7S or 8S inverter setup?

I have a MS4024PAE inverter...24 volt


I bought 100 packs of those hoverboard battery on ebay and trying to minimize work by having to disassemble the complete packs... By unsoldering just the addon top 4 cells on the BMS, I can get a 8S pack and utilizes the included BMS (after testing they are just high and low voltage disconnects, not balancing).

I am currently trying to use 8S setup, but not sure if the inverter will allow me to charge to 4.1v @8S.

manual for the 4024 says max charge volts is 32volts (4.0v @8S)
high battery voltage cutout is 34 volts.

Anyone running their inverter on 8S?
Anyone know if you can actuallyget up to32.8V with ARC remote for charge? (4.1v@8S)

Looking at the BMS, i can mod it to get to 7S but dont want to if i can run at 8S (higher volts andless overall current draw on pack)


I plan on making a bus that allow just plugging in the 100 packs as 8S2Punits.

If it is the PIP you are going to run i recomend 7s only. They are not known to work that well with over voltage. (Rumours on old models)

I know you already have the 24V inverter. But you could try getting a 48V inverter and run two cell packs in series to go 16s, which is for 48V

Not sure what your plans on your powerwall were, but if you could get the 48V, it would be more efficient, as well. But I agree with daromer that you can't go that high with the 24V pip. You'll either end up with short capacity on the cells (since they can only charge up to 4V), or you'll blow something in the circuitry.

Off Topic:

Tom - the seller- got those battery packs from the two-wheeled, lean to steer, "hoover boards" because of a massive recall. No one would sell the hoover boards any more because they would catch fire. Many of the issues were directly related to the BMS/ charging circuit. ( I wrote a small piece about it on EEV Blog Forum). Please test the management system well before you choose to reuse it. I know its temping to take the short cut and not remove all the cells, but just remember why you got those packs so cheap. The 18650's are excellent and no one anywhere has reported any issues, but the BMS unit is another story all together. Again, I am not saying don't use it, just make sure you've tested it well before you trust it in your home, and I think this is a great idea if it works out.

ltdorn said:

I bought 100 packs of those hoverboard battery on ebay and trying to minimize work by having to disassemble the complete packs... By unsoldering just the addon top 4 cells on the BMS, I can get a 8S pack and utilizes the included BMS (after testing they are just high and low voltage disconnects, not balancing).

Click to expand...

I had the same idea - but not the tech skills to identify how/what could be changed on the BMS. One thing that I thought I'd liked to have done is get a jumper into the BMS's cell monitor cable - that way I could periodically check the cell voltages. And perhaps a temp gauge for each. Worse case scenario, if find out down the road that the BMS is bad - you can just tear them down. They are good cells!

ltdorn said:

I plan on making a bus that allow just plugging in the 100 packs as 8S2Punits.

Click to expand...

400AH?
There are 36v inverters that prob are not as good as the one you have though. That's the route I was going to take before deciding on using lifepo4.



Be sure you have the system away from anything and a fire extinguisher nearby, Inverted 18650 makes a good point.

I look forward to your success, let us know how it goes.

Inverted18650 said:

Off Topic:

Tom - the seller- got those battery packs from the two-wheeled, lean to steer, "hoover boards" because of a massive recall. No one would sell the hoover boards any more because they would catch fire. Many of the issues were directly related to the BMS/ charging circuit. ( I wrote a small piece about it on EEV Blog Forum). Please test the management system well before you choose to reuse it. I know its temping to take the short cut and not remove all the cells, but just remember why you got those packs so cheap. The 18650's are excellent and no one anywhere has reported any issues, but the BMS unit is another story all together. Again, I am not saying don't use it, just make sure you've tested it well before you trust it in your home, and I think this is a great idea if it works out.

Click to expand...

Ah thanks for the input... i did notice there were 2 types of BMS that came with those packs..
There was a fat square one strapped tot he side, and the other was the thin version between the cells. I did start checking on 2 random packs with the BMS.. i picked 2 random packs, over charged and over drained and verified they released from bus. Parallelcharged them and discharged and didnt note any thing squirrelly.they both maintained a balance voltage.
I probably will have to break them down and make 7S packs because the 4024 will not effectively support a 8S pack. i did figure out how to strip out another cell to make the packs 7S...

DO you happen to have the link to your BMS Post.

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Korishan said:

I know you already have the 24V inverter. But you could try getting a 48V inverter and run two cell packs in series to go 16s, which is for 48V

Not sure what your plans on your powerwall were, but if you could get the 48V, it would be more efficient, as well. But I agree with daromer that you can't go that high with the 24V pip. You'll either end up with short capacity on the cells (since they can only charge up to 4V), or you'll blow something in the circuitry.

Click to expand...

If i didnt pick up this MS4024PAE for only $950 (build date 1qtr 2017) i would have gone 48 volts.