Mr Gus wrote: ↑Sat Apr 22, 2023 1:19 pm
Wouldlike to phase out another element of "disposable"
batteries & get another duracell off my back where typical monoxide detectors are concerned.
A few years ago the PP9 was a bit of a rarity, now as a rechargeable Li it is commonplace.
Anyone fitted any to monitoring items?
Two comments on batteries and "monooxide" detectors - some of which applies to smoke/heat detectors as well.
Firstly, depending on the type of sensor, CO detectors (and non optical smoke detectors) have a limited life. The CO detector I fitted 7 years ago now has a life of 10 years, the battery is "integrated" and is expected to last the life of the device, so no need to change it.
With regard to smoke and heat detectors a few years back I "upgraded" the ones we had. At first I thought SWMBO had improved her cooking as the frequent "dinner is ready" alarms had ceased. I checked the batteries and they were fine, the test button said all was A'OK, but the smoke detector was very insensitive - the radioactive source had depleted and the "small print" on the unit said replace after 7 years. So I fitted mains powered ones that are all linked but have battery back up. They are optical units (apart from the heat detector) and a standard alkaline battery.
Secondly, and to my opinion, more importantly unless otherwise stated the manufacturer designs these units to run on Alkaline batteries which have a very specific voltage characteristic. They are low drain devices with low battery detection. (the annoying beep at 3AM caused by a drop in voltage due to lower overnight temperature). The low battery warning gives plenty of time to replace the battery while still having a functioning alarm. Changing to a Li rechargeable (or even a PP3 NiMh rechargeable) will result in a battery with a different voltage characteristic, the worst bit being the rapid drop off in voltage near exhaustion. Most Li batteries (collection of cells) have built in protection board (BMS) which literally cut off the supply if any cell goes too low. If that happens, no functioning detector!
Also what happens while you are recharging the Li battery?? do you leave the detector unpowered, thus no protection/alarm? or do you have two batteries and swap them over at intervals.
For the tiny potential of "phasing out" disposable PP3's I would not do it. PP3's in smoke detectors last years so the saving, if any at all, would be minimal and the downside risk is I think high - (thinking low cell V disconnect here). Also at end of life which is worse in disposal terms a couple of PP3 alkalines or a PP3 Li battery?
