10kW, 5kWh battery

[CharlesM99]

Anyone know of a 5kWh battery that can output 10kW?

I'm researching converting a riding mower to electric, but I don't really want to build a DIY battery.

 

[BentleyJ]

10kW at what voltage? First step is to determine the continuous amperage and that will give you the discharge C rate. If the C rate is 2 or below you may be able to find a Li-NMC or LiFePO4 battery. If the C rate is higher than 2 then LTO chemistry or a supercapacitor storage system may be needed.

 

[CharlesM99]

10kW at what voltage? First step is to determine the continuous amperage and that will give you the discharge C rate. If the C rate is 2 or below you may be able to find a Li-NMC or LiFePO4 battery. If the C rate is higher than 2 then LTO chemistry or a supercapacitor storage system may be needed.

At sorry of course. I'm looking for 48Vdc nominal.

I'm wanting to output at least 10kW to a 48Vdc motor to power a riding mower. I don't think I'd run it continuously at 10kW.

My initial thought was a server rack battery, but that's limited to 100A @51.2V, so that would've been drastically under powered.

 

[BentleyJ]

10kW at 50V requires 200A (not figuring in losses) Not sure how much space you have available for the battery but if you could squeeze in a 10kWh LFP battery that would put you at just over 1C for the discharge rate. If the battery is only going to be 5kWh then you are over 2C which is on the high end of most typical LCO, Li-NMC, LFP. Its possible but you would have to shop around for a suitable high amperage product.

 

[CharlesM99]

10kW at 50V requires 200A (not figuring in losses) Not sure how much space you have available for the battery but if you could squeeze in a 10kWh LFP battery that would put you at just over 1C for the discharge rate. If the battery is only going to be 5kWh then you are over 2C which is on the high end of most typical LCO, Li-NMC, LFP. Its possible but you would have to shop around for a suitable high amperage product.

Ok, thanks for that info.
I'll keep an eye out, but maybe two server rack batteries is the way to go

 

[Steve_S]

Have a look at TWO Tesla 5.3kWh packs @ $1600 USD ea to deliver that amount of power.
https://stealthev.com/product/tesla-module/ * Several vendors have them.
You'd be looking at some serious hardware to go with that...
Orion BMS, BMS Cell Tap, and Charger +++

Alternately you can look at the BestGo Li-Ion NMC packs here:

48 volt lithium battery|Solar energy storage system of 48 volt

When you are looking for 2C+ Batteries most will not accommodate that unless you get really $eriou$.
DIY is a Mixed Bag and most LFP will not deliver 2C+ unless you get deep into Winston Cells etc.
Also, you'd need to consider if you want an AC or DC Motor and everything associated with either is quite different.

Now a Gotcha of sorts. There are LEV DC Motor kits (transaxle with motor built-in) available on AliBaba / AliExpress along with all the required items "except Batteries" which are separate and can be powered by LFP.

I Strongly urge you to have a LOOK HERE:

Products

lawn tractor, tractor, electric lawn tractors, battery tractor, DIY project, electric tractor conversion, gas lawn tractor, electric lawn tractor, solar lawn tractor, zero pollution, no gas or oil, battery, rechargeable,

electrictractor.net

 

[CharlesM99]

Have a look at TWO Tesla 5.3kWh packs @ $1600 USD ea to deliver that amount of power.
https://stealthev.com/product/tesla-module/ * Several vendors have them.
You'd be looking at some serious hardware to go with that...
Orion BMS, BMS Cell Tap, and Charger +++

Alternately you can look at the BestGo Li-Ion NMC packs here:

48 volt lithium battery|Solar energy storage system of 48 volt

When you are looking for 2C+ Batteries most will not accommodate that unless you get really $eriou$.
DIY is a Mixed Bag and most LFP will not deliver 2C+ unless you get deep into Winston Cells etc.
Also, you'd need to consider if you want an AC or DC Motor and everything associated with either is quite different.

Now a Gotcha of sorts. There are LEV DC Motor kits (transaxle with motor built-in) available on AliBaba / AliExpress along with all the required items "except Batteries" which are separate and can be powered by LFP.

I Strongly urge you to have a LOOK HERE:

Products

lawn tractor, tractor, electric lawn tractors, battery tractor, DIY project, electric tractor conversion, gas lawn tractor, electric lawn tractor, solar lawn tractor, zero pollution, no gas or oil, battery, rechargeable,

electrictractor.net

Yeah thanks for that. I've come across that link before, but I can't believe they're only using 1000W for the drive motor. Seems drastically under powered given most riding mowers are around 20HP. I think 20HP ends up being around 15kW, I figured settling for 10kW would be fine for me though.

 

[JoeHam]

There are a number of mower threads on the forum.

Perhaps you can find something helpful there ?

Search results for query: Mower

diysolarforum.com

 

[eXodus]

Yeah thanks for that. I've come across that link before, but I can't believe they're only using 1000W for the drive motor. Seems drastically under powered given most riding mowers are around 20HP. I think 20HP ends up being around 15kW, I figured settling for 10kW would be fine for me though.

The hydraulic drive jas insanely inefficiencies. You looking at 60% from engine to wheel. So your 15kw engine maybe delivered 8kw to the wheel. But that 15kw is probably highly overrated and not what the mower is running at. Just think a Tesla model 3 needs 14kw to drive 70mph.
A golf cart drive motor is around 3kw

So 1000w for a lawnmower seems to be adequate

 

[CharlesM99]

The hydraulic drive jas insanely inefficiencies. You looking at 60% from engine to wheel. So your 15kw engine maybe delivered 8kw to the wheel. But that 15kw is probably highly overrated and not what the mower is running at. Just think a Tesla model 3 needs 14kw to drive 70mph.
A golf cart drive motor is around 3kw

So 1000w for a lawnmower seems to be adequate

We've taken the blades off our mower since we just use it as a mini tractor. But it still feel like we're using the motor pretty hard going up hills in roughish terrain.

Our 20HP engine is pretty dated, so I'm sure it's not outputting that much anymore. But man, going from 15kW down to 1 kW seems like a big drop. That's why I'm trying to figure out what kW motor the factory electric mowers use for their drive motors.

 

[eXodus]

But it still feel like we're using the motor pretty hard going up hills in roughish terrain.

what you mower hydraulic drive is doing on hills is converting power into torque - that's something a Electric Motor has plenty off already at low RPM

Horsepower = [(torque*engine RPM)/5252].

When you think about old diesel tractors - with massive multi ton flywheels - those things had like 30HP but where able to pull a house in mud.

Since your mower is not going to be very fast - all those high RPMS from that 15KW is being wasted. While the Electric drive has it's maximum torque right away.

But man, going from 15kW down to 1 kW seems

I guess it's 1KW per rear wheel. So 2 KW, still that's a lot of power since it's direct. Humanity wasted a lot of energy in ineffective drivetrains because fuel was cheap and we didn't know any better. I converted all my garden tools to electric - even with 1/4 power of a gas chainsaw - the electric is better.

 

[CharlesM99]

what you mower hydraulic drive is doing on hills is converting power into torque - that's something a Electric Motor has plenty off already at low RPM

Horsepower = [(torque*engine RPM)/5252].

When you think about old diesel tractors - with massive multi ton flywheels - those things had like 30HP but where able to pull a house in mud.

Since your mower is not going to be very fast - all those high RPMS from that 15KW is being wasted. While the Electric drive has it's maximum torque right away.

I guess it's 1KW per rear wheel. So 2 KW, still that's a lot of power since it's direct. Humanity wasted a lot of energy in ineffective drivetrains because fuel was cheap and we didn't know any better. I converted all my garden tools to electric - even with 1/4 power of a gas chainsaw - the electric is better.

Yeah, fair enough. You're giving me a lot of confidence in being able to use a much smaller motor! We'll see what I end up sourcing