Battery life

WheezyRider

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Are there any BMSs which will do balance charges at lower given voltages? Seems to make sense to always do a balance charge, to keep battery life of individual cells as similar as possible, yes not at full voltage.
There are some programmable BMS out there, but they are not very common and tend to be for larger applications than e-bikes. There are some with Bluetooth for cell bank monitoring though.
 
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soundwave

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How much would Peter charge for frictionless synthetic sapphire bearings? :eek:

it is the cost of manufacture and how much better they would be as he has to order 1000 of each bearing he cant get off the shelf as none of them sell bearings but did ask if a 80 quid ceramic bearing would last any longer on my ses wheel and it will but not at that price as can get a pack of ten for under 5 quid.

pro road bikes racers will change wheel bearings or wheels every stage and use baby oil in the bearings for less friction.
 
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WheezyRider

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If they are always balance charged (to a lower voltage than maximum), the internal resistance would remain similar? If the cells were manufactured consistently.

If the cells were manufactured consistently, matched for their initial internal resistance, capacity and voltage when they are assembled into a particular pack, then they should all age in a similar way, even if balanced at a lower voltage.
 

soundwave

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If they are always balance charged (to a lower voltage than maximum), the internal resistance would remain similar? If the cells were manufactured consistently.
yes and thats why you get cells from a trusted supplier but not every corn flake out the machine can be trusted and why qc is very important but they can still go bad and why a decent bms will kill the pack if it sees a problem.

bosch ebike batts have a 2 year warranty or 200 charge cycles which is about right if you dont use a dongle just plodding along on the flat going 15mph same as using a flash light on low beam but you up the amps and it will use power faster and reduce charge cycles than at lower amps.
 

Nealh

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soundwave

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An example of a programmable BMS, this one comes with uart or BT connection.
One can monitor & set balance voltage and a few voltage parameters to one's liking.

12S 30A/40A/60A 50.4v BMS New Lithium Ion Smart PCM With Android Bluetooth compatible UART APP Software Monitor|bms pcm|pcm bmsbms li-ion - AliExpress
dont buy any bms with Bluetooth it will drain the pack flat my bike light does this if the pack is connected even turned off as constantly searching for the remote. :rolleyes:


 
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guerney

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An example of a programmable BMS, this one comes with uart or BT connection.
One can monitor & set balance voltage and a few voltage parameters to one's liking.

12S 30A/40A/60A 50.4v BMS New Lithium Ion Smart PCM With Android Bluetooth compatible UART APP Software Monitor|bms pcm|pcm bmsbms li-ion - AliExpress
My brother made one for a solar power system at university using a FPGA, but we don't talk anymore so I don't know the details:


 

soundwave

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i bet they dont get many charge cycles out of there batts 200A fkn have it ;)
 

soundwave

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guerney

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View attachment 49682


.

and that was the 1980s just no profit in it for mugs like us 40 years later we will have to just send sin bag down the lithium mines to get all the good stuff to make batts in 3rd world country's and dont forget all those cpus and transistors from china :p
China shows nuclear powered Lunar rover

 
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guerney

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It depends on the charger/battery. One brand is <1w so shows 0, the other two are <2w.
Don't they ever shut off completely? Even if the battery only has a two wire connection to the bike, surely it can't be impossible for BMSs of sufficient smarts to disconnect the power being supplied by the charger, after balancing? There's more of a business case for battery manufacturers to not equip battery packs with smarter BMSs which damage battery packs less, as they'll make and sell more batteries at a lower price and more often, as they fail.

I read there was a Chinese EV (car) maker at the Paris motor show this year using "blade" batteries... i.e. you slide old ones out and new ones in, rather like changing AA batteries in a torch.
Looks like it's BYD, who are also starting to make hatchbacks with sodium-ion batteries. It'd be nice to see more standardisation of connectors at charging stations too.

Toyota to launch EVs in China with BYD blade batteries

BYD to supply key tech including its blade batteries.






BYD to launch electric hatchbacks with new Sodium-ion batteries

 
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cyclebuddy

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Don't they ever shut off completely? Even if the battery only has a two wire connection to the bike, surely it can't be impossible for BMSs of sufficient smarts to disconnect the power being supplied by the charger, after balancing?
I haven't measured the DC side, but I'm sure they are effectively shut off. The idle current measured is on the charger's AC input.
 

georgehenry

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I think cost comes into it. The cheapish (£165 .62 delivered including a charger) 15Ah Yose silverfish battery that I bought in March this year is working well and hopefully of decent enough quality not to be a fire risk. It lives on one of my rear hub bikes in my attached garage and is charged there using a timer plug. I do set the plug to the maximum time it has which is 8 hours to allow for balancing. I also tend to use the bike the following day so that it does not sit there fully charged too long. But that is basically it on my battery care.

I have had a previous Yose battery that has lost some capacity but not that much and is over four years old so I am hoping this newer one will be similar. I even have the original silverfish battery that came with the rear hub bike that I bought for £100 from the clasified section of pedelec, and that still works and dates from 2011.

Less capacity of course but I did use it to ride 10 miles to work on full assist on a bike that assisted to 20mph carrying sadly over 100kg of me and two full panniers. I could charge it at work so it was full for the return trip. I guess what I am saying is if the batteries are less expensive you are less worried about how you look after them. The benefit is that the bike is ready to use without any pre ride battery charging planning.

The Yamaha battery on my Haibike is available for me to buy from the shop where I bought my bike but only the more expensive larger 500Wh battery priced at £849.99. My whole bike cost £1,750 to put that price into perspective and does not include a charger. If you needed a charger that would leave you only a couple of pence change from a thousand pounds.

As a consequence I do my best to look after my original 400Wh battery. But this really only entails bringing the battery into the house after a ride. Storing at 50+%, and only charging it back to full as close to riding the bike as possible.

At some point when I was using my bike very regularly to commute to work and having read that lithium batteries lasted longer if you charged them to around 80% rather than full, I made a few trips to work with a not quite full battery, but it would then be charged back to full at work. However Nealh pointed out that ebike batteries are different to electric car batteries and it was better to fully charge the battery each time so that the cells balanced. So I reverted to this but tried only to charge it close to when I planned to use it. This means that using the Haibike involves some forethought and planning which means it can be not available when you suddenly want to use it or conversely very occasionally has a full battery and your plans change and it does not get used. In those circumstances I take it out as soon as I can, generally the same day and ride it up and down a steep hill to take the edge of the battery.

There is none of this fluffing around with my ever available rear hub bikes.

However the Yamaha battery cared for in this way is lasting extremely well (Thank goodness) with still good capacity and working very well. I don't tend to ride less than about 20 miles and do use the higher middle assist to blast up the last steep hill home and am usually still above (just) 50% capacity left when I get home.

I meant to say that The Yamaha Battery is 7 years and 9 months old and my bikes total mileage to date is 16,774. Thank you the other useful replies, I will try and comment when I have more time.
 
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Nealh

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The Smart BMS in #65 uses B/T as an option to plug in so one doesn't have to use it , the uart to pc option is likely one good route but the optional add on may be pretty good. It utilises a seperate plug in uart lcd screen which one can make the adjustments with and to check cell levels.
 

egroover

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I think cost comes into it. The cheapish (£165 .62 delivered including a charger) 15Ah Yose silverfish battery that I bought in March this year is working well and hopefully of decent enough quality not to be a fire risk. It lives on one of my rear hub bikes in my attached garage and is charged there using a timer plug. I do set the plug to the maximum time it has which is 8 hours to allow for balancing. I also tend to use the bike the following day so that it does not sit there fully charged too long. But that is basically it on my battery care.

I have had a previous Yose battery that has lost some capacity but not that much and is over four years old so I am hoping this newer one will be similar. I even have the original silverfish battery that came with the rear hub bike that I bought for £100 from the clasified section of pedelec, and that still works and dates from 2011.

Less capacity of course but I did used it to ride 10 miles to work on full assist on a bike that assisted to 20mph carrying sadly over 100kg of me and two full panniers. I could charge it at work so it was full for the return trip. I guess what I am saying is if the batteries are less expensive you are less worried about how you look after them. The benefit is that the bike is ready to use without any pre ride battery charging planning.

The Yamaha battery on my Haibike is available for me to buy from the shop where I bought my bike but only the more expensive larger 500Wh battery priced at £849.99. My whole bike cost £1,750 to put that price into perspective and does not include a charger. If you needed a charger that would leave you only a couple of pence change from a thousand pounds.

As a consequence I do my best to look after my original 400Wh battery. But this really only entails bringing the battery into the house after a ride. Storing at 50+%, and only charging it back to full as close to riding the bike as possible.

At some point when I was using my bike very regularly to commute to work and having read that lithium batteries lasted longer if you charged them to around 80% rather than full, I made a few trips to work with a not quite full battery, but it would then be charged back to full at work. However Nealh pointed out that ebike batteries are different to electric car batteries and it was better to fully charge the battery each time so that the cells balanced. So I reverted to this but tried only to charge it close to when I planned to use it. This means that using the Haibike involves some forethought and planning which means it can be not available when you suddenly want to use it or conversely very occasionally has a full battery and your plans change and it does not get used. In those circumstances I take it out as soon as I can, generally the same day and ride it up and down a steep hill to take the edge of the battery.

There is none of this fluffing around with my ever available rear hub bikes.

However the Yamaha battery cared for in this way is lasting extremely well (Thank goodness) with still good capacity and working very well. I don't tend to ride less than about 20 miles and do use the higher middle assist to blast up the last steep hill home and am usually still above (just) 50% capacity left when I get home.
Have you considered an aftermarket compatible battery like this at £283

 
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flecc

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The electric mini is a retrofit using large prismatic cells, and a weird shape to fit where they've ripped out the transmission and fuel tank
The Mini isn't the only one. All the Nissan Leaf models for more than a decade use flat cells and I believe their partner Renault also do on all the Zoe models for a decade. Many of today's electric buses too.

And most are weird shaped too. For example here's the latest Nissan Leaf floor pan, the blue battery in two parts under the seats., bridged by part which would have been a transmission tunnel on an ic car:

Leaf chassis and battery.jpg
 
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guerney

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The Smart BMS in #65 uses B/T as an option to plug in so one doesn't have to use it , the uart to pc option is likely one good route but the optional add on may be pretty good. It utilises a seperate plug in uart lcd screen which one can make the adjustments with and to check cell levels.

It's unclear from the AliExpress listing how programmable that BMS is - could it charge my 36V battery to 39.5V, then balance in stages, in a manner similar to the description by @cyclebuddy in post #32, if paired with a programmable charger?



I'd find that sort of voltage useful for my 19.2ah battery, because I could set the timer to balance charge for the range I actually need - some days I may need only 12 miles in total, other times I might need 40+, in which case I'd do a full voltage balance charge.
 

Nealh

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It's unclear from the AliExpress listing how programmable that BMS is - could it charge my 36V battery to 39V, then balance in stages, in a manner similar to the description by @cyclebuddy in post #32, if paired with a programmable charger?

One doesn't need to mess with many parameters , only a few programmable parameters are the necessary ones.

Balance range adjustment 3.3v - 4.2v .
Over voltage 3.6v - 4.3v.
LVC 2v - 3.3v.
Over current & temperature.

With a large battery capacity if one has the needs to carry a so much weight and range then 4 - 4.05v balance will likely suffice , with a smaller capacity battery then 4.1v will be ok. The top end 0.1v of a charge carries little mah capacity and for most ebike batteries only equates to 1- 1.5 miles in range.

A monster pack of plus 30ah one could opt for less then 4v, though it is dependant how one uses that capacity vs discharge current used.
 
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cyclebuddy

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...or conversely very occasionally has a full battery and your plans change and it does not get used. In those circumstances I take it out as soon as I can, generally the same day and ride it up and down a steep hill to take the edge of the battery.
I do much the same as you, except if I find I'm left with a fully charged battery with no prospect of using it imminently, I'll usually burn off that energy using a string of 12v halogen lamps to get it back down to about a 38v storage level.

More recently though, it occurred to me that's useful energy being wasted. I've now bought a simple buck converter (£10-£14) to take battery voltage down to 12v, from which I've then got two 5v USB outputs (phone charging etc), 12v to power (as examples) my cool box, tyre pump, 12v heated blanket etc, and using a cheap inverter, powering my laptop and recharging my table-top radio.

It's early days and new uses keep emerging, but it's working so well I'm now fully cycling my e-bike batteries using them as power banks to power many things in my home. That keeps them active in times of low use/over the winter, and I'm guessing could prove quite useful in a power-cut!
 
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