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Old Jul 6, 2007, 5:21 PM   #1
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Apologies for a long post here. However, I think it's potentially important information, as interchangeable rechargeable CR-V3 style Li-ion batteries become more widespread.

Background

I and others have been in a state of confusion over CRV3-type Li-ion rechargeable batteries for the Kodak Z712is superzoom camera. I must stress I and others round here are pleased with the camera. It's excellent and remarkably cheap.

The Z712is is packaged with a single CR-V3 throwaway lithium battery pack, but the manual says it also takes the Kodak KLIC-8000 rechargeable Li-ion battery. The very similar Z612 predecessor model was packaged with a KLIC-8000 and charger. The warning that...
"Not all manufacturers' Li-Ion rechargeable batteries are compatible with the camera. Damage caused by unauthorized accessories is not covered under warranty."...
... is present near the beginning of the on-line manual for the Z612, but is absent from the equivalent pages for the Z712is. See wwwuk.kodak.com.

I, and others, have bought 'rechargeable CR-V3' batteries and chargers for our Z712is cameras. I and 'Crazy4Stang' 's wife have also tried pairs of AA Ni-MH, unsurprisingly giving very poor battery life. Never having seen a KLIC-8000, I wrongly assumed that the technology was identical to Kodak's and the different name was to keep clear of Kodak's trademarks. "Kodak Lithium Ion Camera – geddit? You don't have to be Alan Turing to decrypt it.

I have a charger and 'rechargeable CR-V3' battery branded as 'Digital', and also a Uniross CR-V3 rechargeable. I have done some measurements, and researched a bit by phone and web searching, since my post this morning (UK) at...
http://forums.steves-digicams.com/fo...=51&page=2
..but I'm rather intrigued by some of what I've found. I think there are some general safety implications, from which Kodak are sensibly aiming to keep well away.

Observations

A disposable CR-V3 battery has a pair of contact plates at one end of the pack, and no others. The two 'rechargeable CR-V3' batteries I own also have a third, small contact plate, offset between the large pair. The Maplin (Vanson) charger I have uses this centre contact and the "-" contact when charging. From looking at web pictures, I believe my charger and the Uniross charger and one other I saw are identical.

The Z712 camera battery compartment has a pair of contact points that meet the two main contact plates, but also a centre side contact that won't meet the little centre contact on my rechargeables. On looking at web images of KLIC-8000 batteries, and several third-party 'replacement KLIC-8000's, I see a single end contact, plus a side strip contact that will mate with a camera side contact inside the battery compartment.

Measurements

Now we get to the interesting bit
. If I measure the voltage at the small centre terminal relative to the 'negative' terminal on my two CR-V3 batteries, it's higher than the voltage between the two main terminals. On a fully charged cell it's 4.2V against 3.65V; 350mV higher; 10% of the terminal voltage! So the camera will only see 90% of the total battery voltage.

I've had two stories as to why this is. Both may or may not be true. One was 'it's the protection', meaning a safety feature to protect the camera from overvoltage. The story is that a resistor is in series to reduce the voltage to accommodate cameras, designed for disposables, that might be damaged by the full 4.2V cell voltage of a freshly charged unit. Note that my little-used CR-V3 disposable has a voltage of only 3.08V. If this is true, more than 10% of the available battery power will, annoyingly, be dissipated as heat in the resistor.

The small centre contact is used for charging, and shorts out the resistor, so at least we don't waste any energy during charging.

The other story is that the centre contact, used on the chargers, is to prevent their being used for accidental and dangerous attempts at recharging throwaway CR-V3s. My late father, an inveterate battery tinkerer, would certainly have tried it, and possibly died sooner. The throwaway batteries' contacts don't fit these chargers.

Now we get to the potentially dangerous bit. I have Googled this afternoon and spoken to an excellently comprehensive battery supplier in London at http://www.smallbattery.company.org.uk/ . They are now offering a new, confusingly named battery, a "CR-V3R" which has only the two main contacts, and alarmingly, a 2-contact-only charger. I can see no reason why this charger can't be used to attempt to recharge a throwaway CR-V3 Li battery. I hope there's at least some thermostatic protection built in somewhere. I'm told there are strong warning notices, but how is ordinary Joe Public who doesn't read warnings to avoid becoming John Doe?

A good start would be to rename CR-V3 rechargeables "NKLIC-911" or similar (Not Kodak) to prevent confusion. I think someone at Kodak maybe saw this problem and avoided it through astute renaming. They shouldn't then have given out throwaway CR-V3's instead of KLICs with the Z712, though, in my opinion.

If anyone has firmer information than my various suppositions above, I'd be delighted to hear it, especially about what's actually inside the case of these batteries. I expect many purchasers of Kodak Z712s to make the same assumptions as me, and buy the cheaper rechargeable CR-V3, which will work well, but not as well as the KLIC-8000.

Thnaks for your attention! Alan T

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Old Jul 6, 2007, 9:48 PM   #2
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You can get the KLIC-8000 and charger for around 30.00. These are from reputable sources too. The best deal I have seen on the battery is from bestbatt.com. Here is a link:

http://www.bestbatt.com/Kodak_KLIC_8...lic8000-01.htm

They have the KLIC-8000 charger also but you can get a high qualitycharger from Battery Merchants on Ebay. Alot of the batteries and chargers on Ebay are junk but this is a good one. Here's the link:

http://cgi.ebay.com/Battery-Charger-...QQcmdZViewItem


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Old Jul 6, 2007, 9:51 PM   #3
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You can get the KLIC-8000 and charger for around 30.00. These are from reputable sources too. The best deal I have seen on the battery is from bestbatt.com. Here is a link:

http://www.bestbatt.com/Kodak_KLIC_8...lic8000-01.htm

They have the KLIC-8000 charger also but you can get a high qualitycharger from Battery Merchants on Ebay. Alot of the batteries and chargers on Ebay are junk but this is a good one. Here's the link:

http://cgi.ebay.com/Battery-Charger-...QQcmdZViewItem


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Old Jul 6, 2007, 9:51 PM   #4
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Repost...Sorry
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Old Jul 7, 2007, 8:38 AM   #5
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If you look on the charger chip manufacturer's sites like Maxim http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4612 , you'll see that some Li-On batteries have a thermistor inside them and that the chip detects the battery temperature via this, turning off charging if it gets too hot for instance. Third pin?

The only time I've come across this on a test bench was with industrial 21 volt Li-On batteries, they certainly had a thermistor inside them connected to the outside world connector. Disconnect it and the charger stops charging.
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