Fix for Shimano Error Code E020: Battery contacts

[Spiff]

During a long ride and after switching from my first battery (External BT-E8010) which was at 10% to my second battery which was at 100%, this second battery throw an E020 error, which means:

E020:

• A communication error between the battery and drive unit was detected.
• Power assistance is not provided during riding.
• Check that the cable between the drive unit and battery is properly connected.

So I checked the cables and removed and installed back the battery several times but it failed again inmediately. To finish the ride, I installed back the first battery which was at 10% and configured ECO to minimum assistance and after 25 additional Km mainly downhill with only 250m altitude gain Ï finished the ride with the battery at 7%

When at home I tried to fix the problem and I "painted" the male pins in the battery holderwith conductive grease and after plugging and unplugging the battery, the large male pins for positive and ground show that the battery socket (female) pins have pressed against them, but the small pins for communication do not show sign of contact with the battery socket.

So then I "closed" the spring tabs in the battery small center sockets (for communication with motor) so they make contact with the male pins in battery holder. As the hole is tiny I used a thin sewing pin to carefully press the "spring tabs" towards the center of the hole.

After this, battery started working again and there were no more error codes.

 

[Spiff]

After a more detailed analysis of the Battery and holder contacts, I can say that this is another true design from Shimano famous designers Dumb and Dumber.

So, let me explain, Battery Holder in frame has four male tabs:

• One Short and wide (High curren) for +VBatt
• One long and wide (High current) for 0VBatt. Being longer insures that it is the first one to make contact.
• Two short and narrow (Low current) for data interchange. Probably I2C protocol

And the Battery has the 4 matching sockets and each of them has 2 metal springs at each side that make contact with tabs in Battery holder. So far, so good. But the bad part is that the spring contacts for data tabs are recessed inside the batery, that is:

• Data Male tabs in Battery Holder are 10mm long
• Data Metal Springs in battery are recessed 9mm

In the following picture we can see the Battery metal springs footprints in Battery Holder tabs and we can see that +VBatt and 0VBatt make a good and long contact, but Data tabs and its corresponding springs have only 1mm contact, but as the spring tip has a curved shape to allow insertion of the tab without damaging the springs, really the contact is less than 1mm so any tolerance will make that there is not a good contact, so motor will throw an E020 error.

After finding this, I am astonished that there are not many people complaining of battery E020 Error Code.

 

[Paul66]

After a more detailed analysis of the Battery and holder contacts, I can say that this is another true design from Shimano famous designers Dumb and Dumber.

So, let me explain, Battery Holder in frame has four male tabs:

• One Short and wide (High curren) for +VBatt
• One long and wide (High current) for 0VBatt. Being longer insures that it is the first one to make contact.
• Two short and narrow (Low current) for data interchange. Probably I2C protocol

And the Battery has the 4 matching sockets and each of them has 2 metal springs at each side that make contact with tabs in Battery holder. So far, so good. But the bad part is that the spring contacts for data tabs are recessed inside the batery, that is:

• Data Male tabs in Battery Holder are 10mm long
• Data Metal Springs in battery are recessed 9mm

View attachment 81409

In the following picture we can see the Battery metal springs footprints in Battery Holder tabs and we can see that +VBatt and 0VBatt make a good and long contact, but Data tabs and its corresponding springs have only 1mm contact, but as the spring tip has a curved shape to allow insertion of the tab without damaging the springs, really the contact is less than 1mm so any tolerance will make that there is not a good contact, so motor will throw an E020 error.

View attachment 81410

After finding this, I am astonished that there are not many people complaining of battery E020 Error Code.

Hi Spiff, thank you for the detailed response. Very helpful. Could you advise the conductive grease you painted the pins with?

 

[Spiff]

Hi Paul, I used this conductive grease, but it is currently Sold Out, but you can use a similar grease CONDUCTIVE BUT NOT DIELECTRIC.

 

[ScrappyDude]

Hi Paul, I used this conductive grease, but it is currently Sold Out, but you can use a similar grease CONDUCTIVE BUT NOT DIELECTRIC.

Hi Spiff, before reading this thread, I had smeared on a thick coating of dielectric grease into all of the female battery connections. Now I’m concerned that I have made the problem worse. Is there an easy and effective way that you know of to remove the dielectric grease so that I can put on the conductive grease? Do you know if it would be safe to use hot steam from a kettle to remove the grease and then clean it up with alcohol?

 

[Bill in Tomahawk]

Over the years there have been many products.


In a pinch we offten used disc brake cleaner if it was all we had. When I was learning mechanics as a kid(I'm 78 yrs) I had electrical problems aplenty and often my engines in $50 vehicles were covered with oil. That bothered me so I was always anxious to degrease engines. An old mechanic was watching me work on a '49 Chevrolet and asked me about my labors so I told him how the engine would run better when I was done with it. Yes he said, maybe it will but I've nevber seen a greasy connection fail. It took me a while to realize that electricity's enemy is not oil, it is corrosion. So I startrd oiling connections 50 years ago.

I have never had one fail.

I rode my motorcycles to South America(Tierra del Fuego) and agross Russia, Mongolia and Europe not to mention all over the USA, never had a oily connection or battery connection fail. I have used dialectric grease, it doesn't get hard...but neither does electric motor oil.


If you decide to try some be aware that if you shove the spout in and don't cap the tube a positive temperature change will force oil up the tube and you will have a mess so save the cap or leave the tube extended.

Bill in Tomahawk