How can I verify that my 9000mA batteries are really 9000mA?

[witold]

I recently bought 9 "D" Size 9000mA batteries and I want to make sure that they are what I paid for. How can I verify the 9000mA number?

On my charger, when the battery is full, it just says 1.40v.

Can someone enlighten me on this, please? I couldn't find anything useful via google.

BTW, the batteries will be used for a) heated motorcycle gloves, and b) battery pack for digital camera.

Thanks guys.

Witold
www.witold.org

 

[Zepper]

Battery testing:
. You did not mention what type of batteries you have NiCd or NiMH. IAC, they are rechargeable so they are probably rated at 1.2V and the 9000 is not mA but probably mA hours. So you will need a load that draws about 300 mA or about 4 ohms (or you could use a load equivalent to the device the battery is to be used in and adjust the hour estimate to match). Do the test in an environment that closely matches the one in which the batteries will be used to get a more realistic result. Cold temperatures will reduce the total available power as it slows the chemical reaction rate inside the battery. The battery rating is determined at STP [standard temp (72 deg.F) and pressure (sea level)]
. You could use a bulb or LED in series with a resistor to provide the load. If so, you will have to measure the hot resistance of the bulb or determine the forward resistance of the LED in order to decide the size of the resistor you will need. You then connect the resistor and bulb/LED in series with one of the batteries. If it's really a 9000 mAh battery, it will last (keep the bulb/LED reasonably lit) for about 30 hrs. A simpler method is to just use a 4 ohm resistor and measure the voltage hourly with a digital meter. At some point the volt reading will start dropping rapidly and that's the "usable life point" which should also be at around 30 hrs., if the rating is true.
. One of the battery types' voltage really drops off a cliff when it runs out of juice. IOW, at one reading it will be lit pretty good, and at the next reading, it will be stone dead - I'm not sure which, but I think NiMH. You don't want to keep it hooked up for very long after that point so as not to damage the battery. So at about the 25hr. point you should start watching the test rig closely.
. More thoughts: You could keep the digital meter hooked to the test rig constantly as they don't add appreciable load. If the batteries will be used in situations where they will be turned off and on, you will get more mAh from them, as batteries have a recovery effect during the off periods. If used with a constant load, the mAh will be less. The factories test with a certain on/off duty cycle to get their ratings. IOW, a constant load test as above will give about the lowest possible mAh rating. You could devise your own duty cycle (e.g. 45min on/15min off - 75% duty cycle) to get a more realistic result, or look at mfr's spec sheets (usually in the footnotes) to see what they use.
.bh.

 

[dude]

Don't worry about it that much. There's no real way to test it easily. the mA rating is just to tell you how long it should last before it drains and needs another recharge.

As for the voltage, if you're looking for 1.5 volts, forget it. These are recharables and they are usually at 1.3v only. But, they are better than Alkalines as alkalines will drop their voltages sharply after slight use. Rechargables such as NiMH don't. Their drop in voltage is more linear.

 

[witold]

Thank you for your response Zepper. This is alot of information for me to digest, as I know very little about electrical stuff, so I'll be saving this for a close reread after I get home from work.

The batteries are indeed Ni-mh from Ccrane (direct link) The brand is Hitech - Digi-USA/ GN National Electric CA. They are rated 9000mAh. I plan to use these batteries with Kreamer heated glove liners. I ride my motorcycle during the winter, so these will be a blessing if they work as expected.

Witold
BTW, here's my bike.

Also, I'm a big fan of Dostoevsky. I read most of the stuff he published, so I was puzzled as to what "Grand Inquisitor" is. (I thought it was some short story I overlooked). Eventually I looked up the reference.

 

[Zepper]

That D-Cell battery pack is only eight batteries. Obviously designed for Alkaline batteries that are rated at 1.5V each. You would need 10 rechargeables for the equivalent voltage. If you use your NiMH in there they will not heat the liners quite as warm as alkalines. You should install a jack into your bike's 12v circuit and run your glove liners that way. Unless you are just using the batteries for pre-heating.
. Your bike looks good, but I prefer the old japanese standard street bike style with a fairly full-size fairing. That radical style isn't very useful and can get painful on a long trip. I once rode a Yamaha 350 2-stroke from Florida to Canada and back. My back could have never taken it on a bike like yours. You must be a young kid... I was probably 30 or so when I did that Canada trip and I wore a kidney belt even then.
.bh.

Oh yeah, the glove liners present a 9.6 ohm load Ohms(9.6)=Volts(12)/Amps(1.25). So for one NiMH battery, the load resistor should be 1.2 ohm to simulate the load (glove liners). At that load you could get up to 9 hours at the factory's duty cycle (probably less, because the factory's test load would more like my original suggestion of 4 ohms. The higher the load, the shorter the hours because there is only x amount of chemicals in the battery to react and the reaction efficiency decreases during the load cycle.
Brief analogy for simple resistive electrical circuits (glove liners): Amps like volume of water thru a pipe; Volts like pressure in a pipe; Resistance (ohms) like the inside diameter of the pipe. To get the same volume thru a smaller diameter you have to increase the pressure. I.e., to get the same current (amps) thru a higher resistance wire, you have to increase the Voltage. There are the basic relationships. Some different issues would obtain in the digital camera application.
.b.h.

I went to a battery web site that a lot of people here use: www.bydusa.com and found that their batteries can do 85% of their mAh rating when loaded at 1Amp like your gloves. Let me know what you find on yours. This site has 4-packs of D for about $36. each but they are only 8000 mAh. They are changing over to using another site for retail sales of their batteries: www.batteryspace.com .bh.

 

[Zepper]

Duplicate, Sorry.

 

[witold]

After charging the batteries, I tried everything yesterday. (Temps were in the teens, no less )

The liners provided some heat in the wrist area, but the glove fingers provided no heat whatsoever. It looks like I will have to modify the battery pack to accept 10 Nimh batteries, instead of current 8. Ultimately, this is a temporary solution and I plan to hook up the liners to the bike battery.

I am 23, but more importantly, I have a couple of thousand miles on my road *bicycle.* After riding on that bicycle, with it's radical geometry and rider posture, I fell right at home on R6. My R6 feels like a couch compared to my bicycle. Funny but true.

Thanks for the explanation. It helps alot.

Witold
www.witold.org

 

[Zepper]

YW. It was 16 below zero here (upstate NY) a couple of days ago at about 10 P.M. A little warm front snuck up from the south about that time and the temp acrually rose for the rest of the night. We got a little 40 deg. teaser today, but it won't last long. Of course, we have it pretty good here. Some places in and near the Adirondaks were at nearly 40 below several times this winter. 18 degrees sound positively balmy...
.bh.