[Benjaminpalma]

Inspired by this site, I'm looking at 18650 cells to power a car with, say, a 72v WarP 9 DC motor.

I've found a UK source of 18650 cells with prices and spec as follows:

Rated Capacity: 3Ah
Amp Rating: 18A (Mooch)
Full Charge Voltage: 4.2V
£3.35 each

Am I right in thinking that 560 x 18650 would make a battery of 20kWh - enough for maybe an hour's worth of relaxed driving?

How do they stack up against other types of cell?

Is it worth the hassle of buying and breaking old laptop battery packs?

 

[Kevin Sharpe]

£3.35 each

That's very expensive... you can typically buy Tesla 5.3kWh modules for ~£840 (here is one example) which contains 444 (3400mAh) cells at £1.90 each

The modules are 23V nominally and can be modified to 46V with some effort. They also have heating/cooling systems and a BMS board as standard.

 

[Kevin Sharpe]

Is it worth the hassle of buying and breaking old laptop battery packs?

If you factor in your time I suspect this is a very expensive way of buying cells.

 

[Benjaminpalma]

That's very expensive... you can typically buy Tesla 5.3kWh modules for ~£840 (here is one example) which contains 444 (3400mAh) cells at £1.90 each

The modules are 23V nominally and can be modified to 46V with some effort. They also have heating/cooling systems and a BMS board as standard.

Interesting - thanks. They'd be cheap as chips on Alibaba too if I was feeling brave enough and I missed out on a Tesla breaking over here in the UK.

BTW - have I got my maths right roughly here?
Car (SWB Land Rover Series) - 1,200 kg
72v motor
20kWh battery
Enough for maybe an hour's worth of relaxed driving?

 

[Kevin Sharpe]

BTW - have I got my maths right roughly here?
Car (SWB Land Rover Series) - 1,200 kg
72v motor
20kWh battery
Enough for maybe an hour's worth of relaxed driving?

Here's the Nissan Leaf;

1,500kg
360V
24kWh
80 miles 'relaxed' range

 

[Benjaminpalma]

Here's the Nissan Leaf;

1,500kg
360V
24kWh
80 miles 'relaxed' range

Thanks, Kevin. So, about bang-on, then.

With a bit more research it turns out that 18650s can be bought on eBay for less than £1 each - if you don't mind opening dozens of old laptop batteries, testing them and finding some dead ones.

It's the battery management system which now has me stumped. There doesn't deem to be an off-the-shelf solution - and my understanding of electronics is limited.

 

[Duncan]

Benjamin

Your 1 pound cells - 2 Ah x 3.2v = 6.4 Watthours
To get a 24Kwhrs pack you will need 3750 of them

So over 4000 pounds PLUS all of your time and you will end up with a kludge - also some of those 4000 cells will fail - probably killing their pals as well

Sounds to me like you should be able to get a complete Leaf battery pack for less than that

 

[Benjaminpalma]

Benjamin

Your 1 pound cells - 2 Ah x 3.2v = 6.4 Watthours
To get a 24Kwhrs pack you will need 3750 of them

So over 4000 pounds PLUS all of your time and you will end up with a kludge - also some of those 4000 cells will fail - probably killing their pals as well

Sounds to me like you should be able to get a complete Leaf battery pack for less than that

All things considered - yes!!

Thanks very much for your thoughts, Duncan.

 

[Kevin Sharpe]

All things considered - yes!!

Thanks very much for your thoughts, Duncan.

Duncan is spot on... I'd recommend you buy a wrecked Leaf and use that as a donor car... you can often pick 2014 cars up for £2500 at auction in the UK. Even if you decide to use a different motor you can sell the Leaf parts and may even get the battery for 'free'.

Here are a couple of threads to consider;

Re-using complete Leaf Drive System (w/VCM)

Leaf module based 150V 65Ah battery pack...

If you want to discuss this in detail I'd be happy to show you around my project which was Leaf based and is now Tesla;

1967 VW Split Screen Van - "ICE Breaker"

 

[Benjaminpalma]

Duncan is spot on... I'd recommend you buy a wrecked Leaf and use that as a donor car... you can often pick 2014 cars up for £2500 at auction in the UK. Even if you decide to use a different motor you can sell the Leaf parts and may even get the battery for 'free'.

Here are a couple of threads to consider;

Re-using complete Leaf Drive System (w/VCM)

Thanks, Kevin.

The Leaf motor looks like it has a built-in reduction gear - which could be attached my Land Rover's Power Take-Off on the rear of the gearbox. This can be manually engaged and disengaged but only offers 1:1 gearing like being in 4th gear. I could then leave the ICE engine in the front!

Trouble is, it also looks like the Leaf motor needs to talk to all the other Leaf electrical gubbins in order to work...?

Leaf module based 150V 65Ah battery pack...

If you want to discuss this in detail I'd be happy to show you around my project which was Leaf based and is now Tesla;

1967 VW Split Screen Van - "ICE Breaker"

Thanks so much, Kevin. Youtube channel bookmarked. Splitty - what an awesome platform to use!

 

[Karter2]

?.......
Trouble is, it also looks like the Leaf motor needs to talk to all the other Leaf electrical gubbins in order to work...?
!

Search and read around these forums more.
There are several options for powering and controling the Leaf motor independently.
http://www.diyelectriccar.com/forum...olmes-controller-leaf-motor-build-186585.html

 

[Benjaminpalma]

Search and read around these forums more.
There are several options for powering and controling the Leaf motor independently.
http://www.diyelectriccar.com/forum...olmes-controller-leaf-motor-build-186585.html

Thanks - yes, I've had a good read through. I came across this universal controller which is said to work with a Leaf motor but have received no response to my inquiries...

 

[Kevin Sharpe]

... but have received no response to my inquiries...

That's been said a few times... I think it's a dead project

If you don't plan to use the whole Leaf system then I'd suggest you use the Open Source controller (here). I know Johannes is working on the Leaf motor and Damien on the BMW i3 motor so they should be ready when you are

 

[brian_]

The Leaf motor looks like it has a built-in reduction gear - which could be attached my Land Rover's Power Take-Off on the rear of the gearbox.

The motor itself doesn't have any gearing, but the entire Leaf drive unit consists of the motor plus a transaxle. The transaxle is a set of reduction gearing plus a differential; the overall ratio from motor speed to axle speed is 7.9337:1.

Because the transaxle includes a differential, you would need to make a spool to replace the differential gearing to use just one output... otherwise, the shaft to your PTO would not turn because the other shaft would just spin freely.

This approach has been discussed for other projects in this forum, but I don't recall anyone actually building it. Some searching in the forum for references to "PTO" might be educational.

 

[Karter2]

Another Leaf controller option..
http://www.diyelectriccar.com/forums/showthread.php/1988-crx-diy-controller-and-nissan-178169.html
Or ..same guy...
https://endless-sphere.com/forums/viewtopic.php?f=30&t=63982&p=963227#p963227

 

[Benjaminpalma]

If you don't plan to use the whole Leaf system then I'd suggest you use the Open Source controller (here). I know Johannes is working on the Leaf motor and Damien on the BMW i3 motor so they should be ready when you are

Thanks - I hope so. That thread is 186 pages of mostly (to me) gobbledegook!

There Are Now 300,000 Nissan Leafs In The World - so if anyone can come up with a plug-and-play solution for the hundreds of thousands of classic cars in the world, they're going to do very nicely in the years to come!