Focus Jam2 2017 battery drops to zero on Boost mode

[rmcr88]

I bought a used 2017 Jam2 cheaply. It has the Shimano E8000 set up. The previous owner said he had had it derestricted, and since then it works well in Eco mode but putting it in Boost mode causes the battery charge to deplete immediately. It goes from high charge to zero as soon as effort is applied in Boost mode, such as going up a hill. I can live without Boost mode but I'm interested to know what might be causing the battery to deplete so rapidly, and whether it's fixable. The bike came with a PC linkage kit which makes me think that the bike was desrestricted via software, but I don't know how to determine that. I managed to update the motor's firmware in the Project app using the PC linkage cable, but it didn't fix the issue obviously. Any thoughts would be appreciated.

Before anyone says I was an idiot for buying the bike, it was very cheap and I knew what I was buying, so I have no regrets on the purchase. Using it in Eco mode is fine for my needs, but the geek in me wants to know if I can fix it.

Thanks

 

[RustyMTB]

Obvs thing is to try it with a different battery. That would rule that out if the fault disappeared, then factory reset the firmware by disconnecting the battery for a few minutes or holding down the power button for a minute or so. After that I think Shimano have downloadable diagnostic software available if you wanted to dig right into it.

 

[Mikerb]

I think what you are seeing is the battery switching off when you go into boost. I assume that has something to do with the derestriction system. If the voltage is too high or indeed too low, the battery switches off as a protection method.

 

[rmcr88]

Hi, I’m just sharing this in case it helps someone else with a similar problem. I’ve now done all I can to reset the bike to what I believe are the factory specs. That required downgrading the firmware and connecting the eTuning app (after paying for it). With the app, I could see that the wheel circumference had been set to a smaller wheel, so I put it back to 27.5”. The chain ring was 43T, so I swapped it for a 32T ring and reflected that in the app as well. Finally, I changed the region back to my region, which limits the speed to 25kmh.

I also removed the motor and disconnected the battery, in case that reset something. I didn’t want to remove the battery from the frame to press the reset button on the actual battery, because that looks like a big job. The battery charges fine,, so I didn’t want to risk bricking the whole bike by messing with the battery.

I took the bike for a ride just now and it was fine in Eco mode, and Trail mode. I ended the ride by going up a hill in Boost, and the problem is still there. The screen indicated that the bike had a full charge (all bars) before I put it into Boost mode. After about 10 seconds the battery indicator dropped to one red bar, and in another 10 seconds the electronics shut off completely (motor & screen). It won’t start up again, and I’ll need to recharge the battery in order to power up the bike.

So, short of removing the battery to see if it resets, I think I’ve done everything I can do on the bike to try to fix whatever the problem is. I haven’t upgraded the firmware (4.8.x to 4.10.x) as I haven’t found anything to suggest that that would help, and it’s a pain to downgrade it again in case I want to make further adjustments.

I did wonder whether it would help if I lowered the torque setting for Boost mode (currently 70NM) and max wattage (currently 500). That assuming the motor is overloading the battery in Boost mode and lowering those settings would limit the max load. Not sure if it works like that.

As always, any clues or guesses about what might be going on would be welcome. The bike runs fine in Eco mode, so I’m not desperate - just curious to see if it can be fixed.
Thanks R

 

[Eckythump]

The original Jam2 has a small battery 378wh which was a selling point, kind of the OG SL bike.
Downside to this you are probably seeing voltage draw down when in boost which the aging cells are struggling to keep up with.
Do you have the TEC pack? Adding the second battery will tell you if it is draw down.
Another option is to turn down the settings in boost.
The bike originally came with a de-tuned settings so if you have reset to Shimano Factory the motor might be asking for too much.

If all else fails having the battery rebuilt with new cells is possible. The battery is pretty easy to disassemble on the Jam2.

Great bike though. My wife still runs one.

 

[steve_sordy]

This may give an indication of battery health in the absenceof any other method.

When you first turn on the bike, with the mode in Eco, what range does the display show. I had a 2019 Jam2 and from memory, the range shown on the display was about 48 miles. I know that this changes once you start riding, but it's always the same on start up. My current bike, another Shimano, the range on start up in Eco has dropped from 105 to 95 miles, but it is over 4.5 yeras old.