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| Battery options for test meters (Brymen) |
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| TopQuark:
I realise the OP was asking about AAA batteries, but for my Brymen 869s and Fluke 87V, I exclusively use these rechargeable 9v batteries, which are basically 2 LiPo packs in series, packaged with balanced charging and protection. - They don't leak (they might explode, but that's another story ::)) - They don't have any voltage regulation (no smps noise, battery charge indication works) - They are protected against shorts and over discharge (I've tested it) - They can be recharged through USB, which is available anywhere these days - They offer great energy density, the multimeter simply works longer I like these batteries so much, I use them everywhere, not just multimeters, but for any circuit that needs a clean safe rechargeable floating power supply. |
| BillyO:
How about the BM786? It uses 3-AAA cells and turns on a low battery warning at ~3.7V. Ni-MH cells don't last long before the low battery warning comes on. Do these multi-hundred dollar meters not have some sort of regulation on them? Would Lithiums really be that big of a threat? It seems I'm either recharging Ni-MH cells every few weeks or taking the risk of destroying my meter by having alkalines leak in it. You'd think these geniuses that design these things would either choose Ni-MH, 1.5V Lithium or an easy to find Lithium rechargeable battery pack like a D-90. Are they just plain stupid? I think I'll resort to modifying my BM786 and put a diode in the circuit so I can use the Lithiums safely. This is just madness. >:( >:( >:( >:( |
| BILLPOD:
My main calculator, TI-85, runs on 4 AAA cells and it won't work on NiMh Eneloops, so I've had store brand alkalines in it. I've got in the habit of checking for leaks on a monthly basis. Well, yesterday I saw a tiny amount of the crusty white build up around the neg. end of one of the cells, so they went in the trash. I found some LiPo AAAs advertised as 1.5 Volt, so I've got them on order. Hopefully their fully charged voltage is not as high as the single use lithiums, (1.65V). |
| monkey_magic:
--- Quote from: wraper on November 09, 2022, 01:31:33 pm --- --- Quote from: monkey_magic on November 09, 2022, 01:26:51 pm ---However, the 257s didn't show any low battery running on two eneloop cells @ ~1.28V so that may be the best option for it. --- End quote --- Because it has 2.3V low battery spec in the datasheet (1.15V per cell), not 2.5V. http://www.brymen.com/images/ProductsList/BM250s_List/BM250s_Catalog.pdf --- End quote --- Sorry I must have misread that - you are quite correct 2.3V min on the 257s, it is the 079 that has the minimum of 2.5V for "other functions" and 2.85V for Capacitance and Frequency. I was also just looking at another of their meters which has a 2.6V minimum, so it does seem to very much depend on the series. I think i read on here Dave stated that the maximum voltage for the 235 is 3.6V – not sure if that applies to all of them. It has to be said it isn’t the most convenient operating window for battery choices. I know it is a minor complaint but it is a shame as I really do like my Brymen meters. |
| wraper:
--- Quote from: monkey_magic on November 09, 2022, 04:10:22 pm ---It has to be said it isn’t the most convenient operating window for battery choices. I know it is a minor complaint but it is a shame as I really do like my Brymen meters. --- End quote --- It's not a minor complaint. It's so bad it should have never left R&D and go into production. What's the point of functionality which requires that alkaline battery charge must be above 90% full. 2.5V spec is a total garbage too as it makes you toss alkalines which are 50% full :palm:. I actually have BM037 for some time and it has the same battery voltage spec. But have never before looked at this spec as I have barely used it and almost entirely on a clamp meter functionality in times of occasional need. I installed LADDA and did not see an issue as did not switch to capacitance/frequency and batteries were still at almost full charge. Now I'm mad at Brymen. They should effing use 3 batteries instead of 2 in their design, not make ridiculous spec. Even if using low power LDO to reduce the voltage to 3V, you would need to buy lower amount of batteries long term since you would use their full capacity. IMHO if EU busybodies were aware of this shit, they would ban it for sale because it's "not green" and makes you throw out batteries which are still good. |
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