acensor
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Why does Mitsubishi recommend fully charging every 2 weeks?

Fri May 10, 2013 6:21 pm

On page 1-19 of the owners' manual it reads:
"Fully charge the vehicle by regular charging every 2 weeks?"

Seems that everything I've read about TLC for the batteries would loosely translate as "if you don't really need to for the range it's best to never ever fully charge these batteries for longest life."

I note that sentence is a few parapgraphs below the suggestion that repeatedly quick charging isn't such a great idea..... So maybe it's in THAT context?

Alex
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JoeS
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Fri May 10, 2013 7:51 pm

Alex, we already have plenty of threads discussing battery charging regimens. 'Twould have been better to tack this question onto one of them instead of starting a new thread (you'll understand why when you try to retrieve some prior information).

The Owner's Manual was superseded by the February 2012 letter from Mitsubishi which addresses the battery scheduled maintenance. Wee John posted the letter here.

The letter recommends fully charging the battery (from 2 bars) in the first year, and every two years thereafter. I suspect all of us end up fully charging the battery more frequently - for example, I do it just before embarking on a long trip. I now normally try to keep my fuel gauge somewhere between 5 and 12 bars and certainly avoid full charge + high temperatures.

Question for recent iMiEV purchasers: is there any newer information provided by Mitsubishi?
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acensor
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Fri May 10, 2013 9:24 pm

JoeS wrote:Alex, we already have plenty of threads discussing battery charging regimens. 'Twould have been better to tack this question onto one of them......

....The [Mitsubishi update] letter recommends fully charging the battery (from 2 bars) in the first year, and every two years thereafter. ........
.......Question for recent iMiEV purchasers: is there any newer information provided by Mitsubishi?

'm
I was kind of torn between posting on an existing thread (in part because there were, IIRR, several that meandered into the battery chargin turf, and in part because I thought having a specific subject line might be MORE helpful if others later search. But as moderator I'll defer to you.

Thank for the link to the Mitsubish update letter.

I'm a very new owner (barely more than a month). Only info I got was the clearly older gray owners' manual. I'm even a registered-with-Mitsubishi owner and they have not contacted me with any supplementary info.

Alex

Alex
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JoeS
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Sat May 11, 2013 3:43 am

acensor wrote:... and in part because I thought having a specific subject line might be MORE helpful if others later search...
No worries, as there's certainly much merit to your approach. I've been a little too touchy lately and perhaps need a vacation...

In re-reading Mitsubishi's letter, I find it interesting that the stated reason for the full charge routine is for instrument calibration ("...maximize accuracy of SOC indicator..." - i.e., the 'fuel' gauge), and eliminating the need for routine maintenance. The battery itself is not addressed.

Somehow, I would have thought that Mitsubishi would want to test the traction battery capacity, if for no other reason than to garner feedback. As it now stands, we have no quantitative measure of pack state of health. Perhaps just as well, as we won't experience the Leaf community obsession and paranoia with that capacity number. :lol:
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acensor
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Sat May 11, 2013 9:25 am

JoeS wrote:
acensor wrote:...
In re-reading Mitsubishi's letter, I find it interesting that the stated reason for the full charge routine is for instrument calibration ("...maximize accuracy of SOC indicator..." - i.e., the 'fuel' gauge), and eliminating the need for routine maintenance. The battery itself is not addressed.

Somehow, I would have thought that Mitsubishi would want to test the traction battery capacity, ....


I wondered a bit too about their stated rreason . Wondered is in part it had to do with wiping out undesirable battery "memory" which was/is the bane of nicads but which I thought was a nonissue with lithium.
But I guess having a reasonably calibrated SOC indicator is important.

Alex
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iDriver
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Fri May 17, 2013 9:44 am

acensor, I hope this helps. The car is actually never charged to 100% of the battery capacity. It could have been, but Mitsubishi intentionally limited the amount of voltage each battery can take. I'm sure this is specifically to ensure a long life and limit the rate of pack degradation.

So good news. Charge the car as much as you want! :)

I had my annual maintenance done about 4 months ago. Everything was fine, Mitsubishi dealer hooked the car up to a computer and checked the voltage on each Cell. Here's a picture of the printout. As you can see, the Cells are limited to 3.955 Volts, rather than the 4.25 they are capable of. So no matter what, you're only ever charging to 92% of "full". Pretty cool!

Image

acensor
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Fri May 17, 2013 10:19 am

iDriver wrote:.... The car is actually never charged to 100% of the battery capacity. ....Mitsubishi intentionally limited the amount of voltage each battery can take. .... to ensure a long life and limit the rate of pack degradation.

So good news. Charge the car as much as you want! :)

I had my annual maintenance done about 4 months ago. ..... only ever charging to 92% of "full". Pretty cool!.....


Thanks iDriver,

Yeah, I think most of us here knew that the onboard charger is configured to protect the battery longevity that way. Not sure your calculation of 92% is right. Think it might be a bit less than that we're capped at as the total kilowatt-hours stored isn't exactly proportinal to voltage level charged to.
Still everything I read and think I understand suggests that for maximum life ideally you'd keep the battery charged somewhere in mid capacity, not fully charged.
I realize that's not always practical, and no, occassional or even modertely frequent fully charging isn't a cardinal sin. But if your driving style permits you'd be better off for long life never charging to more than two bars short of full.

It's also my understanding that if 8 year from now you come into a dealer complaining that your maximum ranges is down 20% and that's intolerable they can reprogram it to allow 100% charging to stretch your useful full range life a bit further down the calendar before you have to ditch those batteries.

Finally: Three questions which I will post under the cost of operation topic (so please don't answer here):
1) You didn't show the price on what you were charged for your annual inspection. What was it?
2) Is there an "annual inspection?" I only see offhand something due at about 15,000 miles.
3) Anyone know if you don't bring it in on the required schedule can and will Mitsubishi use that to wiggle out of covering something that otherwise would be on warrenty coverage?

Alex
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mixmike6
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Tue Sep 09, 2014 12:54 pm

So just to be clear on this subject, I should never or rarely fully discharge or fully recharge my battery?

My understanding of InfoLithium batteries was that to optimize it's life you should fully discharge and fully charge the battery once a month and then charge it from 90% then 80% then 70% then 60%...so on and so forth until you reach 10%. Then you repeat the process.
I've always done this with my iPhones and seems to have worked as my battery life is always so much greater than that of my friends.

Now I know I probably shouldn't compare the battery of an iPhone to our i-MiEV but can anyone confirm what is the absolute best way to ensure a long healthy life of my battery pack and why?

Also is the Battery pack a Toshiba SCiB or not? There's a lot mixed info on the forum and according to Wikipedia and Toshiba the battery is SCiB..
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PV1
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Tue Sep 09, 2014 1:20 pm

Definitely never fully discharge if you can help it. I've been fully recharging nearly every day that I drive the car for a year and a half now and haven't noticed any difference in range.

The i-MiEV takes the cells to 4.1 volts (CaniOn), and I believe their max is 4.2 volts. My laptop takes its cells to 4.3 volts, though they may be a different chemistry. My cell phone goes to 4.325 volts.

The regular i-MiEV battery is a standard lithium chemistry, not SCiB. Japanese i-MiEVs have an optional SCiB battery (at 14.5 kWh capacity) since they are much more tolerant to repeated quick charging, which is in no short supply in Japan.
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Re: Why does Mitsubishi recommend fully charging every 2 wee

Wed Sep 10, 2014 4:25 am

mixmike6 wrote:So just to be clear on this subject, I should never or rarely fully discharge or fully recharge my battery?
I don't think we know that for sure - Lots of what you read on this subject is opinion based on whatever research the poster has read somewhere else

No question though that keeping the battery pack charged between 20 or 30% and 60 or 70% is probably best for it, but that's not always practical to do - It turns a 75 mile range car into a 30 mile car for one thing. It also builds in some range anxiety no matter how carefully you calculate your usage

I would try (and I do in actual practice) to do partial charges as much as is practical, but an occasional 'full' charge (whatever percentage Mitsu has limited it to) is probably not a bad thing either - Occasionally balancing the cells in the pack is probably a good thing

There are many, many owners who do a full recharge every single day and quite a few of those with longer commutes are doing full recharges twice per day, so for you and me to do a full recharge once or twice per month can't be a bad thing, can it? It remains to be seen 5 or 6 years from now who has the most pack capacity left and that will modify our 'assumptions' and opinions further

Long story short - You bought the car to commute from place to place. Use it as you need while partially charging it whenever possible but fully whenever you need and 5 or 6 years from now you're bound to be near the top of the heap ;-)

Don
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