[dantheteslaman]

I'm looking into using a Tesla motor for a time attack car and are having questions regarding what batteries and how many it is going to require. My current plan is to use the batteries from a Chevy Volt to run the motor but I am looking for other options. The Chevy Volts battery bank is a little large and heavy for my current plans.

What should I be looking for specs wise for alternatives to the Chevy Volt batteries?

 

[brian_]

If you want to drive any Tesla motor anywhere close to it's peak performance (and a Time Attack application would suggest that you want to drive it hard), a complete Volt battery would be inadequate. If you expect to find something smaller and lighter, I think you'll be disappointed.

Which Tesla motor will you be using? If you know how much power you expect to get out of the motor, and so how much power you need to put into it, you can start looking for a battery configuration which will work. If you know how much energy you need before recharging (based on how much power for how much time), you have the another specification for the battery.

I note that in his converted 911 with a Tesla motor, mfor1000 used two complete Volt packs.

The Volt battery, depending on generation, is rated by GM for 110 to 120 kW for a short period (10 seconds). It has about 16 kWh nominal capacity, but of course not all of that is usable.
From GM: 2016 Chevrolet Volt Battery System

 

[Duncan]

Hi
I'm using most of a Chevy Volt battery - and I pull 300+ kw from if for a short period so I would say that these are a good battery for that

The complete battery has a fair amount of extra weight that you don't need - strip it down to the module level and use the modules

https://www.diyelectriccar.com/foru...dubious-device-44370p11.html?highlight=duncan

 

[brian_]

I'm using most of a Chevy Volt battery - and I pull 300+ kw from if for a short period so I would say that these are a good battery for that

It's true that the factory rating can be exceeded, assuming that you don't need long-term reliability. One issue would be that a heavier vehicle (than Duncan's "Device") would need to use high power for longer periods, which would be a problem for the battery.

What is the vehicle in this case?

 

[piotrsko]

I don't know about long term reliability, I have only had my 2011 volt pack for 6 years now with no issues.

 

[brian_]

I don't know about long term reliability, I have only had my 2011 volt pack for 6 years now with no issues.

Running a Tesla motor in competition? If so, that's a strong vote for the Volt battery.

 

[dougingraham]

I'm looking into using a Tesla motor for a time attack car and are having questions regarding what batteries and how many it is going to require. My current plan is to use the batteries from a Chevy Volt to run the motor but I am looking for other options. The Chevy Volts battery bank is a little large and heavy for my current plans.

What should I be looking for specs wise for alternatives to the Chevy Volt batteries?

Tesla batteries were selected for their high energy density, not high power output. I made a pack for my RX7 conversion just for drag racing composed of the batteries John Metric sells just for this purpose. It weighs about 60 lbs and will give me the maximum capability of my Soliton 1 controller. In other words 1000 amps at 190 motor volts ( single warp 9). It can sustain this for the duration of a drag race. Total range is only 9 miles. But it is an exciting 9 miles. A Tesla wants to see 403.2 volts fully charged. This is going to be a 96S pack. The battery modules are 6S and there are 16 of them in the car. The P85 (rear wheel drive) was specked at 416 HP which would be 310 kw. At 400 volts this is 775 amps. The bricks I got from John Metric are capable of doing 450 amps for the duration of a drag race. To meet the single motor Tesla specs I would parallel two of these and then series those pairs to make a 2P 16S arrangement of modules. 32 modules total. This would give you a pack that for a drag race could do the job. It would be a 2.84 kwh pack and would be able to drive a carefully driven Tesla model S about 11 miles. This is probably not enough to do what you want so at least 3 packs in parallel would be needed. The Tesla does regen at a peak of about 60kw. This would be about 150 to 200 amps charge current to the batteries. To allow this safely you would need 4 modules in parallel. That would be my minimum suggestion. I don't know the current price. What makes the John Metric modules better than the RC packs is that you can get them with 8 gauge wire standard and for a little more you can get 6 gauge wire. That is the way to get the lightest pack. If you look at the RC packs you can get a little cheaper but they can't handle the current until you have paralleled so many that the mass goes up and so does the cost.

I think the Volt pack is only 300 volts. The Bolt pack is 350 volts. You would probably need at least 4 volt packs and quite a bit of reworking it to get a pack that will not be stressed by the Tesla drive. You want 400 volts and 800 amps discharge capability and you want to be able to accept a charge at 150 amps.

Hope that helps.

 

[brian_]

I think the Volt pack is only 300 volts. The Bolt pack is 350 volts.

Both Volt and Bolt packs are 96S sets of pouch cells for 360 volt nominal pack voltage.

• First generation Volt: 3 NMC-LMO cells in parallel @ ~15 Ah per cell
• Second generation Volt: 2 NMC-LMO cells in parallel @ ~22 Ah per cell
• Bolt: 3 NMC cells in parallel @ ~53 Ah per cell

96 S configurations are extremely common... Leaf, Bolt, Tesla (all models), etc. With NMC and NCA having similar nominal voltages, pack voltage is very commonly about 360 volts (of course fully charged is higher and discharged is lower). This is what the Tesla motors are intended to work with.