First display suddenly stops while riding (damaged) second display also fails riding back home

[SpanishFlyer]

Hi,
As I say, I purchased two 1500W kits from CSC with different wheels (20" and 26"). With the 20" on the bike I went out for my third ride, and this time I set the battery charge when decelerating to its minimum (hub motor DD, no gears); I have 1 to 3 options, being 1 the mildest of all.
Anyway, after a short 6 km ride, as I was returning home, the bike died on me; battery still had 3 leds from a total of 6. Once bask in the garage, I checked everything and topped up the battery, but still the same. This kit includes a by-pass plug/wire that allows the bike to run without any info, just throttle, brakes and motor. As soon as I installed the by-pass the back wheel started running again, all controlled by the throttle. It was clear the display was damaged.
Removed it, installed the spare one I had and all came back to life.
Went out for a ride and it was perfect; this time I made it shorter (just in case) and sure enough, the display went black again and the bike stopped. This time I was ready and had the display connector easy to reach and plugging the by-pass I managed to get back home. By the way, the configuration was exactly the same as the other burnt unit.
Now I know that the display is not the culprit, but more like the one that suffers the consequences.... : (
Can someone help me out here?
Best regards
Spanish Flyer

 

[SpanishFlyer]

Hi again,
Just wanted to mention that item 13 on the display is the one that configures the way the motor turns into a generator that charges the battery as you close the throttle and also acts as a sort of brake causing drag on the rear wheel. 0 is not activated and from 1 to 3 goes from mild charge to 3 being the strongest (not recommended by the manufacturer due to the possibility of locking the rear wheel); I had 1.... I just wonder if the motor to battery recharging effect can cause some over-voltaje to the system and damage the weakest elements, such as the display.

 

[harryS]

The screen shot is the display before it blew up? Or does the LCD still run, but the bike is dead with it connected? You should get one PAS lvel with the shorting connector,

The display sees the whole battery voltage. It could blow up if that got very high.

 

[SpanishFlyer]

Harry, the screen shot was taken once I rode the bike home the second time the bike quit; I started checking everything; the first display I took it apart because it smelt pretty badly of burnt electronics. The only thing I found (as a non electronics expert, by any means), was that the burnt place was the USB circuit board ??.... I had never even removed the rubber plug protecting it, but seems to be the weakest point on the display; Once I removed the USB board de-soldering its cables, I crossed my fingers hoping the display would start working, but that was not to be the case. I now have a dismantled display and the second one also dead, but I still keep it mounted on the bike.
Both failures happened as I was going down a hill, no brakes, just the hub motor slowing me down to some extent. As I'm riding, the screen goes black and the throttle does not work; no lights, no horn and no way to see the battery state.... Once I remove the screen wiring and plug the shorting connector, the motor reacts once more to the throttle; that way I manage to get home.
The more I think about it, the more I believe that the over-voltaje produced by the motor is what caused both failures. Problem is I have no more displays, just waiting for the vendor to contact me and give me a solution; I don't even know if the BMS is prepared to receive charge from the battery outlet...
Best regards and thanks,
Spanish Flyer

 

[PedalUma]

Similar cases have been reported from some years ago in San Francisco when people had regenerative braking. They would fully charge a new bike overnight then head down the hill first thing in the morning. Parts would fry. When you get the new displays, consider disabling this feature. No modern high-end bikes have it. That you opened your display and used a soldering iron is commendable. Also that you are willing to ask for help.

 

[SpanishFlyer]

Thaks PedalUma,
I was thinking exactly the same, would never try regen braking ever again; Once I get a new display (hopefully free from the vendor), I will surely leave the parameter 13 to 0 (no braking streght and no energy recovery). What you mention that happened in San Francisco makes total sense, since a fully charged battery can take more charge and end up damaged. Strangely enough, in both my cases, the damage occurred as I was returning home with less than 3/4 of a charge... Still I have no doubt that the problem lies on the regenerative mode, where god knows what kind of voltage the 1500 W motor is producing, and being these kits some sort of a sum of parts all made in China, with no technical background or information and less help from them it only calls for something to fail. Just hope they contact me and send me at least one new display.
Best regards,
Spanish Flyer

 

[PedalUma]

Thanks. I think you are right. Components were taken off the shelf by marketing people and put together to meet marketing goals. It was not refined and tested as an integrated system, but as you said, the sum of the parts, parts that each looked good on paper. That could be a stellar regeneration unit! A theoretical team individual stellar parts is different than parts that have worked things out, like a band who has played together for awhile. That is why Charlie Watts was a better drummer than some hotshot, he supported the team effort.
Just for fun, here are a few of my electric bikes.

 

[harryS]

OK. The display still lights up and can still go thru the setup screens, It also starts up the controller, I guess the serial data lines between LCD and controller no longer work. Your over voltage blew up the data chip. Hope they will give you new ones, as that's like $80-100 USD in displays, Seems to me that they should have designed the LCD not to blow up with regenerative braking,

I agree, don't use regen. There's also a jumper wire on most KT controllers that must be connected to enable regenerative braking, Disconnect that just to be sure. I don't use direct drive motors so like to remove it. I also remove the connectors for the speed limiter, and the connectors for the external light relays, I pull the wires back inside the controller and wrap them up,. SImplifies the wiring, not habving fibe connectors that I don't need.

 

[SpanishFlyer]

Thanks for the pics of your beautiful bikes PedalUma; mine looks more like a tractor.... and with the 20" rear and 26" front, it is just as ugly as they can get... ; )
And harryS, both my displays are dead plus one of them stripped open and the USB module removed (see pic). The fact is that right now, since both displays are dead, I have no way of adjusting any settings; I will however try and find the regen connector and disconnect it.
My Display unit is a KT LCD 8H E Bike Special Meter, and I just hope I can get a free replacement from the vendor, because they are very expensive..
Best regards,
Spanish Flyer