Use of Rechargeable batteries in Test Equipment - Page 1
Forum section: electronics / testgear

author: watchmaker
author_rank: Unknown
timestamp: November 17, 2024, 02:23:19 pm
content: I decided to get rid of all my alkaline batteries, even found leaking Energizers in our hiking pack headlamps.Too many things to keep track of (like emergency headlamps in the Jeeps) and long periods of no use.First I bought Eneloops which were ok for the AAA headlamps; but the low voltage was too low for the Rx1 in my Simpson 260s using a D cell adapter. Sent most back to Amazon.I am now trying BlueSky AAs which have true 1.5 V output for my meters, and will try 9V next.BlueSky provides a note that the PCB in the battery emits HF radiation, and cautions against using in sensitive devices.Not too concerned about the VOMs, but what are the limitations for the use of these batteries?THANKS!

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 17, 2024, 02:37:31 pm
content: Most likely -but have to verify the assumption- these batteries incorporate a switch mode converter inside. If you have access to a scope I would attempt to view the ripple voltage and how much it changes with load.I would appreciate if you post a link to the battery supplier. Googling it gives a bunch of irrelevant results.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: November 17, 2024, 02:57:06 pm
content: similar situation discussed here:https://www.eevblog.com/forum/testgear/ansmann-9v-rechargeable-li-ion-battery-in-fluke-87-high-pitched-noisei'd be inclined to find a solution containing 3 Li-Ion cells in series without any boost converter.cheers,rob :-)

author: watchmaker
author_rank: Unknown
timestamp: November 17, 2024, 04:00:54 pm
content: Quote from: schmitt trigger on November 17, 2024, 02:37:31 pmLink is here. The notice was included in the package document.https://www.amazon.com/dp/B0BT4FTH85?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

author: unseenninja
author_rank: Regular Contributor
timestamp: November 17, 2024, 04:11:42 pm
content: These batteries consist of a single 3.7V lithium ion cell and a buck converter to give the 1.5V output. As the note in the packaging says, they're not suitable for anything which expects the power to be low noise. Most likely there will be many tens to hundreds of millivolts of switching noise on the output.

author: watchmaker
author_rank: Unknown
timestamp: November 17, 2024, 05:27:12 pm
content: Quote from: unseenninja on November 17, 2024, 04:11:42 pmThank you! So we are stuck with Energizers for 9 volt batteries?I am going to look at the traces of these rechargeable. The Eneloops AAs will power a 4AA radio and the AAAs will power headlamps. So that at least works out. At least the VOMs only use batteries on the Ohms meter.Another case where application has to be thought through.

author: PlainName
author_rank: Super Contributor
timestamp: November 17, 2024, 05:46:26 pm
content: Won't the Li-ion batteries run down quicker than alkalines (and you then find them flat just as you need to use them)? Eneloops only have self discharge to cope with, whereas the lithium stuff has a buck or boost converter to continuously power. Presumably there's an output cap, so it would also depend on the leakage of that as to how much power is used to keep it topped up.Note: I know nothing about these so happy to learn from someone that does

author: watchmaker
author_rank: Unknown
timestamp: November 17, 2024, 05:59:47 pm
content: Here is the trace of the Bluesky battery with the buck converter. No load.

author: stj
author_rank: Super Contributor
timestamp: November 17, 2024, 11:38:43 pm
content: maybe knowing the freuency you could filter it with an inductor?

author: J-R
author_rank: Super Contributor
timestamp: November 18, 2024, 12:08:46 am
content: For the Simpson, could you place the AA alkaline into the D cell adapter? That should provide adequate leak protection.

author: AVGresponding
author_rank: Super Contributor
timestamp: November 18, 2024, 06:26:30 am
content: I use a Znter PP3 in my 87V (single cell lithium with boost convertor), don't have any problems with noise that I've noticed. Guess it depends on the brand

author: watchmaker
author_rank: Unknown
timestamp: November 18, 2024, 12:09:13 pm
content: Quote from: J-R on November 18, 2024, 12:08:46 am

author: Hydron
author_rank: Super Contributor
timestamp: November 18, 2024, 02:47:23 pm
content: Maybe put some absorbent material in with the alkaline it if the D cell adapter allows?As for 9V batteries, I've been using a mix of Ansmann 8.4V NiMh LSD (very compatible with 9V nominal alkalines) and some cheap 2S LiPo batteries. The latter don't have a DC-DC or charger built in (just a protection PCB), so the device must accept the ~6.5-8.4V range it outputs, which many do. The cases don't quite fit the 9V size though due to sharp rather than rounded corners (very annoying as there is room left inside, the wrong case shape is just incompetence) and I ended up using the more expensive Ansmann NiMh batteries in a couple of devices that were happy with the 2S LiPo voltage but not the shape.