E8000 turned off all assist modes at 8% battery

[mark.ai]

Just wondering if anyone has experienced anything like this:

I was heading back home up a road hill in boost mode. Battery started at 32% at the bottom, and about 8 minutes later I was nearly at the top and battery was down to 8% (roughly as expected). Suddenly the assist mode turned directly to off, and it wouldn't allow me to select any other assist mode. The display stayed on and Di2 gear changing kept working. No errors were displayed, and no info about why it wasn't allowing any assist to be selected.

I decided not to try turning everything off/on straight away in case that caused a worse problem like stopping the gear changes working. Luckily it wasn't too bad to pedal the rest of the way with assist off once I was over the top of the hill.

So once home I turned it off & on as a test and it was allowing me to change assist modes again. It showed 6km range in eco, 4km in trail and 3km in boost. Battery was still showing as 8% at this time.

I have boosted up this hill before, but with a higher battery percentage remaining. I have also boosted up a smaller hill, getting to the top with about 5% battery remaining and it automatically switched to eco mode. So I was expecting it to do something similar.

I'm wondering if the removal of all assist modes could have been because it was a longer hill this time and I was burning through the battery fast, so it didn't think it would last long enough to still allow even eco mode. And if having Di2 makes its safety margin even larger than non-Di2. Or if maybe the motor overheated temporarily - though I would have expected an error.

At least I know in future I can turn it off/on if this happens again and get eco to work for a bit. Or maybe switch out of boost mode before 10% battery to pre-empt it.

But interested to hear of others experience at low battery when using boost.

 

[R120]

it does switch assistance off when you get down to a certain level (cant remember exactly what) - maybe the brain was making an assumption based off available range given that you had been in boost for a while? I.E it made the call that the battery was about to go based on Boost usage, and would make the same call deeper into the percentage left if you had been in ECO/TRAIL

 

[Gary]

My E8000 display doesn't show exact percentages (Or not that I know of anyway)
normally my battery will go from 2 green to one green then fairly quickly go from that to red and then flashing red before forcing the mode to OFF
When using boost climbing this happens very quickly, sometimes (steep climbs) jumping straight from green to flashing red.
Di2 only uses a tiny amount of battery and the E8000 system was designed to keep it running even when the battery has used all it's (safe) motor juice.

 

[njn]

Where are you reading battery percentages from?

 

[mark.ai]

It's part of the information I get displayed on my Garmin Edge 1000 when I wirelessly connect it to the bike - which may only work as I have a Di2 rear derailleur connected to the rest of the E8000 system? It gets displayed as Di2 battery percentage.

Although I assume the E7000 connector thingamajig (EW-EN100) when it's released will also allow the same thing (but I haven't found a manual for that yet …)

 

[Kernow]

The way it runs out seems to have changed since the last update , I don’t often get to red but last time I did I am sure i had 2 red bar on the display which quickly dropped to one but two greens on the battery , I don’t think it locks into eco until the red starts flashing I don’t think I’ve ever tried boost when that low so I think your right asking for a long period of boost on a very low battery it drained it so fast it just shut down probably to protect the battery , cordless tools do the same thing
Since last update it seems to retain the fist 3 bars much longer then goes to red quicker than before .

 

[Gary]

I wish Shimano would document all the changes in their updates.
Over run has changed slightly over the last couple of updates
and so has motor assist control in Trail - Both are really noticable when wheelying the bike.
It's cool that Shimano are working on "improvements" and giving us regular firmware updtates but I'd like to know what they've actually done before blindly downloading the latest patch.

The sooner someone builds an app to allow more user customisable options the better.

 

[Deleted member 1478]

Battery sag?

Experience with my Bafang Fun-8 36V system on my commuter suggests that when you get down to low battery levels (that is, less than 20%) the battery can get quite 'saggy' - in that you can't run high assistance levels without sucking too many watts, causing the motor to stall because it isn't getting enough juice. The trick when this happens is to limp home gently with minimal assistance levels.

See Voltage sag explained - Electricbike.com Ebike Forum

As I have just taken delivery of my e8000, I am not sure yet how best to limp home, other than to toggle between eco and off?

 

[R120]

Yup, turbo/boost at low battery levels is not the same assistance as you get at higher levels

 

[Gary]

other than to toggle between eco and off?

I do this on the flat anyway and it definitely makes the battery last a hell of a lot longer
I also reckon higher cadence in low gearing helps as you're not pushing the motor to assist so much (looking at the power band on the display)