Quest for an Electric Porsche Boxster.
Finally back on the road today after a lot of work. Netgain diagnosed a fan failure and sent us a new fan. We tried to follow instructions, but the fan is so tightly fixed to the shaft, we broke the replacement fan trying to install it incorrectly. We paid for another fan, about $240, and used a PVC pipe over the motor shaft, with a 2x4 on top of the pipe, and a hammer on the 2x4 to force the fan onto the shaft. It took an hour of hammering, checking, hammering, etc. Finally got the fan on, reassembled and presto... IT SPUN UP! So, almost 4 weeks later and about 8 hours of work tearing down, fixing motor and reassembly. Back on the road!
If this happens to you, strongly consider sending back to Netgain for repairs, as if you break the fan you will have to pay for another and it will delay the repair by at least a week. If you repair it yourself, DO NOT HAMMER ON THE OUTER RIM OF THE FAN. It will not work and the fan is very strong, but brittle like ceramic. IT WILL CRACK. Also be sure and remove as many fragments as possible using a powerful vacuum and forced air if available. We had a small fragment we missed and were worried it caused some damage. Had to take the fan grate off and remove it. The fragment fell out, and it was fine afterwards with no damage to the new fan.
Friday, January 28, 2011
Friday, January 7, 2011
Warp 11 Fan Destroyed, Netgain to Rescue!
Quest for an Electric Porsche Boxster.
Here are some photos of the fan failure... Netgain is sending a replacement and we will hopefully have it fixed in a week or so without having to ship it back.
Here are some photos of the fan failure... Netgain is sending a replacement and we will hopefully have it fixed in a week or so without having to ship it back.
Saturday, January 1, 2011
Warp 11 Motor failure
Quest for an Electric Porsche Boxster.
Drove out to the lake and back. Something came loose in the motor when driving in 2nd gear up to about 4000rpm when leaving the marina parking lot . It clinked and scratched loudly at first, as if bouncing around, and eventually settled down, temporarily went away at lower rpms. I was able to drive home and heard the noises a few more times when going up hills or perhaps bumps as if something plastic was bouncing around in there. It wasn't as loud as at first. It would settle down on even road and had no perceptible noise for fairly long distances at 2500rpm going about 50-55mph. Once home, I tested the motor in neutral and you can hear scraping sounds. I think this motor is going to need TLC from Netgain.
On a lighter note, replacing the motor mount has made a noticable difference on take offs, and overall the handling going to the lake was very good. The efficiency on the trip was about 1.8Ah/mile which is pretty good, and power performance is pretty good too, particularly since lowering the minimum voltage limit on the Zilla. I don't think there is much more room for maximizing performance with this battery pack however, and I may swap out the Zilla Z2K for a Z1K as that should be more than enough for this pack.
Drove out to the lake and back. Something came loose in the motor when driving in 2nd gear up to about 4000rpm when leaving the marina parking lot . It clinked and scratched loudly at first, as if bouncing around, and eventually settled down, temporarily went away at lower rpms. I was able to drive home and heard the noises a few more times when going up hills or perhaps bumps as if something plastic was bouncing around in there. It wasn't as loud as at first. It would settle down on even road and had no perceptible noise for fairly long distances at 2500rpm going about 50-55mph. Once home, I tested the motor in neutral and you can hear scraping sounds. I think this motor is going to need TLC from Netgain.
On a lighter note, replacing the motor mount has made a noticable difference on take offs, and overall the handling going to the lake was very good. The efficiency on the trip was about 1.8Ah/mile which is pretty good, and power performance is pretty good too, particularly since lowering the minimum voltage limit on the Zilla. I don't think there is much more room for maximizing performance with this battery pack however, and I may swap out the Zilla Z2K for a Z1K as that should be more than enough for this pack.
Battery Capacity and Range part II
Quest for an Electric Porsche Boxster.
I did another capacity test yesterday. Started at 276Ah and went to 204Ah limping into the garage for a total of 72Ah. Blade 33 performed well, but this time 35-2 went south in hurry. I think the shoulder on this pack is about 2.75V with light amp draw of about 60-100A. At brief rest, 35-2 went back to 2.9V so I decided to go around the block again, which ended up being about 2.6 miles. Too much, and I briefly went to 1.4V on 35-2 when drawing 50-60A getting back to the house. I wish I could have taken 1 mile back. It went back up to 1.9V after brief rest. Most other cells including blade 33 went over 3V and a few were at 2.9V. The other cells in 35 were not as weak as 35-2. Anyway, I don't think blade 33 is a problem anymore than the general capacity of the pack. Various blades took turns as the minimum voltage with accelerations during the drive, and cells in blade 33 only came up once I think. Blade 35 came up a few times, but I wouldn't have singled it out earlier in the drive. So right now I think we have a fairly stable pack, of around 70Ah (safely at 1.8Ah/mile).
I left the charger on 2A overnight which eVision showed about 0.5A going to the pack. Before going to bed the pack was at 278Ah with 42-1 reaching shunt at around 3.56V, and the rest of the pack still around 3.3-3.4V. The pack balanced about 7.5 hours overnight to the following...
B# mV T
cell 1 cell 2 cell 3 cell 4
01 3575 024 3583 024 3573 024 3584 024
02 3573 025 3577 025 3575 025 3576 025
03 3571 020 3576 020 3578 020 3578 020
04 3575 028 3577 028 3578 028 3577 028
05 3578 028 3578 028 3576 028 3575 028
06 3578 028 3576 028 3571 028 3571 028
07 3577 028 3577 028 3576 028 3572 028
08 3580 028 3577 028 3579 028 3574 028
09 3580 026 3579 026 3579 026 3579 026
10 3580 032 3579 032 3571 032 3570 032
11 3577 029 3576 029 3573 029 3575 029
12 3576 031 3579 031 3575 031 3573 031
13 3579 031 3579 031 3576 031 3577 031
14 3574 032 3576 032 3574 032 3575 032
15 3577 029 3577 029 3575 029 3574 029
16 3582 031 3583 031 3583 031 3582 031
17 3565 028 3570 028 3572 028 3572 028
18 3577 033 3577 033 3571 033 3572 033
19 3576 028 3577 028 3574 028 3574 028
20 3575 033 3575 033 3572 033 3576 033
21 3572 029 3572 029 3566 029 3566 029
22 3572 029 3573 029 3570 029 3571 029
23 3576 033 3577 033 3571 033 3571 033
24 3574 026 3575 026 3571 026 3569 026
25 3576 028 3576 028 3572 028 3571 028
26 3571 029 3573 029 3569 029 3566 029
27 3573 032 3572 032 3566 032 3564 032
28 3574 033 3575 033 3570 033 3572 033
29 3571 031 3571 031 3566 031 3565 031
30 3574 027 3576 027 3572 027 3572 027
31 3570 029 3573 029 3570 029 3568 029
32 3556 026 3561 026 3570 026 3567 026
33 3573 029 3571 029 3570 029 3571 029
34 3567 032 3567 032 3568 032 3565 032
35 3573 033 3575 033 3570 033 3570 033
36 3572 035 3574 035 3569 035 3572 035
37 3573 034 3573 034 3574 034 3574 034
38 3576 036 3575 036 3571 036 3571 036
39 3572 035 3572 035 3567 035 3566 035
40 3570 037 3567 037 3570 037 3568 037
41 3570 036 3571 036 3566 036 3564 036
42 3569 035 3571 035 3569 035 3567 035
43 3569 035 3572 035 3569 035 3566 035
44 3572 035 3572 035 3567 035 3566 035
45 3567 034 3566 034 3567 034 3566 034
46 3574 032 3573 032 3572 032 3572 032
47 3573 032 3574 032 3564 032 3565 032
48 3570 028 3571 028 3570 028 3568 028
Max Voltage: 3584 (14)
Min Voltage: 3556 {321
Max Temp: 37
Min Temp: 20
Most all the cells showed the orange lights shunting, so not all the Ahrs overnight shown on eVision went in the pack. Nonetheless the total on eVision was 285Ahrs from 204Ahrs before charging. So, even including shunt losses, the pack only took in about 81Ahrs. 35-2 was not the first to reach full, and so I don't think we have anymore blades that stand out as being bad. We just have a lower than expected usable capacity for this pack. If it is supposed to be 96Ahrs, then we are still missing at least 16-20% capacity. Unless something else is wrong, I think we have no more than 80Ahrs or about 47miles range at 1.7Ah/m at the very maximum.
I don't see this pack safely producing 10C continuous discharge rates. It barely produces 5-6C with a full pack. 5C discharge is what K2 lists as "nominal capacity" on their spec sheet. Without lowering the Zilla voltage limit further, 5-6C is probably the maximum useful draw on demand for acceleration in our arrangement. Therefore, the Z2K is probably not going to be better than the Z1K with this pack producing around 500-600A maximum. If I recalculate the cell capacity from the expected 3200mAh down to 2700mAh (about what we are seeing now), then discharge rates appear higher. So with 500A on acceleration, that results in a 6C discharge rate based on the lower capacity. 630A, which I saw once with a full pack, is about 7.7C, which is not too bad and overall performance is pretty good but not as exciting as we hoped.
Digesting all this, I guess we would like to know the maximum tolerable voltage limit we can set on the Zilla for brief accelerations without "abusing" the cells, since we are not seeing much beyond 5-6C discharge rates with Zilla set at average 2.4V sag. Will the cells tolerate going to 2.0V sag for less than 30sec? How about 1.5V, if brief rest brings them back to over 3V? And finally, why are we not getting closer to expected capacity from this configuration? These are all questions I will need to review with K2 to see if we are missing something or if they have any suggestions. These were much more expensive batteries than the Thundersky variety, and I am not seeing the energy density or power advantage at this point.
I did another capacity test yesterday. Started at 276Ah and went to 204Ah limping into the garage for a total of 72Ah. Blade 33 performed well, but this time 35-2 went south in hurry. I think the shoulder on this pack is about 2.75V with light amp draw of about 60-100A. At brief rest, 35-2 went back to 2.9V so I decided to go around the block again, which ended up being about 2.6 miles. Too much, and I briefly went to 1.4V on 35-2 when drawing 50-60A getting back to the house. I wish I could have taken 1 mile back. It went back up to 1.9V after brief rest. Most other cells including blade 33 went over 3V and a few were at 2.9V. The other cells in 35 were not as weak as 35-2. Anyway, I don't think blade 33 is a problem anymore than the general capacity of the pack. Various blades took turns as the minimum voltage with accelerations during the drive, and cells in blade 33 only came up once I think. Blade 35 came up a few times, but I wouldn't have singled it out earlier in the drive. So right now I think we have a fairly stable pack, of around 70Ah (safely at 1.8Ah/mile).
I left the charger on 2A overnight which eVision showed about 0.5A going to the pack. Before going to bed the pack was at 278Ah with 42-1 reaching shunt at around 3.56V, and the rest of the pack still around 3.3-3.4V. The pack balanced about 7.5 hours overnight to the following...
B# mV T
cell 1 cell 2 cell 3 cell 4
01 3575 024 3583 024 3573 024 3584 024
02 3573 025 3577 025 3575 025 3576 025
03 3571 020 3576 020 3578 020 3578 020
04 3575 028 3577 028 3578 028 3577 028
05 3578 028 3578 028 3576 028 3575 028
06 3578 028 3576 028 3571 028 3571 028
07 3577 028 3577 028 3576 028 3572 028
08 3580 028 3577 028 3579 028 3574 028
09 3580 026 3579 026 3579 026 3579 026
10 3580 032 3579 032 3571 032 3570 032
11 3577 029 3576 029 3573 029 3575 029
12 3576 031 3579 031 3575 031 3573 031
13 3579 031 3579 031 3576 031 3577 031
14 3574 032 3576 032 3574 032 3575 032
15 3577 029 3577 029 3575 029 3574 029
16 3582 031 3583 031 3583 031 3582 031
17 3565 028 3570 028 3572 028 3572 028
18 3577 033 3577 033 3571 033 3572 033
19 3576 028 3577 028 3574 028 3574 028
20 3575 033 3575 033 3572 033 3576 033
21 3572 029 3572 029 3566 029 3566 029
22 3572 029 3573 029 3570 029 3571 029
23 3576 033 3577 033 3571 033 3571 033
24 3574 026 3575 026 3571 026 3569 026
25 3576 028 3576 028 3572 028 3571 028
26 3571 029 3573 029 3569 029 3566 029
27 3573 032 3572 032 3566 032 3564 032
28 3574 033 3575 033 3570 033 3572 033
29 3571 031 3571 031 3566 031 3565 031
30 3574 027 3576 027 3572 027 3572 027
31 3570 029 3573 029 3570 029 3568 029
32 3556 026 3561 026 3570 026 3567 026
33 3573 029 3571 029 3570 029 3571 029
34 3567 032 3567 032 3568 032 3565 032
35 3573 033 3575 033 3570 033 3570 033
36 3572 035 3574 035 3569 035 3572 035
37 3573 034 3573 034 3574 034 3574 034
38 3576 036 3575 036 3571 036 3571 036
39 3572 035 3572 035 3567 035 3566 035
40 3570 037 3567 037 3570 037 3568 037
41 3570 036 3571 036 3566 036 3564 036
42 3569 035 3571 035 3569 035 3567 035
43 3569 035 3572 035 3569 035 3566 035
44 3572 035 3572 035 3567 035 3566 035
45 3567 034 3566 034 3567 034 3566 034
46 3574 032 3573 032 3572 032 3572 032
47 3573 032 3574 032 3564 032 3565 032
48 3570 028 3571 028 3570 028 3568 028
Max Voltage: 3584 (14)
Min Voltage: 3556 {321
Max Temp: 37
Min Temp: 20
Most all the cells showed the orange lights shunting, so not all the Ahrs overnight shown on eVision went in the pack. Nonetheless the total on eVision was 285Ahrs from 204Ahrs before charging. So, even including shunt losses, the pack only took in about 81Ahrs. 35-2 was not the first to reach full, and so I don't think we have anymore blades that stand out as being bad. We just have a lower than expected usable capacity for this pack. If it is supposed to be 96Ahrs, then we are still missing at least 16-20% capacity. Unless something else is wrong, I think we have no more than 80Ahrs or about 47miles range at 1.7Ah/m at the very maximum.
I don't see this pack safely producing 10C continuous discharge rates. It barely produces 5-6C with a full pack. 5C discharge is what K2 lists as "nominal capacity" on their spec sheet. Without lowering the Zilla voltage limit further, 5-6C is probably the maximum useful draw on demand for acceleration in our arrangement. Therefore, the Z2K is probably not going to be better than the Z1K with this pack producing around 500-600A maximum. If I recalculate the cell capacity from the expected 3200mAh down to 2700mAh (about what we are seeing now), then discharge rates appear higher. So with 500A on acceleration, that results in a 6C discharge rate based on the lower capacity. 630A, which I saw once with a full pack, is about 7.7C, which is not too bad and overall performance is pretty good but not as exciting as we hoped.
Digesting all this, I guess we would like to know the maximum tolerable voltage limit we can set on the Zilla for brief accelerations without "abusing" the cells, since we are not seeing much beyond 5-6C discharge rates with Zilla set at average 2.4V sag. Will the cells tolerate going to 2.0V sag for less than 30sec? How about 1.5V, if brief rest brings them back to over 3V? And finally, why are we not getting closer to expected capacity from this configuration? These are all questions I will need to review with K2 to see if we are missing something or if they have any suggestions. These were much more expensive batteries than the Thundersky variety, and I am not seeing the energy density or power advantage at this point.
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