Answered discharging shimano e8000 battery.

[sam-widgers]

guys, is it possible to do a partial manual discharge of an e8000 battery?(without actually riding ) mine`s currently sitting with a full charge but i`d like to reduce it to 60-80% while it`s not being used.
thanks.

 

[nosenada]

Other than putting your bike in a mechanics stand and zip tying the walk mode button, no there is no way.

The batteries use some sort of CAN bus and must receive instructions to output any voltage to the terminals.

I would not worry about it too much especially if it is a internal e8035 battery as a cycle is far more degrading to that model of battery than keeping it at full charge.

 

[sam-widgers]

Other than putting your bike in a mechanics stand and zip tying the walk mode button, no there is no way.

The batteries use some sort of CAN bus and must receive instructions to output any voltage to the terminals.

I would not worry about it too much especially if it is a internal e8035 battery as a cycle is far more degrading to that model of battery than keeping it at full charge.

Funnily enough I saw that method on YouTube and gave it a go but reckoned it would take a week to use any juice at all.
It's the e8020 external battery.
I'll just have to get out on knock a few road miles off and use some battery life that way.
Thanks for the input.

 

[flash]

I would not worry about it too much especially if it is a internal e8035 battery as a cycle is far more degrading to that model of battery than keeping it at full charge.

How did you get that information? I haven't seen anywhere that a cycle (in this case 20% of a cycle) would do more damage than storage at a high SoC. There's nothing particularly special about any of the Shimano batteries.

Certainly for a few days it's hardly worth the effort but if storage is several weeks or months then getting charge to 70% would be a good idea for maximum battery health.

Gordon

 

[nosenada]

How did you get that information? I haven't seen anywhere that a cycle (in this case 20% of a cycle) would do more damage than storage at a high SoC. There's nothing particularly special about any of the Shimano batteries.

Certainly for a few days it's hardly worth the effort but if storage is several weeks or months then getting charge to 70% would be a good idea for maximum battery health.

Gordon

My experience from owning 4 batteries (internal 504wh bt-e8035) and watching them all rapidly decline in health regardless of how I stored them. Three of the batteries were always stored at 40-60%, one of them I always charged to 100% after my rides. As you can see it does not seem to matter as they all declined in the same manner.

Battery 1 - Original Battery
90% health; 10 cycles
87% heath; 23 cycles (at 87% agreed to warranty)
85% health; 32 cycles
84% health; 38 cycles
82% health; 40 cycles

Battery 2 - New Battery Purchased as Second Battery
90% health; 10 cycles
87% health; 20 cycles (either at 90% or 87% Shimano agreed to warranty)
85% health; 30 cycles

Battery 3 - Warranty Batt (24) (4/23/2020)
91% health; 4 cycles and - only 20 days old (4/23/2020)
89% health; 11 cycles
87% health; 20 cycles (Shimano refused warranty says has to be 60% 10/6/2020)
84% health; 30 cycles (11/29/2020)
82% health; 40 cycles (1/8/2021)

Battery 4 - Warranty Batt (B0) (4/23/2020)
90% health; 11 cycles (Shimano said they wanted more degradation)
90% health; 14 cycles
87% health; 21 cycles (Shimano refused warranty says has to be 60% 10/6/2020)
85% health; 30 cycles (12/20/2020)

 

[flash]

Where did you get those figures? Did you notice any change in range?

I have 3 external 504wH Shimano batteries. All show different "health" levels in STUnlocker. Between 85% and 97%. When my first battery quicly hit 90% after about a month I though WTF!. But in reality it hasn't actually showed up in the range I can get from it. They've been like that for 2 years and there's no appreciable difference in range between any of them. I have two steps bikes and it doesn't matter which bike or which battery. They have almost exactly the same range on the same bike. I don't think the figures from STUnlocker really give a true indication of battery health. I get pretty much the same range today as when I bought them. Each battery has well over 100 full cycles.

I have done some formal training on Lithium batteries (as part of my commercial drone program) and LiOn batteries don't like being stored at a very high or low rate of SoC. A single cycle does little damage compared to charge state and temperature. These things are rated for a 1000 charge cycles (at 60-80%). It's likely that they don't ever actually get to 100% SoC based on a quoted figure of 1000 cycles.

Gordon

 

[sam-widgers]

i`ve always recharged shortly after returning from a ride when i was riding weekly but my last ride was november last year so it`s been sitting for almost 2 months all full charge. what`s puzzled me though is that the estimated range in eco on 100% has always shown 52 miles but when i checked a couple of days ago it`s dropped to 44. i put it on charge (i realise now it probably wasn`t the best idea) but range still showed 44. is it normal to drop as much as that so quickly?
i`ve discovered stunlocker thanks to this forum so attached a shot of the battery data,not sure if it shows good,average or bad stats.

 

[flash]

2 months at full charge isn't a great idea. Not good for battery health. But you really need to ride it before you can tell if range has dropped. The estimates on the bike are pretty poor and I don't personally trust the data shown by STUnlocker (not sure how it's reported to the app from the battery) is a real indicator of range either.

Strongly suggest you move to charging battery the night before you ride.

Gordon

 

[sam-widgers]

Yep I'm definitely going to change my charging/storage regime,going to get out at the weekend get the battery level lowered.
Thanks.

 

[nosenada]

Where did you get those figures? Did you notice any change in range?

eTube app using the pce02 interface. Yes, range has been reduced although it is hard to notice until it gets to 85% and below.

 

[Gary]

The estimates on the bike are pretty poor and I don't personally trust the data shown by STUnlocker (not sure how it's reported to the app from the battery) is a real indicator of range either.

When I had two Shimano E bikes and each used the same 504wh external batteries. Stunlocker would give me a different battery health % for each bike. One showed as 100% and the other 92% and if I swapped the batteries between the bikes the health %s would remain the same for each bike. So yeah. I've no idea how it's reported to the app either but it's definitely not accurate.

 

[Doug Stampfer]

Ive thrashed battery tools every day for years & can't think if I have had a battery fail before the tool up. Is this just a bit of paranoia with bike batteries?