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| Fluke 123 Scopemeter and battery replacement |
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| Cones:
Hi, I bought a cheap Fluke 123 scopemeter from ebay with lines on the screen and a flat battery. No problem I thought, I can live with the lines and I will just get a new 3rd party battery for £15 from Amazon here in the UK. This is where all the fun and games starts! The original Fluke battery is a BP120 and is a 2000mAh NiCd unit. It would not charge in the scopemeter and would only maintain the unit for 30 second or so before it powered down. The new replacement battery is made by Cameron Sino and is a BP130 Equivalent 3000mAh NiMh unit. But on comparing the wiring on the 6 pin connector for the two batteries the new 3000mAh one is wired wrong and will not work at all in the scopemeter. As it was low cost and not worth the hassle of changing it. I have investigated further and resolved all of the problems with it. This is the correct pin wiring for the scopemeter battery connector. Pin 1 Not Connected Pin 2 + Pin 3 - Pin 4 I Identification (0 Ohms=NiCd) (825 Ohms=NiMh) Return on Pin 3 Pin 5 Not Connected Pin 6 T Temperature Sensor (NTC Resistor) Return on Pin 3 So I swapped the connector pins round in the plug on the new battery and then the meter would power on with it. But it still would not charge fully or perform a battery refresh operation. After a bit of Googling and a look at the Fluke service manual I found the above pinout information and I also discovered the correct resistance value for the NiMh battery. I measured the value on my battery Identification resistor and I got a resistance of 0.8301 Meg Ohms not the 825 Ohms it is supposed to be. So the manufacturer not only wired the plug wrong they also compounded the problem by putting the wrong resistance value in as well! So I have now cut open the heat shrink and corrected their mistakes as you can see in the pictures below. Battery Original and pending replacement resistor Crap insulation on the opposite side of the original resistor Removed resistance value Replacement Resistance Value Correct Plug wiring Repaired and heatshrink added for a slightly better insulation Red insulation tape as I have run out of larger heatshrink. This may get replaced in future if I can be bothered! Original Battery pack Refresh now detects the NiMh and changes from 12 (NiCd) to 19 Hours! Result. |
| SeanB:
Are you sure they got the thermistor right as well? Often I just do a transplant from the old to the new and it almost always works. |
| Cones:
Hi, yes I remember the values being similar on the thermistors. I will check again after it has finished the 19 refresh cycle it is currently running. As a further footnote to the old battery I have cycled it on my hobby charger a few times. The first time at a 1 amp charge rate to try and get the cell chemistry started. After 3 cycles at 200mA charge and discharge is now reports just over half its original capacity and will run the scopemeter for 2.5 hours. I might try a few more cycles and see what happens! NiCd and NiMh are relatively low capacity and old tech compared with the new Lipo or LiIon. But I suspect not of those would still take a charge after nine years!! Progress is not always what it seems. Mark |
| amyk:
The wrong resistor looks like orange and brown mixup. They do look very similar colours in the photos. Wrong resistor is grey-red-green-orange brown, 825k +/- 1% Right resistor should probably be grey-red-green-black brown, 825 +/- 1% |
| jivega:
Hi. I also recently bought a Fluke 123 with V1.08 firmware without battery. I made a purchase of a Cammeron Sino BP120 NiMh 3000mA, the connector goes both ways, I had to check the manual for how to connect. The connector also bad wiring in the terminal (Identification). No has resistor identification (0 ohms) to negative. I made the modification and included a 820ohm resistor between Identification cable and negative terminal, but when I do the refresh battery, this indicates 12 hours for NiCd battery not 19 hours. I tried with various resistor values ??but does not work. I dont know if it's the firmware version supports this type of battery. Cones: What is the firmware version on your Fluke?, thnks. |
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