Running a Moscow+ 48v bike on a 36v battery

[Bitmugger]

Anyone try this?

My idea is that the C7 display can toggle between 36v and 48v. I'd like to add a range extending battery that is a 36v battery.

I ordered the correct connector for the bike (from greenbikekit.com) and my thinking is once the 48v battery is depleted I'd connect the 36v battery and switch the display to 36v and ride on. I realize the maximum power to the motor will only be a fraction of what it would be under 48v but if I can get anywhere near 1/2 the torque out of the motor I'll be delighted.

The use case is that a few times a year my son and I go bike camping and we'd be in the back country away from power so for those rare trips I need a little range extension and thought this might work.

Anyone try this already? I am very confident that using a 36v battery won't harm anything but just want to know if anyone's done this and what their experience with the motor power output was running a 48v motor well below it's intended voltage. I'll also need to be careful not to accidentally pop my 48v battery in while the display is set to 36v but I doubt it would fry anything just deplete the 48v battery pack to the point the pack itself shuts down due to under voltage.

 

[harryS]

I have dual voltage controllers, and displays that can automatically figure it out during powerup, so I do mix 36V, 48V and sometimes 52V. In my case, I don't use the higher speed available with higher voltage much, so it's just for versatility.

Where I have to be careful is recharging, I messed up badly a few years ago, hooking the wrong charger into the wrong connector that happened to be poking out of a battery bag. Cooked the battery.

 

[Bitmugger]

Wait, you want to switch to 36V to extend the range?
Voltage is not what determines the range, Wh is.

No I want to use a 36v battery because I have a 36v battery. I understand it's the ah (and voltage to some degree) that determine range. This is a range extending battery I am trying to implement to get some more range on rare occasions I need it

 

[harryS]

He already has a second bike with the battery, If the Moscow will run on 36V and he has the battery in the pannier, and the 48V is flat, does he really care about WH? The question is whether his C7 will allow the bike to run, plus will the connectors match, and if not, will it be secure. You don't want loose wires,

 

[Bitmugger]

Guys trust me when I say I understand the voltage/watts/current situation, my question isn't about range, amp-hours, watts or anything else. My question is has anyone running the Moscow/Magnum Peak/Aspen/etc tried it at 36v and what was their experience with motor torque? Was it sufficient for getting around?

Timpo I have no idea why you are mentioning they are "both" reention dorado's, my 36v is NOT compatible with the Dorado, as mentioned I ordered the connectors and will be running 10ga wires (overkill but I have 10ga) from the 36v battery to a connector compatible with being plugged into the Moscow.

Timpo you also have a flawed assumption that the motor will draw 500w regardless of voltage, that's not how motors work. In fact running a motor under voltage can cause more heat (for the given watts consumed) and the motor can under perform vs doing a simple calculation and saying it will get 2/3 the torque.

Also I'll toss out there the basic truism that motor speed is proportional to the voltage applied to it, while the torque is proportional to the current. BUT there's a motor controller involved that can use PWM and/or current limiting to have an impact on the motor and potentially muddy the water. I just wondered if anyone has tried this is real life and what their experience was with cheeks on the seat riding.

 

[Bitmugger]

I didn't assume the motor will 500W regardless, that's why I said "(However, in reality, your power output will constantly change)"

But anyways, I don't know what you mean by Reention Dorado isn't compatible with 36V??

Reention Dorado is a case, so you can set the cell layout to make it 36V.
Some ebike companies do that, for example, Eunorau offers 36V in Reention Dorado, HillEater offers 72V, and many companies offer 52V.

I'm not trying to be argumentative but let me just say that using 36v there should be NO way to draw 500watts with the Moscow Plus 48v motor and stock controller. All your calculations assumed constant wattage between the two voltage levels when that's not what happens in real life. Yes your Wh are correct given the values you used, yes your time estimates are correct given the values you specified, you just chose to specify values that aren't what you'd see.

As for the battery case, yes I suppose you can buy 18650's and a Dorado battery case, but I have no idea why you went on that tangent or have assumed I ever said the Dorado case is not compatible with 36v. Not that it matters but my 36v battery is a 10ah bottle battery and I have no plans to disassemble it and re-assemble into a Dorado case. Unsure why that's been brought up. The ah of my 36v battery, watt-hours, run-time and the form factor it's in are not relevant to my question about torque, I really just wanted to know if anyone tried it and how their experience was. I've seen other people have done it on other bikes, I just couldn't find anyone with a 48v NCM/Magnum/Amego bike like mine who's tried it and wondered about the torque.

I think I'll just drop out of this thread