Kentli PH5 AA lipo as L91 replacement in ultra low drain applications? (or PM5 or PK5

Naguz

Newly Enlightened
Joined
Mar 29, 2011
Messages
43
In my condo building we have a lot of combined smoke, temp and humidity sensors. So not exactly flashlight related, but definitely battery related! These smoke detectors for some reason (at least allegedly) REQUIRES 4xL91 batteries. They don't just need Alkalines instead of NiMHs, no not even alkaline is good enough. Supposedly because of the voltage, I guess even the alkaline voltage drop is not something it can handle. Someone has not done a good job designing those units. Replacing the 92 L91 batteries would cost close to $400 a year, as they seem to last on average 7 months. It's not much in the grand scheme of things of course, but it's extremely annoying.

If the Kentli PH5 lasts about 4 times as long as the L91, in total, not per charge obviously, it makes financial sense. And according to reviews it should last a lot longer than that, even if it's longevity is not the best. But noone would bother to charge and change batteries every month. The self discharge test here seems very promising, and HKJ mentions they seem to have good self discharge in his test. Is there any reason to believe it should last for a shorter time than the difference in mAh (2000 vs 3000 for the L91) accounts for, ie 2/3 of the L91s? Has anyone run them in applications such as this? I fear that the "self discharge" in a low drain scenario could potentially be way worse than the real self discharge, due to the buck converter, safety PCB and such being powered up and taking it's share of the energy constantly.

I see they also have a PM5 and a PK5 model, but am unable to find any tests of these at all.
 

HKJ

Flashaholic
Joined
Mar 26, 2008
Messages
9,715
Location
Copenhagen, Denmark
They will have some self discharge, but it was low enough that I could not see it on the capacity when doing a weeks test with low drain.
 
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