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Old Dec 2, 2003, 10:05 AM   #1
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Default Li-ion battery management

I recently bought a Minolta A1 and a spare battery.
Since Li-ion batts don't like to sit around fully charged (the Minolta manual mentions this), here's how I plan to manage the batteries:
I've hooked the charger to a one hour timer.

http://tinyurl.com/xd1s

When a battery gets low I'll charge it for one hour. That will fill
it to about 40%. It can be happily stored at that charge level. For
casual shooting two batteries at 40% will be adequate. I can charge
for shorter times to bring the batt back up to ~40%. I can measure
the battery resting voltage to judge SOC (7.6V @ 40%, camera cuts off
at 7.05V). When I have a big job coming up I can fully charge one or
both batteries. I tested the charger to make sure that it won't drain
the battery when it is not powered (after the one hour timer cuts
off). The camera doesn't seem to come close to deep discharging the
battery, which I would expect to be ~6V.

Tim
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Old Dec 2, 2003, 11:25 AM   #2
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Your Minolta manual flies in the face of my experience. I store my LiIon batteries fully charged (Sony InfoLithiums for their DV camcorders). I find they hold their charge forever. After as long as 6 months, my LiIons retain over 80% of their charge.

Maybe the Minolta batteries are not as good as Sony's.

Declan
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Old Dec 2, 2003, 1:43 PM   #3
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Quote:
Originally Posted by amazingthailand
Your Minolta manual flies in the face of my experience. I store my LiIon batteries fully charged (Sony InfoLithiums for their DV camcorders). I find they hold their charge forever. After as long as 6 months, my LiIons retain over 80% of their charge.

Maybe the Minolta batteries are not as good as Sony's.

Declan
I have a Sony camcorder and the manual for it also recommends against storing Li-ion batteries fully charged. Charge retention has nothing to do with it. All the technical literature I've seen states that Li-ion has a shorter life if kept fully charged.

http://www.batteryuniversity.com/parttwo-34.htm
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Old Dec 2, 2003, 4:16 PM   #4
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I thought most mobile phones were on Li-ion now? I'm on pay as I go 'cos I don't use it much. From fully charge, it sits in my car glove box (with a 12 v charger lead as backup) in case I need it. After 3 months I can still make emergency calls. I might re-charge it every 6 months. I have been doing this for 2 years and my batteries are still good. VOX
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Old Dec 2, 2003, 6:02 PM   #5
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Quote:
Originally Posted by voxmagna
I thought most mobile phones were on Li-ion now? I'm on pay as I go 'cos I don't use it much. From fully charge, it sits in my car glove box (with a 12 v charger lead as backup) in case I need it. After 3 months I can still make emergency calls. I might re-charge it every 6 months. I have been doing this for 2 years and my batteries are still good. VOX
And how much capacity is left in those batteries? Making one call now and then does not answer that question.

George Burns lived to 100 smoking cigars. Does that mean that they are not harmful?
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Old Dec 2, 2003, 6:53 PM   #6
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Well I see 4 clicks on the battery monitor, even after using it for 10 minutes and max is 5. Now I'm not about to do the Duracell kiddies toy battery capacity test nor do I know how close I am to a cell and how much the phones erp is being backed off, 'cos as I said I always keep the 12 volt lead with the phone. But I'm not rushing out buying replacement batts just yet. As you probably know, Li-Ion knocks the spots off NiMh for low self discharge and cold weather performance.

PS in UK they've just made using handheld mobiles illegal on the move, so I only use it when the engine's switched off, but I have to turn on the ignition to make the cigar socket live - one of those General Motors good design ideas, only allowing lighting up on the move. VOX
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Old Dec 2, 2003, 9:43 PM   #7
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Well, I read my manuals and my Sony camcorder manual does not have any reference to storing the InfoLithiums.

My LiIon batteries are now over 4 years old and still give me almost 5 hours of run time, same as when I first got them. So I think maybe Minolta (and Sony, if they state it in their current manuals) are just being overly cautious. Legal CYA.

Hell, Minolta apparantly stated that their 100-240V charger should not be used overseas. Go figure that one out. More legal CYA.

Bottom line - blame the lawyers.

Declan
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Old Dec 3, 2003, 12:41 AM   #8
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Default Re: Li-ion battery management

Quote:
Originally Posted by browntimdc
Since Li-ion batts don't like to sit around fully charged (the Minolta manual mentions this),
This was discussed in the "Batteries" forum near here recently. There seems to be very low self discharge and no resulting harm from fully-charged storage.

See http://www.stevesforums.com/phpBB2/v...ic.php?t=16006

'MrBattery' seems to know what he's talking about. I am interested in this because I've just acquired my first Li-ion battery, on a second hand Sony Video8 camcorder. It'll last for a full 90min tape if I'm frugal with it. However, I'm appalled at the price of a spare battery (45 ukpounds), and I'm going to have to buy a bulky 18ukpound 12VDC-240VAC inverter in order to recharge it when away from a mains power supply in my camper van.

By comparison, Ni-MH (especially camera AA cells) are very cheap and fully flexible in the way of chargers. At least we still have a choice on whether to go for AA Ni-MH or Li-ion for digicams. As far as I can see, all current camcorders are Li-ion powered.
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Old Dec 3, 2003, 11:17 AM   #9
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Quote:
Originally Posted by browntimdc
Quote:
Originally Posted by voxmagna
I thought most mobile phones were on Li-ion now? I'm on pay as I go 'cos I don't use it much. From fully charge, it sits in my car glove box (with a 12 v charger lead as backup) in case I need it. After 3 months I can still make emergency calls. I might re-charge it every 6 months. I have been doing this for 2 years and my batteries are still good. VOX
And how much capacity is left in those batteries? Making one call now and then does not answer that question.
Well, the same article you referenced also says this:

"lithium-ion has not yet fully matured and is being improved continuously. New metal and chemical combinations are being tried every six months to increase energy density and prolong service life. The improvements in longevity after each change will not be known for a few years."

So, I don't think anyone really knows the long term impact of leaving newer Lithium Ion based batteries fully charged yet.

I have two mobile phones using Lithium Ion Batteries that are going strong after several years (and I usually fully charge 'em). I don't even use them much anymore for calls (except for looking up phone numbers, since I've never gotten around to replicating all of the phone number contacts from them in my newer phones).

In any event, Generic Lithium Ion Batteries (many using Japanese Cells) are becoming very inexpensive.

For example: for my latest digicam (Konica KD-510z), you can find Generic 850mAh Lithium Ion Batteries with Japanese Cells on Ebay for around $10.50 now.
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