Pulsating regen

[sveinf]

Hello everyone!
My MP give me a very pulsating experience using the regen-brakes, the peaks are quite hard.
Only sometimes it gives a steady (but hard) effect.
Is there some bad connections fooling around here?
BR Svein, Norway

[Bikemad]

Hi Svein,

Has it just started doing this, or has it always been like it, and does it behave any differently after the battery has been used for a while and is more discharged?

It might be a good idea to just check the connections are clean and dry, and perhaps you should also check the wheel nuts are still done up tight on the axle.

Alan

[sveinf]

Hello BikeMad!
Thanks for your answer!
I just realised that the battery is broken!
I haven`t used my bike since oktober 2010 due to the norwegian winter.
During these wintermonths; have I really done some completely wrong? 
I have done recharging of the battery every 2 months, located in a cool place(10 - 15 grades Celsius).
And to really make my day, the warranty is due by 3 weeks...
I`ll ask Tom about the warranty issue if there still is a one...
Have I made it all wrong regarding taking care of the battery during the winter?

PS: I remember that the pulsating regen ocurred in august/september 2010.

BR
Svein

[Bikemad]

Svein, it sounds like you have taken correct precautions by charging the battery every 2 months to prevent it from discharging too much.

What exactly is broken on your battery?

Does it still charge up to the correct voltage?

Alan
 

[sveinf]

I haven`t done any measuring yet, but the battery disconnects automaticly after a minute or two when using power.
This ocurr when the battery is fully charged.
I`ll put on the charger after work today, and measure the voltage tomorrow.
I`ll let you know the result.

BR

Svein

[sveinf]

Hello again!
The battery is OK, I measured 54 Volts, fully charged! 
The problem was the connector at the end of the main powercable connecting to the battery. It was badly damaged and made the connection very unstable.
And it was all hidden under the rubber hose... 
I do ride along some bumpy roads, fixing of the connector and making some modifications fastening the cable and tighten up the battery is needed, obviously.
Thank you for your advice, anyway! 
Tomorrow I`ll ride my MP again! 

[GM Canada]

That plug GM uses in the battery is a knock off of an Anderson plug. It is not very strong and not unusual for it to break. I would suggest looking around for a real anderson plug to replace it and you should have no problems after that.

Gary

[SydneyCommuter]

Did anyone get to the bottom of the pulsing regen?? 
I've just taken my new build (36v 16ah, 26inch) for its first full test 33km run and it did this most times whilst breaking.
Id' describe it as a surging, almost grabbing and then letting go, then after more prolonged breaking it was more like the backpressure on a petrol engine with a nice purring sound.
Its that hard surge that concerned me.

I also have a problem of the motor cutting out after stopping, give the throttle a couple of turns on and off and then it comes good, anyone had this? sorry if its my not understanding some feature.
My Anderson plug was a dud, lead fell out after first 10mins, replaced with new one with cable clamped onto it so no mechanical force on the wires, all still fitting under the supplied rubber boot.

My key switch also was very intermittant on arrival, I replaced it with a simple 20amp toggle switch and moved the internal wires over to it and reliable on/off since, just use the key to keep the physical attachment.
Are these common issues??

[MonkeyMagic]

Howdy

I think (think!) everyone who is posting here has not had too much experience with ebikes + regen....

Regen will NOT pull you to a complete stop. It is not a brake as such, but known as 'regenerative braking' because it slows you down.


YES it will give the feeling it is 'pulsing' because the initial 'grab' feels like alot of braking power and if you have your regen set at 100% then it could even be the controller or the BMS on your battery cutting out with too much current.

If you use it down a hill it will be strong at first, then it will slow you down. If it's cutting out while going downhill then its most likely a loose connection you could tell by holding in the throttle and if that turns on in between, then its definitely a loose connection

I mainly only use mine at the beginning of braking - there is potential for damage (overheating) by using it too much. Think of using regen constantly as you constantly going up hill, the controller won't like that!

Sydney, hey mate was it you that had a throttle problem with 5v and fixed the red wire? If so, check your white wire too as that's the throttle signal, if its playing up I'd be looking there

MM

[SydneyCommuter]

Monkey many thanks for the quick response, much appreciated,
In my case it is definitely an inexperience factor as I've only just started using my bike after sorting through all the little 'special features', like the dodgy anderson plug and faulty batter switch.
I just needed to know if I'm getting the expected outcome as I have no other reference point.
So sounds like my regen is working as expected which is reassuring.
BTW I have the USB cable for changing the settings, but haven't tried it yet, so my controller is set to the factory settings for now, I did order it with the 36 volt battery so I hope that the settings are most appropriate for this or is it an idea to change it to a non out of the box more suitable setting, can anyone refer me to a post that has a good well tried setting for a 36volt??  Any recomendations would be appreciated. ps on the stock settings the bike performs much as I would have expected given approx 500watts pulling my 110kg bod but relatively light bike up hills. mottors along on the flat between 25-30kmh, 15-20km on hills, peddle assistance depending.
Do you have any issues with delays or none responsiveness to the throttle input after braking?? Could it be some aspect of the controller setting?
Not me with the speedo cable, I think mine is all connected ok. it doesn't behave like an intermittent connection issue as it seems to consistently come back on after a short delay or a couple of turns of the throttle.
Also I went 33kms and the battery indicator started moving from full always lit to just going fully off and the half full still fully on, how much further do you usualy get once the indicator goes fully half ??  understand its a bit subjective but just a general idea as I didn't want to drive it till it fully flattened and got stuck humping it home on legs only, will do a fully drain out test soon though to be sure. 
Sorry about the endless questions, sure I wont be the last newbie doing that.
Cheers

[Magneto81]

I have been getting this a lot for the last year - I think it is a loose connection so I'm going to redo a bunch of connections to see if that fixes it. Both my regen and my throttle do this. I have a cycle analyst and it looks like the voltage drops when I try to accellerate, but after a minute, it's usually fine. This morning I couldn't get the bike to 'snap out of it' and my theory is that my on off switch (I used a standard 3-way light switch for houses) may not be connected as well as it should be. Does this make sense?

I can tell you that the pulsating breaking is NOT normal. The breaking always starts out strong and slowly weakens until about 5k/hr and then it doesn't slow you down at all.

[MonkeyMagic]

I like pancakes

[Magneto81]

Hi Bikemad,

I know how it is supposed to work - the way I described it! But initially, it really pulsates as if it's turning on and off, IE it slows you down and then "lets go", slows you down more and "lets go" again - this is pulsating and that is definitely abnormal behavior - and perhaps this is what is happening to our thread author. It happens I'd say about every second giving a real jarring effect. Again, after I've come to a few stops the pulsating goes away and it works 'normally' as in, it slows you down strong and weakens as you lose speed with no pulsating at all.

Do we have any theories other than loose connections? Is this the best place to check?

[Bikemad]

Svein, the OP, has already located the cause of his problem:

The problem was the connector at the end of the main powercable connecting to the battery. It was badly damaged and made the connection very unstable.

If it's not a poor connection, then it might be the battery management system (BMS) limiting the current.

Regen current is usually much higher with lower voltage batteries than it is with higher voltage packs, my maximum measured regen current was 23.35 Amps (681.5 Watts) using a 7 cell LiPo pack (25.9V 10Ah) and 9.65 Amps (525.8 Watts) using 14 cell LiPo pack (51.8V 5Ah), and these readings which were obtained at approximately the same speed.

If the current or voltage is too high, the BMS may be limiting this to prevent the battery from being charged too quickly (or too high) by momentarily disconnecting the battery. This might possibly cause this pulsing effect that you describe.

What type/voltage battery are you using, what size wheels and at what speed does the problem occur?

Does it happen more with a freshly charged battery, and less as the battery becomes more discharged?

Alan
 

[Magneto81]

I'll let you know how it goes with the connections - the likely culprit. I have my own batteries and no BMS. It's a 21 speed adult-size mountain bike I converted, I can't think of the wheel size at the moment. Thanks for your helpful questions

My regen experience is topping out at 17 Amps. I have a 48V SLA setup for batteries. Charge level doesn't matter. Pulsing happens when I try to go forward as well - giving me a low Voltage reading on my Cycle Analyst, so it seems the undervoltage protection is being utilized.