Some Silver uMax voltage and current info...

[Clay Slayer]

I'm doing some testing on rechargeable batteries and emailed Tesoro today asking for a little voltage and current info on the Silver uMax. They were happy to respond with the info I asked for...I was pleasantly surprised. Most electronics manufacturers don't bother with customer service like that.

Anyway, I was interested in two things -


First, the min and max current draw so I could calculate an average using a duty cycle of my choice.

Second, I asked for the threshold voltages of the battery check beep sequence.

The info given to me was this -

Answer to my first question...Min current is approx. 15mA, detector on, speaker quiet. Max current is approx. 40mA, detector on, speaker on. I figured a duty cycle of about 12% on the high side (speaker on) which gave me an average current of about 18mA. Using 18mA and 8.4V max charge you get about 467 ohms, close enough to 470 to go with that. So...using a 470 ohm, 2W resistor I'll be testing the discharge rate of an EBL 600mAh Li-ion battery. 7V will be my cut-off on the low side. This just happens to coincide with my second question I asked them about their battery check circuit.

Answer to my second question...The battery test works like this - 9 volts you get 8 beeps, 8 volts 6 beeps, 7 volts 3 beeps and 6 volts 1 beep. The natural drop-off of the Li-ion should be right around 7 volts so this should work out pretty good and at 3 beeps it'll probably be time for a battery change.

I'll be sampling voltage levels at a constant load until the drop-off and see what kind of battery life (hours) I can get out of this particular battery. I may test an alkaline type Energizer/Duracell just for comparison.

Anyway, I know this is WAY more info than anyone is probably interested in, but I'll post my findings soon. HH

 

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[rainyday101]

Man, you have way too much spare time! I would have guessed that current draw would have been in the 100-150 mA range. I am surprised it is that low, which is a good thing. Although your testing method is valid, in real life you will get more time out of the battery. This is because you are doing your test at constant load all in one shot. In real life you use it for a few hours, let it sit for days, then use it again etc.

You could also just take the mA hour rating of the battery and divide by 40 mA to get a good idea of the time you will get on the battery.

Interesting though and seeing you are willing to take the time, please post your results!

 

[jld66]

i do not use the rechargable batteries. i hear a good brand of battery will last longer. i went through 8 energizer max ones this season. thats even changing it when down to 3-4 beeps. about 18 dollars for 6 months of detecting. that is cheap. bought a 6 pack for $13. read look for a shelf life of at least 4 years. i just dont think the rechargables are really worth it for detecting.

 

[Clay Slayer]

i do not use the rechargable batteries. i hear a good brand of battery will last longer. i went through 8 energizer max ones this season. thats even changing it when down to 3-4 beeps. about 18 dollars for 6 months of detecting. that is cheap. bought a 6 pack for $13. read look for a shelf life of at least 4 years. i just dont think the rechargables are really worth it for detecting.

Yeah, I'm not really worried about saving $20 bucks a year or whatever it may come out to be either. I just like doing the testing and getting the results...electrical engineering is my background so I just like tinkering with that kind of stuff.

 

[jld66]

Yeah, I'm not really worried about saving $20 bucks a year or whatever it may come out to be either. I just like doing the testing and getting the results...electrical engineering is my background so I just like tinkering with that kind of stuff.

oh, ok. haha. looked liked you were getting a bit carried away with battery life. i did some reading on it. recharge ones do not last as long and at a full charge, dont have as much power as a new non recharge one. so, while your tinkering around, maybe find out if that is actually true?

 

[rainyday101]

Nothing wrong with tinkering. I would do that test myself but I work on that high tech crap all day and don't want to work on it when I get home. Kinda like the car mechanic who drives a junker. Let me know what you get for results!

A few years back I did a drain test on a Ace hardware store alkaline to test a low voltage alarm circuit I made. I started with a 100 mA drain and let it discharge for about 6 hours. Checked the voltage under load and could not believe it. Took the load up to a 200mA drain and it still took over a day to drain it down enough to trigger the alarm circuit. It just boggled my mind how long that battery lasted.

 

[luvsdux]

I'm interested in what you turn up, also.
luvsdux

 

[Clay Slayer]

Nothing wrong with tinkering. I would do that test myself but I work on that high tech crap all day and don't want to work on it when I get home. Kinda like the car mechanic who drives a junker. Let me know what you get for results!

A few years back I did a drain test on a Ace hardware store alkaline to test a low voltage alarm circuit I made. I started with a 100 mA drain and let it discharge for about 6 hours. Checked the voltage under load and could not believe it. Took the load up to a 200mA drain and it still took over a day to drain it down enough to trigger the alarm circuit. It just boggled my mind how long that battery lasted.

I've been in the offshore oilfield business for about 20 years. Started with 2-way comms, telephony microwave stuff, then veered off into the PLC and metering world. Past 10 years I've been taking care of automated well & process control systems and personnel safety systems on offshore production platforms. Lately, mostly management and sitting in my office the past few years, so I enjoy getting my hands back on my test equipment once in awhile.

 

[Clay Slayer]

I've posted a couple of battery results on another topic in GD. I went with a different type of battery load for the testing other than resistors, but I explain that in that post. Check it out if you're interested in batteries.

http://www.treasurenet.com/forums/general-discussion/432704-need-input-true-9v-rechargeable-batteries.html