“Test Results” Watts per Mile”

I wanted to share some numbers. We all know the #1 question people ask about your Gem is (What’s the range) well because we have so many factors that can change how far your car will go, you can’t accurately give a answer. Or can you? The first step it to figure out How much energy on Average does your car chew threw per mile. Example if you car takes 100Wh per mile and you have a 500 Wh Battery Pack you can go 5 Miles. Ok that’s over simplifying it. But here are some real time number I came up with.

Here are some numbers as far as power consumption on my 2013 E4
The car has been converted to Lithium with David’s help but all other running equipment is stock except for the 17inch wheels and David’s Magic Magnet (car has stock 5hp GE motor and 12:44 gears T-4 controller with stock programming)

I picked a semi flat (very small rolling hills) its a 1 mile stretch. The test will be 1 mile in each direction with the power consumption of both miles combined to average out the up’s & downs.

I will do a power consumption test at 25 mph (turf mode) regulated at 80 amp draw max & 1 more test at wide open close to 40mph un regulated Amp draw.

I’m using David’s BMS 24 with Current Draw Meter to collect my numbers of how much power each mile is sucking from the pack.

Test# 1 25Mph start with 5120 Wh finish Mile 1 with 4895Wh
Test#1 25 mph start with 4895Wh finish with 4673 Wh (limited at 80 amp max draw average 60 amp draw)

448 Watts for 2 Miles traveled = 224 Wh per mile

Test # 2 40 mph (out)
Start with 4666 Wh finish with 4381Wh
Test #2 40 mph (back) start with 4381 Wh finish with 4108 Wh

Total 2 Miles traveled 558 Wh consumed = 279 Wh per mile
(Max amp draw of 225 amps, Average amp draw 120 amps)

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With your 8KWh pack, that works out to a theoretical 28-35 mile range. Is that what you figured?
In your install, it appears you built up the battery compartment to make it level and then strapped in the batteries. Were the straps a local purchase?
I have a 2014 e2. I have been cutting the plastic water jackets to give a secure fit in the wells. The battery in the rear compartment will have no modifications. The right side has both water jackets cut and gives a nice tight fit. I will leave the left compartment empty for storage. The center will house both batteries and will be a snug fit. My thoughts at this time are using J-bolts for tie downs.

You have done better than I have with speed. I am pretty sure mine has 12.44 gears. I think it came with a 7hp motor as it was huge. I was able to do about 32. I changed it out for a ride4ffun 7.5 hp and able to do about 34-35. My thoughts are that 90+ volts should make a difference:grin:

I purchased the straps to hold down my battery’s from Amazon. They are made to hold down a plastic gas tank in a small boat. They come 2 to a pack. Like $12-$14 each if I remember correctly.

My car go’s 46Mph with a slight downhill run but will do 40 on the flats.

I have a Ride for Fun motor that I’m going to install and see if my Whatt per mile range go’s up or down. Gonna do that same test run a few more times and just double check that my whatts per mile is accurate.

Is there any chance that your gears are 10.35 to 1?
I am running 205/40-17’s at 23.4 inches. I would need to be turning 8000 rpm to do 45 mph.
With the 12.44 gears that I am running now, it takes 6300 rpm for me to do 35 mph.

Double check calibration against the charger.
1 amp in 10 is 6 amp error at 60 amps.
You should be able to charge at 15 amps with the C10325 and see if bms-24 reads the same.
It seems I can run on the level 25mph less than 40amps. 144wh per mile if you can average 40amps.@90v
60a average is 216wh per mile. same 90v. Take it slow up hill and coast down hill. I might have been trying to run constant current more than constant speed. Skewing my results.
Have to wait for summer to double check.

I’m 99% sure my gears are 12:44
As far as power consumption I’m sure I could have picked a 100%! Flat section to do my test that would have made the amp draw less. I will check the input amps on the new charger and see if the Dash mounted BMS is telling me is accurate. I would guess a stock gem is a bit more efficient then my big wheel car

Proev is doing a 2017 Volt conversion.
See if you can talk him out of his 16s modules, like your “spark”.

Yes I’m in the Market for some new cells for another conversion


i thought gem in 2013 put in 10.35 gears and 7hp advanced motors stock . pretty sure that is what my 2014 has .

Mike: I’m pretty sure I’m running the 12:44 gears.
Here is the Part number on my transmission if anyone knows.

Dave and I figured out that my BMS amp draw was or could have been “of by a bit” and the amp draw numbers I posted may have not been accurate.

I’m going out to do a new test right now and see if my amp draw number change. One thing I’m gonna do different is on the 25mph test, I’m gonna run the car in ROAD mode and regulate the throttle to maintain 25mph instead of switching it in turf and holding the pedal to the floor.

On my 2nd Test I did get better
202Kwh per Mile at 25
250Kwh per Mile at 40.

I gotta say at 40 Mph you do the Mile in what seems like no time. 25mph feels like a snails pace. I guess it depends on the road your on. I can’t see being able to go 25mph on a golf course

I just got my Volt pack installed yesterday along with the BMS24. This morning I made a 5.5 mile round trip by myself and averaged 180 Kwh per mile. Ground was mostly level and my goal was to stay at 29 mph. Half of the miles were in the dark using my headlights. My car is a little lighter than Grant’s as I have a 2014 e2. And, I did keep my foot out of it.
BTW, I weighed one of my 12s “volt” packs before trimming and it weighed 39.8 pounds. With 4 packs, that is 160 pounds versus 420 for Group 31’s.

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That’s great info.
My test was to determine best case watts per mile, in a stock Gem, at just under plugging speed.
I came up with 150w per mile.

That means 1/2 of a volt pack is theoretical 50 miles. Using the same criteria Gem may use when stating mileage.

180 KWh per Mile seems pretty good. Better then my 202 KWh per Mile. I would bet if I was on flat ground I could get 180 KWh per mile but for my Aera flat ground is pretty rare. I’m in a very hilly aera, so that’s why I choose rolling hills because dead flat road is few and far between and testing on it will not be real world numbers. A bonus if you use 202 or 180 as your KWH per Mile on your stock car you can always get better.

The rumor is that the D&D motor is More efficient. Now that i changed my stock 5 hp for a stock Ge 7 hp I wonder what the consumption diff is gonna be?

size motor2
My 2014 supposedly came with a 5hp motor. (according to the factory). I think it is a 7hp. Here it is side by side with a Ride 4 Fun 7.5hp. The original is 4" longer and a LOT heavier. However, when I changed it last summer, the R4F motor did give me a little more speed and perhaps a little peppier. The testing I did able was with the R4F motor. In Surprise, AZ, the largest hill that I see is an overpass:wink:

So I worked on a few diffrent gems this weekend.
Both of them had Flooded lead acid packs. What’s so funny is stepping into a car with Flooded lead acid. The performance or lack of get up and go is laughable. Example standing on the gas in a Flooded Lead Acid car is a “Request” not a Demand.

Stand on the gas in a Lithium car and you know it.

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Check this out if you want a set of Volts.

Not mine!