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Re: Weber and Coulomb's MX-5

Posted: Wed, 10 Jan 2018, 16:25
by jonescg
weber wrote:
Mon, 29 Feb 2016, 03:54
And with the auxiliary battery fixed, it became worthwhile to fix the power steering, again with help from Bladecar.
For some reason I found myself looking at radio controlled hobby motors and found some in-runner motors that spin up to 5000 rpm and are good for about 2 kW. I thought to myself maybe these could be good for driving power steering pumps in conversions where replacing the power steering system with a complete electric system would be too difficult.

Do you think it's possible to use one of these motors:
RC_Motor_inrunner.jpg (49.51 KiB) Viewed 799 times
And one of these speed controllers:
RC_Motor_ESC.jpg (31.78 KiB) Viewed 799 times
And control the speed of the motor (and therefore power consumption) by making it inversely proportional to the speed of the vehicle?

I have no idea how much power a power steering unit needs, but surely a 1 kW brushless motor is up to the task?

Re: Weber and Coulomb's MX-5

Posted: Wed, 10 Jan 2018, 16:54
by weber
Not really sure Chris. I suspect it might be a bit too high speed and low torque. But mine is current limited to 30 A at 12 V (360 W) so maybe.

Re: Weber and Coulomb's MX-5

Posted: Mon, 02 Jul 2018, 16:47
by coulomb
It's project day at Weber's house, and he's finding lower range than usual (80 km compared with 130 km when new). One of the cells has been playing up, and was replaced a few weeks ago. He replaced it with one that seemed to have the lowest internal resistance of his spares. But that one seems to have low capacity. So today's project was to find the best of the spare 8 cells, 4 of which are being used as his auxiliary battery.

We spent half the day getting the 8 cells top balanced. Well, 7 of them; one of them ruled itself out of contention by its behaviour when charged at a paltry 6 A. While that was happening, Weber constructed the load resistor: about 2.5 metres of 0.7 mm dia steel wire, aiming for about 1 Ω. This was wound around a piece of wood (ceramic would have been better, but wasn't to hand). The ends were soldered to some copper wire and battery clips from some other project. The resistor and board went into a 10 litre bucket of water. The wood tended to float (who'd have thought), so a dead drill battery was used as a weight to hold it down.

This is near the end of the test:

Making bubbles sm4.jpg
Making bubbles sm4.jpg (129.81 KiB) Viewed 462 times
You can see hydrogen and oxygen bubbles streaming from it, due to electrolysis of the water. The blue thing is an ice-brick.

After about 70 minutes, the first cell went low voltage, with its Cell Monitoring Unit beeping. The others had a good enough spread of voltage that we could pick the winner, and in fact rank the rest of the cells in case more are needed later.

Re: Weber and Coulomb's MX-5

Posted: Tue, 03 Jul 2018, 16:31
by jonescg
For only the strong survive.