Could I run power tools off this setup? 12v 280AH LiFePO4 - 12v 4S 100A LiFePO4 BMS - 3000W or 5000W inverter

[I was never given a name]

Hello all! Could I run power tools (for van conversion) of this setup?

12v 280AH LiFePO4 - four 3v cells - (the ones off Alibaba everyone is talking about)
12v 4S 100A LiFePO4 BMS (the one Will is currently recommending)
3000W or 5000W inverter (maybe a Xantrex)

I don't need advice on the charging portion so I left that out. I'm assuming my limitation is the 100A BMS and the draw from the inverter. What would be the most logical/easiest/cheapest things to change to be able to run power tools? I'd like to roughly keep my power capacity 280AH similar in size.

My ideas, numbered for ease of reference: (feel free to rip them to pieces)

1. Get smaller size cells (to keep roughly same costs) like 12 x 3v 100ah cells to make 300ah of 12v w/ the ability to draw 300A (3 x 100A BMS)
2. Do a 24v system maybe 8 x 3v 200ah cells to make 200ah 24v - I don't even know the advantages there

I appreciate any thoughts!

 

[mndare]

Hello all! Could I run power tools (for van conversion) of this setup?

12v 280AH LiFePO4 - four 3v cells - (the ones off Alibaba everyone is talking about)
12v 4S 100A LiFePO4 BMS (the one Will is currently recommending)
3000W or 5000W inverter (maybe a Xantrex)

I don't need advice on the charging portion so I left that out. I'm assuming my limitation is the 100A BMS and the draw from the inverter. What would be the most logical/easiest/cheapest things to change to be able to run power tools? I'd like to roughly keep my power capacity 280AH similar in size.

My ideas, numbered for ease of reference: (feel free to rip them to pieces)

1. Get smaller size cells (to keep roughly same costs) like 12 x 3v 100ah cells to make 300ah of 12v w/ the ability to draw 300A (3 x 100A BMS)
2. Do a 24v system maybe 8 x 3v 200ah cells to make 200ah 24v - I don't even know the advantages there

I appreciate any thoughts!

Yes you can easily run regular power tools power tools. Change BMS wires to 3 8 gauge on each side and the BMS can handle 150 amps

 

[mndare]

3 x 8 guage

 

[I was never given a name]

Yes you can easily run regular power tools power tools. Change BMS wires to 3 8 gauge on each side and the BMS can handle 150 amps

Thank you for the quick reply, and thank you for your original post about the batteries.

I am having a hard time with the math. If I'm pulling 3000-5000W through an inverter, how many amps are being drawn from the battery accounting for loss due to the inverter?

 

[mndare]

Thank you for the quick reply, and thank you for your original post about the batteries.

I am having a hard time with the math. If I'm pulling 3000-5000W through an inverter, how many amps are being drawn from the battery accounting for loss due to the inverter?

No regular power tools full that many watts at all

 

[mndare]

Thank you for the quick reply, and thank you for your original post about the batteries.

I am having a hard time with the math. If I'm pulling 3000-5000W through an inverter, how many amps are being drawn from the battery accounting for loss due to the inverter?

depends on the effeciency of the inverter. You would need to see the specs on the inverter for max DC draw

 

[I was never given a name]

depends on the effeciency of the inverter. You would need to see the specs on the inverter for max DC draw

Here's the specs for the 3000W inverter. Is it the input current - 260A?

 

[upnorthandpersonal]

Since Watts are Watts, suppose we take 80% efficiency, 5kW out means 6kW in. At 12V, that makes 500A. I highly recommend going higher voltage on the input if you can, or not pull 5kW. At 24V, this becomes 250A, and at 48V a mere 125A.

If we take a more reasonable number for power tools, 3kW max, you can halve the numbers.

 

[mndare]

If you run full 2500 watts then you need 256 amps was that what I read. The point is most power tools will run on a 500W inverter. What tools are you thinking of using.

 

[I was never given a name]

If you run full 2500 watts then you need 256 amps was that what I read. The point is most power tools will run on a 500W inverter. What tools are you thinking of using.

ryobi table saw, harbor freight grinder, 20gal compressor (specs say 15amps ac), possibly a vitamix, etc. Stuff like that. Never simultaneously.

 

[I was never given a name]

Since Watts are Watts, suppose we take 80% efficiency, 5kW out means 6kW in. At 12V, that makes 500A. I highly recommend going higher voltage on the input if you can, or not pull 5kW. At 24V, this becomes 250A, and at 48V a mere 125A.

If we take a more reasonable number for power tools, 3kW max, you can halve the numbers.

That makes sense. Price wise, there's a good jump for 24/48v inverters, correct?

 

[upnorthandpersonal]

Price wise, there's a good jump for 24/48v inverters, correct?

Could be, not sure. It's been ages since I built a 12V system.

 

[mndare]

ryobi table saw, harbor freight grinder, 20gal compressor (specs say 15amps dc), possibly a vitamix, etc. Stuff like that. Never simultaneously.

Then you will never hit high amps other than loaded table saw working hard

 

[John Frum]

Cheap chinese bms's should be derated by .5

 

[mndare]

Cheap chinese bms's should be derated by .5

I have tested my Chinese Cheap BMS extensively and it handles much more than my 120 Amp rating. Tested tom 180 amps and handled with no issue. China makes some of the best and nearly all of the electronics for the world

 

[BiduleOhm]

I have tested my Chinese Cheap BMS extensively and it handles much more than my 120 Amp rating. Tested tom 180 amps and handled with no issue. China makes some of the best and nearly all of the electronics for the world

I agree for this BMS, the board seems well constructed and it has some margin on the components specs

But not all BMS are equal, the derating is still needed for the other ones.

 

[QuickQuue]

It is possible to easily run regular power tools. The best way is to change BMS wires to 3x8 gauge on each side and the BMS can handle 150 amps. Really, the board seems well constructed and it meets good characteristics. I also have some old tools that remained me from my dad, and honestly, they are dead. I want to order some new ones, so there was all the necessary equipment in my garage. We decided to make some renovation works in our house and I need really good equipment. I learned the reviewing high-quality miter saws for woodworking but I remained totally confused about which one to select. Because all correspond to the best characteristics.

 

[babybober]

Thank you for the quick reply, and thank you for your original post about the batteries.

I am having a hard time with the math. If I'm pulling 3000-5000W through an inverter, how many amps are being drawn from the battery accounting for loss due to the inverter?

The size of the inverter is the MAX continuous draw not the normal draw. Plan for up to 20% loss with the inverter for cheaply made modified sine wave inverters. 15% for better quality pure sine wave inverters. You will never be able to run a 3000 or 5000w inverter full load off of the batteries you mention. That doesn’t say they won’t run, just the draw is far to much to run that much all at once. So.. What is the max continuous need at any one point? Build your system around that. Just because you have 10 tools that all draw 10 amps each doesn’t mean you need a 100a unit if you only ever run one tool at a time, you only need a 10 am unit...