Search found 253 matches

by nuxland
Jul 21 2021 2:24pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

Have now tried in two different tracks and this water mist cooling is helping.
In our latest test on most demanding track in Estonia we managed to drive 15 laps and keep motor temperature under 110 degrees.

by nuxland
Jul 15 2021 3:06am
Forum: Motor Technology
Topic: Sevcon motor cuback
Replies: 2
Views: 256

Re: Sevcon motor cuback

Tested lipo battery addon and motor cooling with water mist yesterday and it seems to work, outside was 30 degrees. This was 10 laps. LipoAddonAndMist.jpg But then decided to go one more time with my bigger lifepo4 battery and did not used mist at all. And managed to get motor temperature to 140 deg...
by nuxland
Jul 12 2021 12:08pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

Actually the phase change (evaporation of the water) has much more cooling effect. Maybe an idea to use dryice, or CO2 canisters. Dryice is one option, but I have not figured out how to make a wire mesh and then put it inside to cooling chamber before race. CO2 I actually bought 425g canister and o...
by nuxland
Jul 12 2021 10:43am
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 42
Views: 3603

Re: 30Ah 28s LiPo from 7s bricks

Installed 4pcs of extra 7s2p 21700-s and will test on wednesday at the track.
Will charge these to 4,2v each separately and also lipo back to 4,2v.
So connecting these xt90 connections is safe :)
by nuxland
Jul 05 2021 1:44pm
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 42
Views: 3603

Re: 30Ah 28s LiPo from 7s bricks

Zipped and weighted how much extra weight I have to carry.
7s2p_Weight.jpg
7s2p_Weight.jpg (194.05 KiB) Viewed 42 times
Also made myself 4 pcs of XT90 male<->male extensions to connect these to my lipo pack.
7s2p_Charging.jpg
7s2p_Charging.jpg (271.68 KiB) Viewed 42 times
by nuxland
Jul 02 2021 8:36am
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 42
Views: 3603

Re: 30Ah 28s LiPo from 7s bricks

1st 7s2p brick is done (heatwraping remaining). 3 more to go.
Regular nikkel and 0,2mm copper on top. Should be enough for 70A cells are capable of.
by nuxland
Jun 30 2021 1:42am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

Installed water mist cooling using clutch leaver :) Now need to find time to go to racetrack and to test how it works.
by nuxland
Jun 28 2021 12:04pm
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 42
Views: 3603

Re: 30Ah 28s LiPo from 7s bricks

January 2019 I tested one of my 7s 5Ah brick with 70A As you can see that after 3 minutes my duo 4010 stopped discharge because of cell voltage went under 3,5v under load. I must admit that it was not charged to 4,2v but to 4,1v so there can be a little bit more inside :) And as I said earlier I go...
by nuxland
Jun 27 2021 1:59pm
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 42
Views: 3603

Re: 30Ah 28s LiPo from 7s bricks

Concluded that 7pcs in paraleel (35Ah) is not enough for 14 laps, so will add one more in parallel. But there is a problem, hobbyking does not have my 7s 5Ah Turningy heavy or in warehouse and ETA is september :( So instead bought 56 pcs of 4Ah samsung 21700 and will build 4 pcs of 7s2p units instea...
by nuxland
Jun 22 2021 12:36pm
Forum: Motor Technology
Topic: ME1616 motor with sevcon gen4 size 6 80V low power??
Replies: 24
Views: 1288

Re: ME1616 motor with sevcon gen4 size 6 80V low power??

Zero motor is also only peaks around 50kw. If you want to race 10 or more laps, you have to dial it down to 25kw max with your closed zero motor :(
by nuxland
Jun 22 2021 12:33pm
Forum: Motor Technology
Topic: Sevcon motor cuback
Replies: 2
Views: 256

Re: Sevcon motor cuback

Yeah, it seems there is some options somewhere that is ignoring my "User definable motor cutback map" :( Controller should have limiting current from 113 degrees but it gave 100% until 128 degrees when it got current fault (because motor was hot and it was misaligned in that qualification ...
by nuxland
Jun 15 2021 1:38pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

For serious heat dissipation (eg, on heavy truck brake rotors).. a water spray direct onto the heat sink area is very effective. Motor outside is not that warm because i push air through. So water sprayng these will not give me that effect. But I got another idea, to use sodastream or similar 425g ...
by nuxland
Jun 14 2021 10:10am
Forum: Motor Technology
Topic: Sevcon motor cuback
Replies: 2
Views: 256

Sevcon motor cuback

Are someone actually used motorcutback with sevcon and was it working and cutting power/torque? I raced in the weekend and for me it seems that it is not working and I can not see any real cutback. As you can see that at 122 degrees it should give me only 0,4 or 40% of torque. And then linear got to...
by nuxland
Jun 13 2021 1:46pm
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 42
Views: 3603

Re: 30Ah 28s LiPo from 7s bricks

Even my lipos that should be very high C rated warmed up a lot after 14 laps of racing. I have 7 of 5Ah packs in parallel so 35Ah in total and used ~32Ah from them during the race. Temp sensors are between bricks so measuring outside temperature of 5Ah turningy heavy 7s brick. 2021_Temps_14Laps.jpg ...
by nuxland
Jun 13 2021 12:31pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

Building some oil/liquid a no. I just can justify it to myself :) There is a lot of work. But there is one thought that I can cool down pushed in air. I could make some 1 liter pocket out of aluminium outside of the motor, where this thin 1mm aluminium is. And then just put dry ice inside at the sta...
by nuxland
Jun 13 2021 12:46am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

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 co...
by nuxland
May 20 2021 11:08am
Forum: Large EV General Discussion
Topic: EKartGo Project
Replies: 76
Views: 6740

Re: EKartGo Project

Latvians have ready made 7kw plug and play for kid's kart. https://blueshockrace.com/electric-kart-power-units/#7kw http://blueshockrace.com/wp-content/uploads/2020/11/PowerUnit_BSR2_0_7kw.pdf But why ME1717 and not QSMOTOR QS138 4000W 90H or similar. And why kelly and not Nucular 12F. For battery w...
by nuxland
May 19 2021 9:10am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

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 ...
by nuxland
May 18 2021 10:37am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

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 ...
by nuxland
May 18 2021 1:35am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

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 minut...
by nuxland
May 17 2021 1:17pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

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.
by nuxland
May 17 2021 4:57am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

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.
by nuxland
May 17 2021 3:29am
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

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 :) ...
by nuxland
May 13 2021 12:40pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

Thanks for that info Luigi, will try that after the race :) Finished rendering video also yesterday, but forgot to link it here. You can clearly see that in the middle of the last lap 10th cell voltage dropped below 3v. Also we drove the best time ever and around 1s faster than with old frame 43,245...
by nuxland
May 12 2021 1:24pm
Forum: Large EV General Discussion
Topic: Electric kart
Replies: 242
Views: 49358

Re: Electric kart

Pushed my lipo battery to the limit to test can I race 14 laps with it. We raced 4 laps and then changed front wheel width to get better grip turning on to corners. And then raced 11 laps until I saw that minimum cell voltage wen under 3v and then we stopped. So conclusion is that I have to top the ...