[dk6780]

You want to mount the batteries as close as possible to the supercharger to minimise the weight of the wires connecting them and the losses in them.
Do you have an idea of what the duty cycle of the supercharger is going to be? The hybrid battery from something like a Fiesta would seem appropriate based on a few guesses.


HYBRID BATTERY FORD FIESTA 2020 2021 48V 8AH LX7A-10B759-AD 2495700 BOSCH | eBay

Also, how do you intend charging the battery?

 

[dk6780]

duty cycle ive no idea what that is. I know what it means though I have that on my welders. How would i find out? Idont think its going to be easy to get data sheets

Given that this is your install you can make the numbers up. By duty cycle I mean how often is it going to operate and for how long each time. For example if it is just to get you off the line from idle until the engine reaches max boost you are probably looking at around 10 seconds at most. In that case you are unlikely to need to use it again for at least another 30 seconds and for say a maximum of 10 times in a row. Anything else would be after a suitable cool down/recharge period. If those figures are correct you are using 7kW x 10 seconds x 10 times = 700,000 Joules which is about 200Wh or 0.2kWh. So that's in the capacity of the battery suggested earlier.
What's not possible is to run the electric turbo for more than twice that - in other words for more than 200 seconds continuously. But why would you? The standard turbo is for that, not an electric powered one. Even if you are into running 0-100 times it will be over in less than 20 seconds in a standard car, and it takes time to slow down to do it again.
I'd be interested to know how you intend to control it. Have you an ECU for it or are you using simple pressure switches?

 

[dk6780]

Don't listen to the nay-sayers on this. I did something similar using a built up electric powered Garrett turbo for Escort Cosworths. It worked in a crude way but was much heavier and complex than anti-lag that was developed at the same time and didn't require homologation.

 

[dk6780]

So ive been doing a bit of research ive found some places do 1000w 48v alternators is that enough? i also found out that many cars with 48v systems use a dc to dc converter for charging but i didnt find any info on the alternators themselves but i expect they are probably 48v alternators which are used to charge both the 48v battery and the 12v.

also i foumnd an original audi battery and here isa picture from the sticker so we can see what its specification is. battery doesnt look tall but i would like to know how long and wide it is

At £1,500 and only 20% more capacity than the Fiesta one I'd suggest it's not worth pursuing.
The Audi charging system remains 12v with a DC : DC step up to charge the electric turbo battery. Note Audi also do "mild" hybrids that use a 48v motor/generator but those are only "greenwashing" in a vehicle that weight.

 

[dk6780]

hmm interesting well my alternator is 150a, even the bigger engined ones use the same because its based on charging the size of battery.

So 150A @ 14v is 2.1kW max - we are back to the duty cycle question again - how long is acceptable between electric supercharger uses to recharge the battery? Assuming that you use all 0.8kWh it'll take 24 minutes to recharge with no losses, other loads etc. Is that good enough?

 

[dk6780]

Enjoy your ICE whilst you still can, they are very much time limited. If you want instant low down torque perhaps the Nissan e-power concept might interest you?
No, I thought not.

 

[dk6780]

It'll also be interesting to see if sales do actually stop, or if there will be some derogation due to a complete lack of available cars and viable charging infrastructure. I suspect the latter, TBH.

The issue is that EVs aren't the answer to the true problem, but instead are a relatively pain free short term fix. They allow us to continue with excessive consumption for a while longer. The average Millennial and Generation X, as well as Boomers, is unwilling to give up consumption and prefers the technology solutions where nobody pays or better they are fiscally incentivised. BIK, road fund, low VAT, no road fuel tax, and purchase grants are all part of easing their transition. But at some point we all have to pay.
But the can has been kicked down the road. I think that climate issues will be too well established to go back to producing vehicles that consume fossil fuels except for edge cases such as the military. The question of synthetic fuels has to be addressed.

 

[dk6780]

It is already commercially available. I mean from renewable sources.

I've been using Methanol like that in ICE for years. But not as an affordable road fuel. My concern is that Big Oil will choose to supply them from non-renewable resources "as an interim", much like "blue" hydrogen.

 

[dk6780]

other thing i found out is its controlled by the canbus which is fantastic news it gives more flexibility in setting it up for the car because the car has a canbus system and it can be configured.

Is there sufficient capacity in the ECU to do this? I'd suspect that the control required is quite complex, not just an "on off" type.