Re: R-CRV3
From: Alexandru-Cristian Sarbu [EMAIL PROTECTED] Hi, I'm looking for some rechargeable batteries for my DS. I would prefer Li instead of NiMh (I don't shoot many pictures at once), and I've saw some R-CRV3 advertised as having 3V and capable of 1100mAh. But... isn't 1100mAh a little low? Anyone here uses such things? I've been watching these with some interest. Quick summary of information gleaned: Rechargeable CRV3 batteries (R-CRV3) actually have a higher voltage (up to 1.8v) than standard CRV3 disposables (1.5v) or NiMh (1.2v). This is the reason that Pentax state they should not be used however (As 'tother Rob posted) Moby, and I think others, have produced CRV3 batteries that claim to operate within normal voltage and be safe to use. The claim this is accomplished via a 'protection device' built into the battery - whatever that is. There are some rechargeable 'low voltage' recheargeable CRV3 batteries on the market which are actually just a couple of NiMh cells packaged together rather than LiOn batteries. Obviously there are no voltage problems here but no advantage either - just an expensive alternative. Folks who have used R-CRV3 batteries in their cameras seem pleased with them. Advantages claimed are: a) Faster autofocus, sometimes significantly faster. This seems plausible if the batteries are operating at higher voltage, the flip side is that the autofocus mehanics will be stressed a bit more. b) They don't suffer the same self-discharge problems as NiMh i.e. you can charge and forget for a while before use. b) Greater usable capacity despite the lower theoretical capacity . I'm not sure I believe this and put it down to either rose tinted vision after laying out a lot of cash for batteries, or alternatively comparing to NiMh batteries that aren't fully charged. The distributors of these batteries make a big thing about the actual capacity (even at 1100 mah) being higher due to the camera reaching cut off voltage before a (2300 mah) NiMh is fully discharged - but I'm not sure the actual maths would justify this. Likewise there is a real issue in that you should not over discharge a R-CRV3 and if the full capacity is used bacause the camera is actually assuming different battery types you will be damaging the battery. It isn't clear if the faster autofocus claims relate to the 'safe' voltage R-CRV3 batteries or the original higher voltage ones, or both. Their distibutors claim that the expensive R-CRV3 batteries are actually 'more economical' than NiMh as they can be recharged many more times. Too say I'm highly suspicious of all their figures and testing methodologies is an understatement, I believe that LiOn battery technology is generally regarded as more fragile than NiMh. Time will tell. My current view is that good quality high capacity NiMh batteries and charger are the current best and safest options for most usage patterns -ntil the Sanyo low discharge batteries come on the market you just need to remember to top them up every couple of weeks before use. If you use autofocus with big heavy lenses a lot it may be worth experimenting with R-CRV3 batteries, I am tempted myself although I don't have that autofocus need - we all like new toys :-) Rob. -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.362 / Virus Database: 267.12.8/163 - Release Date: 08/11/2005
Re: R-CRV3
On 9 Nov 2005 at 11:18, Rob Smith wrote: Folks who have used R-CRV3 batteries in their cameras seem pleased with them. Advantages claimed are: a) Faster autofocus, sometimes significantly faster. This seems plausible if the batteries are operating at higher voltage, the flip side is that the autofocus mehanics will be stressed a bit more Rose coloured glasses I bet and a combination of never having used a properly charged Ni-MH cell. If the battery voltage is regulated (I expect that it has to be for an L-ion cell) to be the same as a conventional cell there will be no reason why any motors may run faster or provide greater torque. In fact with a regulator device in series I'd expect performance would be poorer than a Ni-MH cell as the instantaneous peak current would likely be reduced. My current view is that good quality high capacity NiMh batteries and charger are the current best and safest options for most usage patterns -ntil the Sanyo low discharge batteries come on the market you just need to remember to top them up every couple of weeks before use. If you use autofocus with big heavy lenses a lot it may be worth experimenting with R-CRV3 batteries, I am tempted myself although I don't have that autofocus need - we all like new toys :-) I say put your cash away for a couple of sets of the long life Ni-MH cell, they should be great (or buy yourself a neat La Crosse BC-900 charger, that's a great toy). Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: R-CRV3
On 11/9/05, Rob Studdert [EMAIL PROTECTED] wrote: I say put your cash away for a couple of sets of the long life Ni-MH cell, they should be great (or buy yourself a neat La Crosse BC-900 charger, that's a great toy). Thank you (all) for your answers. So it seems the R-CRV3 are just expensive, so for now I'll stick with Li batteries (I should be able to find AAs) and see how many pictures I can get from those. I think they'll be fine for now, long life NiMh cells sounds nice - I'll think about that (not sure I can find them in Romania :( ). -- Best regards, Alex Sarbu
Re: R-CRV3
On 9 Nov 2005 at 14:52, Alexandru-Cristian Sarbu wrote: Thank you (all) for your answers. So it seems the R-CRV3 are just expensive, so for now I'll stick with Li batteries (I should be able to find AAs) and see how many pictures I can get from those. I think they'll be fine for now, long life NiMh cells sounds nice - I'll think about that (not sure I can find them in Romania :( ). Ah but that's the beauty of being a participant on an international list, when the time is right just ask and someone will find a way :-) Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
R-CRV3
Hi, I'm looking for some rechargeable batteries for my DS. I would prefer Li instead of NiMh (I don't shoot many pictures at once), and I've saw some R-CRV3 advertised as having 3V and capable of 1100mAh. But... isn't 1100mAh a little low? Anyone here uses such things? -- Best regards, Alex Sarbu
Re: R-CRV3
Hi, The R-CRV-3 batteries are not recommended for use in the Pentax cameras. They supply too high a current that can cause motors to burn out. The MZ-5n had a warning about using lithiums in the AA battery attachment. I have heard of 2 cases of the auto focus motor burning out and both those people used the lithium batteries in their cameras. Use them at your own risk. Leon http://www.bluering.org.au http://www.bluering.org.au/leon Alexandru-Cristian Sarbu wrote: Hi, I'm looking for some rechargeable batteries for my DS. I would prefer Li instead of NiMh (I don't shoot many pictures at once), and I've saw some R-CRV3 advertised as having 3V and capable of 1100mAh. But... isn't 1100mAh a little low? Anyone here uses such things? -- Best regards, Alex Sarbu
Re: R-CRV3
Leon Altoff wrote: Hi, The R-CRV-3 batteries are not recommended for use in the Pentax cameras. They supply too high a current that can cause motors to burn out. I'm not sure I understand how that can happen. Aren't batteries voltage sources, not current sources? - T
Re: R-CRV3
Leon Altoff wrote: The R-CRV-3 batteries are not recommended for use in the Pentax cameras. They supply too high a current that can cause motors to burn out. How does that work? Do they really have a lower internal resistance than NiMH batteries? S
Re: R-CRV3
On 8 Nov 2005 at 12:51, Toralf Lund wrote: Leon Altoff wrote: Hi, The R-CRV-3 batteries are not recommended for use in the Pentax cameras. They supply too high a current that can cause motors to burn out. I'm not sure I understand how that can happen. Aren't batteries voltage sources, not current sources? These cells rely upon a higher initial and average voltage to achieve an acceptable run time (until the camera deems that the voltage is too low to operate) even though they hold a lower total charge. A battery is a complex device, it can loosely be considered as a voltage source (with unlimited current) in series with a resistance (an internal dynamic resistance which varies dependent upon load current). Current and hence power in the a linear circuit increases as voltage rises for a constant load, it's ohms law. Being that the terminal voltage is higher than the normal battery voltage there may be potential for damage of the camera electronics. I assume that the cameras in question employ electronic power supply regulation, if so these circuits could potentially be stressed or damaged by an over voltage battery supply. Care to test the theory? Given the high cost of CRV3 rechargeable batteries, non-uniformity of systems and specialized chargers required I really don't see why it would be worth the effort. Also I'm not aware of their self discharge rate either but from practical experience with other L-ion powered devices they aren't my favourite batteries in this regard. Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: R-CRV3
Rob Studdert wrote: On 8 Nov 2005 at 12:51, Toralf Lund wrote: Leon Altoff wrote: Hi, The R-CRV-3 batteries are not recommended for use in the Pentax cameras. They supply too high a current that can cause motors to burn out. I'm not sure I understand how that can happen. Aren't batteries voltage sources, not current sources? These cells rely upon a higher initial and average voltage [ ... ] Being that the terminal voltage is higher than the normal battery voltage [ ... ] Care to test the theory? No, I believe it. The point was that the post I responded to suggested the maximum current, as opposed to the voltage, was different - and I really can't see how that would damage the motors. A change of voltage is an entirely different story - although electric motors don't tend to be too fussy about that kind of thing. - Toralf
Re: R-CRV3
Toralf Lund wrote: Leon Altoff wrote: Hi, The R-CRV-3 batteries are not recommended for use in the Pentax cameras. They supply too high a current that can cause motors to burn out. I'm not sure I understand how that can happen. Aren't batteries voltage sources, not current sources? - T Well, with my rudimentary knowledge of D.C. theory, I've a problem with that, too, Toralf... A load (the camera body into which you install the battery) takes whatever current it needs from the power source. The voltage level (what I call the current 'vehicle') is essentially fixed, as is the resistance of the load. The result is a specific current DRAW, if the supply is capable of supplying it. A larger current capacity supply leads to a more stable supply, as it's not straining to give out what's asked of it. In other words, if you have a load that requires 1.0 amp of steady state current, with only occasional spikes, a power supply only capable of delivering 1.0 amps is going to strain if a 1.5 or 2.0 amp surge is required. The 2.0 amp or greater supply will go along for the ride, easily supplying what's been asked for. I also think of amperage as a fixed reservoir of water. Empty it with a 1/4 tube, and it supplies it readily. Attach a 2 tube to the reservoir and it will deliver it much more rapidly, and unless it's large enough, it might almost empty before the need is met.. So, you increase the size of the reservoir, just in case. which provides a margin of safety. I've always believed this and it's never led me astray. Now people talk of current as something that's delivered, unbidden, to some poor load that can't handle all that current. Most perplexing! At least that's the way I've been taught, but I'm a mechanical guy, not an electrical one. Usually know just enough to get by... If I'm wrong, one of your EEs out there will let me know! ;-) keith whaley
Re: R-CRV3
Rob Studdert wrote: On 8 Nov 2005 at 12:51, Toralf Lund wrote: Leon Altoff wrote: Hi, The R-CRV-3 batteries are not recommended for use in the Pentax cameras. They supply too high a current that can cause motors to burn out. I'm not sure I understand how that can happen. Aren't batteries voltage sources, not current sources? These cells rely upon a higher initial and average voltage to achieve an acceptable run time (until the camera deems that the voltage is too low to operate) even though they hold a lower total charge. Arent they the same voltage as the crv3 lithium batteries that come with the *istD in the box? A battery is a complex device, it can loosely be considered as a voltage source (with unlimited current) in series with a resistance (an internal dynamic resistance which varies dependent upon load current). Current and hence power in the a linear circuit increases as voltage rises for a constant load, it's ohms law. Being that the terminal voltage is higher than the normal battery voltage there may be potential for damage of the camera electronics. I assume that the cameras in question employ electronic power supply regulation, if so these circuits could potentially be stressed or damaged by an over voltage battery supply. Again, I thought Pentax supplied 3v Crv3 batteries (thats whats in my camera now), or are the batteries in question (R-CRV-3) higher voltage per cell, i.e. higher than the normal 1.5v? NiMh are 1.2v, but also have very low internal resistance, so even pretty good loads dont move the voltage much. Care to test the theory? Given the high cost of CRV3 rechargeable batteries, non-uniformity of systems and specialized chargers required I really don't see why it would be worth the effort. Also I'm not aware of their self discharge rate either but from practical experience with other L-ion powered devices they aren't my favourite batteries in this regard. Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: R-CRV3
On 8 Nov 2005 at 19:27, Gonz wrote: Arent they the same voltage as the crv3 lithium batteries that come with the *istD in the box? Some are, some aren't. Again, I thought Pentax supplied 3v Crv3 batteries (thats whats in my camera now), or are the batteries in question (R-CRV-3) higher voltage per cell, i.e. higher than the normal 1.5v? NiMh are 1.2v, but also have very low internal resistance, so even pretty good loads dont move the voltage much. It seems some manufacturers are now building rechargeable CR-V3 batteries which match the voltage of the disposable cells. It must have posed a problem though since it's noted as a feature, see: http://mobypowerus.com/mp-rcrv3.htm Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
