What to do with my Fluke 867 - Page 1
Forum section: electronics / repair

author: viper
author_rank: Regular Contributor
timestamp: December 04, 2023, 01:55:33 am
content: I own it for certain reasons. Some of that is having a blend between a scope and DMM in the field. It is built solid, but some things are not great.Not great.1. Display works but very hard to see.2. Battery is old NiCad and is mostly toast. Learned how to jump start it to force meter to charge it.3. It is slow to activate functions. Just sluggish.4. Rotary dial is obviously a problem. I got it with a problem and had to tear down at least twice to deal with it. Won't turn certain functions on.Good....1. Build quality is BA!2. Kicks out AC ripple on DC circuits.3. Some waveforms help quick diagnostics.4. DCV is deadly accurate to many zeros. Nice to have in field.5. Auto polarity on diodes.6. Insane fast for continuity beep. Helps me move faster when checking stuff.7. Lots of other functions that I need to learn to use better but come in handy.So the battery is 7.2V. I am really debating on getting another or trying to convert to Li. I need to look at charge curves. Even if 18650 cells are not optimally charged, I have enough around to feed it till Jesus returns.I really wanted to get another display online that are out there,but really hard for me to put even $50 into that meter, especially if that display turns out to be crap.Help me make decisions here!

author: coromonadalix
author_rank: Super Contributor
timestamp: December 04, 2023, 05:04:54 am
content: you're not happy toss it, no need to create a thread to rant ?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: December 04, 2023, 05:18:47 am
content: Quote from: viper on December 04, 2023, 01:55:33 amHave you seen this thread:https://www.eevblog.com/forum/testgear/fluke-867-vs-867b-anyone-know-the-difference/msg2421294/#msg2421294There is a difference between the non-B and the B models. It seems you can install the B display in the non-B model.Regards,Jay_Diddy_B

author: tooki
author_rank: Super Contributor
timestamp: December 04, 2023, 07:46:02 am
content: Quote from: viper on December 04, 2023, 01:55:33 amDon’t eventhinkof trying to charge Li-ion in a NiCd charger! It’s not just about voltage curves, it’s that charge termination is determined entirely differently. A lithium battery will never exhibit the behavior that causes a NiCd charger to terminate charging.This isn’t just an issue of convenience or battery longevity; Li-ion cells can fail in catastrophic ways that can burn down your house. It’s not worth it. Treat them properly.A 2S (7.4V nominal, ~8.4V maximum) Li-ion battery is a good match for the 7.2V (nominal, max. ~9V) NiCd battery, as far as being a power source. But you’ll need to ensure it’s charged separately.

author: DeepLink
author_rank: Regular Contributor
timestamp: December 04, 2023, 05:37:55 pm
content: I changed the original Ni-Cd batteries after a few years, crappy qualityInstalled a new set of quality Ni-Mh, and it has been great ever since - and it more than 10 years agoMine is the 867B model

author: philwong5176
author_rank: Unknown
timestamp: December 04, 2023, 05:42:32 pm
content: Quote from: DeepLink on December 04, 2023, 05:37:55 pmWhich charger did you use for the new Ni-Mh batteries?

author: viper
author_rank: Regular Contributor
timestamp: December 04, 2023, 06:03:59 pm
content: I cut the battery pack open to see what's going on. The OE batts are not really "bad", but I think the lack of use coupled with the self discharge of the chemistry is at issue.Other things I learned. If the battery is low enough, the meter will refuse to attempt charging so I have to jump start the battery. The voltage to the battery is regulated internally. The PS brick is 12V. It is only 300mA. As I have read, the charging on these is quite primitive. It is like a 12hr charge timer or something.The cells are arranged as a 6S with what appears to be an auto reset breaker. Tiny little guy. There is also a temp sensor that appears to provide a negative reference to another pin. If that sensor opens, it will remove the ground reference to that pin and charging stops.I don't know if the PS is designed to run at saturation and can't give more or what. I know the internal resistance of Li has presented some challenges but I have several cheap China cell chargers that are nothing more than voltage regulated. They just trickle up to a set voltage.The cells are 1700mah Sanyo so running just a pair of 18650 should nearly double the capacity I guess. I am very much banking on those batts having only a fraction of new capacity anyway.

author: Gertjan
author_rank: Frequent Contributor
timestamp: December 04, 2023, 06:23:17 pm
content: I have a Fluke 867B too.It is very easy to replace the old batteries with new NiMH ones.So just put new batteries in the existing housing, and be happy againNew ones have more capacity than old NiCd's anyway, so do not mess with Li-Ion, those need a very different charger.