Lead acid to lithium conversion

Technical discussion on converting internal combustion to electric
Ribfeast
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Re: Lead acid to lithium conversion

Post by Ribfeast » Wed, 06 Mar 2019, 07:56

Forklift is probably better rated lol

Toro Workman MDE is rated for 363kg towing, about 10% of what you want. On flat ground I'm sure it would do it, but doubt it would be good for it.

http://www.toro.com.au/media/4094/200-4 ... X-MD-D.pdf

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Re: Lead acid to lithium conversion

Post by T1 Terry » Wed, 06 Mar 2019, 11:24

Thanks for that, back to the big wheeled forklift. It seems the battery forklifts are all the small solid tyre type and I doubt they would be any good on the gravel driveway. I'll go back to my original search.

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Re: Lead acid to lithium conversion

Post by Ribfeast » Thu, 07 Mar 2019, 07:37

If you lived a bit closer you'd be welcome to try, I should try it on our 1500kg horse float sometime actually.

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Re: Lead acid to lithium conversion

Post by Dan007a » Thu, 14 Mar 2019, 18:07


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Re: Lead acid to lithium conversion

Post by Ribfeast » Fri, 15 Mar 2019, 08:40

Aaaargh! That would have been perfect! And saved me a few grand! :(

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Re: Lead acid to lithium conversion

Post by Ribfeast » Fri, 15 Mar 2019, 12:05

I've picked up a 2000W pure sine 48V inverter (4000W peak), it appears to run my compressor, power tools, heat gun and other items easily, problem is it is so big I can't mount it anywhere on the kart! Will cut a suitable place for it over the weekend.

But it could run the 650W server rack, or a fridge for many hours if there is a power outage, as it has a 5kwh pack. So it's basically a portable power station and saves using the smelly generator.

https://imgur.com/a/jpPw2rc

Also mounted some 72W LED spotlights on top for when I need to cut firewood etc at night.

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Re: Lead acid to lithium conversion

Post by Ribfeast » Wed, 03 Apr 2019, 11:19

Finally mounted up the inverter, here's a quick video of the BMS and inverter doing their thing, with the air compressor running off it.

https://imgur.com/a/Kux2ZZB

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Re: Lead acid to lithium conversion

Post by Ribfeast » Wed, 01 May 2019, 06:26

My girlfriend parked up the Toro Workman MDE 48V kart yesterday and then went to use it later in the afternoon, it makes all the right noises (reverse beep etc) but the main contactor doesn't click on, and getting 4 flashes on the dash.
Tried bridging the 2 large terminals on the contactor to allow current flow but this didn't make a difference.
Applied 48V to the contactor and it clicked over fine and reads 0 ohms when energized, so it appears OK. So it seems the Sevcon isn't outputting a contactor charge to energize it. It's now just giving 3 flashes which indicates the controller is likely faulty :(

So it appears that I have a faulty Sevcon Millipak controller. Does anyone know where I can get one of these affordably? Most seem to be around $700-1000US :(
It's a model 633T46301.
Are some of the other visually similar models interchangeable? eg: https://www.cartpartsrus.com/SevCon/sevcon.htm
I think these work by switching things to ground, vs switching to positive, so not sure if I can change to another brand of controller.

If I was to buy a new Sevcon, would it need to be programmed also? Or just plug and pray?
Does anyone maybe have a good one they are selling?

I've pulled it apart and it's full of that black potting epoxy, so I'm going to have a hard time getting to the innards to try and repair it otherwise. Has anyone repaired one successfully? Any tips on getting the epoxy out safely?

Thanks for any help :)

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Re: Lead acid to lithium conversion

Post by coulomb » Wed, 01 May 2019, 08:18

Ribfeast wrote:
Wed, 01 May 2019, 06:26
Any tips on getting the epoxy out safely?
Some of them (by no means all), you have to bake them at a certain temperature and it runs off. Might be worth Googling. I believe that these are the hard ones, that feel like epoxy glue.

If it's soft stuff that you can push around a bit with your finger, you can dig it out with a screwdriver initially (when far away from components) then a wooden chopstick. I use one with a flat at one end and a point at the other. Sharpen the pointy end in a pencil sharpener, and the flat end with a file. If the potting is crumbly, then it's the easiest to get out.

Some types, typically the yellow type that reminds me of liquid nails, respond to a hot air gun at about 150-200°C. Give the components time to cool between blasts if using that. The heat softens it, but you still need the chopstick.
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Re: Lead acid to lithium conversion

Post by Ribfeast » Wed, 01 May 2019, 11:16

Cheers I'll give it a go ::) It's black and quite hard. When I hit it with the heat gun it gets a bit crumbly.

Going to check the contactor coil resistance tonight, and the condition of the motor brushes before digging into the controller further.

Would be nice if there was a way to bench test the unit.

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Re: Lead acid to lithium conversion

Post by Ribfeast » Wed, 01 May 2019, 18:26

Just rechecked, only getting 1 volt between Pin 8 (contactor) on the Controller, and the 12V switched pole. The controller is supposed to drop pin 8 to ground when ready, and it doesn't seem to be doing this, it just floats up to positive voltage. Tried fooling it with a resistor but no luck.

Going to have to try and get the potting out and disassemble :(
Motor brushes look good and contactor reads 123 ohms on the coil, within spec.

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Re: Lead acid to lithium conversion

Post by Ribfeast » Fri, 10 May 2019, 10:52

New controller has arrived at work, can't wait to get home and fit it! It's a generic one with the same model number, hopefully there is no Toro-specific programming in the old one.

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Re: Lead acid to lithium conversion

Post by Richo » Fri, 10 May 2019, 12:29

Did you try bypassing the controller and manually turn on the contactor?
So the short answer is NO but the long answer is YES.
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Re: Lead acid to lithium conversion

Post by Ribfeast » Mon, 13 May 2019, 07:42

Yes contactor clicks on, and resistance between the outputs drops to zero.
Was interstate for the weekend so will fit it one night this week.

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Re: Lead acid to lithium conversion

Post by Ribfeast » Wed, 15 May 2019, 06:31

Installed the controller in the kart last night finally, great to have it up and running again! Had to adjust the accelerator stop button to eliminate a 2-flashes issue.
For some reason this new controller appears to draw a bit more current than the old one, so maybe it has some different motor parameters in it. It also seems to have less regen, likes to coast a bit more gently to a stop, but maybe it will self adjust over time.

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Re: Lead acid to lithium conversion

Post by Ribfeast » Thu, 16 May 2019, 06:41

The controller seems to have recalibrated itself and now drives the same as the old one. Must be some pretty clever electrickery going on inside.

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