the inverter. But bearing in mind, I only want to charge the Batteries to a max of 85% and the max lowest discharge level I want is 25% so effectively using only 60%. When it reaches 25% discharging SHOULD STOP and switch to the Grid. I also want that the Battery absolutely stop discharging when it reaches 15% capacity, this is as safeguard.

what i have seen in the manual of the Inverter (Menu option #29) the max "Low DC cut-off voltage" can be set at is 48V.
Also I can only set whole values except for bulk and floating.

Thank you in advance for pointers you can give me, as at the moment I am bit stumped.

 

[wpns]

We see a lot of problems here with batteries in series after operating 'just fine' for a year or two, and while the sales guys say you can do it, the warranty folks get unhelpful and unresponsive when the inevitable problems arise.

The HC02 may help, only time will tell.

Batteries without Bluetooth or some kind of comms are especially frustrating when problems crop up, as there's no way to tell what's going on inside, and poking at four batteries one at a time with a bench supply for weeks at a time is going to be very frustrating.

If at all possible get 48V batteries with wired (or at least BT) comms so you know what's going on at the individual cell level.

 

[wpns]

I only want to charge the Batteries to a max of 85% and the max lowest discharge level I want is 25% so effectively using only 60%. When it reaches 25% discharging SHOULD STOP and switch to the Grid. I also want that the Battery absolutely stop discharging when it reaches 15% capacity, this is as safeguard.

Why? By failing to charge to 100% at least weekly (I preger daily) you'll forgo balancing, which will greatly accelerate problems.

While determining SOC from voltage is less than ideal (and impossible outside the knees of the voltage curve), 48V is about 10% and the point where the voltage really falls off a cliff so not a bad place to stop.

 

[Mitsu2]

Thx but in my post I wrote that HC02 balancer will be attached to the Batteries.

 

[Mitsu2]

We see a lot of problems here with batteries in series after operating 'just fine' for a year or two, and while the sales guys say you can do it, the warranty folks get unhelpful and unresponsive when the inevitable problems arise.

The HC02 may help, only time will tell.

Batteries without Bluetooth or some kind of comms are especially frustrating when problems crop up, as there's no way to tell what's going on inside, and poking at four batteries one at a time with a bench supply for weeks at a time is going to be very frustrating.

If at all possible get 48V batteries with wired (or at least BT) comms so you know what's going on at the individual cell level.

If budget would allow this, then I would for sure do that, but that is not an option, so I have to deal what I can afford.

So setting Voltages is not an option???, and even if they would live only for a couple of years I would be further then where I am now, when the grid fails we are in darkness.

 

[Mitsu2]

While determining SOC from voltage is less than ideal (and impossible outside the knees of the voltage curve), 48V is about 10% and the point where the voltage really falls off a cliff so not a bad place to stop.

That is why I want to stop at 25% and absolutely stop, if having a large load *which I will prevent* when it reaches 48V, but I need the voltage to set for the 25-85%, i tried with ChatGPT and Gemini and they gave me conflicting info. Even wanting to set FLOAT to high, which for LFP is absolutely not advisable AFAIK

 

[wpns]

300AH 12V Lithium Energy Storage Battery

200AH MINI Lithium Battery with a nominal voltage of 12.8volt ensures more than 4000 life cycles.

powmr.com

Is $450 and

316AH 51.2V Lithium Battery with Max Charging & Discharging Current 200A

High-capacity 316Ah LiFePO4 Lithium Battery of 51.2V, delivers reliable and long-lasting power for various applications.

powmr.com

Is $1800. Same price but intrinsic voltage is 48V and has wired comms. Maybe your region has different pricing?

 

[Mitsu2]

I have a paid a lot less for that 300Ah ones, it was a promo and it was extra discounted as it was on back order. In total I have paid 1200 USD for all four of them. Price now is 361 USD (exclu Shipping)

And They don't carry that battery 316Ah here locally. A comparable (read no name) brand will be 69000 THB which is around 2100 USD. *give and take a few dollars*

Link to mine: https://www.lazada.co.th/products/pdp-i5349932985-s22733664614.html

link to a 314Ah 48V set

Lithium Battery 51.2V 100Ah 200Ah 314Ah G3 G4 LVTopsun Li-ion battery แบตเตอรี่ลิเธียมมีมาตรฐาน แบตเตอรี่สำหรับโซล่าเซลล์ | Lazada.co.th

แบตเตอรี่ลิเธียม LVTOPSUN 51.2V 100Ah 200Ah 314Ah สำหรับโซล่าเซลล์ รุ่น G3 G4 ที่มีประสิทธิภาพสูง พร้อมมาตรฐาน IP65 ช่วยเพิ่มความปลอดภัยและทนทาน เหมาะสำหรับใช้งานในระบบพลังงานแสงอาทิตย์. - Lazada

www.lazada.co.th

See the price, 74000 THB = +/- 2300 USD

 

[wpns]

If budget would allow this, then I would for sure do that, but that is not an option, so I have to deal what I can afford.

So setting Voltages is not an option???, and even if they would live only for a couple of years I would be further then where I am now, when the grid fails we are in darkness.

In a couple of years you'll be in darkness and broke, but we'll still be here to try to help.

 

[wpns]

i tried with ChatGPT and Gemini and they gave me conflicting info

Please don't use the Artificial Idiots, ask us Real Idiots.

 

[Mitsu2]

- post withdrawn -

 

[wpns]

And They don't carry that battery 316Ah here locally.

Hmm, sorry I can't parse Lazada, is there a 280AH 48V battery in your price range? [And is a 300# battery managable for you?]

Not trying to be obnoxious, and your English is way better than my Thai, and I was hoping that other folks from Thailand would hop in with suggestions...

 

[Mitsu2]

With Lazada (Thailand) it's unfortunate that if you go over let's say a price of (converted) 400 USD *i don't know the exact amount* you can't use COD which is *Cash on Delivery*, thus anything over that you have to pre-pay, and that deal IMHO was very good as it's the lowest price I have seen in a long time for quality batteries.

Unfortunately the ones I bought they are "dumb" batteries thus no way to connect communication cable to the inverter, but I am just looking to setup the inverter manually, Inverter set to "USR" and that is why I need the voltages for the range i am looking for. Thx

 

[Offgrid Philippines]

That is why I want to stop at 25% and absolutely stop, if having a large load *which I will prevent* when it reaches 48V, but I need the voltage to set for the 25-85%, i tried with ChatGPT and Gemini and they gave me conflicting info. Even wanting to set FLOAT to high, which for LFP is absolutely not advisable AFAIK

Greetings from The Philippines.

You don't have to stop at 25% in fact it may be difficult to see exactly where 25% is - especially if you do not charge to 100% form time to time to reset the BMS calculations. 10% or so as suggested is where the voltage starts dropping noticably so that would be much better as it'll be accurate and won't hurt the batteries either, that is IF you can see what each cell is doing.

Personally I really wouldn't buy a PowMr battery on special, they do like 30% off normal price, I guarantee they don't have 30% margins so where do the cost savings come from???? That is my concern especially as they don't have connectability for you to see what is happening inside short of pulling the battery open and individually testing each cell.

On that I'd definitely go for batteries with bluetooth so you know what is going on inside them, you can also adjust the BMS settings to your desire with bluetooth as a second failsafe if your PowMr inverter fails unexpectadly (which isn't unheard of, there are several posts on this forum).

Sometimes float does need ot be set "high" though "high" has different meanings to different people. "High" when considering only the total cell voltage of hte pack may be enough to cause major issues with a cell - again if you want safety get a BMS with connectability then you can watch the individual cells for abherations as do occur in cheaper builds of batteries.

Gentai and James Watt brands had the best results in local tear down tests here if they are availble next door in Thailand?

 

[Mitsu2]

Thanks @OffGrid. But if you read my other posts, the batteries are already bought and paid for.

Yes I know now that buying that PowMr inverter was a mistake, will start looking for another one, but it was one of the few that has 2 X Mppt. I personally want to go with Sofar or Growatt, but the Hybrid ones are difficult to find.

Yes James Watt is available but 4 of them I would be paying more for them then a no name complete set.

【แถมที่ชาร์จ】James Watt 12V 300Ah LiFePo4 แบตเตอรี่, พร้อมระบบบาลานซ์แอคทีฟ, Bluetooth & BMS อัจฉริยะ 200A, ใช้งานได้กว่า 10,000 ครั้ง ความจุ 3840Wh สำหรับเก็บพลังงานโซลาร์เซลล์ | Lazada.co.th

James Watt จีน

www.lazada.co.th

19599 THB (exclu shipping pp) = +/- 600 USD per battery

Problem here they charge an awful lot of import tax on those things when they are not produced here. Self Protection

 

[Offgrid Philippines]

Thanks @OffGrid. But if you read my other posts, the batteries are already bought and paid for.

Yes I know now that buying that PowMr inverter was a mistake, will start looking for another one, but it was one of the few that has 2 X Mppt. I personally want to go with Sofar or Growatt, but the Hybrid ones are difficult to find.

I know, I actually want one for that same reason. I'll research the model heavily as some seem to be good, some dodgy. And like you said getting a Victron or something here is terribly difficult and expensive.

Yes James Watt is available but 4 of them I would be paying more for them then a no name complete set.

【แถมที่ชาร์จ】James Watt 12V 300Ah LiFePo4 แบตเตอรี่, พร้อมระบบบาลานซ์แอคทีฟ, Bluetooth & BMS อัจฉริยะ 200A, ใช้งานได้กว่า 10,000 ครั้ง ความจุ 3840Wh สำหรับเก็บพลังงานโซลาร์เซลล์ | Lazada.co.th

James Watt จีน

www.lazada.co.th

19599 THB (exclu shipping pp) = +/- 600 USD per battery

Problem here they charge an awful lot of import tax on those things when they are not produced here. Self Protection

Holy Buffalos Batman! Fair enough - James Watt $440 here ($310 normal pricing for the PowMr). OK, I thought you COD'd them as well as that's the only way I take deliveries.

Lazada delivery hands me a $250 invoice and a small box, open it, it's the $15 TV stand "Where's the TV?". "That's the complete delivery sir", "Take it back", get another black mark on my account for not accepting COD delivery..... Go to Shopee until they temp ban COD for me for the same bulldust, back to Lazada.

As the tourism slogan goes "It's more fun in The Philippines"

 

[Mitsu2]

aha the same policies there as here. refusing a COD and forget about doing it afterwards again.

I have to life with what I have bought, even if it fails me after a year I am willing to take that dive as today we experienced another blackout for close to 2 hours and in 39c (or 102F) that is NO FUN (nights only cool down to 27c or 81F)

Will wait for replies to my voltage questions as that is the only way I can control the batteries,

But coming back to your question? Why 25%? I was thinking of saving the battery by letting it stay in a 25-85% (or maybe even 80%) SOC so 55% usable

6ish+ kWh will get us through the night easily.

 

[Offgrid Philippines]

Ahh, I like your thinking then that'll protect the batteries. My next system will be non-critical so I'll have more leniency in hardware choice, maybe by then we'll have reliable online delivery (and returns) down at the farm, we're the equivalent of a four hour drive from "Nakhon Nowhere".

I think this is what you are looking for for voltages?

Guide for LiFePO4 Voltage Chart & SOC 12V/24V/48V

The LiFePO4 voltage reflects the battery SOC. Explore our detailed guide for 12V, 24V, and 48V voltage charts and reference tables for battery management.

powmr.com

BTW Manila is supposed to be unreasonably hot and low humidity (for there - built on a swamp, same as BKK) at the moment, we told the sister to go use our aircon room there in the middle of the day, it needs a run every now and then anyway. On the farm we do not use aircon, don't need it away from all the concrete, it's cold at night, had to use a light blanket last night and even put on two t-shirts early this morning even..... back to shirtless at 7am though Makes our power requirements quite low.

 

[Daddy Tanuki]

Ahh, I like your thinking then that'll protect the batteries. My next system will be non-critical so I'll have more leniency in hardware choice, maybe by then we'll have reliable online delivery (and returns) down at the farm, we're the equivalent of a four hour drive from "Nakhon Nowhere".

I think this is what you are looking for for voltages?

Guide for LiFePO4 Voltage Chart & SOC 12V/24V/48V

The LiFePO4 voltage reflects the battery SOC. Explore our detailed guide for 12V, 24V, and 48V voltage charts and reference tables for battery management.

powmr.com

BTW Manila is supposed to be unreasonably hot and low humidity (for there - built on a swamp, same as BKK) at the moment, we told the sister to go use our aircon room there in the middle of the day, it needs a run every now and then anyway. On the farm we do not use aircon, don't need it away from all the concrete, it's cold at night, had to use a light blanket last night and even put on two t-shirts early this morning even..... back to shirtless at 7am though Makes our power requirements quite low.

i call BS on you their friend... there is nowhere in the PI that AC does nto make it better!

 

[wpns]

I was thinking of saving the battery by letting it stay in a 25-85% (or maybe even 80%) SOC so 55% usable

Again, why do you think this will save your battery from speedy irreversible damage? Cycling from 100% to 50% every day will be fine, you'll get some balancing time in, and you'll have some margin for those cloudy/rainy/stormy days when your production is low and you still need power.

Chasing the chimera of 25-85% is arguably going to make things worse, as there's no balance time.

 

[Mitsu2]

Again, why do you think this will save your battery from speedy irreversible damage? Cycling from 100% to 50% every day will be fine, you'll get some balancing time in, and you'll have some margin for those cloudy/rainy/stormy days when your production is low and you still need power.

Chasing the chimera of 25-85% is arguably going to make things worse, as there's no balance time.

You are forgetting I am in Thailand, with temperatures reaching 40c++ easily

• LFP cells hate being at 100% State of Charge (SOC) when it's 35°C (95°F) or hotter. High voltage increases chemical "tension" inside the cell; heat acts as a catalyst for that tension to cause permanent capacity loss.
• The Compromise: By staying at 85% I am extending the chemical life of the battery, especially in a tropical climate.

and if it doesn't work then so be it. I am only learning by doing as I said previously if they last me one year I am more then happy, the power outages here got more and more frequent and in 40c a power outage is no fun.

 

[wpns]

I have an active balancer attached to it an HC02, see my first post

I get that, and replied, FWIW.

How about balancing the cells inside the batteries? If you never fully charge them, they'll never balance, and you'll notice degraded capacity sooner rather than later.

But you'll save a lot of money, because money is alternately very tight and not important, so win/win.

Fortunately, Murphy (and physics) says it'll fail when you need it most, but then you'll have this thread to console you that you made all the right decisions.

 

[Mitsu2]

Fortunately, Murphy (and physics) says it'll fail when you need it most, but then you'll have this thread to console you that you made all the right decisions.

And you then will gloat that I made a mistake and that you were right, I get it. You learn from your mistakes.

The only advice I got from this thread is thus far

1- Buy complete sets
2- don't do 25-85%

But no answer to my questions (except one by OffGrid Phillipines) to voltages.

 

[Offgrid Philippines]

Again, why do you think this will save your battery from speedy irreversible damage? Cycling from 100% to 50% every day will be fine, you'll get some balancing time in, and you'll have some margin for those cloudy/rainy/stormy days when your production is low and you still need power.

Chasing the chimera of 25-85% is arguably going to make things worse, as there's no balance time.

The way I read it is he got a cheap brand on sale (with possible A- cells) without connectivity, keeping it within bounds means no one cell is going to fry the entire battery.

@Mitsu2 if you're not aware you probably should balance each battery seperately to start out, then again every 6-12 months. The video in this first post seems (watching it now) particularly relevant:
EDIT: Note to self RTF thread: You already got the HCO2 balancer mentioned in that thread.

Thread 'Balancing Dumb Batteries and regaining battery capacity'

Sep 25, 2025

This topic comes up on occasion so I put this together to show how I balance dumb/cheap batteries. Use CV charging and low charging currents to allow the BMS time to balance cells.

• Zwy
• Replies: 62
• Forum: General Battery Discussion

• 
• 

i call BS on you their friend... there is nowhere in the PI that AC does nto make it better!

Ptthhhhh! Who "needs" aircon???

 

[Mitsu2]

@Mitsu2 if you're not aware you probably should balance each battery seperately to start out, then again every 6-12 months. The video in this first post seems (watching it now) particularly relevant:
EDIT: Note to self RTF thread: You already got the HCO2 balancer mentioned in that thread.

Thanks yes, When they arrive they will be balanced separately. The Batteries arrive early May, the inverter later.

I am in the process of trying to cancelling the inverter, but with Lazada that is not easy, and they only gave me the option to refuse it on the doorstep and then go through the process of getting money back. Is it worth it because there is a real chance that I will lose the inverter and the money any how.

 

[Mitsu2]

@wpns

You keep saying money is tight. Money isn't tight, but SWMBO is totally against spending a lot on Solar.

Someone told me a long time ago, slowly slowly catch a monkey, and if this setup survives at least the hot season I am more then sure I will be able to get more and better stuff in.

I have started with a simple plug in device that just spins my meter back with 1 solar panel. Since then I upgraded to an On-Grid system with 7 Panels, and now this. So Slowly Slowly expanding to keep SWMBO happy and money spending limited. So instead of (using THAI Baht here) spending 70.000 THB for a 51.2V 314Ah set and at least 40.000 THB for an Hybrid Inverter (Deye for example) I am now have more then halved that amount, oke with it's own problems.

And when you going to say, Yeah Buy a new system what about the old one? oooh then you are forgetting I am in rural Thailand and Solar is King here. BIL and the rest of the family or even the village would be jumping at the chance to get and pay for my OLD setup.

 

[Daddy Tanuki]

The way I read it is he got a cheap brand on sale (with possible A- cells) without connectivity, keeping it within bounds means no one cell is going to fry the entire battery.

@Mitsu2 if you're not aware you probably should balance each battery seperately to start out, then again every 6-12 months. The video in this first post seems (watching it now) particularly relevant:
EDIT: Note to self RTF thread: You already got the HCO2 balancer mentioned in that thread.

Thread 'Balancing Dumb Batteries and regaining battery capacity'

Sep 25, 2025

This topic comes up on occasion so I put this together to show how I balance dumb/cheap batteries. Use CV charging and low charging currents to allow the BMS time to balance cells.

• Zwy
• Replies: 62
• Forum: General Battery Discussion

• 
• 

Ptthhhhh! Who "needs" aircon???
View attachment 386285

me I have been in mainland japan too long, when i lived on Okinawa we never had a/c but moved up here and everyplace you work had a/c so you get used to it unfortunately.

 

[Daddy Tanuki]

And when you going to say, Yeah Buy a new system what about the old one? oooh then you are forgetting I am in rural Thailand and Solar is King here. BIL and the rest of the family or even the village would be jumping at the chance to get and pay for my OLD setup.

smart....

 

[Offgrid Philippines]

And when you going to say, Yeah Buy a new system what about the old one? oooh then you are forgetting I am in rural Thailand and Solar is King here. BIL and the rest of the family or even the village would be jumping at the chance to get and pay for my OLD setup.

You've really thought this through. Was that website or the video what you were after for voltages? Sorry I'm no expert on the electrics I just know how to use my setup.

I got some flexible panels when I first bought as I thought they'd be easy to move about the yard to maximise solar on cloudy days, after roughly a year in the sun the 200W panels are producing 90W each now. Same idea, I have a half good lead acid 12V sitting about, these panels, add a $10 PWM inverter thingy and someone has free basic electricity - the blackouts here were weekly, they're down to monthly. I'm too far from power lines (strung from coconut tree to bamboo pole to coconut tree) to care either way.

 

[Mitsu2]

You've really thought this through.

Thanks. Yeah I must do to outsmart SWMBO hahahahahaha

A friend of mine once said, do you wanna be right or stay married

Was that website or the video what you were after for voltages? Sorry I'm no expert on the electrics

No worries at all, it's a good start. Appreciated.

 

[Offgrid Philippines]

Thanks. Yeah I must do to outsmart SWMBO hahahahahaha

A friend of mine once said, do you wanna be right or stay married

lol, I'll take it to PM - so as not to deter rose coloured glasses wanna be expats

For everyone else in The PH, I'm the man, I'm in charge.... or is that just me???

 

[scottu5]

.....

I am in the process of trying to cancelling the inverter, but with Lazada that is not easy, and they only gave me the option to refuse it on the doorstep and then go through the process of getting money back. Is it worth it because there is a real chance that I will lose the inverter and the money any how.

Hello,

Just for reference, I have and use that inverter on my farm now (off grid) for almost 3 years.

First 2 years with PMr 100ah 48v LifePO4 battery (open loop) and most recently with PMr 200ah 48v (51.2v) LifePO4 battery (closed loop).
So far, all good.

scott

 

[Mitsu2]

Hello,

Just for reference, I have and use that inverter on my farm now (off grid) for almost 3 years.

First 2 years with PMr 100ah 48v LifePO4 battery (open loop) and most recently with PMr 200ah 48v (51.2v) LifePO4 battery (closed loop).
So far, all good.

scott

WOW thank you. First positive comment I got about the PowMr

Can you remember the settings (voltages) you used for your system as that is what I have to do with my PowMr 12V 300Ah (LFP) Batteries (No RS485 connection possible with those)

Thanks again, really appreciated.

 

[Daddy Tanuki]

lol, I'll take it to PM - so as not to deter rose coloured glasses wanna be expats

For everyone else in The PH, I'm the man, I'm in charge.... or is that just me???

translation for those not in the know.... his wife being form the PI is a firecracker and will chop his dangly bits off if he gets to far out of line.

 

[Mitsu2]

translation for those not in the know.... his wife being form the PI is a firecracker and will chop his dangly bits off if he gets to far out of line.

55555 same for mine, she is from Thailand and will feed my dangly bits to the ducks.

In case someone doesn't understand the 55555 comment.

In Thai, "5555" (or "555") means "hahahaha" and is used to express laughter or "LOL" in texting and online chats. The number 5 is pronounced "ha" (ห้า) in Thai, so repeating it mimics the sound of laughter, similar to "haha" in English.