[EVEngineeer]

I hope someone can answer me. If I get a Warp 9 motor with a 2006-present Honda Civic + all the other components for the EV, I would also buy LiFePO4 from either Thundersky, GBS, or CALB. I also know that I would need to get 45-55 3.2v batteries. I know it would cost over 10k, but i don't care about the cost. I just want to know the figures. The only thing that I don't know is how much ah is required. I have compared other vehicles on the evalbum and noticed that to get approximately 100 range at 30mph and 70 range at 55mph with somewhat less aerodynamic vehicles than the civic they had about 50 3.2v 100ah batteries. I would like to do a little better than that. I would like to get about 75 miles range at 65-70mph. For a little more efficiency I would put on racing hubcaps aka moon wheel hub caps. I would also like to have 80% DoD or better, maybe someone could explain my options. I saw somewhere that 70% DoD could be 3000 cycles instead of the 80% with 2000 cycles. I'd rather spend a little more to get much more life than to have to spend a lot more in a shorter time period to replace them all. So I guess the 75 miles range at 65-70mph with 80% DoD or better would actually end up being closer to 100 miles range. If I need to answer any questions let me know. Thank you.

[adeyo]

I'm not trying to bury the previous post. Please don't look over EVengineers question above, but when that is dealt with, please advise.

Can anyone tell me, i have a motor that unfortunately is very high voltage (230/460 AC motor with 135/67.8 amp rating...60HP continuous). With an inverter, what voltage do i need my batteries at and what batteries do you think are best suited for that high voltage?


(if EVEngineers batteries are 3.2 volt 100amp hour, wouldn't i be need 100 in series just to get close to my operating range? Is there anyway to use my motor and get the voltage i need with any type of battery??)

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[TomA]

EVEngineer, there's a very good rough number emerging from the growing fleet of LiFePO4 vehicles: The cars are using about 1 Wh per mile per 10lbs of curb weight- regardless of drive system. Some cars do a little better, some a little worse, and of course YMMV, but its a workable number. Here's how it would work with example numbers in your case:

Let's say your Civic weighs 2700lbs. Let's also say you strip 350 lbs of ICE gear out of it. Then you put back 250lbs of EV drive components and battery boxes, and 550lbs of cells. (45 180Ah prismatic cells.) That's a curb weight of 3150lbs. Using the good rough number, the car will use about 315Wh per mile.

The 45x180Ah pack has about 26kWh in it, about 20,750wH of which is usable to 80% DoD. Dividing that by 315Wh/mi, you can expect the car to have a usable range of about 66 miles on that pack. To get to 75 miles, you're going to need more batteries and more weight.

Adding 5 more cells at about 60lbs puts the car over 3200lbs, and you'd have a 28.8kWh (23kWh usable to 80%DoD) pack that you'd be using at 320Wh/mile, so you could expect to go 72 miles on it. Another 5 cells for a total of 55 (now you have over 675lbs of batteries in the car!) brings the pack up to 31.7kWh (25.3kWh usable) and the car up to 3275lbs. At 328Wh/mi that pack should take you about 77 miles.

Of course, these are not precise calculations, nor are the curb weights actual, just all based on assumptions about your car, but it does give you a good measure of estimation. Weigh up your stuff and run your own numbers. You can improve efficiency (lower you Wh/mi consumption) with tire upgrades and pressures, aero mods and driving style, but I wouldn't count on all being worth more than 5%-10% if you really need the range.

The obvious conclusion from the example is that long range costs you big time. If you absolutely have to have 75 mile range, you're going to have to stuff 650+lbs of cells into the car. That will require suspension and chassis changes, and will flirt with the GVWR of the car. On a 4 door sedan, that could render your rear seats unoccupiable in some jurisdictions (in Australia, for example, they would de-rate the passenger capacity of the car if you were only a few hundred pounds under the GVWR.)

Anyway, that's how you run the numbers. YMMV, especially on stripped glider weight. Not precise calculations here, but actually very close, and a total fogbuster of blind optimism about range.

HTH,

TomA

[GizmoEV]

Originally Posted by TomA

EVEngineer, there's a very good rough number emerging from the growing fleet of LiFePO4 vehicles: The cars are using about 1 Wh per mile per 10lbs of curb weight- regardless of drive system.

Tom, do you know if that average includes pickups too? I know that the number doesn't work for my Gizmo. Typically it ranges between 120-150Wh/mi but then it is quite a different shape. Curb Weight is 829lbs so about 875lbs with me in it.

It would be interesting to plot the data from the different vehicles on a graph to see if there are some general trends based on vehicle type or what happens at the extreme ends where I would guess my Gizmo would be.

[GizmoEV]

EVEngineer,

Once you figure out what you need to 80%DOD you might want to consider increasing the size of the pack a little to account for the loss of capacity of the pack over time so that you still can get your desired range a few years down the road. Maybe size your pack for 70%DOD to give you a 10% buffer.

[EVEngineeer]

gizmoev, yes i agree with adding more batteries, for that reason.

tomA, thanks for your help.

[GizmoEV]

Also, based on my CycleAnalyst numbers 3.2V is a reasonable number for calculating Wh capacity for continuous currents in the 0.6C range. At least for my TS cells so I would think that CALB cells are a little better.

[Robocar]

Wow, now I'm depressed. I was excited when I got a good deal on a motor for my old Nissan Pulsar but after reading this and checking battery prices a half decent running car is way out of my price range. I may as well just buy a golf cart to drive aroung like they do up in The Villages (retirement area in Florida).

I was hoping for 55+ mph with 40+ miles range minimum but a few thousand dollars in batteries is way out of my reach. Time for a new project.

Or I could put a couple resistors and vacuum tubes in a 2 foot box with a couple of rods sticking out and drive around with NO batteries.

[Robocar]

Dang, I just missed out on 6 Trojan T-105 225ah batteries for $640 on Craigslist. That would have been a start, at least egtting the car running initially.

[Ziggythewiz]

6 trojans...is that for the golf cart? I'd say that's a deal if they were new, but craigslist?