36v hub motor using 24v controller?

[BMEBIKE]

i just purchased a hub motor kit and got the wrong wheel size, so looking for some options, I found a 36v hub motor for cheap, Can I use the kit I bought for the 24v setup and just run a 36v hub motor with it at 24v?

 

[d8veh]

It'll max out at 2/3 the speed if you run it at 24v and have 2/3 the torue. You can get the torque back by adding solder to about 30% of the shunt in the controller, but there's nothing you can do about the speed.

 

[dnmun]

why not make the controller run at 36V and get a 36V battery too.

 

[BMEBIKE]

I already have a 24v battery, I got it working but its very slow, think I may just buy a another battery and do 48v and just order another kit, whats the cheapest best 48v kit these days?

 

[BMEBIKE]

I already have a 6s battery to use, but I did finally get it to work after 36 different combinations, its not super fast but not terrible, would having a 24v motor make it run any faster then using the 36v motor? or should I over volt my controller and add a 3s pack to bump up the voltage or will that burn out the controller? I'm not looking for much faster top speed but maybe a little more power for hills.

 

[d8veh]

You can add a 3s pack, which most likely won't burn your controller;however, it brings a lot of complications for monitoring and charging your batteries. You can get some very cheap 36v batteries from Aliexpress, which would be a much better solution.

 

[wesnewell]

I already have a 24v battery, I got it working but its very slow, think I may just buy a another battery and do 48v and just order another kit, whats the cheapest best 48v kit these days?

That all depends on where you live. I asked for that info in your first thread, but since you seem unwilling to do that......so am I.

 

[dnmun]

so you are using a 6S lipo pouch pack and using a balancing charger to charge?

if you go to 2 of the 6S packs in series and use your balancing charger that would get you to 50.4V DC which is a little more than the 36V lifepo4.

you can open the 24V controller and look at the parts and google the mosfets to determine if the 50V is too high for the controller.

if the mosfets and the input and S/D buss caps are ok with 50V then you should look at the power resistor on the input to the voltage regulator to see if it is adequate. we can advise how to adjust that too.

it is a 24V controller so it has 20V for LVC and will not interfere with the operation. i always recommend people build a regular battery though and avoid using the shrink wrapped pouches because of how the shrink wrap damages the pouches. also i recommend using a BMS to protect from shorts on the output of the battery and to protect against over discharge.

 

[BMEBIKE]

I am located in San Diego, Yes I am using a balance charger for the 6s battery, from all my RC junk, if I get another battery to add to the mix I would just plan on charging separately, the setup I have now isnt terrible just not sure how much power I am loosing by running a 36v 500w motor with a 24v controller and battery, would it be night and day if I had the correct 24v 350w motor that came with my kit?

 

[wesnewell]

Your cheapest way out now is to just buy a cheap 48V controller and use with the 36V motor you have now. With an added 6s pack in series with the one you have, you will double your speed and acceleration. This, are one similar, would be my choice.
http://www.aliexpress.com/store/product/Greentime-36V-48V-500W-600W-30Amax-BLDC-Motor-Controller-Electric-Bike-Tricycle-Controller-Driver/313864_2012487273.html
Do not buy a 36V controller to use 12s lipo. LVC will be too low at 30V.

 

[dnmun]

if you are not able to examine the inside of your controller like him then if you wanna use the two 6S packs in series there is not a single reason in the world you cannot use the 36V lifepo4 controller. i don't know why people make this stuff up and tell newbies stuff that is not true. you should use a BMS to protect against over discharge. some people use cellogs and hang them on the pack so they get an alarm but a BMS is the best solution because you have output protection against shorts as well as against over discharge. but 50V is not too high for a 36V controller.

 

[wesnewell]

The standard 36V controller has an LVC of ~30V. Run 12s rc lipo down to 30V and that's an average of 2.5V per cell. He already stated he's using an rc charger to charge the rc lipo. He doesn't have a bms. So if he listens to your advice, he's at best going to ruin his lipo, and at worst send it into thermal meltdown.

 

[BMEBIKE]

Thank you for everyones help and suggestions, one last question, I know its not the best Idea but I do have a new 3s 5800mah 25c pack, How bad would it be to run the 6s 10000mah 10c pack in series with it? I checked with the company of the controller and they said it would be no problem to overvolt the controller to 36v, I have a voltage alarm so I'm not worried about running low.

 

[wesnewell]

As long as you remember that the lower capacity pack/cells in the series will deplete before the others and you monitor this and not let them over discharge then there's no problem. It's just not a good practice to series packs/cells of different capacities. In the case of 10ah and 5.8ah, then you'll never use the total capacity of the 10ah pack before the 5.8ah pack needs recharging, thus cutting down your range to that of a complete 5.8ah battery pack.

 

[d8veh]

You need a voltage alarm on each pack. Ideally, you want the one for the small pack where you can see it so that you can see what's happning with its cell voltages.