Batteries in the GW121 - Page 1
Forum section: electronics / testgear

author: iXod
author_rank: Frequent Contributor
timestamp: September 16, 2017, 04:38:15 am
content: I know the BT makes a single 9v impractical. But I'd rather have two 9v's than AA/AAA cells. All my meters have 9v's.But real estate probably makes this impractical...

author: tautech
author_rank: Super Contributor
timestamp: September 16, 2017, 04:50:06 am
content: IIRC Dave said that a DC-DC convertor would be used to increase test voltages, what's wrong with that ?

author: iXod
author_rank: Frequent Contributor
timestamp: September 16, 2017, 05:08:53 am
content: For me it's a matter of stocking different kinds of batteries for all my meters.Cheers.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2017, 06:10:33 am
content: With a 9V battery you don't get much capacity.For example, the 121GW consumes about 5mA in normal operation, that will only be circa 100-150hrs operation from a 9V battery. Using 4xAA's gets you 500-600hrs.It has nothing to do with Bluetooth, the 121GW could use a 9V battery with no changes.Using two 9V batteires in series to avoid the DC-DC convertere for the 15V diode mode will not work because the battery voltage will very quickly drop below 15V during use so it's pointless to try and do that.With a single 9V you'd still need a DC-DC boost converter anyway, so there is no advantage at all to using 9V, you just lose battery life.Even the best 9V batteries will be hopeless at 5mA:Sure, if I wanted a (slightly) smaller size meter then you could argue the trade-off might be worth it, but I value a long battery life meter. And many people have said they hate 9V's in meter and wanted AA's.

author: iXod
author_rank: Frequent Contributor
timestamp: September 16, 2017, 06:41:08 am
content: Thanks for the detailed, respectful reply. Now I know!Sign me up for a GW121...Cheers.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2017, 07:10:34 am
content: Just did a video on this:

author: Gonzy78
author_rank: Contributor
timestamp: September 16, 2017, 11:43:46 am
content: Hello Dave, nice work by the way again ... ^^I am wondering, why not use a Lipo (much more compact and or higher capacity) with a boost with dc linear regulator after that ? If needed a very low noise, use capacitor multiplier circuit. Very handy to kill noise. You could fill the battery with a regular phone charger. It's kinda fast ... That could be nice. I don't know if this is more eco friendly to buy lipo once or buy AA and throw them away ...I am not a big fan of all integrated DMM chipsets, or dual chipsets solutions. Why not use a 24-32bit Delta sigma dac ?The arm is quite nice. I would be great that the software could be tweakable or opensource for community updates. I know this is a hardware product from a manufacturer, but I am ready to pay for "hobbyst" (and good) DMM that I can tweak a bit. Or it would nice if it's sold like the fluke kit tooI am quite intrested by the bluetooth function. If that function works well with a laptop & ready to python scripts that would be great... If the beast don't power off all the timeGood luck to you in this Adventure Dave.I am thinking about a product that could be handy myself. Unfortunatly in my country open a company is quite a challenge ... way too much bloody documents and taxes ...

author: Fungus
author_rank: Super Contributor
timestamp: September 16, 2017, 12:03:58 pm
content: Quote from: orgitello on September 16, 2017, 11:43:46 amNot for something that has to last many years.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2017, 12:10:15 pm
content: Quote from: orgitello on September 16, 2017, 11:43:46 amYou don't put LiPo into a product that already has 600hrs of operation, let alone one that is used fairly infrequently compared to consumer gear, and unlike consumer gear will not be obsolete in 2-5 years time.Then you have the problem of how do you charge it. It's not as easy as you think, you can't just add a USB connector as it would never pass safety standards.QuoteMultimeter chipsets do the job very nicely. You have a LOT of stuff to add if you don't use a chipset, it's not just an ADC. Take a look at what's inside a chipset and you'll see.QuoteYou'll be able to hack it if you want, but the source code will not be open source.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 16, 2017, 02:57:19 pm
content: Quote from: EEVblog on September 16, 2017, 06:10:33 amIt sounds like you have moved away from the 7V and now plan to release it with the 15V diode check. It's a nice feature IMO.

author: nidlaX
author_rank: Frequent Contributor
timestamp: September 17, 2017, 12:26:51 am
content: Are you planning to do private sales to forum supporters and Patreon, then run an open Kickstarter?

author: EEVblog
author_rank: Unknown
timestamp: September 17, 2017, 03:17:17 am
content: Quote from: nidlaX on September 17, 2017, 12:26:51 amThat's the plan, yes.

author: EEVblog
author_rank: Unknown
timestamp: September 17, 2017, 03:18:23 am
content: Quote from: joeqsmith on September 16, 2017, 02:57:19 pmIt's always been 15V. That one you see just had a label that said 7V because we were hacking around with it.

author: TD-Linux
author_rank: Contributor
timestamp: September 17, 2017, 11:49:52 am
content: I was happy to see AA cells because I have tons of LSD rechargeable ones, but 9V is far rarer. With a 1.05V dropout, NiMH should be fine. Of course, at 600 hours, rechargeables are barely necessary... but I use them for everything else.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 17, 2017, 02:41:24 pm
content: Quote from: EEVblog on September 17, 2017, 03:18:23 amGlad to hear you're keeping it.

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 17, 2017, 03:21:25 pm
content: Quote from: orgitello on September 16, 2017, 11:43:46 amI can pick up gear that's 50 years old and as long as batteries haven't leaked, I can still power them with contemporary batteries. The chances of that working out with a lithium-ion based battery pack are near zero.Lithium-ion technology is great for packing a lot of energy in a package that you need right now, without costing an arm and a leg. In other areas, the technology is not so great. Self discharge is much higher with lithium-ion. The battery packs age and wear out. Safety isn't quite that great either, with packs occasionally failing spectacularly. So if you want to power a quad copter, lithium-ion is a sweet option. If you want to power a device that sips power, might likely be used for years to come and could go months between uses, the technology is not that great.

author: Fungus
author_rank: Super Contributor
timestamp: September 17, 2017, 04:17:09 pm
content: Quote from: Mr. Scram on September 17, 2017, 03:21:25 pmHow about a super capacitor? They don't wear out and you could connect it to 5V for a couple of seconds then use it for six months.

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 17, 2017, 04:26:44 pm
content: Quote from: Fungus on September 17, 2017, 04:17:09 pmI've actually been looking at the long term performance of supercapacitors the other day, but I couldn't quite come up with definitive answers. I gather electrolytic types suffer from the same problems their regular brethren do, eventually drying out. I'm not sure about solid state supercapacitors at all.If you have any interesting information, links or documentation, I'd be most interested to hear about it.

author: f4eru
author_rank: Super Contributor
timestamp: September 18, 2017, 11:22:19 am
content: How long would it last with Batterizer?)?Quote from: Fungus on September 17, 2017, 04:17:09 pmThe energy in a supercap is aboud 1/10 that of an alkaline cell. So you'll slash your time from 400 to 40 hours....

author: BBBbbb
author_rank: Unknown
timestamp: September 18, 2017, 12:05:09 pm
content: Quote from: f4eru on September 18, 2017, 11:22:19 amI actually think Dave is making all this stuff up so he could justify using Batterizer compatible batteries. He just loves that miracle product.

author: Fungus
author_rank: Super Contributor
timestamp: September 18, 2017, 12:17:11 pm
content: Quote from: f4eru on September 18, 2017, 11:22:19 amI know, hence the emoticon.Also: Dave correctly pointed out that any external connector would instantly disqualify any CAT ratings. Recharging is really out of the question.

author: f4eru
author_rank: Super Contributor
timestamp: September 20, 2017, 11:28:47 am
content: QuoteNot if you do it the agilent's way : recharging through the normal banana terminals.At work we have U1252B models.They recharge on the measuring port, andthey suck.The battery life is quite low, and they must often be recharged.They probably do it to have the same moldymeter platform than the shiny OLED ones, where the battery life is low due to the display anyway.

author: HKJ
author_rank: Super Contributor
timestamp: September 20, 2017, 01:14:20 pm
content: Quote from: f4eru on September 20, 2017, 11:28:47 amA primary battery will give about 3 times longer battery life, at least as long as you do not try to charge it.I do not get the idea with a rechargeable multimeter, when the battery runs out I cannot wait a couple of hours for it to charge.

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 20, 2017, 03:14:36 pm
content: Quote from: f4eru on September 18, 2017, 11:22:19 amWhich isn't as much of a problem if you can charge it within a few seconds, some long data logging scenarios notwithstanding.

author: chefkoch84
author_rank: Contributor
timestamp: September 20, 2017, 04:10:17 pm
content: On the supercap Idea:I own much less Multimeters than the average user here...But one thing I own is the Voltcraft VC2000. It is powered by a "goldcap" that can be recharged at 12V or 230V through the testleads.http://www.radiomuseum.org/r/conrad_green_multimeter_vc200.htmlI like the concept but it also gets annoying if you just wanted a quick measurment and the thing is empty again.Charging is like 3-4 minutes.This thing dates back to 1995 and I only once changed the cap.(btw: the another meter is daves eevblog brymon)GreetingsMaxEDIT: Of course: Please sign me also up for a GW121...

author: jazper
author_rank: Regular Contributor
timestamp: December 25, 2018, 04:50:28 am
content: Any reason you can think of not to run the 121gw on disposable lithiums? Eg energizer Ultra lithiums?

author: beanflying
author_rank: Super Contributor
timestamp: December 25, 2018, 04:58:00 am
content: Quote from: jazper on December 25, 2018, 04:50:28 amBecause it would be over voltage for a lot of the cycle. The meter was designed for 4x1.5V maximum not 4x1.6-7. There was some posts in one of the 121GW threads including a post from Dave saying it was a bad idea.https://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/msg1782236/#msg1782236