Traction problem with Big Bear

[Marwood Hill]

You are too modest, you did fine so far all by yourself.

Thank you Woosh. And thanks for supplying the new rear wheel with motor. The Big Bear is now even bigger. What a bike it would be with 2 wheel drive option but i’m thinking that another £300+ for battery / controller would be just too much at this time. I may just fit connectors as you suggested. Who knows, a bargain price for all the extra bits to make it 2 wheel drive may come along one day.


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[Woosh]

I think the easiest/cheapest way to make a 2WD is to fit a dual motor controller. KT may supply you one for sensorless motors. You would also need to replace the King Meter JLCD with one of theirs.

http://www.szktdz.com/en/news_show.php?article_id=523

 

[Marwood Hill]

I think the easiest/cheapest way to make a 2WD is to fit a dual motor controller. KT may supply you one for sensorless motors. You would also need to replace the King Meter JLCD with one of theirs.

http://www.szktdz.com/en/news_show.php?article_id=523

This looks good. Scratching head, a lot of wires and housing it could be a problem. Would this just use my existing one battery?
Has anyone ever ridden a dual motor bike? Imagine i’m struggling uphill pulling my trailer using my existing rear wheel drive. If was able to activate the 2 wheel drive would this help on the hills?


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[Deleted member 4366]

I've built several bikes with two motors and one with three. Traction is their main advantage, but only when you use low-power motors. if the back one gives too much torque, it unloads the front one and makes it spin or skip, like you had before.

Like I already said, your battery isn't strong enough to work two motors. you need one that can supply 40 amps or more continuous.

 

[Woosh]

Like I already said, your battery isn't strong enough to work two motors. you need one that can supply 40 amps or more continuous.

that KT09S2 outputs 2 x 17A, I specified the Big Bear battery with a 30A BMS.

This looks good. Scratching head, a lot of wires and housing it could be a problem. Would this just use my existing one battery?
Has anyone ever ridden a dual motor bike? Imagine i’m struggling uphill pulling my trailer using my existing rear wheel drive. If was able to activate the 2 wheel drive would this help on the hills?


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Nobody I know besides d8veh has built a dual drive. However, the wiring of the KT09S2 is similar to the Lishui LS947 on the Big Bear. Yes, you should be able to run the bike on the same battery if you so wish, albeit 2 x 17A = 34A, the BMS may trip.

 

[Marwood Hill]

I will contact and get a price for the KT09S2.


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[Marwood Hill]

Which option would i need?


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[Deleted member 4366]

Square wave for sensorless.

It's not just that your BMS will trip. You'll get massive sag and you'll wear out the battery quickly.

 

[Marwood Hill]

I don’t think i will ever get a reply back re. KT09S2. They don’t seem to have any stockists. So, i’m thinking this bottle battery with integrated controller and with LCD just about covers everything i need. Apart from a throttle, no problem. Costs £290 inc shipping.

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[Marwood Hill]

Even cheaper. £219 inc shipping. Will this do me ok?

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[anotherkiwi]

China cells vs brand name cells. Some of those cheap bottle batteries are only capable of 10 Amp constant output.

 

[Marwood Hill]

China cells vs brand name cells. Some of those cheap bottle batteries are only capable of 10 Amp constant output.

It’s nearly £100 cheaper than the Panasonic. As it’s only for occasional use, to bring in the front wheel drive on the steepest hills i thought it would do. Now i’m wondering?


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[Deleted member 4366]

Don't forget that you'll have to pay about £25 duty when it arrives.

I think it would be better to buy the controller and battery from Ebay.

https://www.ebay.co.uk/itm/36V-48V-350W-Electric-Bicycle-Brushless-Motor-Controller-For-E-bike-Scooter/382230093235?epid=847872114&hash=item58feb05db3:g:EQAAAOSwDQJZrQLW

https://www.ebay.co.uk/itm/DuraB-36V-10Ah-Lithium-Bottle-Battery-for-Electric-Bicycle-Li-ion-Power-E-bike/162616636290?epid=1562843050&hash=item25dcb4f382:g:ka4AAOSwBEpZnq5M

 

[Marwood Hill]

Don't forget that you'll have to pay about £25 duty when it arrives.

I think it would be better to buy the controller and battery from Ebay.

https://www.ebay.co.uk/itm/36V-48V-350W-Electric-Bicycle-Brushless-Motor-Controller-For-E-bike-Scooter/382230093235?epid=847872114&hash=item58feb05db3:g:EQAAAOSwDQJZrQLW

https://www.ebay.co.uk/itm/DuraB-36V-10Ah-Lithium-Bottle-Battery-for-Electric-Bicycle-Li-ion-Power-E-bike/162616636290?epid=1562843050&hash=item25dcb4f382:g:ka4AAOSwBEpZnq5M

Thanks for this. I didn’t realise there was duty to pay. It’s all mounting up. I would much rather buy from Ebay. That is what i shall do and those prices are good on Ebay.


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[Martin56]

I admire your achievements so far but I think you have taken it as far as is practical and it might be best to sell your front wheel and put in a regular wheel. A motor car with effective 4wd would have some kind of differential or traction control which you will always be lacking. For steep hills a chain drive bike with high gearing is probably best. Good luck!

 

[Nealh]

I was going to suggest the 10.4a 4P with Samsung 26H(2600MAH) cells from Elifeshop for £185, however the one d8veh linked to is 5P 10a (2000mah) cells. Though maybe crappier China cell they do provide a slightly better discharge rate.

 

[John_S]

Two-wheel drive electric bikes are not road-legal. Its not worth the risk in my opinion.

I would recommend to you the new 48v rear SWX02 kit that Woosh do. It is a fully legal setup that has masses of torque for getting you up the hills. It has even greater torque than that of the 36v BPM setup on the Big Bear.

 

[Marwood Hill]

Well, it’s been a nice mild sunny day and i’ve taken Big Bear rear wheel drive for a good hilly ride. It’s fantastic, there was no wheel-spin. Handling and control is so much better. A much more relaxing ride and so quiet with the motor behind. Without that dreadful front wheel drive wheel-spin it pulls up hills even better. As you all said i certainly don’t need 2 wheel drive. And it’s all road legal.

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[Deleted member 4366]

Now you need a normal wheel for the front. Luckily, it should fit without modification. You can find them on Ebay, but make sure that you get one with the disc brake fixing.

 

[Marwood Hill]

Now you need a normal wheel for the front..

The weight will stop me pulling wheelies [emoji468][emoji41][emoji106]


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