# Optimal Lithium Ion charging practise



## major (Apr 4, 2008)

My opinion is that you should charge every 2 days. I feel it is better to avoid low State of Charge compared to more frequent cycles of lesser total charge. I have not yet used a Lithium battery to its normal end of life, but who has? I have maybe 500 cycles on my Think EV. Looking like another 10 years for my battery


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## dougingraham (Jul 26, 2011)

Most of the damage seems to happen when the state of charge is near empty or near full. More near the empty end than the full end. Leaving the cells fully charged doesn't seem to have any adverse effect on them. Leaving the cells fully discharged does seem to degrade the cells. So Majors recommendation is a good one. If there was some way to turn the charger down so it didn't fully charge the cells that would also help. But you probably don't have any control over that. I have my charger set to stop early and because of that I just charge every day.


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## kennybobby (Aug 10, 2012)

*E20 BMS data?*

Do you have access to the BMS data during charging, for example does it monitor cell or pack temperatures in addition to voltage and current, that you could download and graph to see the time histories? Voltage and temperature during charging seem to be primary factors that affect battery life and nunber of cycles.


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## Kamleshgk (May 24, 2012)

major said:


> My opinion is that you should charge every 2 days. I feel it is better to avoid low State of Charge compared to more frequent cycles of lesser total charge. I have not yet used a Lithium battery to its normal end of life, but who has? I have maybe 500 cycles on my Think EV. Looking like another 10 years for my battery


Hey major,

thanx for the tip. so u have 500 cycles in how many years?
I have around 40 cycles in 6 months!
At this rate i will take 6 years to complete 500 cycles!!!!!


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## Kamleshgk (May 24, 2012)

dougingraham said:


> Most of the damage seems to happen when the state of charge is near empty or near full. More near the empty end than the full end. Leaving the cells fully charged doesn't seem to have any adverse effect on them. Leaving the cells fully discharged does seem to degrade the cells. So Majors recommendation is a good one. If there was some way to turn the charger down so it didn't fully charge the cells that would also help. But you probably don't have any control over that. I have my charger set to stop early and because of that I just charge every day.


Thanks. I agree and understand. Its better to stop charging when the SOC is 90% than 100% right? 
We have SmartPhone integration with we dont have any way to control the charge. I can stop charging using my smartfone app, when it reaches 90%.
That is possible!

Do you recommend to stop at 90% SOC?


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## Kamleshgk (May 24, 2012)

*Re: E20 BMS data?*



kennybobby said:


> Do you have access to the BMS data during charging, for example does it monitor cell or pack temperatures in addition to voltage and current, that you could download and graph to see the time histories? Voltage and temperature during charging seem to be primary factors that affect battery life and nunber of cycles.


Cool!

I shall try to get that data from the company!
If they share it, that is!

Thanks!


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## Kamleshgk (May 24, 2012)

This is what my car's documentation says about staying charged


```
Every e2o is incorporated with an advanced ‘Intelligent Energy 
Management System’ (IEMS) to optimise drive range 
performance. The IEMS comprises of a powerful on-board 
computer, that keeps constant tab on the state of the 
batteries and usage patterns.
The batteries need regular balancing and recharging, 
since low usage of the car and not keeping it plugged in 
overnight once in 3 days leads to the development of 
unequal states between the batteries.
 
Not plugging in could result in the activation of Safe 
Mode and the EV warning lamp on IP Cluster, despite 
higher charge levels while driving. We recommend that 
once in 3 days, you plug in the car for overnight charging 
(of about 10 hrs) since this enables the on-board 
computers to check and balance batteries that are low 
on charge in the battery pack, keeping all of them at same level.
```
I think i should be able to download the BMC reports.
Also it tells me to plug in overnight for 10 hours!!
I only plug it in until it reaches 100% SOC. Say from 8 pm to 11 pm and i unplug the charger!


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## dougingraham (Jul 26, 2011)

Kamleshgk said:


> Do you recommend to stop at 90% SOC?


I have the charger set to stop early. It stops around 95% but it depends on temperature as to where exactly it stops. I don't have any kind of BMS and one is not needed because the cells do not drift out of balance on their own. I think that the BMS's are the source of imbalance (the individual load on each cell varies) and so if you have one you probably need to let it do its nightly balancing act or you will end up with cells out of balance.


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## Kamleshgk (May 24, 2012)

dougingraham said:


> I have the charger set to stop early. It stops around 95% but it depends on temperature as to where exactly it stops. I don't have any kind of BMS and one is not needed because the cells do not drift out of balance on their own. I think that the BMS's are the source of imbalance (the individual load on each cell varies) and so if you have one you probably need to let it do its nightly balancing act or you will end up with cells out of balance.


Ok. So its recommended to keep it plugged in to balance the cells so that all the cells have the same load.
Thanks for the reply.


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## Kamleshgk (May 24, 2012)

So to summarize,

These are the steps that can be taken to keep the Lithium Cells happy and balanced to give us a looooong life 


Charge frequently - mostly every 2 days even if the SOC is 60%
Charge upto 90% SOC instead of 100% SOC
Atleast once a week, keep the cells in balance by plugging in for 10 hours overnight

So thank you everybody and do mention anything else i have missed!
You guys rock! I get so many answers here!

Thanks again.


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## major (Apr 4, 2008)

Kamleshgk said:


> Hey major,
> 
> thanx for the tip. so u have 500 cycles in how many years?
> I have around 40 cycles in 6 months!
> At this rate i will take 6 years to complete 500 cycles!!!!!


Hi Kam,

It was a demo a year old when I bought it in July 2012 with ~3500 miles on it. So I put about 14,000 miles on it in 19 months. I drove it today for the second time in the past 6 or 7 weeks. Snow and cold has kept in the garage way more than I like. Been a hard winter here; all time record snow and cold. Also needed to drive the truck (4WD) lately to do trailer towing.

As Doug mentioned, you need to leave your EV on the charger for extended periods periodically so it can balance. Once every week or two leave it on for 12 hours or more. I think pretty much all factory EVs need this. What I call short charging (unplugging it before it reaches 100%) is O.K. and some guys think it extends cycle life. For regular usage, the experts with whom I have spoken don't think it is necessary. But they do recommend leaving it at about 60% SOC if you store it for like a week or more.


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## Kamleshgk (May 24, 2012)

major said:


> Hi Kam,
> 
> It was a demo a year old when I bought it in July 2012 with ~3500 miles on it. So I put about 14,000 miles on it in 19 months. I drove it today for the second time in the past 6 or 7 weeks. Snow and cold has kept in the garage way more than I like. Been a hard winter here; all time record snow and cold. Also needed to drive the truck (4WD) lately to do trailer towing.
> 
> As Doug mentioned, you need to leave your EV on the charger for extended periods periodically so it can balance. Once every week or two leave it on for 12 hours or more. I think pretty much all factory EVs need this. What I call short charging (unplugging it before it reaches 100%) is O.K. and some guys think it extends cycle life. For regular usage, the experts with whom I have spoken don't think it is necessary. But they do recommend leaving it at about 60% SOC if you store it for like a week or more.


Hey Major,

Wow 22,500 km in 19 months. Around 1200 km per month.
I average around 600-700 km per month! - Sorry i dont understand miles 

The Think EV seems like a nice car! 
But i read that the production of these is stopped and the company went bankrupt? How are you managing servicing and other aspects if the company has stopped manufacturing and supporting these?

Thanks for these great tips!


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## major (Apr 4, 2008)

Kamleshgk said:


> The Think EV seems like a nice car!
> But i read that the production of these is stopped and the company went bankrupt? How are you managing servicing and other aspects if the company has stopped manufacturing and supporting these?


Service is provided when needed. The only item so far for me was a recall replacement on the heater core. They sent a 2-man crew to my home and did it in a few hours. So far; so good


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