Using NiMh or lithium rechargeable 9V batteries on Fluke meters? - Page 1
Forum section: electronics / testgear

author: Nick12961
author_rank: Newbie
timestamp: May 31, 2025, 08:37:32 am
content: I have 3 Fluke 115s on hand I can grab and go as I need them so I do not need to rush to find meter. The meters use 9V batteries which none of my lesser meters like the 4000 count TRMS Klein use - that uses AAA which is much easier to eradicate the alkaline cells from.If I buy some disposable 9V batteries as a stopgap and run the NiMh or Lithium rechargeable 9V batteries the majority of the time will the meter run fine without them, possibly with some minor hour losses which is bearable given I can recharge the cell and have some on standby.

author: Hydron
author_rank: Super Contributor
timestamp: May 31, 2025, 10:54:42 am
content: Key thing with the rechargeables is making sure they physically fit - some are slightly too large or too boxy for a tight battery compartment. My fluke 87V is running fine on one (8.4V nominal NiMH I think) but the LiPo I tried first didn't fit.

author: Nick12961
author_rank: Newbie
timestamp: May 31, 2025, 11:11:09 am
content: I did find some on Amazon that are lithium rechargeable. I did see some Paleblue batteries I can get 3 2 packs of, so I always have an even amount of spares. I ordered one of the smaller ones (2 pack) to do a fit test. The rest seemed less reputable.

author: Martin72
author_rank: Super Contributor
timestamp: May 31, 2025, 07:41:55 pm
content: Quote from: Hydron on May 31, 2025, 10:54:42 amWe (Work)thought so too, and that's how it is until you do continuity-tests with the beeper on.The Fluke 87s we equipped with rechargeable batteries indicate low battery faster.8.4V is already close to the lower limit of the corresponding detection range.We are using normal 9V batteries again, but we plan to buy rechargeable “real” 9V cells soon to test them out.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: May 31, 2025, 07:42:56 pm
content: Good Morning Nick12961, I use 9 volt rechargeable lithium batts in my Brymen 869S and it runs for quite a while before I need to recharge, (I have 2, so I always have a freshly charged one ready to go). Getting the boot off the meter is a royal pain, so if it didn't last long I wouldn't use them.

author: Nick12961
author_rank: Newbie
timestamp: May 31, 2025, 07:45:54 pm
content: Quote from: Martin72 on May 31, 2025, 07:41:55 pmSo yeah, I think the way to go is 9V lithium, given the meters begin to warn you around that point and are critical at 6- 7V.

author: Fungus
author_rank: Super Contributor
timestamp: June 01, 2025, 06:39:24 am
content: Quote from: Martin72 on May 31, 2025, 07:41:55 pmThere's some PP3s which use a 3.7V LiPo with a booster circuit.I don't know if the boost circuit noise/ripple could affect the meter's readings or not.The meter's very low power so ripple would probably be negligible.

author: AVGresponding
author_rank: Super Contributor
timestamp: June 01, 2025, 08:00:24 am
content: Quote from: Fungus on June 01, 2025, 06:39:24 amI've been using one of that brand in my 87V for a couple of years now and the only issue I've encountered is that there's no low battery warning, as it maintains 9V until it shuts off.I've also a couple of other brands I've been using in other meters; they all seem to do the job without problems, though some have obviously lower capacities than others.It might be nice if the manufacturers would make them run at a lower voltage when the Li-whatever cell is low, just so you get a low battery warning. Seems a reasonably easy thing to do, since they all likely run micro-controllers with some spare programming capacity in them, and even if they don't, I'd happily pay an extra {insert local monetary unit} for them to include that feature.

author: Nick12961
author_rank: Newbie
timestamp: June 06, 2025, 07:21:50 am
content: Quote from: AVGresponding on June 01, 2025, 08:00:24 amThe plan is to buy one and see if the voltage drops with a 1/2 watt 300 ohm resistor. If it doesn’t I know it has the bad buck converter which doesn’t simulate battery drain. If it does I plan to use a meter just for testing and keep my main meter on alkaline or lithium primary for now until I know it behaves.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: June 06, 2025, 10:37:36 am
content: from a teardown video of the Fluke 115, it looks like there may be quite a bit of unused space inside, perhaps sufficient to fit a set of three 14430 sizedLiFePO4cells that, with a couple of series diode, would give a discharge curve going from a bit over 9v at 90%, down to 7.8v at 10% remaining, and 6.3v at 0% (based upon this chart:https://appbattery.com/faq/ultimate-guide-to-lifepo4-voltage-chart/the trick would be to have the cells fixed in place, with a charging port accessed by removing the battery cover.cheers,rob :-)

author: beatman
author_rank: Regular Contributor
timestamp: June 06, 2025, 01:04:03 pm
content: I use on my 177-179 and few other clamp and LCR meters rechargeable AA and 9v li ion batteries for over a year now without problems and most important no fear for leak on my expensive meters.I found time to upload the type and model of the batteries.

author: AVGresponding
author_rank: Super Contributor
timestamp: June 06, 2025, 01:08:54 pm
content: A super fresh alkaline PP3 is going to have an open circuit voltage of 9.9 or so. I've been using NiZn in my 289 for a couple of years now also, without issues. I suspect you could use Li-po cells without a problem (LiFePO4S are safer though, if you have them). I'm lucky, my job gives me access to all sorts of rechargeable batteries, from NiCd and LiFePO4S to lead acid. I recently acquired a few NiCd 4S D-cell packs, with the intention of treating my Fluke 8125A to a new battery.

author: beatman
author_rank: Regular Contributor
timestamp: June 07, 2025, 12:38:50 pm
content: Fenix ARB-L14-1600U AA and Powerex 9.6V