Question for NLee the Engineer I have a Canon PowerShot A550 camera. I love it. I use Eneloop and Rayovac Hybrid batteries exclusively. I use the Eneloop charger and the Rayovac charger. My problem is that my Canon keeps flashing the low battery signal when I know the batteries are charged (they just came out of a charger and my Radio Shack battery tester shows the charge to be good). Can the low discharge of these batteries be tricking my camera into thinking that the batteries are not fully charged? I'm not sure what the problem is but it happens with both battery brands. I'm thinking about buying yet another battery brand (Duracell or Energizer) but don't want to keep having this problem. The last thing I want to consider is that it's my camera! Any advice you can provide will be deeply appreciated.
asked by Cedar on April 30, 2008
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Rechargable battery technologies such as NiMH (your batteries) and NiCD operate at a lower voltage than traditional alkaline cells. An alkaline cell out of the package starts @ about 1.5 Volts, while a rechargable battery might start out around 1.4V but quickly drops to 1.2 Volts duing most of its use. Most electronic devices stop operating at somewhere from .8 Volts to 1 Volt per battery, so your camera should still work fine, you just give up the low battery indicator. Your camera should still work much longer on rechargables than on ordinary disposable batteries.

Some electronic devices have a setting where you can specify battery type (alkaline or rechargable) to allow low battery warnings to work. It is also worth mentioning that some devices won't work at all on 1.2 Volts per cell, but in my experience these devices are few and far between.
bt@ answered on May 20, 2008
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Thanks bt@!
Cedar answered on May 27, 2008
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Cedar,
Sorry that I didn't notice your question until just now. But the answer given by 'bt@' is exactly correct. In the future, you may submit your question as a comment to one of my reviews. That's the only way I can notice it sooner.
NLee the Engineer answered on June 2, 2008
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While my response is also late, you may want to try using CHDK for your camera. This will give you a full-time battery indicator, as well as indication in volts or percentage.

You can get information about this hack here: http://chdk.wikia.com/wiki/Main_Page

The "low discharge" is actually "low self discharge;" this means that the batteries will not self-discharge as rapidly as conventional NiMH cells when not in use. Output is still similar to other NiMH cells.
true answered on June 12, 2008
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NLee,

I am looking at either the BC-700 or the Duracell Mobile Charger CEF23DX4N. I would like the option of in-car charging. Your reviews on both have been helpful.
1. The BC-700 does not come with a DC adapter. What size inverter would I need to run this off my car DC output? (LaCrosse could not really answer that for me). The specs say it uses 0.6 A at 100-240 VAC, which is not helpful to me. Does that mean I need a 60 Watt (0.6A*100V) or 144 Watt (0.6*240V) inverter?
2. I don't know anything about USB ports as power sources. My GPS (DeLorme PN-40) will run off the power of my computer when it is connected via a USB cable. Can I then assume I can power the GPS safely off the Duracell Mobile Charger DC output when the Duracell is plugged into the car?
3. The GPS is a battery hog so I need to keep the batteries in top condition. What would I lose in terms of maintaining batteries if I went with the Duracell? In sum, would you have an overall recommenation for my situation (DC-700 plus ??Watt microinverter, or the Duacell?
-Rob
Robert R. Bryan answered on May 21, 2009
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Bob,
For your application, I think the Duracell CEF23DX4N is a better choice becuase it comes with 12V car adapter, plus it provides a 5V USB port to charge your GPS.

1. To use the BC-700 in a car, you could use a 12V-to-110V inverter (you don't need a high power one, the charger consumes less than 10W even at full load). But a simpler solution is to get a 12V-to-3V down-converter. The maximum current required at the 3V output is about 2.8A (0.7A * 4), less if you use lower current settings.

2. You should be able to use the CEF23 to power your GPS. The CEF23 can power the 5V USB port when it is plugged in to AC outlet, or connected to 12V car battery. You can also use a set of 4 AA NiMH cells to power the USB port, but it should be more efficient just to use two AA NiMH cells directly in your GPS.

3. The BC-700 is a more powerful charger compare to the CEF23, becuase it provides you all the extra functions to analyze and recondition your batteries. But for most daily charging the two charger are about the same. If you cannot decide which one to get, here is my advice: Get the CEF23 for travel, and the BC-700 for home. Now you have everything covered. You just need to find more battery-operated appliances and switch them over to use rechargeable batteries.
NLee the Engineer answered on May 25, 2009
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NLee,
Thanks for the reply.

One more question: I have fairly decent digital multimeter that I use to get voltages for my cells. Can that be used to analyze their condition (for example, after charging I see differences in the voltages between cells) or will the BC-700 tell me things that need to know but that I can't figure out with my multi-meter?
Robert R. Bryan answered on May 26, 2009
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The BC-700 will tell you the capacity in mA hours. The fully charged voltage on NiMH cells varies between cells from about 1.2V to over 1.4V, and is not a good indication of the capacity of the cell.

Also, if you have finicky devices that cutoff before a cell is discarged (I have a four cell device that cuts off at 5.0 volts, or 1.25V per cell average), you can use the BC-700 to monitor a cells voltage performance over the discharge cycle, and pick the cells which keep the highest terminal voltage for the longest period of time for your finicky devices.
J. Ray answered on May 26, 2009
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Bob,
The terminal voltage of a NiMH cell can give you a rough idea on how fully the cell is charged. For example, if you measure the voltage to be 1.35V or higher, that means it is fully charged. If it is 1.15V or lower, then it is nearly exhausted. However, the voltage does not translated to the amount of charge stored inside the cell. That is, you cannot tell the difference between a fully charged 1000mAh cell and a 2000mAh cell based on terminal voltages.

The only reliable way to determine the amount of charge stored inside a cell is to slowly discharge it with a fixed current over time. The product of current (mA) and time (hour) gives you the charge capacity (mAh). You can use the Charge/Test function on the BC-900/700 to do this.

Note that the 'mAh' number obtained during Charge/Test is different from the 'mAh' you get during normal charging. The latter measures the amount of charge going INTO the cell, not the charge acutally STORED by the cell.
NLee the Engineer answered on May 27, 2009
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Q for NLee:
1. How do the BC700/900 measure battery temperatures? What are the temperature ranges?
2. I bought 20 Rayovac Hybrids (AA) and have found 2 cells that go 'dead' - ie won't charge - (~ 0.1 - 0.2v). On one of them - a day or so offline wait - and it recovers. The other, 2+ days so far - still not chargeable. I have called Rayovac support on this and they have sent a complementary 4-pack. What do you think of 'priming' them with a regular/no-smarts charger??
BillT
Toolster answered on September 20, 2009
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