More powerful battery for Hopper Shopper

[paulc1976]

Hi Everyone,

I'm new to the forum. I've just myself a cheap Tesco Hopper shopper as a runabout. I really like it but I'd like a little more torque and performance on hills. I read on this link (for Viking eco stepper, same bike)

http://www.pedelecs.co.uk/forum/threads/hi-and-advice-on-spare-battery-purchase.14247/

that swapping the battery over from the original 24v to a 36v would provide more power/torque and a little more range (I'm not too bothered about increasing the limited 15mph top speed). I just wanted to know if there would be a noticeable difference and whether any modifications would be required to the controller part or any other part of the bike.

many thanks,

Paul

 

[Deleted member 4366]

Most 24v controllers work with a 36v battery. In fact I still haven't heard of one that didn't. Controllers are not too expensive anyway if yours does pop. The only down-side is that you lose the controller's control, so you have to rely on the LVC in the battery, which are not so reliable. Your battery level indicators will also not help because they'll all be on all the time due to the higher voltage.

You should be able to do about 30 miles with a 36v battery, so if you don't go more than 20 miles, it won't be a problem. You'll have the probably working LVC in your battery anyway. If you get a 36v controller too. none of this will be a problem. You can get the battery from BMSBattery, and then the KU65 controller is only £14 extra.

 

[Alan Quay]

The increase in voltage probably won't give you a great deal more torque. Assuming you can override any speed limit the controller imposes (if it does that) then you should get a speed increase, somewhere about 5 mph extra (probably, ish).

To get more torque you need to increase the current. You can do this by modding the controller, or installing a different one.

You need to be carefull how far you push it though, otherwise you could damage your motor/cables/controller/health/marriage.

 

[paulc1976]

Thanks for the replies guys. If it won't make much difference then I'll leave it. I wouldn't know where to start with modding the controller and I don't want to break it!

 

[Deleted member 4366]

It'll make a massive difference. 50% more speed and a lot more torque.

If you read this thread, it'll give some idea of what it does:

http://www.pedelecs.co.uk/forum/threads/cyclamatic-the-beastamatic-is-dead-long-live-the-beastamatic.9857/

Photos here:
http://s451.photobucket.com/user/d8veh/library/Beastamatic?sort=3&page=1

 

[Alan Quay]

Sorry Dave, our posts crossed.

I agree, it's worth doing, and if your putting in a new controller with a higher current then it will be greatly improved.

 

[paulc1976]

Thanks for the update guys, I read through that thread, really interesting and great to see a cheap bike being transformed into a monster! Ok say I took the plunge and bought the 36v battery and KU65 controller, how difficult would it be to fit? (Bearing in mind I've never touched a soldering iron!) Also would I still be able to switch between the 3 power levels as I'm doing at the moment?

 

[Alan Quay]

If it was me, I'd order the ku65 with the battery, and keep hold of it.

Then install the battery with the original controller, see how it goes, safe in the knowledge that if it goes bang you have a replacement.

If you want a bit more torque, solder the shunt in the original.

I think you would be wise to invest in a soldering iron though if you want to start messing about with electric bikes. You will also need a few other minor hand tools - side cutters, snipe nose pliers etc.

Learning to solder is easy and a skill worthwhile possessing, although you will have a constant stream of friends and familly expecting you too spend an hour fixing their broken headphones, remote controllers and pace makers.

 

[Deleted member 4366]

That's it. The new controller is just for insurance.

You could fit the new controller without soldering, but it's better to solder it if you can. If you're lucky, you'll only need to sort the battery connector - 2 wires. Everything else will probably be the same..

Mike, when you use a 36v battery, you get more torque without soldering the shunt.. Each PWM pulse will be the same width, but 50% higher, so more energy goes into the motor with each timing pulse. Hence, you get nearly 50% more torque as well as speed.

 

[paulc1976]

Thanks for the info Mike, you've both convinced me that it's a good idea! I will look into that soldering mod. Just one last thing, Dave mentioned in his post about losing controllers control and relying on LVC in the battery. Not sure what this means, do I lose my 3 speed settings if I use the 36v battery with the original controller? Sorry if it's a stupid question, my knowledge in this area isn't good!

 

[Alan Quay]

....
Mike, when you use a 36v battery, you get more torque without soldering the shunt.. Each PWM pulse will be the same width, but 50% higher, so more energy goes into the motor with each timing pulse. Hence, you get nearly 50% more torque as well as speed.

When I upped my SWX from 24v to 36v I didn't see as much of a torque increase as I'd expected. Plenty more speed, but not much more torque. Soldering the shunt had more of an impact.

However, that was with a 7.5 amp controller (IIRC)

 

[peerjay56]

Thanks for the info Mike, you've both convinced me that it's a good idea! I will look into that soldering mod. Just one last thing, Dave mentioned in his post about losing controllers control and relying on LVC in the battery. Not sure what this means, do I lose my 3 speed settings if I use the 36v battery with the original controller? Sorry if it's a stupid question, my knowledge in this area isn't good!

Both the controller and the battery have a low voltage cutoff (LVC) to stop the battery cells discharging too far. If you still use the 24v controller, its lvc will never kick in if you are using a 36v battery, so you will be relying solely on the batteries LVC to protect itself from overdischarging. Your 3 pas levels should still work, I think, but will give different power outputs compared to 24v operation.

 

[Deleted member 4366]

When I upped my SWX from 24v to 36v I didn't see as much of a torque increase as I'd expected. Plenty more speed, but not much more torque. Soldering the shunt had more of an impact.

However, that was with a 7.5 amp controller (IIRC)

You need to do a definitive test. I have a 14% hill right next to my house, so it's easy to see the difference. My Xiongda could just get me up it without pedalling at 15 amps and 36v. When I changed to 44v , it was much faster up it. I then soldered the shunt to 20 amps and went back to 36v. Now it's about the same speed up there as 44v 15 amps. It's the same with just about every motor I've tested. The Xofo 500w motor could get me up the hill fairly well with 36v and 30A. Then I tried it at 64v, when It didn't stop accelerating all the way up. I had to brake hard at the top to avoid running onto the road. It's a cyclepath/footpath underpass.

 

[paulc1976]

Thanks for that peerjay and also Dave and Mike for your advice. I've taken the plunge and bought the 36v battery and KU65 controller from BMS battery. I'll try it with just the battery replacement and see how it goes.

 

[Kelvin Willshee]

You didn't update your posts to tell anyone how you got on with the new battery. I'm interested and I bet the guys who gave you advice were interested. You sought advice, received it, and rode away into the sunset. LOL

 

[paulc1976]

Hi Kelvin,

Wow this is an old post!
I didn't go through with it in the end, cancelled the order and sold the bike soon after, I really wanted a hybrid.
I have a carrera crossfire e from Halfords now and that is significantly better in terms of power and features, which it should be given how much more it is..
Nevertheless, I would still like more power for hill climbing and 20mph ability so will look at converting my specialized hybrid next year.

Many thanks,

Paul