• RE: Sensor to measure amount of dripping water?

    I would think that it's the ambient air temperature that affects how much condensate you collect, together with how much fuel was burned. After the initial warm-up that gets you to steady state, wouldn't the efficiency be constant?

    If the acidity is a problem, you can run the condensate over a bed of acid neutralizing rocks before it goes down your main drain. It's a thing.

    posted in Hardware
  • RE: Sensor to measure amount of dripping water?

    Some kind of through-beam sensor might work: https://www.amazon.com/Optical-Endstop-Photoelectric-Control-Printer/dp/B07MFT8NWJ/ref=asc_df_B07MFT8NWJ/?tag=hyprod-20&linkCode=df0&hvadid=241938907421&hvpos=&hvnetw=g&hvrand=9189408107204898573&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9028292&hvtargid=pla-664653941028&th=1

    I once was interested in the same sort of thing for monitoring the effluent from a reverse osmosis filter at the air-gap to confirm that it wasn't wasting a lot of water. In my case there turned out to be an easier way.

    posted in Hardware
  • RE: Sensor to measure amount of dripping water?

    If it drips slow enough, maybe a simple photocell and led could be used to count each drip as it drops in-between. Use arduino analog input to look for a drop in the light intensity. i.e. a simple electric eye.

    posted in Hardware
  • RE: 💬 Fork of BigClive AA Battery Trickle Charger

    @gregvp said in 💬 Fork of BigClive AA Battery Trickle Charger:

    I have a project on my list to make a NiMH capacity tester using as the load a boost regulator loaded with a range of resistors. But at my current rate of progress through the list, I'll be dead first. 🙂 😕

    Luckily, if you want to do some testing before you die, you can get pretty decent load testers for cheap these days. Not sure how accurate they are in an absolute sense, or how accurate you would need them to be for your particular purposes, but for anything I do they seem "good enough" and provide repeatable capacity numbers.

    load_tester.jpg

    https://www.aliexpress.us/item/2255800047204598.html?spm=a2g0o.productlist.0.0.1e963f191wOpcX&algo_pvid=8930e84c-2b17-4afd-9458-68d1aabbc9bc&algo_exp_id=8930e84c-2b17-4afd-9458-68d1aabbc9bc-20&pdp_ext_f={"sku_id"%3A"10000000947167753"}&pdp_npi=2%40dis!USD!13.43!9.67!!!!!%402101d8b516678388477845208e191c!10000000947167753!sea&curPageLogUid=kEzSSWx2qqOU

    I agree with your comments regarding the likely use of niMH batteries. Not sure what load to pick, but I do need to pick some kind of reference load--maybe 1C?--so that I have some way of gauging whether or not the cells kept 24/7 in the forked BigClive trickle charger degrade noticeably more than cells which aren't. In the end I suspect Calendar aging will be the biggest effect, but I won't know for sure unless I run the experiment.

    posted in OpenHardware.io
  • RE: 💬 Fork of BigClive AA Battery Trickle Charger

    @mfalkvidd As near as I can tell, there's is commonly a conflation of ideas that really should be separated. According to Dave Jones here:
    EEVblog #515 - Battery Ionic Resistance Investigation – 27:52
    — EEVblog

    internal resistance (at least in the case of a 9v battery) 1. is quite small, and 2. doesn't vary much if at all over the life of the battery. Apparently it is what's measured with the 1kHz signal. However, what is much larger than that is what he calls "ionic resistance", which has to be measured under load. So..... I'm not sure which of those two, or what mix of those two, the battery charger is measuring. I've tried two alternate battery chargers for measuring "IR", but they each appears to measure different numbers.

    The number I rely on the most is usuable mah in a battery that's arrived at by a constant current discharge, and I use an OPUS BT-C3400 to measure that. Its a repeatable number, and it's definitely a useful number. However, I'm unsure as to what value the "IR" number has, but I'm collecting it anyway in case I/we eventually figure it out, or else figure out how to measure it in a way where it has actual usefulness. So far it seems like "ionic resistance" is the more useful concept, because it indicates how much the voltage drops under a particular current load, and, anecdotally, that voltage drop does seem to be less when a battery is new or almost new as compared to when it is older and closer to failing.

    Plainly, the voltage drop is greater the greater the current draw, so I'm developing skepticism that there really is a single number that represents battery health in that regard. Perhaps the only number that matters is the voltage drop that a particular application experiences from the current that it happens to draw? At the moment, I'm leaning toward that hypothesis. i.e. there is no single context free number that has meaning. Instead, maybe pick your own test conditions that have meaning for your particular application, and measure that instead. Not entirely sure though. Everybody knows that you should measure battery voltage under load, but exactly what load and for how long it should be applied before taking the voltage measurement..... I'm not aware of any standards in that regard.

    Actually, the closest thing I've found to answering this question comes from putting LiFePO4 batteries under high load and seeing how they respond:
    The Final Word On Grade B - Lifepo4 cells Grade A vs Grade B - SFK – 33:33
    — Sun Fun Kits LLC

    In that video a guy who claims to have tested thousands of LiFePO4 batteries claims it to be the method he uses to separate "Grade A" cells from "Grade B" and below cells. First he fully charges the battery, then he hits it with a 100a to 200+a load to see how it reacts. If the voltage in a cell then sags below 3.2v during that load test, then according to him it's not a "Grade A" cell. He also looks at how quickly a cell "snaps back" to inits initial voltage after the loading stops. My point is: he's looking at battery dynamics; he's not measuring a single number to determine how "good" a cell is. On the other hand, I would imagine that any sort of dynamic could be reduced to a number using mathematics....

    So.... that's how a pro does it. Unfortunately, his method is more like a comparison of battery dynamics, centered around what is EVE certified as "Grade A" rather than arriving at a single hard number, but even so it's an enlightening youtube video--better than the meandering eevblog youtube video IMHO.

    I suppose I could come up with a similar test for NiMH batteries, but it would be derived from a similar method of making dynamic comparisons against "known good" high quality Eneloop cells rather than referencing a single IR hard number spit out by a battery charger. That is.... unless someone here has a better way. If so, please post!

    posted in OpenHardware.io
  • RE: 💬 Fork of BigClive AA Battery Trickle Charger

    @mfalkvidd Presently, I'm just reading the IR value off the charger (see photo above), on the assumption that whoever designed it knew what they were doing (not always a good assumption). For instance, in the above photo you can see that it is reporting 72millohm on the cell in position #8 (the rightmost cell). By changing the slot selection, I'm able to read the millohm measurements off of each of the other cells in slots 1 to 7 as well.

    posted in OpenHardware.io
  • RE: 💬 Fork of BigClive AA Battery Trickle Charger

    Reporting back:

    I purchased brand new Amazon Basics that I'll use to trial this charger:
    test_batts.JPG

    I'll be recording both their internal resistance and capacity prior to the start of the test, and then measure them again somewhere down the road to see how they do or don't degrade relative to a control group of cells from the very same batch of brand new Amazon Basics NiMH rechargeable batteries. Not sure how long will be long enough to trial this method of charging. Any suggestions? Otherwise, I'll just re-test them whenever the spirit moves me to do so and report back at that time.

    I understand that BigClive meant for this to be a simple design and a simple project, but depending on how the trial goes a a refinement might simply be to insert a circuit which charges them for, say, an hour or two each day rather than charge them continuously. Of course, you can easily buy off-the-shelf timers to accomplish that already, so that might be another way to arrive at an equivalent solution without needing to make any changes to the circuit board.

    Anyhow, I rather do like the idea of having fully charged AA batteries always available.

    Is battery internal resistance a meaningful measurement? I ask because I have yet to find a battery charger that measures internal resistance in a repeatable way. Is there a better, more repeatable wayt to measure it? As you can see from my markings in the photo above, the reporting internal resistance on each of gthe batteries is already all over the map, with a low of 52milliohm and a high of 90milliohm.

    posted in OpenHardware.io
  • RE: Anyone here tried either LoRa Meshtastic or LoRaWan for grid-down emergency communications?

    @mfalkvidd If things go sideways in the "you know where" region of eastern Europe, such that they affect Sweden, feel free to open a thread and ask for help. I'm sure everyone on this forum will do their best to get you any information or other resources you might need to adapt to events as they develop.

    posted in General Discussion
  • RE: Anyone here tried either LoRa Meshtastic or LoRaWan for grid-down emergency communications?

    This youtube is perhaps a little tangential, but I found it both informative and entertaining to watch. It makes an argument for why you'd want to have a stand-alone GPS (no, not the usual "connected" one in your phone) for use in emergency scenarios:
    Why Everyone Needs a GPS – 27:34
    — T.REX ARMS

    This youtuber also has a great sense of humor and demos some interesting products.

    FWIW, the Red Cross recommends everyone should have paper maps as a backup, but these days who keeps up-to-date paper maps anymore? What this youtuber describes might make more sense as an alternative to paper maps, and he gives a compare/contrast as to why.

    Although he didn't cover it, I'm fairly sure there's a way to download google maps to your phone so that you can be stand-alone that way, and this method wouldn't require any added expense (provided you have enough spare storage in your phone).

    The same guy also did an interesting overview of emergency radio communications, which is very much on-topic for this thread:
    An Introduction to Radios and Emergency Communication – 21:25
    — T.REX ARMS

    posted in General Discussion
  • RE: Anyone here tried either LoRa Meshtastic or LoRaWan for grid-down emergency communications?

    @JeeLet The Things Network claims 89,623 gateways connected via LoRaWAN: https://www.thethingsnetwork.org/map

    posted in General Discussion