Time for another quick deja-vu with our second attempt to test the 9V Maxell Zinc battery as the last time we have tried over 5 years ago the battery we received was past its expiration date and although we tested it we did not include the results in our test for comparison with other batteries. This time around the battery we got was a fresher one with expiration date 08-2020, so close to a year and a half left, so not going to skit the results this time around.


We started with a deja-vu this post as the usable capacity of the 9V Maxell Zinc battery we got this time was almost the same as with the expired battery we have tested a while ago. At 95 mAh capacity in our 0.05A constant current discharge test the results are not great, but it is to be expected from a Carbon Zinc battery anyway. So apparently even at the end of its shelf life you can expect similar performance to the one at the middle and maybe not that much different even with freshly produced battery of this model… if properly stored of course.

The performance of the 9V Maxell Zinc batteries in our tests:

– 95 mAh at 0.05A load

– 0.690 Wh at 0.05A load

We are not big fans of Carbon Zinc single use batteries as a cheaper alternative to alkaline batteries, but from time to time we still pick up some cells to test and reaffirm that we do not like them. Carbon Zinc batteries are designed to be used on devices with smaller power consumption and they do not offer as much capacity as their alkaline counterparts, but they do come cheap and are widely available in various stores. We are giving the 9V GP Powercell Heavy Duty another chance as we have tried to test one of these a couple of years ago, but it has arrived with at the end of its shelf life. The one we received this time is slightly fresher with 10-2019 expiration date, so this time with half a year left of its shelf life we have decided to include it in our test results.


As expected the 9V GP Powercell Heavy Duty Carbon Zinc battery did not do much better than our previous try, it has managed to give out just 32 mAh capacity at our constant discharge test with 0.05A. The previous test of expiring 9V GP Powercell Heavy Duty battery with just one month left was a bit better with 38 mAh, but this can be a result of different storage conditions. Anyway, we warn you once again to be careful when buying Carbon Zinc batteries to always check the expiration date and always go for fresh ones (never buy these online if the expiration date is not stated!), or better yet – go for alkaline batteries instead.

The performance of the 9V GP Powercell Heavy Duty Carbon Zinc batteries in our tests:

– 32 mAh at 0.05A load

– 0.234 Wh at 0.05A load

Time for another try at a Znter rechargeable LiPo battery with USB port for charging in the form of a 9V 400 mAh battery as an alternative to traditional 8.4V NiMH or 9V Alkaline battery. With our initial bad experience with the 1500 mAh Znter ZNT18650 that came dead and after opening it up we were not that happy with the build. The 9V rechargeable battery from Znter however looked much more interesting as it actually comes with higher advertised capacity than pretty much all 8.4V NiMHs and falls a little short in capacity compared to the best 9V alkaline batteries in terms of mAh. It is most likely a single cell LiPo battery with a step up voltage converter to output 9V in the size of a standard 9V alkaline battery. Fortunately the 9V 400 mAh Znter battery we got was what it was supposed to be and not with a dead LiPo cell inside, so we headed to testing its capacity…


Doing our regular 0.05A test we use for the 9V Alkaline and 8.4V NiMH batteries we got 338 mAh out of the rated as 400 mAh Znter battery, a really good result compared to 8.4V NiMHs we have tested so far. That result is also on par with an average performing 9V alkaline battery, but the Znter can be recharged and reused via a standard USB, so it is much more convenient. Things however get even more interesting when we look at the voltage curve during the discharge tests as it is essentially flat up until the end of the available capacity and we do not normally see this with NiMH or Alkaline batteries, it is the expected behavior for power banks however. The pretty stable at 9.51V output during the whole discharge test means much higher capacity in Wh compared to traditional batteries with the same mAh results where the voltage is dropping during the cycle. As a result we can say that we are quite happy with this particular product from Znter and it can be a really good alternative to traditional 9V Alkaline and 8.4V NiMH batteries.

The performance of the 9V 400 mAh Znter USB Rechargeable LiPo Batteries in our tests:

– 338 mAh at 0.05A load

– 3.212 Wh at 0.05A load

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