Open Source Electric Supercharger

[KroozX]

Are you giong to use this 3D printed motor mounting plate or will it also be machined?

[al3k]

Originally Posted by KroozX

Are you giong to use this 3D printed motor mounting plate or will it also be machined?

I found this part on ebay which is for glass tables, its the exact same diemensions as my drawing ( casue I made the drawing using that piece )
I will only need to drill a few holes to it and its done.

link: https://www.ebay.com/itm/80mm-Diamet...72.m2749.l2649

[al3k]

Ive been thinking about a battery and charging solutions, what if by for example using lipo pack and have the main + - wires to the motor controller (ESC), then use a 12v to 3.7v step down from the main car (start)battery and wire the 3.7v output from the step down converter to the balance plug positive wires, then all cells would only ever get 3.7v and use a current sensor or relay controlled by a microcontroller to disable charging when the electric supercharger is running on higher loads than the step down converter is able to supply (amps). Wouldnt that be much safer? Could also work with ultracaps or other cells as long as the step down converter voltage match the nominell cell voltage rating.

[al3k]

I gues if the balance charging and output is connected at the same time it would short the battery so there needs to be a relay or something to disconnect so its only doing charging or only power the ESC, cant do both

[KroozX]

Originally Posted by al3k

use a 12v to 3.7v step down from the main car (start)battery and wire the 3.7v output from the step down converter to the balance plug positive wires

It could be possible with some proper converters, one for each cell.

[al3k]

Originally Posted by KroozX

It could be possible with some proper converters, one for each cell.

I found that 3200kv motor you mentioned and since it runs on 24v and 75k rpm it is probably what I will go for.
Having a 24v version does also make it easier to make a safer battery system, you could have 2x 12v in series and have a 12v to 24v step up converter 5-10A with a relay or one with a auto discharge protection circut so it shuts off the charger when supercharger is runnig.
The TP 4070-CM 3200KV can handle up to 382Amps@24v peak (~9kw) and continious 208Amps @24v (5kw) which is really good!
If there is some compact 12v batteries that can handle ~200-250A for around 10sec it all good.
I do wanna avoid lipo pack unless there is some way to safely charge them while having it connected to the ESC, it would need to have a 12v input to the charger and a auto feature to disable charging while supercharger runs, I cant find anything of the shelf stuff

[al3k]

Originally Posted by KroozX

It could be possible with some proper converters, one for each cell.

I was looking more into this and the balance plug pins is not 3.7v each pr pin, only the first pin is 3.7v then 7.4v, 11.1v....etc
But if there is a balance charger that can run without manual inputs then use a step up from the start battey and slow charge it, and disconnecot it when the ESC runs with a arduino and a relay.
Then use a small 6cell lipo 5000mah(or bigger) to get 4.8kw to motor at 24v in upto 90seconds without charge.

[KroozX]

Originally Posted by al3k

3200kv motor

Imo it's a good choice.

Originally Posted by al3k

Then use a small 6cell lipo

I don't think there is a better way, than using a lipo battery for such hi amp purpose.

[al3k]

I got tip about a system that might be able to charge and maintain a lipo pack while using a load and it supports up to 300A and can be run from DC.
Its called Chargery BMS16 http://chargery.com/doc/Chargery_BMS...ation_V1.1.pdf

[al3k]

So for the battery solution Im now thinking about keeping the 12v car/crank battery, add a 6s lipo pack as a separate battery system.
Bigger capacity is better, but more expensive, Im thinking 5000-15000mah.(needs to have a C rate to support min. 250A, but closer to 350A makes it possible to run the elturbo to the limit with my motor).
Add a DC to DC converter with constant current to get from 12-14v car battery to 80-85% of the full charge lipo pack voltage, I plan to have a arduino to get the throttle input to controll the e-turbo so its only running when 90-100% torque is requested (WOT), this arduino while also trigger a solid state relay to engage the charge voltage from the DC to DC converter to the lipo pack and disconnect when the e-turbo needs to run.
This will be a constant current, constant voltage charging with priority for safty as it would only charge with 80-85% of the max total cell voltage and x/10A where x is the capacity of the lipo pack.
So since its not balance charging Im thinking of just extendig the balance plug connector into the cockpit with a cell monitor that displays each cell on a small lcd monitor OR make a arduino which reads each cell voltage with resistor dividers using analog read 0-5 which is just enough for 6 cells and it will send a message to a display showing each cell voltage and auto disable charging if a threshold of unbalance is reached. and if its gets unbalance after a X cycles I will just take out the lipo pack and balance charge it at home with a proper charger.
In my car the battery is placed close to the windshield and the compartment under the hood is separated from the engine area which makes controlling temps and having wires into the cockpit a lot easier than on some other cars.
Notes to above, having 100% charge is not a priority which would require each cell to reach 4.2v, having max around 80% will increase lifetime and safty margins of the lipopack so thats the priorty. Wire size to the e-turbo controller (ESC) needs to be correct diameter/AWG in relation to distance(wire length) and max amps of the system.
What do you guys thing about this, still unsafe or doable? I will also have the battery in a fireproof case or bag just incase and a temperature sensor to it which the arduino will monitor.

[Matt@Cosworth]

I'd agree that you're right to consider the safety aspect with a Lipo pack
a mate of mine works as the battery man for Mercedes F1 and says once a battery pack overheats and catches fire then there's not much you can do
they have extinguishers but they're just there to buy time

the best defence for a lithium fire is to run away.....
so yes a charging system that monitors cell temperature is very wise

[KroozX]

Last weeks I was trying to make the system simpler, powering the ESC from cars voltage power supply. What I achieved is low degree boost, but much simpler build even with 3d printed parts:

[ame]https://www.youtube.com/watch?v=Hqs3XOCH8XE[/ame]

[jflogerzi]

Man this tech would be really cool with the new generation of cars that use 48volt systems to power the car now... Looks your making 2 psi of boost?

[KroozX]

Correct. It makes 2,1 PSI boost on 14V supply.



Higher voltage would be profitable in some cases, but what matters is power. If cars board supply can deliver enough power, even 14V would be enough. In this case the average consumption is about 600-700W.