18650 cell questions

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
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northeastern Minnesota
Run two of these for $156.

http://www.ebay.com/itm/Taotuo-22-2...988089?hash=item5440893a79:g:JZkAAOSwj85YONps

These would be great for a 48v system because the low cut voltage usually around 42v is in line with the 3.5v/cell generally used a max discharge. You can run em on a 36v or even a 24v if you use a voltage alarm to alert you on the low voltage cut. Cost about $11 and runs off one of the packs balance plugs. The motor doesn't care how much voltage is put to it with in reason, usually depending on phase wire size. Most controllers have 63v caps so they easily handle close to that. Its just the LVC that is different and of course max amperage output. A 24v controller will have slower acceleration and hill climbing than a 48v because the 48v has a higher max amperage. However the 24v controller will still give the max voltage.

I have one total(motor/controller) 24v system that I run on 12s which is 50.4v off charge. Never had an issue with it.

Moral of this story is with in parameters you can pretty much do what you want with the systems. There are some modded 9c 48v hub motors running over 100v over at the Sphere.
Hello, my friend. It has been a long time I’ve been away and good to see you are still posting, You were a great help to me in the past with gas bikes and now I’m asking for some help with an Ebike. I have started a new thread called Pedal Coupe and have a lot to learn. The bike is a four wheeler and recumbent, came primarily as a pedal bike with a 24 volt motor and two 12 volt lead acid batteries. I want to upgrade to 52 volts using 18650 cells. I understand that I will need to replace the controller with compatible voltage. What I don’t know is how difficult is it to wire up a controller to the motor when they were not part of a package? Is this a pretty straight forward - they’re all pretty much the same- thing to do or you’d better have a good schematic not written in Chinese? And offhand is there a plain Jane controller you would recommend? I don’t care about programmable, etc. ..just the basics. Turn the throttle and go. How likely is a 24 V motor going to accept 52 volts without sparks and fire? I’d rather not replace the motor if possible. Not looking for top performance or speed and budget is always a major consideration. Thanks! Anyone else have an opinion?
SB
 
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Tony01

Well-Known Member
Nov 28, 2012
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The 24v is going to run double the speed at double the volts. You can reduce battery amps by half (draw, not capacity) to keep the same overall power. Overvolting is fine as long as you run same overall power which is volts times amps.

52v nominal sounds like a 14-series battery, with a max charge voltage of 58.8v. You’ll need a charger that charges to that exact voltage. Controller wise, most will do 36-72v nominal.

A 48v spec usually means 13s, but it can also be 12s, 14s. Just be sure and check. Your charger just has to not overcharge whatever battery spec you run.

if your motor is brushless, you will need a brushless motor controller. Ie... 3 motor wires with halls? Brushless. Two wires? DC brushed. Hooking it all up is simple and will work without being part of a package. Only thing is you will have to mess with positions of hall sensor wires for the motor to run correctly- 3 wires so 3!=6 combinations to try.
 
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silverbear

The Boy Who Never Grew Up
Jul 9, 2009
8,212
175
63
northeastern Minnesota
Thanks for the thoughtful and informative response, Tony. That's a next thing on my to do list... determining whether it is brushed or brushless. I'll have to dig in to the wiring some to see what's what. The pedalcoupe is supposed to be my winter project, but it is hard to stay away from it when it enters into dreamtime at night. Lots of other things are demanding time right now with remodeling an old cabin and preparing to shut things down there for the coming winter. This is the time of the build to gather information and getting what parts I'll need ordered. I appreciate your input and will try to digest the whole sometimes confusing business of Voltage, wattage and amperage. Being invisible makes it all the more esoteric.
SB
 
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