Hello,
I would like to share with You my observations (because they may be useful to someone) from tests of available firmware (FW) for the M820 engine, which are designed for nominal battery voltages of 36V, 43V and 48V. I did all tests on the DIY 13S3P LG21700 M58T battery (nominal 48V) which, depending on the selected FW version, was used in the voltage range:
- FW48V: 54.6V – 46.0V
- FW43V: 54.6V – 42.0V
- FW36V: 46.2V – 38.0V
I only use the bike in the mountains and that is how I tested it riding on the following support modes: T-50%, E-25%, S-25%
ATTENTION!!! If You want to do such tests yourself, do not charge the battery for a specific FW above the voltage indicated above because you will not start the drive (it helps to upload a higher FW in FORCE FLASH mode or discharge the battery using some load).
My observations:
FW48V:
- the power delivered by the engine is highly dependent on the force put into pedaling - it does not resemble the support known to me from Brose, Shimano engines (surprisingly, I have never ridden Bosch in the mountains), when climbing you can feel uneven power delivery - such power fluctuations, there is no problem with dragging the support after finishing pedaling, the minimum power during gentle riding at a speed of approx. 15 km/h delivered by the engine and read from the display indicates approx. 30W for E÷S+ modes, the engine does not heat up as much as in FW36V, in my opinion FW works well in gentle terrain, it is difficult to ride in the mountains.
FW43V:
- the power delivered by the engine is "flat" - it resembles the work of the Brose and Shimano engines I know, you don't feel the wavering power delivered during climbing like with the FW48V, after finishing pedaling the engine can often work for up to about 2 seconds, and in Boost mode when I pressed harder on the pedals it probably worked even longer (this happens randomly and it's hard to say what it depends on), the minimum power delivered by the engine during gentle riding at a speed of about 15 km/h and read from the display indicates about 60W for E÷S+ modes, the engine heats up similarly to when working on the FW48V.
FW36V:
- the power given off by the engine is "flat" practically as noticeable as with the FW43V, after finishing pedaling ONLY A FEW TIMES did the engine work for a moment - max 1 second or maybe even shorter, the minimum power during gentle riding at a speed of approx. 15 km/h given off by the engine and read from the display indicates for E÷S+ modes approx. 50W, I believe that the engine heats up more than when working on FW43V and FW48V (temperature measured organoleptically each time). Unfortunately, I tested this software on the shortest distances of ~20km and climbing max 1000m due to the limitations of the 48V battery in this case - i.e. the narrowest range of possibilities of using its potential.
Conclusion: for me the most refined is FW36V.
Personally, I would like the FW43V to behave the same as the FW36V so that I could continue using my DIY 48V battery to use its large capacity more widely and limit engine heating due to lower currents.
And I am currently facing a dilemma whether to build a new 11s3p battery on LG M58T cells and use the FW36V or wait for the new FW for 43V - 48V to appear... (I would like a real range in the mountains of ~50km/2000UP using only E/T/S modes as before).
I am curious if You have similar observations, especially when using factory batteries?