albertknappmd Posted March 23, 2007 Share #1 Â Posted March 23, 2007 Advertisement (gone after registration) I have read that it is a good idea to completely discharge each new lithium battery three times so as to expand the memory of the battery to the maximum. This has been discussed solely in reagrds to the M8. DOES THIS NOT ALSO APPLY TO THE LITHIUM BATTERY THAT POWERS THE DMR ? :confused: Link to post Share on other sites More sharing options...
Advertisement Posted March 23, 2007 Posted March 23, 2007 Hi albertknappmd, Take a look here Battery Question. I'm sure you'll find what you were looking for!
Guest guy_mancuso Posted March 23, 2007 Share #2 Â Posted March 23, 2007 Albert it does apply to the DMR also and what leica did recommend there too. Link to post Share on other sites More sharing options...
doubice Posted March 23, 2007 Share #3 Â Posted March 23, 2007 It is an excellent idea to fully charge and fully discharge batteries during their entire 'life'. All batteries have memory, no matter what the battery manufactureres claim; NiCd of course being the worst, NiMH somewhat better and Lithium being much better than what we used in the past. Â The worst thing to do is to 'top up' a battery during its discharge cycle, even worse is not to charge it fully. Even Lithium batteries' life will be shorter by about 50% if the full discharge/charge procedure is not followed. Â Hope this helps..... Â All the best, Â Jan Link to post Share on other sites More sharing options...
albertknappmd Posted March 23, 2007 Author Share #4 Â Posted March 23, 2007 thank you! Albert:) Link to post Share on other sites More sharing options...
barjohn Posted March 23, 2007 Share #5 Â Posted March 23, 2007 Jan, Â What you are saying goes against what every manufacturer of Lithium batteries recommends and what most vendors of electronic equipment recommend. Do you have any engineering data to back up your assertion or is this purely anecdotal? If you have engineering studies could you provide links? Thanks. Link to post Share on other sites More sharing options...
marknorton Posted March 23, 2007 Share #6 Â Posted March 23, 2007 Li-Ion batteries suffer an irreversible loss of capacity if stored fully charged; the greater the level of charge and the higher the temperature, the faster the loss of capacity. For this reason, only buy the batteries you need, not ones to "keep in stock". If you have spare batteries, charge them to 40% and store in the refrigerator but NOT the freezer. Â It is best not to let Li-Ion batteries go completely flat... Link to post Share on other sites More sharing options...
doubice Posted March 23, 2007 Share #7 Â Posted March 23, 2007 Advertisement (gone after registration) Â It is best not to let Li-Ion batteries go completely flat... Â If I have supplied incorect info on the Lithiums, I apologize. I have been following the full charge/discharge procedure on my cellphone's Lithiums and have used the same two batteries for over 5 years, with no loss of capacity. Â Is the general concensus than that it is best to store unused Li-Ion batteries uncharged or charged to half capacity only? Â Albert, sorry for having semi-hijacked your thread.... Â All the best, Â Jan Link to post Share on other sites More sharing options...
wparsonsgisnet Posted March 23, 2007 Share #8 Â Posted March 23, 2007 I believe that the recommendation to "calibrate" the Li-ion batteries comes from Leica instruction books for the M8 and R8/9 bigital back. Â There have also been postings to the effect that battery manufacturers do not recommend this. Â There was an indication that version 1.10 of the firmware will take care of the problem being caused by battery charge indication. This software should be in our hands before too long. Link to post Share on other sites More sharing options...
albertknappmd Posted March 23, 2007 Author Share #9 Â Posted March 23, 2007 well seems we have a bit of a controversy here. The two main issues begging resolution are: 1. do we charge-discharge both the DMR and M8 batteries three times before initial use as described in the M8 manual? 2. How do we store Li batteries, empty, half or fully charged ? Link to post Share on other sites More sharing options...
fotografr Posted March 23, 2007 Share #10 Â Posted March 23, 2007 well seems we have a bit of a controversy here.The two main issues begging resolution are: 1. do we charge-discharge both the DMR and M8 batteries three times before initial use as described in the M8 manual? 2. How do we store Li batteries, empty, half or fully charged ? Â 1. Since you can't do any damage by following this procedure, I think it would be prudent to do it and be on the safe side. Â 2. New batteries are stored uncharged in warehouses and on store shelves, often for months, without apparent damage. The issue begs the question, however, why one would need spare batteries if they are going to just be stored for long periods? I'd suggest using them. Link to post Share on other sites More sharing options...
albertknappmd Posted March 23, 2007 Author Share #11 Â Posted March 23, 2007 sounds like a reasonable and logical compromise to me ! :) everyone else agree? Link to post Share on other sites More sharing options...
scott kirkpatrick Posted March 23, 2007 Share #12 Â Posted March 23, 2007 The battery manufacturers' recommendation (which I have seen in reference books on battery chemistry) is that the maximum life is obtained in LiIon with only shallow discharge. So the deep discharge cycle is needed only to clean up the external characteristics and reset the battery to a standard state so that not very "smart" battery management firmware will do the right thing. My guess is that we should follow the initial 3 deep discharges recommendation and then do an additional deep discharge at intervals like a few months, or a few thousand exposures, whichever comes first. Â scott Link to post Share on other sites More sharing options...
London Lad Posted March 23, 2007 Share #13 Â Posted March 23, 2007 I have worked with lithium cells for years and Scott (and others) are correct. The Leica recommendation is really only to help calibrate the battery meter. Â When using the battery top it up regularly, there is no memory effect with Li batteries. Do not deep discharge. Always use the correct charger as the charging protocol for Li is completely different to other battery's (With the Leicas it would be difficult to use anything other than the correct charger!) Â If storing cells long term, 40% charge is the way to go. Link to post Share on other sites More sharing options...
rwfreund Posted March 23, 2007 Share #14 Â Posted March 23, 2007 NiMH and LiIon batteries are really quite forgiving. Just use them. Deep discharge is neither necessary nor beneficial. Since modern chargers for these battery types use a slight cell voltage drop or a temperature rise to terminate charging, charge termination is automatic. One issue that occurs with new batteries, is that this votage drop occurs at slightly less than full charge. After a small number of recharge cycles, the telltale voltage drop moves closer to "full charge". -bob Link to post Share on other sites More sharing options...
London Lad Posted March 23, 2007 Share #15 Â Posted March 23, 2007 Sorry Bob this is correct for NiMH but is not how Li-Ion charge termination works. Â Li-Ion cells should be charged at a constant current of up to 1C until the voltage reaches 4.2 volts per cell. After this the charge current is gradually reduced to prevent the voltage rising over 4.2 volts per cell i.e. constant voltage charging. This method is referred to as CCCV charging. The delta V effect you describe above does not happen with Li-Ion, only NiMH and NiCad. Link to post Share on other sites More sharing options...
rwfreund Posted March 24, 2007 Share #16  Posted March 24, 2007 I stand corrected. Constant voltage charging to a set point is correct for Li Ion. Source is constant voltage current limited. ref http://www.national.com/appinfo/power/files/f7.pdf  -bob Link to post Share on other sites More sharing options...
skimmel Posted March 24, 2007 Share #17 Â Posted March 24, 2007 How did you all do your initial 3 discharge-recharge cycles? Do you just leave the camera on until the battery goes out (and doesn't this do something like reset the camera)? Link to post Share on other sites More sharing options...
scott kirkpatrick Posted March 24, 2007 Share #18  Posted March 24, 2007 Constant voltage charging to a set point is correct for Li Ion. Source is constant voltage current limited. ref http://www.national.com/appinfo/power/files/f7.pdf  That's a very detailed and readable application note for engineers who want to design a charger. Thanks for the link. It makes it sound as if some misunderstandings between the M8 electronics designer and the engineer responsible for the M8's proprietary charger could be responsible for the problems reported in which the M8 refuses to operate with what the charger claims is a fully charged battery.  To look at these issues from the battery maker's side, the best reference I have found is "Modern Batteries," by CA Vincent and B. Scrosati, John Wiley, NY 1997 (2nd Edition). Does anyone have a more recent reference, that might say more about Li-Ion and Li-polymer systems, or the tiny Zinc-air batteries?  scott Link to post Share on other sites More sharing options...
marknorton Posted March 24, 2007 Share #19 Â Posted March 24, 2007 Yes, an interesting paper. I did some measurements when I was working on my charger and it does present 4.2v across the battery while charging with a charging current starting at 0.75A and going down to about 1/10 of that. It's a pity the charger manufacturer felt the need to scrape of the chip identification because I haven't found it yet from any of the major semiconductor suppliers. Link to post Share on other sites More sharing options...
London Lad Posted March 24, 2007 Share #20 Â Posted March 24, 2007 One thing that's worth remembering when tracking down faults with Li - Ion / Li Po batts and chargers. Â If a Li cell is allowed to drop below a certain voltage, charged above a certain voltage or an excessive current is pulled from the cell the resultant chemical change may (normally will) cause a 'vent with flame' event (an explosion) Â To try to prevent this nearly all Li battery packs have built in protection circuits. Normally these are set to about: Â Overcharge protection at 4.35V Over-discharge protection at 2.45V Short / over-current protection at 2C Â If this protection has been triggered (normally the O/D protection) it is sometimes necessary to reset it by placing the battery in a charger for a minute or two before removing it and then replacing it for the full charge. Â I do not know if the M8 battery operates in this way but it is 99% certain that it will have a protection circuit. Â Please also note that under normal circumstances it is not a good idea to unnecessarily interrupt the Li charge until it is complete. Link to post Share on other sites More sharing options...
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