Bosch Battery Conundrum

[Lengthenby]

Greetings, I live overseas and bought my bike from a dealer over here. And mostly their support has been quite excellent. But I have a rather silly question to which they cannot provide an answer. Perhaps someone has been round this loop:
After a full charge of my 500Wh battery the Intuvia display gives a range of 86km (Eco). After cycling for about 20km this range has increased to 91km.
Does anyone know where I can discover what information the system uses to arrive at the "Range" and whether this information is stored in the battery or in the display unit? It is not vitally important because the "fuel level" bars give a good indication of battery state, but it niggles to wonder why this more "sophisticated" read out seems to be misleading - or to be brutal - not much use!!

 

[sjpt]

As you say, not much use. It depends on a very small window of recent history (looks like a mile or two) to compute miles per watt, and gives the range based on that and current battery charge.

So if the end of your previous ride was somewhat uphill you will have been getting fewer miles per watt, less range. When your start again after battery charging it will give range based on full battery and yesterday's end of ride (lower) miles per watt. After a few miles (possibly slightly downhill now) it will have changed to a much higher estimate of miles per watt, so give more range even with slightly less charge available.

I think (not 100% sure) that unlike less sophisticated systems that base remaining charge on voltage, the Bosch system does actually measure and integrate current to have a much more accurate idea of remaining charge. It would be much more helpful if the display showed that rather than the almost useless estimated range.

The estimated range does give (very slight) added interest to a ride, monitoring how stupid can it be today!

 

[Lengthenby]

As you say, not much use. It depends on a very small window of recent history (looks like a mile or two) to compute miles per watt, and gives the range based on that and current battery charge.

So if the end of your previous ride was somewhat uphill you will have been getting fewer miles per watt, less range. When your start again after battery charging it will give range based on full battery and yesterday's end of ride (lower) miles per watt. After a few miles (possibly slightly downhill now) it will have changed to a much higher estimate of miles per watt, so give more range even with slightly less charge available.

I think (not 100% sure) that unlike less sophisticated systems that base remaining charge on voltage, the Bosch system does actually measure and integrate current to have a much more accurate idea of remaining charge. It would be much more helpful if the display showed that rather than the almost useless estimated range.

The estimated range does give (very slight) added interest to a ride, monitoring how stupid can it be today!

As you say, not much use. It depends on a very small window of recent history (looks like a mile or two) to compute miles per watt, and gives the range based on that and current battery charge.

So if the end of your previous ride was somewhat uphill you will have been getting fewer miles per watt, less range. When your start again after battery charging it will give range based on full battery and yesterday's end of ride (lower) miles per watt. After a few miles (possibly slightly downhill now) it will have changed to a much higher estimate of miles per watt, so give more range even with slightly less charge available.

I think (not 100% sure) that unlike less sophisticated systems that base remaining charge on voltage, the Bosch system does actually measure and integrate current to have a much more accurate idea of remaining charge. It would be much more helpful if the display showed that rather than the almost useless estimated range.

The estimated range does give (very slight) added interest to a ride, monitoring how stupid can it be today!

As you say, not much use. It depends on a very small window of recent history (looks like a mile or two) to compute miles per watt, and gives the range based on that and current battery charge.

So if the end of your previous ride was somewhat uphill you will have been getting fewer miles per watt, less range. When your start again after battery charging it will give range based on full battery and yesterday's end of ride (lower) miles per watt. After a few miles (possibly slightly downhill now) it will have changed to a much higher estimate of miles per watt, so give more range even with slightly less charge available.

I think (not 100% sure) that unlike less sophisticated systems that base remaining charge on voltage, the Bosch system does actually measure and integrate current to have a much more accurate idea of remaining charge. It would be much more helpful if the display showed that rather than the almost useless estimated range.

The estimated range does give (very slight) added interest to a ride, monitoring how stupid can it be today!

As you say, not much use. It depends on a very small window of recent history (looks like a mile or two) to compute miles per watt, and gives the range based on that and current battery charge.

So if the end of your previous ride was somewhat uphill you will have been getting fewer miles per watt, less range. When your start again after battery charging it will give range based on full battery and yesterday's end of ride (lower) miles per watt. After a few miles (possibly slightly downhill now) it will have changed to a much higher estimate of miles per watt, so give more range even with slightly less charge available.

I think (not 100% sure) that unlike less sophisticated systems that base remaining charge on voltage, the Bosch system does actually measure and integrate current to have a much more accurate idea of remaining charge. It would be much more helpful if the display showed that rather than the almost useless estimated range.

The estimated range does give (very slight) added interest to a ride, monitoring how stupid can it be today!

Ah, just exactly so!! Thanks very much for such a quick and helpful reply. So I'm not so crackers as I was starting to wonder. The interest you speak of was starting to become an obsession. Now I can start monitoring some of the useful things on offer!!
It is a pity though, because the system - either display or battery, does have so much data. At the crudest it could use the total energy used to cycle say 3000km and give an average as a base. But actually it has much more information that a reasonably smart system could use.
But as you so nicely put it...just how stupid can it be today. Brilliant.

 

[soundwave]

 

[Fat Rat]

View attachment 37269

If my display ever showed that range at that battery level I would throw it in the tide lol

 

[Fat Rat]

Welcome to the forum

 

[soundwave]

it is because i have a dongle but it is still crap but i get about 5-6 miles per bar if i am hammering it.

 

[Warwick]

The battery charge display is one of my few Intuvia gripes. If I have two bars showing, that could be anything between 40% and 21%. That's quite a disparity. Why didn't they just put a percentage display, or have 10 bars?

 

[soundwave]

The battery charge display is one of my few Intuvia gripes. If I have two bars showing, that could be anything between 40% and 21%. That's quite a disparity. Why didn't they just put a percentage display, or have 10 bars?

when i had that display it could not even keep time lol.

 

[Lengthenby]

Thanks for all the replies and welcome. Sorry for messing up the thread with failed attempts at replying. I will try to do better now.....
A while back when I still believed the "Range" display I made a
VERY EXPENSIVE AND STUPID MISTAKE....
A group of us oldies had planned a longish tour. In the weeks before the start I had decided to try to do a little training for legs and lungs. So I did all my training rides with no battery assistance. I even walked when I got to the long steep bits.
Ten days before the Off I started to use the battery normally. To my horror I found the Range on Eco was down around 15km. Despite a couple of re-charges to the full 5 bars (or 5 LEDs) it didn't come above 20km and of course proportionally less on the more powerful assists.
No way would that be enough for the planned tour.
Corona had ensured I couldn't get the battery to the dealer for a test.
"Knowledgeable" friends assured me I should never have used the bike with the battery off and I had likely ruined the motor as well as the battery. The motor seemed ok. So I bit the hugely expensive bullet and ordered a new battery .
It came, the tour was fine.
I thought I would just see if the old battery would be any use for short trips so I would try a test to see how far it actually would go on Eco.
It still said I had 20km in the tank.
After a tentative 20km it said I had 50km left. After another 20km without a charge it said 80km left. ........and you can guess the rest.
I cannot discover anywhere that Lithium ion batteries behave like this. So the "Stupid" display (credit to sjpt, Esteemed Pedelecer) added to an extremely stupid rider was a bad combination.

(500Wh 2.5 years old)

Has this only happened to me? And if not, how to make folk aware?

 

[soundwave]

Lithium ion batteries also dont like not being used for long periods of time and can damage them so make sure you are using both batts.

i have 2 batts and my 5 year old 400w is still going i just use it for shorter rides as it is showing its age now.

 

[Lengthenby]

Thanks soundwave. I do now try to alternate them.
But the period for which I rode with the assistance off was only about a month so I imagine the battery wouldn't object too much to that?

 

[soundwave]

no it is when you leave it not used for months it then can become a problem esp if it was fully charged.

 

[Lengthenby]

good, thanks.

 

[flecc]

I cannot discover anywhere that Lithium ion batteries behave like this. So the "Stupid" display (credit to sjpt, Esteemed Pedelecer) added to an extremely stupid rider was a bad combination.

Some of the best lithium batteries have a Sleep mode which shuts down the BMS (battery management system) if the battery isn't used for a couple of weeks or more to prevent damaging excess discharge use by the BMS. I'd expect the Bosch ones to be like that.

A "sleeping" battery is woken up by plugging in the charger and recharging to return it to life, so that is probably what happened to yours. It won't have damaged your battery so you now have two good ones.
.

 

[Lengthenby]

That is a really interesting idea, thanks very much indeed. I must try to find out if Bosch claim to have such characteristic in the BMS. Thanks again.

 

[soundwave]

https://www.bosch-ebike.com/fileadmin/EBC/Service/Downloads/Akku_Guide/Akku_Guide_MY20_2/Bosch-eBike-Battery-Guide-MY2020-EN.pdf?_=1559630936

i have never had to wake up my batts with the charger tho.

 

[Samcycles]

Like so many people have said the range estimate on the intuvia fluctuates a lot but I've got used to it quite quickly. When I'm riding on the flat above the cut off the range increases because naturally I'm covering miles without draining power but if there is a hill to climb I will be in sport or even turbo and the range will drop drastically. Over 20-30 miles I find it balances out. My last ride was 32miles. In eco the range started as 81miles and finished on 42 miles and 3 of the 5 bars on the battery indicator.
During the first half of the ride I was in eco and above the cut off quite a bit so the range barely dropped at all but I used quite a bit of sport and tour during the return leg and a bit of turbo as it involved 1300ft of altitude gain. Based on that 39miles of eco range used seems about right.

 

[flecc]

That is a really interesting idea, thanks very much indeed. I must try to find out if Bosch claim to have such characteristic in the BMS. Thanks again.

The excerpt I've posted below from Soundwave's Bosch guide seems to indicate it does prevent or greatly reduce continuously discharging by controlling the BMS drain of current continuously. If it didn't one wouldn't be able to use the battery at any time after winter storage without recharging:

"Very low self-discharge rates – Even after prolonged storage, such as during the winter, it is possible to use the rechargeable battery without recharging it. For longer storage, a charge status of approx. 30 to 60% is recommended."
.

 

[Lengthenby]

https://www.bosch-ebike.com/fileadmin/EBC/Service/Downloads/Akku_Guide/Akku_Guide_MY20_2/Bosch-eBike-Battery-Guide-MY2020-EN.pdf?_=1559630936

i have never had to wake up my batts with the charger tho.

Thanks, they seem to have given a little more info than before. The BMS does appear to work very well indeed. I think my fundamental mistake was taking the Intuvia suggestion as just that. Not in any way gospel.