First a note about my setup. Above are the 3 electronic-loads that I have at my disposal. The 'green' one, my first purchase, is capable of providing 60W of loading, whereas the other 2 'black' ZKE loads manage only 30W. This disadvantage is offset by the fact that the green load's minimum voltage/current settings are 1V/200mA, whereas the ZKE loads are 0.1V/50mA - therefore much more useful for lower voltage/current testing. Unfortunately to their detriment, the ZKE load's firmware sucks! While the green load, during test, will cycle the display continuously, at 1 second intervals, between instantaneous, voltage, Amp-hours and Watt-hours, the ZKE loads must be switched manually to see what's going on - a real handicap when batteries are electrically connected via neo-magnets as you see here, as one's curiosity, followed by the slightest nudge to the test apparatus, can result in an intermittent disconnection, and a ruined test. Maddening, when you're say, 30+ hours into a battery test - as happened with me here, as well as many times in the past! Another huge plus for the green load is that when a test completes successfully, the results will be saved to non-volatile memory, which will then survive even complete power failure, and will be restored on power-up and can be stepped through manually by the user.
Hardware-wise, the ZKE loads are also sub-standard. While both load-types are fan-cooled, only the green tester uses variable fan-speed cooling, dependent on the applied load - unbelievably, the ZKE load's fan will ramp up to full speed and remain there, irrespective of the load being provided, for the entirety of the test. In fact, when I got the first ZKE load, I presumed it was faulty because of this. What was much more worrying however, was that even during a 30W test, the fan speed would vary erratically, going from full speed to on occasion, stopping entirely! Thinking that this was down to a firmware bug, I sent a video (link here) of this behaviour to the Seller (and manufacturer) of the electronic load, and got another one sent to me, gratis - the only reason I have 2 of them! I was not impressed on powering up the replacement to discover that the 'full-speed always' thing was the rule, not the exception! The final insult was delivered not more than 200 hours later (test-wise), when the fan on the replacement load also failed! Evidentially, the manufacturer opted for the cheapest fans possible, which employ dirt-cheap 'sleeve bearings', and from what I've read, are a complete no-no for fans that need to be mounted horizontally. What's particularly perplexing is that as I type this, the exact same ZKE load is for sale on Aliexpress for between $40-$50 - that's literally twice what I paid for my one, 4-5 years ago. Whereas the identical green load is also available on Aliexpress right now, but for between $18-$20 - exactly what I paid for it 5-6 years ago! Makes no sense. But (as always) I digress...
Batteries in play.
Alkaline Aldi Activ Energy (AA, AAA) - all well-within their expiry dates.
Nickel Metal Hydride battery: Panasonic Eneloop Pro (AA)
Generic 'Tronic' NIMH Aldi Rechargable (AAA)
First off, I did an apples-to-apples comparison between the loads in order to convince myself that the (suspect) ZKE load's test-results were accurate (see pic). I checked both load-types using the same Aldi Tronic AAA NiMH battery, and employing the same voltage cut-off/current settings. In practice, I did a lot more than this, comparing both Eneloop & Eneloop Pro AA batteries, but the AA/AAA results will suffice here. The Cut-off voltage used was the 'non-standard' (for NiMH) 1.0V and Load-currents of both 200mA & 500mA gave results that didn't vary appreciably between electronic loads. These tests were enough for me to warrant proceeding, sacrificing a few Alkalines in the interest of curiosity, if not science.
Given the relatively huge 200mA 'lowest' current that can be set with the green load, coupled with its 'above-standard' test-complete voltage of 1V, I decided to confine all my testing to the ZKE load.
My first test of an Alkaline AA @ 200mA with a cut-off voltage of 0.9v resulted in a tested capacity of just over 2000mAh, which I found disappointing, and reckoned the poor result was down to what I considered the large (for Alkalines) current draw. This test also highlighted a[nother?] firmware bug in the ZKE - notice above how the mAh and mWh readings for the Alkaline AA test are identical, though try as I might, I have been unable to reproduce the problem! Anyway, to test my Current hypothesis, a second alkaline AA was tested, this time at a much higher 500mA current draw. Confirmation however wasn't forthcoming, as the battery performed surprisingly well, indicative perhaps that alkalines aren't as awful under load as I had presumed. Unsurprisingly, it delivered marginally less than battery 1's 2000mAh. I then decided to test a third at the minimum-allowable 50mA current-draw, a decision that proved to be bone-headed, as this quadrupled the test-time to about 40 hours. Three-quarters of the way through, I 'nudged' my test setup while checking the current values, resulting in one prematurely terminated test. Grrrr, infuriating.
Finally, some Aldi/Lidl AAA battery testing.
As can be seen below, the old, well-used NiMH battery outperformed the new, unused Alkaline by an appreciable margin, itself a surprise, given my past experience with 'Tronic' batteries - basically, they've never provided their claimed capacities, even when new (1000mAh in this instance), generally deteriorating rapidly over time, before failing entirely.
So, what have I learned from this? First off, the capacities of 'one-shot' alkaline batteries do not seem to appreciably exceed that of 'quality' NiMH batteries. In fact, they may not even approach Premier NiMH battery capacities - my Eneloop Pro batteries, ordered through Aliexpress, to me, have always seemed 'suspect' - they have NEVER been seen to provide their stated Minimum capacities, namely 2500mAh, all 4 instead managing just marginally over 2000mAh. Whereas my Standard Eneloop batteries, ordered through Amazon, performed to specification from the get-go, delivering (when new) the advertised minimum capacity of 1900mAh. But I've whined on about this in an earlier post, so 'nuff said!
Before this, I figured alkaline's 'edge' must be in their higher 'nominal' voltage - 1.5v versus NiMH's 1.2v. Surely, I thought, this 20% higher voltage would deliver 20% higher capacities, when measured in mWh. Not the case as far as I can see from the testing that I've done. In fact, this higher-voltage 'advantage' would seem to me an artificial one, imposed on us by the battery & electronics manufacturers. A good example of electronic goods that almost demand alkalines are cheap LED torches. With LED's fixed voltage-drop, NiMH batteries manage to provide only a fraction of 'useful light' time that their alkaline compatriots provide - despite still retaining much of their initial charge 'when the lights go out!".
Summing up. I'm more convinced than ever that alkaline batteries are a rip-off, and in no way represent value for money. This is particularly evident when it comes to powering heavy loads - something that manufacturers often cite as being their forte, particularly around Christmas time. Even were we to agree that one alkaline costs perhaps a fifth that of its NiMH compatriot, itself unlikely, their 'one-shot' nature would still see NiMH outlast them by at least 100 times. In fact, the only true advantage alkalines appear to have over NiMH batteries is 'shelf-life', ie. the ability to retain charge, unused, over extended periods of time. But even this advantage has seen continuous erosion as 'quality' batteries like Panasonic's Eneloop continue to improve - I think the newest generation retain more than 90% of their charge after a year. Add to that, appliances like smoke-detectors, where alkalines were always the de-facto choice, must be seeing a decline in their use. For example, I've got a few powered by both alkaline and NiMH 9v batteries, Soshines in the latter case. The NiMH batteries seem to last just as long as the alkalines - so why continue to waste money in what to me seems to be a defunct technology? One thing's certain, if we continue to buy them, the manufacturers will continue to churn them out.
