Bosch e-bike battery recharging (and therefore others?)

[slope]

Warning! I read this on the internet and really WANT to believe it. But?

"Also, it’s worth pointing out now that many people think that a part charge counts as a full charge cycle in Bosch’s terms. Unfortunately.. it doesn’t! If you just top the battery up a small amount, only this is recorded and will not be counted until there are enough of these partial charges to count toward a full charge cycle. "

"Unlike the older style batteries where you had to completely discharge the battery and then fully charge it back up again, the new Bosch PowerPacks do not need this. In fact, it’s much better to just top up the battery after every trip. So if you have just cycled 10 miles on your electric bike, it’s better to top it back up to full when you get home rather than incorporating a few trips before charging fully."

Source: https://www.cycle-revolution.net/blog/how-to-look-after-the-life-of-your-bosch-ebike-battery/

Is this true?

How can the BMS decide which sizes of part recharges are within its parameters to equal ONE full charge? Etc?

(asks a person who knows nothing and thinks electricity is a dark other art with the potential to kill and generally piss people off sometimes)

[Pickled Onion]

Warning! I read this on the internet and really WANT to believe it. But?

"Also, it’s worth pointing out now that many people think that a part charge counts as a full charge cycle in Bosch’s terms. Unfortunately.. it doesn’t! If you just top the battery up a small amount, only this is recorded and will not be counted until there are enough of these partial charges to count toward a full charge cycle. "

"Unlike the older style batteries where you had to completely discharge the battery and then fully charge it back up again, the new Bosch PowerPacks do not need this. In fact, it’s much better to just top up the battery after every trip. So if you have just cycled 10 miles on your electric bike, it’s better to top it back up to full when you get home rather than incorporating a few trips before charging fully."

Source: https://www.cycle-revolution.net/blog/how-to-look-after-the-life-of-your-bosch-ebike-battery/

Is this true?

How can the BMS decide which sizes of part recharges are within its parameters to equal ONE full charge? Etc?

(asks a person who knows nothing and thinks electricity is a dark other art with the potential to kill and generally piss people off sometimes)

Sorry, is what true? My laptop adds up part charges as fractions of a cycle when it reports the number of charge cycles, presumably the controller for the Bosch battery does something similar?

As for the "unlike older batteries..." is this a variation on the memory effect myth?

[Kim]

All the BMS has to be able to do is integrate current over time and add it up, so that's certainly well within the capabilities of a microcontroller.  It's probably integrating already to give you a vaguely accurate capacity gauge.

I don't think the memory effect is a myth, but it only ever affected Ni-Cad batteries, and only in applications where they were repeatedly discharged to the same point before recharging.  Most of what's attributed to memory effect is straightforward loss of capacity due to age, overcharging or deep discharging.

I know nothing of Bosch's implementation or warranty terms or whatever.

[Pickled Onion]

I don't think the memory effect is a myth, but it only ever affected Ni-Cad batteries, and only in applications where they were repeatedly discharged to the same point before recharging.  Most of what's attributed to memory effect is straightforward loss of capacity due to age, overcharging or deep discharging.

It was a myth in consumer applications. ISTR it was observed in cells installed in satellites that had an exact repeating charge/discharge cycle.

[Kim]

I don't think the memory effect is a myth, but it only ever affected Ni-Cad batteries, and only in applications where they were repeatedly discharged to the same point before recharging.  Most of what's attributed to memory effect is straightforward loss of capacity due to age, overcharging or deep discharging.

It was a myth in consumer applications. ISTR it was observed in cells installed in satellites that had an exact repeating charge/discharge cycle.

Yeah.  With the possible exception of power tools, where Ni-Cad held on for a surprisingly long time, most consumer NiCad chargers were fairly primitive, and prone to overcharging.

[slope]

Sorry, is what true?

Apologies my bad for not expressing meslef better🙄

Just wanted confirmation that it's ok to recharge/top up these types of batteries after every ride, rather than waiting until they are down to 20%, as I thought/understood/read on the internet/etc was the best practice?

[IanDG]

Just looking at the handbook that came with my Raleigh Trace (Mahle X35 hub motor with ebikemotion B1 internal battery)

- After the first full charge, the battery can be partially charged. Partially charging the battery will not damage it, as lithium-ion rechargeable batteries do not have a memory effect.

- Partial charges are rated proportionally to their capacity (a charge of 50% corresponds to half a charge/discharge cycle).

[slope]

Just looking at the handbook that came with my Raleigh Trace (Mahle X35 hub motor with ebikemotion B1 internal battery)

- After the first full charge, the battery can be partially charged. Partially charging the battery will not damage it, as lithium-ion rechargeable batteries do not have a memory effect.

- Partial charges are rated proportionally to their capacity (a charge of 50% corresponds to half a charge/discharge cycle).

That's unambiguous enough for me For some reason I couldn't find that info on the Bosch website. But that could be my further ineptitude also.

[Diver300]

Sorry, is what true?

Apologies my bad for not expressing meslef better🙄

Just wanted confirmation that it's ok to recharge/top up these types of batteries after every ride, rather than waiting until they are down to 20%, as I thought/understood/read on the internet/etc was the best practice actually?

Topping up a battery after every ride is fine. There have probably been some insufficiently intelligent battery management systems that counted any recharge as the same thing, but there is no excuse for that nowadays. In fact, some battery management systems would turn off the battery after a certain number of cycles, claiming safety as the reason.

I know that lead-acid batteries degrade far less in 10 discharges from 100% to 95% than they would in one discharge from 100% to 50% and I can't believe that Li-Ion batteries suffer worse in lots of short discharges.

EVs obtain relatively homeopathic amounts of charge by generating electricity from slowing the vehicle, and during most driving that is happening frequently*, and the car manufacturers would certainly not program the cars that way if each brief period of regeneration degraded the battery to any measurable amount.

On the other hand, Li-Ion batteries may degrade faster over time (not use) if fully charged. The maximum state of charge is a compromise between capacity and degradation, so there can be avantage in not leaving batteries fully charged.

*I've been logging the traction battery current on my car for about a year now, with the maximum and minimum current recorded every minute. At some point in most minutes the traction battery current is negative (charging). There is almost always something to slow for, downhill slope.

[grams]

The received wisdom with lithium is that it’s better to only charge to 80% and charging to 100% all the time is considered harmful*. Some newer phones and laptops have features to do this for you. So the advice as written is encouraging you to do a different badness.

(* although good luck finding solid numbers for the actual harmfulness)

[aidan.f]

Lots of little top ups maybe more wear and tear on connectors and battery clips. Plus ICBA YMMV.

[slope]

Many thanks all for the enlightenment and alleviating my misery of ignorance. It's a bloody good job electronics are smarter than i.