Electric kart

Electric cars, trucks, ATVs, NEVs - things bigger than a motorcycle.
Ianhill   100 MW

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Re: Electric kart

Post by Ianhill » May 14 2021 5:56am

There's one issue thats going to cause problems with this ride and you have done well its not a problem you have made as such but more of a packaging constraint.

With the battery weight on the outer edges of the ride its turn in ability will be hampered as a results it becomes twitchy easy to pull wide just harder to place consistently on track lines.

Somehow that battery weight needs to be centred but the human stay just as low to the ground as possible, but even if you make a frame with a centre tunnel of some sort it will still make it very difficult package to design and fit the power you need in but that would allow you finer control and bring the laptime down make the kart easier to drive but that design would mean you have cracked it and would have the most advanced driving electric gokart design there ever has been to date.

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hallkbrdz   100 W

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Re: Electric kart

Post by hallkbrdz » May 14 2021 2:41pm

Ian, yes that is a problem with any electric kart that uses an ICE frame. Hanging that much weight out that far creates a pendulum effect, but it's all you can do with existing frames.

I've been working on designs for a new frame built from scratch to place equal weights of batteries on both sides, inside the frame, with the motor in the back. First ones will be kid karts, since the sticker shock over ICE is small for those.

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 17 2021 3:29am

Here is video of qualification in sunday
https://www.youtube.com/watch?v=_7zZfBVIjwY

Official times are here: https://speedhive.mylaps.com/Events/1858002
Look for "RETRO, RETRO N" section and from there "133 Martin PREISMANN" my friend drove because he is 20kg lighter than me :)

Before Race 1 my windows 10 tablet on kart decided to do feature update and it took him 1h, so there is no data from race 1 :(
Rendering it right now and will add here when finished.
Last edited by nuxland on May 18 2021 5:02am, edited 1 time in total.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 17 2021 4:57am

Final 1 with GPS data only.
Used my LiPo that has theoretically 35Ah but all of it is not available with my power levels.
We used ~30Ah and cell voltages were around 3,6v after the race.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

SlowCo   1 MW

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Re: Electric kart

Post by SlowCo » May 17 2021 5:33am

Great racing!
Nice to see it is so competative.

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 17 2021 1:17pm

Race 2 video, where I raced with my first LiFePo4 2p34s 40Ah pack (A123 Pouches).
I have written here that years ago this pack went to 0V and it left scars (I changed around 22 dead cells then)
And with this race cells nr 2 went to zero volts during the race.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 18 2021 1:35am

Took cell voltage readout when we stopped and then 10 minutes later before I started to charge it and then again 5 minutes later when stopped charging. Cell pairs nr 2 are dead but 12,20,31,34 I think one pair is bad (had less capacity that other)
Blue - After the race when we stopped
Red - 10 minutes after we stopped
Grey - 5 minutes later when ended charging
Cells.jpg
Cells.jpg (189.06 KiB) Viewed 461 times
Will disconnect these pairs from others and from each other and let it stay some days to see what needs to be replaced.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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hallkbrdz   100 W

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Re: Electric kart

Post by hallkbrdz » May 18 2021 9:05am

I was surprised that with dead cells, the entire battery didn't give up. I certainly learned something from that.

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 18 2021 10:37am

hallkbrdz wrote:
May 18 2021 9:05am
I was surprised that with dead cells, the entire battery didn't give up. I certainly learned something from that.
These are LiFePo4 cells and they act differently than liion cells.
Reason why there was less ampers from battery was overall voltage. I had configured in sevcon that from 90v it starts to limit torque.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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LuigiDesing   100 µW

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Re: Electric kart

Post by LuigiDesing » May 18 2021 11:50pm

nuxland wrote:
May 18 2021 10:37am
hallkbrdz wrote:
May 18 2021 9:05am
I was surprised that with dead cells, the entire battery didn't give up. I certainly learned something from that.
These are LiFePo4 cells and they act differently than liion cells.
Reason why there was less ampers from battery was overall voltage. I had configured in sevcon that from 90v it starts to limit torque.
In a string of batteries the current is the same for all, and if one cell is out of charge but keep the internal resistance, let pass the current through the series. Usually as soon as reach this cell 0v even inverts its voltage to -Xv figures but only with load, subtracting this volts from the total voltage but keep working. All depends if the BMS can read negative voltages to log it when the system is loaded.
Thanks that this happens with LiFe family cells, if this would happens with LiPo, a fireworks it's more than a reasonable event...

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 19 2021 9:10am

LuigiDesing wrote:
May 18 2021 11:50pm
nuxland wrote:
May 18 2021 10:37am
hallkbrdz wrote:
May 18 2021 9:05am
I was surprised that with dead cells, the entire battery didn't give up. I certainly learned something from that.
These are LiFePo4 cells and they act differently than liion cells.
Reason why there was less ampers from battery was overall voltage. I had configured in sevcon that from 90v it starts to limit torque.
In a string of batteries the current is the same for all, and if one cell is out of charge but keep the internal resistance, let pass the current through the series. Usually as soon as reach this cell 0v even inverts its voltage to -Xv figures but only with load, subtracting this volts from the total voltage but keep working. All depends if the BMS can read negative voltages to log it when the system is loaded.
Thanks that this happens with LiFe family cells, if this would happens with LiPo, a fireworks it's more than a reasonable event...
Replaced these two cells (nr 2) and one had it's juices out and smelled very bad. Other one started to gain voltage as soon I disconnected it from the one that had juices out (the right one in the picture).
186037485_300380128222469_2438103360712909310_n.jpg
186037485_300380128222469_2438103360712909310_n.jpg (220.04 KiB) Viewed 398 times
I already had tools available from last time, so it took me only 2h to open one end, replace two cells and close it up again.
I'm having cells compressed so can not to without that tool.
186504712_979907476148077_4445742711700879911_n.jpg
186504712_979907476148077_4445742711700879911_n.jpg (355.08 KiB) Viewed 398 times
Right now charging to full with 10A and the same time dischargin cell nr 2 with rc charger with 10A because that had higher voltage than others. Red lines show difference when started charging (12,20,31,34 were almoust the same voltage than others)
charging.png
charging.png (111.86 KiB) Viewed 398 times
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

Ianhill   100 MW

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Re: Electric kart

Post by Ianhill » May 19 2021 9:52am

I bet 24 lg 60ah cells could be arranged into a floor pan in rows 6 wide 4 tall so total area is 65mm tall 330mm wide 600mm length then the compresion box can also form the floor pan so the pack is lighter its enclosure plays a dual roll saving weight and that little less total power is soon overcome by weight saving.

Plus that weight is then down low and centred on the frame the savings on time in the bends would make up alone corner exit speed plus not scrubbing off so much speed the pack wont have to work so hard accelerate from lower speeds just maintain high speeds.

A nice front aero kit and your away even if something ice claims more power can it use it on these little tracks, getting carried away with power sometimes gets ahead of the important factors in a ride it loses track of what its designed for and becomes an unusable mess your kart is far from that but those petrol go karts have been finnesed for many a year they can carry alot over to electric but it needs a new approach to crush the competition.

Your still living the dream fella keep at it i live what your doing im just trying to give you some food for thought few years maybe ill see this thread with a hyper kart thats so spot on its sexual to drive it.

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stan.distortion   100 W

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Re: Electric kart

Post by stan.distortion » Jun 05 2021 6:54am

Really impressive build, the issues that have come up and how it's developed are a real wealth of experience, thanks for sharing! :bigthumb:

Is it getting much interest in you home crowd, are others thinking of doing the same? It would be great if an open series came out of it, unlimited performance can always be countered by number of laps with something so light. Had you considered traction control? Not sure if it would be permitted in races but the sprint times could benefit from it. Also, would regen coupled with a small LTO pack work? Considering your fried brakes, regen with LTOs high charge rate could probably reduce energy per lap considerably, maybe enough to save on overall pack weight.
(edit) LTO, roughly 10kg/kwhr, 10C charge rate.
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Ianhill   100 MW

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Re: Electric kart

Post by Ianhill » Jun 05 2021 10:48am

The lg 60ah cells are around 4kg per kwh, each cell is about 880g and 222wh 14.5×100×300mm so a 20s pack is 100×300×300 20kg and should put out in the 15.5kw range or for this big kart may need 2 of them stacked to get the discharge but that would give 7kwh usable power 8.8kwh stored.

Those lto cells look very good for in the home how a tesla power wall sells when these exist beats me.

Id like to say thanks too im following your youtube and build thread taking in what i can as you have inspited me enough to join you been a long time since i took to a decent kart and yours just ruins the competion proper power house well done my friend big 💘 for this.

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stan.distortion   100 W

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Re: Electric kart

Post by stan.distortion » Jun 05 2021 12:30pm

Ianhill wrote:
Jun 05 2021 10:48am
The lg 60ah cells are around 4kg per kwh, each cell is about 880g and 222wh 14.5×100×300mm so a 20s pack is 100×300×300 20kg and should put out in the 15.5kw range or for this big kart may need 2 of them stacked to get the discharge but that would give 7kwh usable power 8.8kwh stored.

Those lto cells look very good for in the home how a tesla power wall sells when these exist beats me.
...
Those figures are for LTO? I'm finding info a bit scarce, hadn't come across anything by LG. Energy density could have come on a fair bit, enough to make an LTO pack viable but I was only thinking of it for regen capacity. Smaller cells make the most sense there, for example:

10300, 2.4v, 0.1ah, 4.7g, 30C charge, 0.25w/hr per cell. 40 cells for 96v, 10w/hr, 0.19kg, 3a or 0.288kw of regen, 4 in parallel would give a little over 1.1kw of braking force and 40w/hr regen capacity for 0.75kg.

14500, 2.4v, 0.5ah, 16.6g, 20C charge, 1.2w/hr per cell. 40 cells for 96v, 48w/hr, 0.66kg, 10a or 0.96kw of regen, 1 in parallel would give a little under 1kw of braking force and 48w/hr regen capacity for 0.66kg.

40-50w/hr doesn't sound like a whole lot but that's 36kw braking force for 4-5 seconds. Obviously there's a big difference between 36kw and the 1kw above, 6 sets of either would be less than 6kg and the 20-30C is manufacturers rated capacity for a life of min 4000 charge cycles. They'll probably go a lot higher and it's apparently a very safe tech, if they'll push as high as 50C with a reasonable lifespan that's more than a minutes worth of 15kw braking regen at under 6kg.
Last edited by stan.distortion on Jun 05 2021 12:52pm, edited 1 time in total.
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Ianhill   100 MW

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Re: Electric kart

Post by Ianhill » Jun 05 2021 12:48pm

Just been looking at the lishen 50c 18ah cell looks tasty 8000 cycle lifes and 900amp but 32 of them make a pack up to get 89.6v and that goes down to 48v at 1.5v cut off so the voltage swing could be a pain to deal with.

The setup your talking of makes sence for a hybrid kart kers system, the thing they got going for them is those charge and discharge rates much better temp range and cycle life but a 22s lipo pack grows by 10 cells and the voltage swing for 22s lipo is 26.4v vs 32s lto 41.6v and they weigh 780g so a 25kg pack and its got 1.44kw about 1.15kw usable if its like lithuim.

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stan.distortion   100 W

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Re: Electric kart

Post by stan.distortion » Jun 05 2021 1:03pm

Ianhill wrote:
Jun 05 2021 12:48pm
Just been looking at the lishen 50c 18ah cell looks tasty 8000 cycle lifes and 900amp but 32 of them make a pack up to get 89.6v and that goes down to 48v at 1.5v cut off so the voltage swing could be a pain to deal with.

The setup your talking of makes sence for a hybrid kart kers system, the thing they got going for them is those charge and discharge rates much better temp range and cycle life but a 22s lipo pack grows by 10 cells and the voltage swing for 22s lipo is 26.4v vs 32s lto 41.6v
Probably better to carry this on in the kart thread you've got going? I'd just suggested it for consideration, shame to clutter this thread up with chatter that might not be related. Sag might actually be your friend with LTO and other battery tech combined. A simple (damn big) resistor and diode between the packs may be all that's needed, LTO is going to get the full hit of regen while the resistor limits the charging current to the main pack and on acceleration sag allows the LTO pack to drop quickly letting the main pack take the load. Probably highly abusive to the LTO cells but what the hell, apparently it doesn't explode into lithium fireballs when abused :twisted:

(edit) Sorry, forgot to mention how that's related to operating voltage ranges. The LTO pack runs at a higher voltage than the main pack, minimum voltages are aligned but the LTO pack has a higher peak voltage. It could run short of regen capacity with a fully charged main pack but as it drops more regen capacity becomes available.
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LSDOG   1 µW

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Re: Electric kart

Post by LSDOG » Jun 11 2021 10:30am

:bigthumb: Hello
I am starting this project too and I want to know the Component that you use in this project

And the performance too
How much time the go kart can run

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Re: Electric kart

Post by LSDOG » Jun 11 2021 3:45pm

try to add EDF to reduce the weight

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jun 13 2021 12:46am

We raced in another Prokart event with Retros again. This time there was one KZ also nr 11 (If you are over 50 years old you can use KZ it seems in Retro class). One Retro was with soviet tires but others were in moder frame and 6 gears motors.
In Qualification I had swapped P2 and P3 and sin and cos wires to get motor to turn in Fwd when in Fwd. (I had motor other way around in old frame). But I did not do aligment because it seems to work and that was wrong, it was misaligned and motor overheated and cot overcurrent error in 3rd lap already :( ANd it took over 70kw from the battery because of that.
I changed phase wires back and also sin and cos signal, because that was the quickest to do.

Here is video from the event Retro Final 2: https://youtu.be/LQF9gsGQzgA?t=35112
My friend made the live videos and he loaned me HDMI transmitter so there is also video live from my kart's GoPro4 :)
And here is my overlay video from the same race: https://youtu.be/nDNooRZDDVw
We had two way communication with the pilot and swiched to 40% torque in 7th lap because motor was already at 128 degrees.

Qualification Power and motor temp chart
Misaligned.jpg
Misaligned.jpg (133.11 KiB) Viewed 199 times
Qualification current chart
Current.jpg
Current.jpg (142.38 KiB) Viewed 199 times
Last edited by nuxland on Jun 13 2021 12:07pm, edited 1 time in total.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

Ianhill   100 MW

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Re: Electric kart

Post by Ianhill » Jun 13 2021 8:10am

Looks like you had a bad day at the office my friend, to be fair the weather looked like it made tyre choice a bit of a gamble moist damp but still dry sections wearimg the tyres quick and that type of start to the day has the potential to end up making the whole thing a fight from the start.

Those temps got a bit out of hand there a custom water jacket would be a good call but then the next weak link will be found its a case of working the heat gremlins out for a repeatable experience but you got a sweet poduim capable machine no doubt little fettling but thats the nature of the sport its never finished in reality.

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stan.distortion   100 W

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Re: Electric kart

Post by stan.distortion » Jun 13 2021 8:19am

Oil immersion is my favourite for the current generation of motors, cooling could be improved in many of them but not by much. We're badly in need of motors designed from the ground up for competition, higher reving and effective cooling as part of the design rather than tacked on as an afterthought.
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Re: Electric kart

Post by Ianhill » Jun 13 2021 9:03am

stan.distortion wrote:
Jun 13 2021 8:19am
Oil immersion is my favourite for the current generation of motors, cooling could be improved in many of them but not by much. We're badly in need of motors designed from the ground up for competition, higher reving and effective cooling as part of the design rather than tacked on as an afterthought.
I wouldn't use oil filled myself its not the best solution by far forced air outperforms oil filled.

Problem with oil is it has no coolant loop so it gets warm and the heat difference between winding and oil becomes less and the hest flow slows to a stop but air keeps pulling in cold outside air so even though its initial warm up is faster the peak temperature doesn't get as high as the oil motor over time as its acting as a blanket.

A simple water jacket on an IPM inrunner could see it perform at the same peak for much longer durations if not indefinite, but i would like to see an advance motor to save weight less steel higher rpm tight airgap better balance but keep in the simular power range as its a struggle to get 50kw discharge and enough capacity on board as is pushing that to say 100kw would need battery innovations more than what teslas battery days has brought us so far.

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stan.distortion   100 W

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Re: Electric kart

Post by stan.distortion » Jun 13 2021 10:34am

Not static, circulating through a radiator. And not necessarily oil, "fluid cooled" would probably have been better. Oil is convenient because it also lubricates but that's not an issue and it's kind of traditional, often used in transformers but someone here suggested glycol would be better. Fluid cooling beats air hands down, fluids downsides are added weight and complexity plus there's going to be some additional drag from an immersed rotor but air would need masses of fin area and flow optimisation to match the cooling capacity of a bog standard motor (edit: other than sealing and plumbing mods ofc) with circulating fluid and a radiator.
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hallkbrdz   100 W

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Re: Electric kart

Post by hallkbrdz » Jun 13 2021 11:11am

stan.distortion wrote:
Jun 13 2021 8:19am
Oil immersion is my favourite for the current generation of motors, cooling could be improved in many of them but not by much. We're badly in need of motors designed from the ground up for competition, higher reving and effective cooling as part of the design rather than tacked on as an afterthought.
THIS!

Tesla S Plaid... now with a 20k RPM motor.

Us... Oh come on already. How about just 10k with water cooling for a reasonable sum?

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