Electric Mini Supermoto Motor/ESC/BMS Help!

General Discussion about large electric scooters and motorcycles and other things with no pedals.
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Scaler98   10 µW

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Electric Mini Supermoto Motor/ESC/BMS Help!

Post by Scaler98 » Jul 11 2019 6:21pm

I just recently finished building an electric scooter and want to move to making an electric supermoto for street use. To make the bike more accesible to others and to make a fun minimoto I am planning on using a cr85 frame with 17" supermoto wheels. My goals for this build are to have 45kw-60KW with a top speed of 100mph. The minimum 45kw is due to the Manual of Motorcyle Sport allowing electric bikes up to 45kw so I am future proofing just in case that rule ever applies in the US. I am planning on using the ME1507 motor from electric motorsports but they dont sell a 120v 550a speed controller. I have been looking for a suitable speed controller but its been proviong dificult to find. As well I am having a hard time finding a powerful enough BMS. I want to run at the max 120V as I believe voltage is tied to RPMs. Can someone help me find a suitable speed controller and BMS?

ME1507 ($1,500): 20kw Cont. 55KW Peak, 48v-120v, 550A peak for 1 minute.
(https://www.electricmotorsport.com/ev-p ... -120v.html) Is there a cheaper/better motor that can provide at least 45kw?

Speed Controller: Require regenative braking

BMS: I would like a single BMS but I was thinking of taking two 60V 600A BMS in series or four 60V 300A BMS in 2S2P.

Battery: I am looking to use lithium pouch battery as they have a high C rating and high capacity
(https://www.alibaba.com/product-detail/ ... 1392hyzbjk)

Grantmac   1 kW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by Grantmac » Jul 11 2019 7:14pm

You need a larger frame. Like a 250/450 4t frame.

flat tire   100 kW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by flat tire » Jul 11 2019 7:18pm

CR85s are for kids. Even girls switch to big bikes at like 13. Get a big bike like that other dude said.

Difficult to find a suitable controller? Sevcon has a bunch.

"lithium pouch" doesn't mean a lot since there are a lot of lithium chemistries available in a pouch. The one you linked is probably lithium cobalt which has the shortest useful life. Like a couple years. It does have the best discharge capability, least sag, and highest nominal voltage. LiMn is a better pouch cell if you want to give up some discharge capacity for a much longer lived battery.

Scaler98   10 µW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by Scaler98 » Jul 11 2019 7:52pm

Thanks for the quick replies. I will look into a bigger frame as the 250/450 frame will be shorter with the 17 inch rims.

Sevcon has controllers but none deliver 120v with 550amps. If you found one could you link it?

Very useful information on the batteries as that explains the price. The battery is what confuses me the most. What would be the best cells to use overall? LiMn? I am willing to sacfrice draw for life as I don't want to replace it in a few years. I wanted to use 18650 cells but they didn't seem to have a high enough discharge, highest I found was 30a.

Any ideas on the bms? What are some good suppliers to check? Can I run multiple BMS in series or parallel to get the power I need?

Grantmac   1 kW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by Grantmac » Jul 11 2019 9:28pm

Is this going to be for road or track use?

flat tire   100 kW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by flat tire » Jul 11 2019 9:59pm

Sevcon gen4 size 6 does 650/550 amps 116v max that's 4.14v / cell @ 28s. That's basically where you're at. What series count were you thinking about to get your 120v?

Scaler98   10 µW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by Scaler98 » Jul 11 2019 10:04pm

I was thinking of using 33s as that would be 122 volts when fully charged but the way you put it I am guessing it wouldn't make that big if a difference. That solves my bms problem.

I am also figuring if I run 28s with 30a 18650 cells I should have more then enough amps for my application. Should I use the 18650 or LiMi pouch cells?

flat tire   100 kW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by flat tire » Jul 11 2019 10:11pm

33s fully charged to 4.2v / cell is 138.6v. I would go with 28S.

18650s are easier to get ahold of domestically, possibly cheaper, lots of available options from well-vetted legitimate manufacturers. They are somewhat of a tedious pain to assemble into a pack, depending on how motivated you are.

Pouch cells you probably are buying from China and unless you have your own QC at the factory, who knows what you will receive.

Pouch has a small density advantage and it could be less tedious to configure a pack since you're using fewer parts. 18650s could possibly be cooled thru the small gaps. Don't worry about the current capacity of the individual 18650s. You can parallel as many of them as you need for increased discharge capacity.

Scaler98   10 µW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by Scaler98 » Jul 12 2019 12:34pm

Thanks for all of your help. This bike would mainly be for road use but I want to use it off road as well.

I will look for some 18650 cells, any good websites to get good deals? I would like to ideally have a range of at least 100 miles but I understand that it can be costly.

Do I need a BMS? I am still looking for a good one.

I was watching some videos on batteries and saw some people water cool their batteries. With my set up should I consider water cooling? It looks like Tesla uses this white water cooling pad between their cells.

flat tire   100 kW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by flat tire » Jul 12 2019 2:12pm

IMRbatteries.com

I look at a BMS as one more point of failure that can ruin your battery or strand you. Most people disagree but the idea is there. If you monitor your batteries closely and manually balance when needed BMS is unnecessary. Depending on how far you discharge, new cells won't get out of balance for quite a while.

A BMS is probably a good idea if you're not the kind to always be tweaking the bike but I don't have one to recommend.

Scaler98   10 µW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by Scaler98 » Jul 12 2019 2:54pm

I will keep looking for a BMS and see what I can do.

For a charger how would I figure out what charger would work, how many amps/volts can I charge at? I would like to make an adapter to use the j1772 standard and the CCS/Direct DC so I can use level 1-3 to charge at any charging station. Do they even make an on board charger that can do that?

flat tire   100 kW

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Re: Electric Mini Supermoto Motor/ESC/BMS Help!

Post by flat tire » Jul 14 2019 7:38pm

Charge amps less than or equal to number of amp hours of your pack. You could charge faster than this but it will damage the pack.

Max charge voltage should be ~4.1v / cell. That is a nice compromise between losing range and stressing the battery with a full charge. Full pack voltage is 4.1v * series count.

For chargers figure out what the nominal voltage is (3.6v * series count) and search for EV chargers that do that voltage. Make sure they are adjustable to your termination voltage of 4.1v. You can also try searching for chargers that do the max voltage since chargers are all listed differently.

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