Regen braking question

[Vipermn]

Hello everyone

I have a couple of questions. I have a front and rear 26 inch MP4 with a dual driver harness which has 2 brake connectors. I need to know just exactly what is happening when the brake levers that came with the motors are pulled. Is the switch in the brake levers simply closing and opening resulting in completing an electrical circuit? Which pins go to the brake lever switch? If I wanted to install a micro switch in my hydraulic brake lever and connect the cable from the electric brake handle that came with the motors to my micro switch are there any special considerations relating to the type of switch I must use like voltage rating? Precisely how does the brake lever that came with the motor work? How is the power to the motor cut when the lever is pulled?  And another question not related to braking - is it possible to utilize the +5v and  (-) connection on the unused cable on the front motor to power a 5 volt led light with it's own on/off switch?  Thanks for any help anyone give me

[Bikemad]

When the lever is pulled, the switch contacts are connected together by a metal disc on the end of the spring loaded plunger pin which simply short circuits the brake signal lead to ground. This forces the controller to cut the throttle and apply regenerative braking and also cancels the cruise control if it was in use.
When the brake lever is released, the plunger is pushed back against the spring and the metal disc moves away from the two contacts creating an open circuit.







The following picture shows the socket fitted on the end of the brake lever cable:



The actual current being switched through the brake switch is very low, so most small microswitches should be able to handle it with ease. Simply connect the two wires that are connected to the existing switch to the "N/C" (Normally Closed) and "C" (Common) contacts on the microswitch.

I strongly advise against using the +5V supply to power LED lights. The +5V supply is needed to provide power for the hall sensors in the motor, throttle and pedelec sensor, and if it is overloaded it could blow the controller's 5V regulator chip causing your controller/motor to stop working completely!

Alan
 

[Vipermn]

Thanks Alan !  Another question - Is regen braking a good thing? Do the benefits outweigh the negatives? I would think that when you turn your motor into a generator, you could create problems you would not normally encounter if your motor remained a motor. Is the amount of charge you receive going to be noticeable? Will one brake lever enable regen on front AND rear motors depending on settings made with programming? Is it acceptable to program each controller to different parameters? What parameters affect regen braking besides ENABLE and how do they affect it? ... I really appreciate the help and support you give . Golden Motor and all us ebikers are blessed with your presence! Thank you very much

[Bikemad]

I really like the regen braking effect and tend to mainly use it to reduce the wear on the brake blocks (and wheel rims) more than anything else. The amount of regenerative charge is governed by the braking speed, and slow speed braking will generally produce very little charge (if any).

On some rides I have actually recovered up to 27% of the consumed battery capacity using regen, but the majority of my slow speed "dog walking" rides do not produce any noticeable regen charge whatsoever.
(Unfortunately for me, the Vector controllers do not produce any braking assistance if you apply the brakes while travelling below 6 mph, whereas the earlier controllers will still slow you down (but not generate a charge) if applied at 3 mph.)

The dual motor harness should be wired so that either brake lever will cut the power and activate regen on both motors (if regen is enabled in the controller settings).

If regen is enabled, the amount or regen (electromagnetic dynamic braking force) is controlled by altering the "Max EBS phase Current (A)" setting, which should ideally be tailored to suit the rider's preference. The higher the current setting, the stronger the electromagnetic dynamic braking force will be (and vice versa).

On a dual drive bike, certain parameters of the controllers can be set differently (i.e. PAS Ratio, Battery drawn current, Rated phase current and acceleration), but if both wheels are the same size, the "Maximum Forward speed (rpm)"should always be set the same to ensure maximum efficiency.
Having a lower braking setting on the front motor than the rear is also much safer, as it reduces the chance of the front wheel slipping away from under you whilst braking on wet grass or loose road surfaces. If the rear wheel looses grip, it's a lot easier to maintain control and not fall off!

The ideal solution for dual drive would be to have independent variable regenerative braking on each wheel, but as yet there is no sign of variable regen controllers from GM. 

Independent regen (albeit non-variable) could be implemented, but it would involve a lot of work on the front harness to incorporate the various diodes/resistors that would be needed to ensure that either brake lever would still cut the power to both motors, and cancel the cruise operation on both motors while still providing individually activated regenerative braking.

Alan
 

[Vipermn]

Thanks for the info. I went ahead and installed a micro switch in my Hayes hydraulic brake lever.WOW!! It almost threw me over the handlebars! I had to turn it way down (with the "max EBS current" setting for both motors) like you said. Works like a champ. Thanks again for all the time and help you've given me. 

[Bike noobie]

I really like the regen braking effect and tend to mainly use it to reduce the wear on the brake blocks (and wheel rims) more than anything else. The amount of regenerative charge is governed by the braking speed, and slow speed braking will generally produce very little charge (if any).

On some rides I have actually recovered up to 27% of the consumed battery capacity using regen, but the majority of my slow speed "dog walking" rides do not produce any noticeable regen charge whatsoever.
(Unfortunately for me, the Vector controllers do not produce any braking assistance if you apply the brakes while travelling below 6 mph, whereas the earlier controllers will still slow you down (but not generate a charge) if applied at 3 mph.)

The dual motor harness should be wired so that either brake lever will cut the power and activate regen on both motors (if regen is enabled in the controller settings).

If regen is enabled, the amount or regen (electromagnetic dynamic braking force) is controlled by altering the "Max EBS phase Current (A)" setting, which should ideally be tailored to suit the rider's preference. The higher the current setting, the stronger the electromagnetic dynamic braking force will be (and vice versa).

hi Bikemad
sorry for the noobie question but I just hoped to clarify before I messed with my options too much, if I understood correctly if you set the max ebs phase current higher it brakes harder and also charges more battery or only brakes harder ?

also would increasing this value too much ever put the motor in danger of overheating or having too much charge going back through it or does it have very little risk other than having too strong brakes?

also would increasing this value have any effect on the drag i've read that e bikes have ? does the drag charge the battery at all or just slightly slow you down?

and ive read that the motor is always engaged in e bikes with regen does this mean the regen braking would work with the bike turned off?

and lastly how could I go about measuring how much it charges the battery ?

p.s I should say also less.
p.p.s after all these questions I feel like I owe you Bikemad many thanks 

[Bikemad]

hi Bikemad
sorry for the noobie question but I just hoped to clarify before I messed with my options too much, if I understood correctly if you set the max ebs phase current higher it brakes harder and also charges more battery or only brakes harder ?

If you are braking at a high enough speed it should produce higher current at the maximum EBS phase current setting. I could be wrong here, but I suspect the speed at which regenerative charging takes place may have to be higher with the EBS Phase Current set higher.
 
also would increasing this value too much ever put the motor in danger of overheating or having too much charge going back through it or does it have very little risk other than having too strong brakes?

It is unlikely to cause overheating damage to the motor as it is unlikely to continue for long periods at high speed. As the braking force is activated, your speed will typically reduce quite quickly and you automatically release the brakes (and deactivate the regen) to maintain a reasonable speed.

On a long incline, if I keep the lever pulled in just enough to activate the braking force the bike will slow to about 3mph, the braking force then stops completely allowing the bike to speed up until it reaches about 6.5 mph when the Braking automatically cuts in again. This on/off braking style will continue until the brake lever is released.

The charging current produced during regen is not usually as high as the current drawn from the battery under power, so there shouldn't be too much charge going back to the battery, which is probably protected by the BMS anyway.

also would increasing this value have any effect on the drag I've read that e bikes have ? does the drag charge the battery at all or just slightly slow you down?

The value of the EBS Phase Current setting will have no effect on the residual drag produced by the motor as it will only make a difference when you pull the brake lever.

The residual drag does actually generate voltage at high speeds, but it would have to be generating a voltage higher than the battery voltage before any current could flow.

and I've read that the motor is always engaged in e bikes with regen does this mean the regen braking would work with the bike turned off?

The braking effect is controlled by the controller which will requires a minimum voltage before it will power it up. If you ride fast enough without a battery, the voltage produced by the motor will activate the controller and allow the electromagnetic dynamic braking force to be activated.

and lastly how could I go about measuring how much it charges the battery ?

A cycle Analyst or a standard watt meter connected in the wrong direction (The Source and Load swapped not the polarity of the leads) can be used to measure the regen current and the battery capacity which has been replenished.

If two watt meters are installed (with one connected normally and the other reversed) you can measure the current drawn and the capacity used from the battery on one meter and the regen current and battery capacity replenished on the other, which is how I was able to calculate the ratio between the consumed and recovered battery capacity (Ah).

The 27% quoted in your last post was actually achieved on a MKI Magic Pie and from what I recall, the trip involved a lot of standing up while pedalling, including pedalling hard downhill with the regen applied to deliberately try and see how much regen I could actually produce.

The Cycle Analyst is a lot more expensive than a couple of cheap watt meters, but it is capable of recording and permanently storing both sets of readings and it also incorporates a lot more useful functions too.   

I already had the Turnigy watt meters, so I simply made up a couple of gender changers to allow one of them to be fitted in reverse so I could measure regen current:

Hopefully this has answered your questions.

Alan