motor/controller/overvolting questions?

[IvanGrozny]

So, I am getting ready for my 3rd season with my ebike. There are some changes and upgrades I want to do but before I want to be sure I understand what I am doing.

My bike is a Cannondale F700 with a Voilamart brushless hub motor36 V, 500/750 watt controller. PAS not installed. I have been using a self made 10s2p battery pack made from SPIM08HP lithium polymer cells 3.7v/8ah each. The cells are capable of 200 amp continuous discharge and 400 A burst for 3 seconds.

I would like to upgrade my controller and increase the voltage, probably to 51.8/58.8, 14s1p. My main reason for this is not to effect any real increase in speed. I am happy with the 20-25 mph I get on the flats for my commute. I would however like better performance on the couple of small hills/slopes I have on my short 1.5 mile commute. I am a big guy, 280 lbs, and yeah I now know i should have gone with a higher voltage/wattage kit. Range is not an issue, when I first built the bike I ran a 10s1p pack for several weeks and got about 3 days commute out of it between charges

Questions;
1. As I understand the voltage and wattage are controller dependant more than specific to the hub motor?
2. Hub motors can run over a wide range of voltages/wattages from what I've gathered?
3. When choosing a controller can I up to a 1500 watt 48V or should i stick with a 48V 1000 watt without damage to the motor. (the voilamart 1500 watt motor weighs like 10 lbs more than the 36v 500/750 or 48 v 750/1000 motor does)

Budget is a serious consideration so I wont be buying an expensive controller, but I am thinking of buying a bluetooth BMS so I can monitor the battery/cells. I am also planning a few superficial upgrades like sensors on brake levers rather than the crappy brake pulls that came with the kit, replacing the lousy freewheel that cames with the kit, switching out disc brake caliper with one that can be adjusted in place (bb7 I think it is, has a wheel that is reachable in spite of the motor).

 

[IvanGrozny]

And an additional question.
Would a sine wave controller be a better choice than a normal controller?

 

[DogDipstick]

Well, I am here in tha same boat, a few month ago. I decided..:

Yes, increase from 10s (36v) to 14s (50.4v) will be fine for you and you should receive a significant increase in power at that improvement. However, you will also increase speed, with the voltage increase. The controller must be rated for 60v here.

The systems are designed to work effectively around the ranges the are built for. I push 3Kw and peaks much much more than that from a 1Kw hub motor, but the controller can do 8Kw+. I limit amps so as to not damage hardware. The hub is made from the manufacture as a 48v hub, but the 72v I run through it does not hurt it. So far.

Sine wave is quiet, I have not ridden any, but have one here for sale. They are acclaimed for many reasons.

The SPIM08 are inherently powerful, and you may be able to afford more amps from your controller IF, and only IF, the hub is designed in the ranges you need. Look at the phase wires.. Are they hot? Are they tiny? Will they be the first thing to go with a high power ( amps = heat x volts)... the Phase wire to my motor is 3mm^2, and can handle the full controller peak, but must be temp limited for I will burn on continuous running. Temp (AUTOMATIC) roll off is important with temp sensors here when you overvolt.

Phase wire 2mm^2? Do not go over 20A of 40A for even a short time, that is getting to small IMO.

The higher the power, the shorter the time till overheat if motor is not built for it.

Over volt, over power, over amp 25% should be fine for your application.

 

[IvanGrozny]

-Thanks for the reply. Just wanted to make sure I had things straight before I started frying parts.

 

[dogman dan]

Not clear enough what motor you have.

the typical 500 w rated direct drive motors can take up to 3000w, for about 40 min. Meaning 72v 40 amps, and riding 35-40 mph till about 700 watt hours are used. Much more, and they will melt, and cook off halls, if not the winding itself.

I assume you have this type, if so, much longer duration and reliability can be had with 52v 40 amps, around 2000w. So providing your battery can handle it, go for 30-40 watts of 48 or 52v. It will zing you up those hills real nice.

If your motor is a 500w rated geared motor, then keep it closer to 1500w max, 30 amps 48v.

 

[IvanGrozny]

Dan,
It's a brushless hub motor. Pretty sure it's the same motor they put on their 1000 watt/48v kit just with a different controller and throttle display. Following advice I think you gave another I will install a volt/ammeter so I can keep an eye on what it's doing. My batteries can definately handle high amp output, they're rated at 200 amp continuous discharge and 400 amp burst for 3 seconds. Good to hear that I am reasonably on target with my plan, the bike is my commuter and has served me well the last 2 years. Thanks for the reply!