dkCambridgeshire Posted February 29, 2012 Share #1  Posted February 29, 2012 Advertisement (gone after registration) A question has arisen as to whether my DMR battery charger is working efficiently .  I have been advised that on a freshly charged battery in good condition, the voltage across the first and second terminals should probably be around 6 volts. However, both my batteries measure 3 volts ... and this could be indicative of a faulty charger.  Leica DMR battery - voltage across 1st and second terminals after battery recharge by s4sargent, on Flickr   The voltage across the first and third terminals is 8.4 volts which is fine.  Leica DMR battery - voltage across 1st and 3rd terminals after battery recharge by s4sargent, on Flickr  Could someone please check their DMR batteries with a voltmeter after a fresh charge and advise:  (a) the voltage reading across the first and second terminals  ( the voltage across first and third terminals.  This would help ascertain whether my charger might be faulty ... on the other hand it is possible that 3v is the correct/expected voltage across the 1st and 2nd terminals.   Many thanks  dunk Link to post Share on other sites More sharing options...
stuny Posted February 29, 2012 Share #2 Â Posted February 29, 2012 With a DMR battery chraged a month ago, but not used since charging, I get the same readings. Link to post Share on other sites More sharing options...
dkCambridgeshire Posted March 1, 2012 Author Share #3  Posted March 1, 2012 With a DMR battery chraged a month ago, but not used since charging, I get the same readings.  That's interesting ... Thank you.  Any advance on 3V for the voltage across the first and second terminals?  Best wishes  dunk Link to post Share on other sites More sharing options...
dave_d Posted March 1, 2012 Share #4 Â Posted March 1, 2012 Why do you suspect your charger is not working? Link to post Share on other sites More sharing options...
dkCambridgeshire Posted March 1, 2012 Author Share #5  Posted March 1, 2012 Why do you suspect your charger is not working?  Because there is a possibility that the batteries are not receiving a full charge - maybe because the charger is not completing the full charge cycle ie might be switching off prematurely . The user manual states that battery recharge should take approx. 2 hours - my charger switches off after approx. 75 to 80 minutes. But, one of the batteries is new and has probably not yet reached its full efficiency - it requires a number of charge/discharge cycles before reaching full efficiency. If the batteries are not being recharged to full capacity then I am advised this might result in the voltage across terminals 1 and 2 being less than it should be. However, nothing is documented anywhere as to what the voltage across terminals 1 and 2 should be. Someone else recalls the measured voltage across terminals 1 and 2 was 6 volts after charging and not 3 volts. Hence my question and request that other DMR users measure their battery voltages after charging.  Best wishes  dunk Link to post Share on other sites More sharing options...
dave_d Posted March 1, 2012 Share #6 Â Posted March 1, 2012 On thing you want to consider is that Li-ion batteries have a flat discharge curve only dropping in voltage toward the very end of their cycle. A voltage reading of a partially charged battery may give the same voltage reading as a fully charged battery. Link to post Share on other sites More sharing options...
dkCambridgeshire Posted March 1, 2012 Author Share #7 Â Posted March 1, 2012 Advertisement (gone after registration) On thing you want to consider is that Li-ion batteries have a flat discharge curve only dropping in voltage toward the very end of their cycle. A voltage reading of a partially charged battery may give the same voltage reading as a fully charged battery. Â Thanks. The normal voltage across terminals 1 and 2 may well be 3volts following charging and for the period of use before it starts to drop off ... but I would appreciate a few more voltmeter readings to confirm this. My source who stated that in his recollection it s/b 6 volts could be incorrect - especially as both my batteries show 3 volts. But, if my charger is not working at its original efficiency then maybe 3 volts is too low. Â dunk Link to post Share on other sites More sharing options...
mmradman Posted March 2, 2012 Share #8  Posted March 2, 2012 I don't have DMR but depending how it is measured it could be either 3V between T1-T3 or 6V between T2-T3, total between T1 and T3 is 8.4V.  Unit voltage of Li-On cells is in the range of 3 -4 Volts so it implies that number of internal cells are wired up in series and maybe in parallel (to boost Ah). So it is either wrongly measured or wrongly wired, if it works ok it is most likely correctly wired.  How to rebuild a Li-Ion battery pack  Perhaps somebody with better understanding of internals of this particular battery can provide better explanation. Link to post Share on other sites More sharing options...
Graham A Posted June 4, 2012 Share #9 Â Posted June 4, 2012 I can't access the Flickr photos so can't be sure what you show but I have four DMR batteries and this is what I get voltage wise. I have the battery with terminals face up and terminals at the top rather than closest to me. Across the two outermost terminals I get between 8.1 and 8.2 volts. Across terminal at far right and centre terminal I get between 7.4 and 7.5 volts. Between centre terminal and far left terminal I get Zero volts. Of these batteries I have only been able to get two of them to take a charge from my charger (I have two genuine Leica chargers). Both chargers react in the same way to all four batteries. The batteries seem to hold their charge so the charger is not activated. This seems strange to me as I would have thought they would have discharged by now - but they could also be in excellent condition ??. I haven't had a chance to use the DMR back to test the batteries under load due to work constraints and that I mostly shoot film. Not sure if this helps any but good luck. Â Cheers, Graham. Link to post Share on other sites More sharing options...
Krauklis Posted June 9, 2012 Share #10  Posted June 9, 2012 ... I have the battery with terminals face up and terminals at the top rather than closest to me. ...  Cheers, Graham.  In October 2010 I had one of my "old" DMR batteries refitted with new cells. After the "refreshment" I charged my batteries and asked an expert to measure the voltage of an old/original battery and the "new" battery.  The results with both batteries fully charged:  original battery - far right to centre terminal 7.5 V - outermost terminals 8,18 V  battery with new cells - far right to centre terminal 7,63 V - outermost terminals 8,31 V   krauklis Link to post Share on other sites More sharing options...
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