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Traction problem with Big Bear

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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.

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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. 77e9d081401286807d902977a3b07c72.jpg

 

 

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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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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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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!
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.

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.

Edited by John_S

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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. 59033b6d112a0a8c1cc65ca63a646065.jpg

 

 

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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.
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Now you need a normal wheel for the front..

 

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

 

 

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

 

 

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I was thinking the same thing. I had a 500w BPM running at 30 amps from a rack-mounted 6kg 20Ah battery. It would nearly always wheelie when I did a quick start. One time I did a real Hi Ho Silver coming out of Tescos. I think yours would probably be OK though, as you only have 2/3 the torque and a lighter battery.

I think yours would probably be OK though, as you only have 2/3 the torque and a lighter battery.

MH runs the SWX02 from the same 20A controller, I expect he gets the same torque at over 8mph, below that, he may lose 10%-15% but gains in better traction.

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I was thinking the same thing. I had a 500w BPM running at 30 amps from a rack-mounted 6kg 20Ah battery. It would nearly always wheelie when I did a quick start. One time I did a real Hi Ho Silver coming out of Tescos.

Ha ha i can imagine that [emoji15][emoji468]. 500W eh!!![emoji15]

 

 

 

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I’ve been out testing again. Acceleration is so much better with the RWD. Not a hint of wheel-spin whatever the gradient and surface. I have tried our killer hill. The BPM FWD on a dry surface is more powerful. I would have liked to have brought it into use with a second throttle on that particular hill. But no, i cannot do that, it wouldn’t be that silly road legal thing!

 

 

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I’ve been out testing again. Acceleration is so much better with the RWD. Not a hint of wheel-spin whatever the gradient and surface. I have tried our killer hill. The BPM FWD on a dry surface is more powerful. I would have liked to have brought it into use with a second throttle on that particular hill. But no, i cannot do that, it wouldn’t be that silly road legal thing!

 

We'll hide our eyes and look the other way... :rolleyes: About the fifth time I was passed (in a car) by a moped with no muffler doing 70 km/h (legal limit 45 km/h) I stopped worrying about "road legal".

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Will the rear wheel with freewheel and brake rotor that i’ve taken off the Big Bear fit a normal bike? I’m thinking of putting it on our local sales page. How much is it worth?

 

 

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I’m thinking of putting it on our local sales page. How much is it worth?

A new BPM motor costs £175, second hand may be £75-£100.

it's difficult to find a buyer for just the wheel. If you have a donnor bike, it may be worth converting it using the BPM motor wheel and buy a kit like you were planning to do.

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A new BPM motor costs £175, second hand may be £75-£100.

it's difficult to find a buyer for just the wheel. If you have a donnor bike, it may be worth converting it using the BPM motor wheel and buy a kit like you were planning to do.

 

I mean just the back wheel as it is. Will it fit a non electric bike?12f3b971a907a3b751d4b9942aa5167b.jpg

 

 

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sorry! yes, it will, it's a standard part.

26" rim.

 

Thanks. Is £20 a fair price to put it at or less?

 

 

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