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Discussion Starter #1
I took my EV for its first drive yesterday and I have a question regarding W/Mile consumption.

Setup:
Kelly 12600 controller
13.2kW Fiat 500e Samsung/Bosch 64Ahr cells
ADC 8" DC motor
TSM2500 charger, 1500W charge rate
1979 Ford Fiesta
clutchless using stock transmission

I only have a volt meter on the pack right now but I verify with a meter. I charged it up to 123V (4.1V per cell) and drove 13 miles between 35-50mph ending around 117V. Returning home, I charged it through my EVSE and dumped 4.5kW into it to get the pack voltage back to 123V.

Considering that the charger is 97% efficient, is this is a reliable way to figure out W/Mile? If so, I'm thinking I have some mechanical problems as I come up with 346W/Mile for a car that weights 1600 pounds.
 

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... I'm thinking I have some mechanical problems as I come up with 346W/Mile for a car that weights 1600 pounds.
That would be the same consumption as a much larger current production EV... but given the current production EVs use AC (PM or induction) motors instead of a brushed DC motor and have better aerodynamics, maybe that's not so surprising.
 

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I charged it up to 123V (4.1V per cell) and drove 13 miles between 35-50mph ending around 117V. Returning home, I charged it through my EVSE and dumped 4.5kW into it to get the pack voltage back to 123V.

Considering that the charger is 97% efficient, is this is a reliable way to figure out W/Mile? If so, I'm thinking I have some mechanical problems as I come up with 346W/Mile for a car that weights 1600 pounds.
4.5 kWh (not kW)? And 346 Wh/mile (not W/mile)? Then yes, this seems like a reasonable way to me to determine energy consumption (in Wh/mile)... as long as the same indicated voltage is really the same state of charge.
 

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Discussion Starter #4
PMDC motors are that much more efficient? Guess I should start looking for one of those then.

Thanks for the correction on Whr! I'm getting used to my charger. It is supposed to stop at 123.0VDC but I think it crept up a little. It might have done better than I thought due to a little extra charge. I was going to stop it at no more than 90% charge and discharge no more than 20%.

I have another 6kW to install into the Fiesta. It should get me the extra range I need to get to work in that 80-20%. Figured I'd ask if that WHR/mile consumption rate seemed fine since the significant weight reduction vs a leaf or 500e I thought would have netted me the same range as current production EVs.
 

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The average consumption rule of thumb is 10% of the weight, so if the weight is really 1600 lbs, then you might expect to cruise on a flat level road using only 160 Whr/mile. That would be measured in realtime from the pack voltage and current and speedometer.

Using the power required to re-charge the pack is not the same as this rule of thumb.

If you could put a clamp-on current probe on the pack during a drive it would help you measure the power for a given mph. For example, if it takes 128 Amps to cruise at 60 mph, then you might get 20 to 30 minutes of runtime and (20-30 miles) of range. [(Volts x Amps) / mph] would then give you a consumption value.
 

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Discussion Starter #6
Thanks! I have several current shunts on the car and nice flat parts of town to try this out. My meter also works out an average so I can get a fairly reasonable figure too. Eventually I'll get a JLD404 but in the mean time, I'll try your method and see what it says.

10% of vehicle weight is a new one to me, but this is my first EV project. I'll do the wheels, some slight aero, and check out the wheel bearings and brakes. Every little bit helps.
 

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Discussion Starter #7
Just keeping this thread alive instead of making a new one.

I took the wheels off and discovered the original grease and bearings in the car. One of which was bad. So I cleaned them all out (front and rear), repacked them with fresh grease, knocked the sticky surface off the shoes, cleaned the drums out (tons of dust and debris), lowered the front of the car an inch (car was raked back an inch), and drove it around. It drives much nicer now, much quieter, and it seems to have more power in first gear. I'll try to drive it on the same path tomorrow and see what my power consumption is at.
 

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With a bearing like that you are bound to see an improvement.

Crunchy bearings or rusty, dragging brakes are a huge load on consumption. Every little thing counts.

Such as alignment--i had a slight toe-out on the front of my Mitsubishi imiev that was scrubbing the inside corner of the tires. i wish i had recorded data for a before/after comparison, but didn't think to do that--i knew it was off and just fixed it. The car calculates an estimated range remaining based upon the previous 15 miles. Overnight charging before would show about 58 to 64 miles, now it shows 65 to 74 miles. Not exactly scientific but it has a definite improvement in range for a full pack.
 

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Discussion Starter #9
Good to know! The front of this car is as aerodynamic as a brick, so hopefully a splitter or front dam will help. I'll also do some kind of under tray to keep water out of the motor bay. Lots of plans, we'll see how it goes.
 

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Discussion Starter #10 (Edited)
Update: After repacking the bearings and cleaning the brake shoes, I then travelled the same route. 3.350kWhr (257Whr/mi) per my EVSE! But then I finally got my laptop connected to Dilithium EVCC and came up with 3.050kWhr (234Whr/mi)! Way better than before but still room for improvement.
 

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Discussion Starter #11
Update: After putting new wheels on I drove the car 17 miles going up and over a long hill and back the same path. If my math is correct, I went from 90% to ~60% (20.1V to 19.36V, 5S) at 9kWhr to 5.4kWhr. That gives me a rough usage of 3.6kWhr at 17 miles....

158kWr per mile!!!!

And my car looks much better doing so, if I dont say so myself. The old tires were extremely soft, dry rotted to hell (you could see cord through the sidewall). The new tires are, well, new.
 

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Discussion Starter #13
I will get it charged tonight and see the actual usage. I might have a couple of batteries straying in their voltage so I'm carefully watching them. They are only 20mV off from the average but still enough for me to be concerned.
 

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Discussion Starter #14
Alright, took a while. Not super thrilled, the evcc logged 4161Wh to recharge my 15 mile trip. That means about 277Wh/mi. I'm going to start looking into rolling resistance issues.
 
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