Hi All
Anyone got any experience of EM3EV
they seem to have some good kit, I like their triangle battery pack and bag which makes a lot of sense rather than rear mounted.
Would a 48v 20ah shrink wrap from BMS fit in the Em3ev or Falcon triangle bag by any chance as they have only 16 amp max.
they seem to explain things alot better to us newbies rather than BMS but not sure if their kit is as good.
Also is a 500w motor the nominal power and will increase up to 1000+ when required, is that how it works???
what connectors should one get for building a kit, will i need bullets, push fits, anderson or do they all come with the kit.
thanks for any info.
EM3EV gets good reports. It's unlikely a shrinkwrap 48V 20Ah battery from BMS battery will fit in a standard triangle. They do vary in shape according to batch (some are long/thinner and others brick-like ... you will know what you have when it arrives !) - but you could msg them and ask for dimensions.
Very basically, direct drive hub motors are quite different from internally geared ones like Bafang CSTs and have fewer moving parts. DDs are often capable of regen braking (can be useful above 28-30mph), are quieter (if you are especially sensitive to that although there is very little noise from a good geared motor, in particular set against general road noise).
Direct drives are often more robust to higher levels of overvolting / pushing further beyond specified design parameters than geared motors, if that is what you want to do. Especially when you start going above 48V nominal. Basically, aside from the limits of the motor windings, you can also wreck the gears on a geared motor if you push them too far. Of the Bafang motors the 500W CST has blue gears like the ones used on certain high end US motors and these are apparently very good.
48V 23-30A is at the upper limit of what you would likely run a geared motor before moving to direct drive. Once you do, there are some downsides - principally, motor drag - which is especially apparent when you try to ride unpowered or if your battery runs out. Geared motors also climb better for the same power without pedalling than direct drives due to the planetary gears in them. Basically you should plan on always riding a direct drive as an eBike (i.e. not switching off the power or leaving throttle fully closed). The drag means you won't get the same downhill speed as with a geared motor, whether or not you have regen braking. To give you an idea my CST geared motor cracked nearly 50mph downhill on a 0.6 mile descent with knobbly MTB tyres. I'm pretty certain I wouldn't get that off a DD bike.
As to the Watts of power input to the motor, this is determined by the AMPS output by the controller multiplied by the VOLTS of the battery. The rating of the motor is not relevant to the power supplied. It is merely an indicator of the continuous power the motor is rated for. So disregard it when looking at the max power of a setup.
Put simply, an S12P controller allows 29A. A 48V battery fully charged will likely be around 57V. So fresh off a charge it is capable of giving the motor 29 x 57 = 1.65kW. Much of this will be lost as heat though. With an S12S controller at 23A it is capable of giving 23 x 57 = 1.31kW peak.
Pop a 36V battery on the same controller at the same amps with the same motor and you will get the following peak power supplied fresh off a charge :
S12S - 23 x 42V (fresh charge voltage) = 966W
S12P - 29 x 42V (fresh charge voltage) = 1.21kW
The connectors you need depends on the parts you use to assemble. Kits with batteries come with all the connectors necessary. However you may wish to upgrade some. In particular if there are bullet connectors on motor phase wires I suggest you either cut off and solder direct to the controller or replace with Anderson connectors (or similar). This is owing to lots of cases of these bullet connectors becoming a bit loose and causing burn out. I would personally also replace the battery to controller connectors with Deans connectors or similar rather than the white plastic ones. You may also want to wire in a fuse between battery and controller.
There's loads you can do if you want to and I upgraded a shed load of stuff. Best to wait and see what you get, whether you are happy with it, test it and then make the connections to fit the setup when you've sorted out where things are all going and decided on which parts you are going to keep and which you are going to bin (e.g. which controller). Most important thing - don't be too hasty, test thoroughly and keep a soldering iron and some shrinkwrap at the ready.
