14S VESC ?

General topics and discussions about the VESC and its development.
joe90
Posts: 49
Joined: 15 Dec 2015, 16:52

14S VESC ?

Postby joe90 » 18 Dec 2015, 16:17

If I want to use it on 14S lipo

I saw that the DVR can have spikes to 70V so it should be able to handle 58V ok
I am using 63v Rated ceramic capacitor
And I plan to use http://www.irf.com/product-info/datashe ... -7ppbf.pdf
that are rated for 75V
I have 39K voltage divider resistor to be able to read 60V
Voltage sag will bring operating to around 54v at high amperage
Anything esle to be able to use 58V fully charged battery?

Traces are ok ? (distance, noise)

Thanks
Michel Cote
Twin v4.7 + SK3 6374 149KV
Bicycle
2500W peak/unit on 12S

benjamin
Site Admin
Posts: 280
Joined: 15 Dec 2015, 08:38
Location: Sweden
Contact:

Re: 14S VESC ?

Postby benjamin » 19 Dec 2015, 12:50

The traces should be OK, but I think the margin on 14s is too low, especially when braking. I don't think you need to change the FETs since they can take some voltage spikes.

joe90
Posts: 49
Joined: 15 Dec 2015, 16:52

Re: 14S VESC ?

Postby joe90 » 19 Dec 2015, 17:44

Ok Thanks
Michel Cote
Twin v4.7 + SK3 6374 149KV
Bicycle
2500W peak/unit on 12S

benjamin
Site Admin
Posts: 280
Joined: 15 Dec 2015, 08:38
Location: Sweden
Contact:

Re: 14S VESC ?

Postby benjamin » 19 Dec 2015, 22:52

please let me know how it goes if you give this a try, it would be interesting to see if it works on 14s. You can set the over voltage protection to 60V or so to switch everything off if the voltage goes that high.

joe90
Posts: 49
Joined: 15 Dec 2015, 16:52

Re: 14S VESC ?

Postby joe90 » 20 Dec 2015, 22:14

OK, worst case scenario is a burned ESC wich is not that big a deal.

I will let you know

Regards
Michel Cote
Twin v4.7 + SK3 6374 149KV
Bicycle
2500W peak/unit on 12S

joe90
Posts: 49
Joined: 15 Dec 2015, 16:52

Re: 14S VESC ?

Postby joe90 » 27 Dec 2015, 21:17

The DRV8302 failed/burned after 5 minutes of playing on 14S
while failling it showed the same erratic behavior it did on 12S so maybe my earlier problem was a not good DRV.
Or maybe a bad ground solder underneat it.
It failed after maybe 30 secondes full throttle.

The buck converter is still working
there were a 2A offset at zero rpm on motor phases.

I will order a new DRV and replace it. But I am not sure if I will continue trying to run 58v
Michel Cote
Twin v4.7 + SK3 6374 149KV
Bicycle
2500W peak/unit on 12S

saul
Posts: 6
Joined: 27 Dec 2015, 10:56

Re: 14S VESC ?

Postby saul » 27 Dec 2015, 23:29

"some men just like to watch the world burn..." :twisted:

mman1506
Posts: 1
Joined: 07 Apr 2016, 00:21
Location: Toronto

Re: 14S VESC ?

Postby mman1506 » 07 Apr 2016, 00:31

Did you ever do any further experimentation on 14s?

joe90
Posts: 49
Joined: 15 Dec 2015, 16:52

Re: 14S VESC ?

Postby joe90 » 07 Apr 2016, 15:31

No, I live with 12S
14S would offer 15% more power, this is a lot but I dont want to replace another DRV.
Michel Cote
Twin v4.7 + SK3 6374 149KV
Bicycle
2500W peak/unit on 12S

rew
Posts: 905
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: 14S VESC ?

Postby rew » 07 Apr 2016, 22:16

One of the things you should realize is that the maximum voltage over the FET during normal operation is not only the battery voltage, but battery voltage + 0.6V. (could even be a bit more).

If you say your battery sags from 58 to 54, it will do the opposite while braking. i.e. when you brake at 58, the voltage will rise to about 62. The fets will have to hanlde almost 63. Many parameters have some margin. but "maximum voltage" for mosfets is not one of them. Apparently some mosfets will breakdown BELOW rated voltage if you cool them down enough! That's how close those specs are!

Anyway, the DRV chip seems also "critical" as it does not tolerate "mistreatment" well.


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