Battery Health

[Kiwi Phil]

Right, got to ask.....
I've done 1123.8km (698.29miles) and the battery has registered only 31 charge cycles. BUT......my battery health has dropped from 95% down to 81% in the last week.
I have done nothing different in the way of charging etc, but concerned that the health has dropped this quickely over a short time.
The bike is due for a free check soon and I have it booked in.
What is everyone elses experiences with Battery Health?

 

[Rob Rides EMTB]

Hmm that doesn't seem right. I haven't checked mine in a while. What I would say is that the health is only usually the software interpretation, so not an exact science, so there may be some error in the way that it is calculating the health. Let me know how you get on.

 

[Eckythump]

You may find it is due to the cold weather.
Lithium battery ‘health’ is normally based on internal resistance, another measure is how many mah it takes to increase from one voltage to another in a pack of a known capacity. Both of these indicators can be affected by temperature.
Good news is it should come back as temperatures rise.

 

[Kiwi Phil]

You may find it is due to the cold weather.
Lithium battery ‘health’ is normally based on internal resistance, another measure is how many mah it takes to increase from one voltage to another in a pack of a known capacity. Both of these indicators can be affected by temperature.
Good news is it should come back as temperatures rise.

Unfortunitely cannot be due to the Cold as it is mid summer here in New Zealand, (temps ranging from 27degC to 32degC)

 

[Kiwi Phil]

Hmm that doesn't seem right. I haven't checked mine in a while. What I would say is that the health is only usually the software interpretation, so not an exact science, so there may be some error in the way that it is calculating the health. Let me know how you get on.

My thoughts too. The battery seems to last a similar distance to before. It just concerned me that it may have indicated faulty cells.
its due into the shop on the 21st so I will get them to check it out.

 

[Eckythump]

Oh well, worth a try??

 

[Kiwi Phil]

Oh well, worth a try??

 

[Japuserid]

I think Ecky is still right, in as much as it is temperature related, only it's not the cold but heat that is the problem.

Lithium Ion Batteries Can’t Stand the Heat

 

[Eckythump]

Maybe.

Another possibility, if you have been short charging it for a number of times it might be worth fully discharging it then do a full charge from empty. It sort of re-calibrates the Battery Monitoring System. Short charging is not an issue for the batteries, it can lead to an accumulation of errors in the brain though. You can see the same effect on mobile phones.

 

[Eckythump]

My LBS have had one or two Specialized battery exchanges so a duff battery is not unheard of.

 

[Kiwi Phil]

Thanks Ecky for the suggestions.
Drained the battery totally on Saturday after an epic ride. Luckily it was only 400m from home when she flattened ???.
I’ve ridden both last night and tonight and down to 20% with no change. Both rides have been in low 20’s (degC) so not overly hot conditions.However, as you say, it may still be temp related.

Interesting read thanks Japuserid ?

 

[Eckythump]

At least a Levo pedals nicely without the battery

 

[Taffyteg]

For battery health to drop so quickly means a suspect cell or it simply needs another discharge / charge up as a bit of a reset. I have had mine for a year now, still on 93% from memory and gets used weekly.
I try to not to let the SOC (state of charge) drop below 20-30%, this is where Li-Ion can start to degrade and reduce battery life. Temperature can also effect battery life / performance, Li-Ion does not work too well in the cold, well below freezing, and starts to degrade above 40/50degsC. I tend not to run my bike in Turbo mode for long periods or run at 100% current in order to stop things getting a bit toasty, plus I am supposed to be exercising

 

[Eckythump]

I wouldn’t worry about using turbo, even if you said the motor used 500 watts In a surge that’s less that 14amps. My Focus probably has the smallest capacity out there (2625mah cells configured 10s 4p) and at a conservative 2C output is good for 21amps continuous.

 

[Taffyteg]

I wouldn’t worry about using turbo, even if you said the motor used 500 watts In a surge that’s less that 14amps. My Focus probably has the smallest capacity out there (2625mah cells configured 10s 4p) and at a conservative 2C output is good for 21amps continuous.

That's handy to know, thanks for that.

I only like to use Turbo when I am having a mess about or sometimes going through deep mud, I want to get fit and ride longer and using Turbo means less effort from me and battery goes flat quicker.

 

[Eckythump]

That's handy to know, thanks for that.

I only like to use Turbo when I am having a mess about or sometimes going through deep mud, I want to get fit and ride longer and using Turbo means less effort from me and battery goes flat quicker.

I’m with you, only use turbo for steep rock climbs.

 

[Taffyteg]

Also I have took a screen grab of the battery health, it is now at 100%
I have had a recent FW update on both the motor and battery, I am surprised to see at 100%

 

[ccrdave]

I think its got something to do with the firmware thinking its a new battery, mine did the same

 

[Japuserid]

Li ion batteries are wonderful things, but not perfect they have some real limitations and they are very susceptible to performance degradation due to temperature.

Maintaining a good battery life / performance, is all about keeping it in the Goldilocks Zone.

Not too cold and not too hot. Not too flat and not too full.

Too cold, is the least problematic as this will only reduce the amount of charge the cell's will take, no long term degradation and capacity will return with increase in temperature.15 degrees Celsius is considered optimal for both storage and charging.

Too hot is much more of a problem, 30 degrees Celsius is considered to be an elevated temperature and running above this level will degrade the cells considerably faster than normal. So if it's 30 degrees Celsius 'ambient' then your battery will probably be running quite a bit above the ambient as it heats up with use.

Good advice from Taffyteg when it's hot outside, stay away from turbo when ever possible.

Too flat or low State of charge is also really not good and should be avoided as much as possible. if you do run your battery out and it shut's down then do not try and force anymore out of it, YOU MUST GET SOME CHARGE BACK IN ASAP, or you can risk long-term damage very quickly.

To full, or high state of charge is also not good, especially if storing for extended periods, the cells become stressed and this will also degrade the battery faster than normal. If you only ever charged your battery to 95% this could extend it's life quite considerably.

Most of all, avoid storing your battery fully charged, and at elevated temperatures, this double whamy is a real battery killer.

Re calibrating is also bit of a myth and really is not required, Li Ion batteries prefer smaller charges more often and so do not ever need to be drained for any reason.

For best results store your battery at room temperature with a partial charge. Charge the battery fully the night before your ride and make sure you use it as planned, if your ride gets cancelled whiz it around the block a few times and knock of a bar, before returning to storage

Sorry Phil, but I guess, poor battery life, is a price you will have to pay for living in one of the most beautiful places on Earth.

The link's below are well worth a read.

How to Prolong Lithium-based Batteries - Battery University

Understanding the life of lithium ion batteries in electric vehicles

 

[Kiwi Phil]

Yip, i'm like you guys and 100% is used rarely. I'm also interested in getting a workout and building leg strength, so its only used when needed.

I have asked the LBS to do a FW upgrade when its in for its check this time next week, so it will be interesting to see if it makes a difference to the battery health once done.

Thanks guys for the feedback

 

[Taffyteg]

Yip, i'm like you guys and 100% is used rarely. I'm also interested in getting a workout and building leg strength, so its only used when needed.

I have asked the LBS to do a FW upgrade when its in for its check this time next week, so it will be interesting to see if it makes a difference to the battery health once done.

Thanks guys for the feedback

If you are going from the old FW to the new FW you will notice a huge difference. I personally love it, but I have also seen a lot of people saying they hate it. Before in ECO mode you could still get high torque output from the motor / lots of assist, with the new FW this is capped to whatever you set it too - which personally I prefer as it makes you work harder ?

 

[Eckythump]

Re calibrating is also bit of a myth and really is not required, Li Ion batteries prefer smaller charges more often and so do not ever need to be drained for any reason.

The recalibrating discussed earlier was for the BMS rather than any ‘battery memory’ effect.

By the sounds of Taffyteg’s post the software update has re-zeroed its history anyway.

 

[Kiwi Phil]

Just checked my Firmware which is 4.22.3

 

[Eckythump]

Is the ‘current level’ charging current or did you screen grab the page while riding?

 

[Kiwi Phil]

It must be charging as I screen grabbed it away from the bike. The last time the app was connected to the bike, the bike was sitting in the rack and I had just connected the charger ready for tonights ride.

 

[Taffyteg]

You are running the latest FW.

 

[Eckythump]

I wouldn’t worry about using turbo, even if you said the motor used 500 watts In a surge that’s less that 14amps. My Focus probably has the smallest capacity out there (2625mah cells configured 10s 4p) and at a conservative 2C output is good for 21amps continuous.

Bit of a correction needed about my bike battery. The apparent low cell capacity based on the packs amp hour rating had me wondering if I could re-cell to higher capacity ones so I took my piggy back pack apart for a look.
It is configured 10s 3p with LG MJ1 cells. These have a rated capacity of 3500mah. They are however a higher discharge, 10A continuous so 30A total from the pack. So plenty for a 250w ebike.
All very nice the pack having fancy cells but no opportunity for increasing range at this stage in cell evolution.

 

[Taffyteg]

Thanks again for this. I wonder which cells Specialized use? They have different sized packs, do they manage this with the number of cells or changing the type of cells used....

 

[Taffyteg]

Just answered my own question here,

460Wh - 40x3.2Ah
504Wh - 40x3.5Ah

 

[kcarbon]

kiwi Phil , what distances are you getting from your battery on one charge?