In store clearance at Kmart Innaloo WA; $1 per six pack 9V Carbon Zinc Heavy Duty Batteries.
Batteries Performer 9 Volt Carbon Zinc HD 6 Pack $1.00 @ Kmart
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There are 3 main types of 9V rechargeables…
a) 7-cell NiMH - these put out a nominal 8.4V
b) 8-cell NiMH - these put out a nominal 9.6V
c) 2-cell Lipo - these put out a nominal 7.4VAll require special chargers. Lipo holds more energy, however voltage is so low that some devices will crap out before using all the juice.
The rechargeable batteries all die fairly quickly as there is no balancing circuits and if one of the cells carks it then the whole thing must be tossed.
Probably the best would be a custom-made cell using a decent sized single Lipo and a Boost converter to provide constant 9V out. Charging would be a definite challenge.
I have a charger from ALDI ( I lost the manual so not sure which type of 9V it can recharge ). I found some on Kogan but not sure about the quality. Is there an URL to what you said ?
Here is the URL to what I said: https://www.ozbargain.com.au/node/330774#comment-5095918 LOL
The Aldi charger will charge NiMH cells. You need a dedicated charger for the Lithium ones.
I am not confident that I can recommend any brand of batteries, as I bought mine years ago from Ebay.
@llama: I meant to say where I can get those batteries … but you answer it already. Alright I shall keep looking then …
There is already something like the following in the market. It got the boost and recharge circuits built in. Seems to be quite convenience to be charged by USB. I have no experience of using them though.
http://www.ebay.com.au/itm/9V-800mAh-USB-Rechargeable-Lipo-B…
Yeah one of those that I found on ebay … the thing concern me is the quality. Kogan's one only claims to have 300mAh, that one is 800mAh!
PLEASE do not use these in your smoke alarms. Heavy Duty batteries are a big risk. Always use alkaline. It may save your life!
When we moved into our rental I checked the smoke detectors and these batteries were in there. Cheapest cheapo rubbish 9V battery around.
These same ones lasted about 1 week in my smoke alarm before the low battery alarm came on
Newer smoke alarms have a 10 year battery built in. Much better than running around changing 9V batteries every 6 months. Check the expiry date on your alarms. Might be time to chuck 'em out anyway and upgrade to something that's not another headache and chore.
I usually get about 3 years out of alkaline batteries in smoke alarms. Full respect to OP, who means well, but I am surprised these batteries are still being made.
3 years? Must be some awesome smoke alarms. I'd be lucky to get much over 13-14 months out of my old ones. Happy to see the back of them.
@syousef: They definitely work and detect smoke quickly. Over 10 years ago I got a sealed 3-pack in the closing stages of a local garage sale - including of course batteries - for $2!
@PJC:
I'll take your word for how well they work. But you'll find they're technical past their "replace by" date, meaning legally they should be replaced. More importantly insurance may decide you've been negligent and decide the fire might have been stopped more quickly if they find 20 year old smoke alarms.
The radioactive element in the ionization alarms has a half life of 432 years.
http://large.stanford.edu/courses/2011/ph241/eason1/
The electronic components certainly won't last 400 years but there are plenty of electronics operating in 25 year old cars, even in life or death components.
@syousef: They are just over 11 years old and I now recall I have replaced one. I use a total of 5 smoke alarms.
@syousef: I got replacements today at Officeworks for $3 each including Duracell 9V battery featuring Duralock Power Reserve best before Mar 2021! They sell 2-packs of the battery for $13.89 https://www.officeworks.com.au/shop/officeworks/p/duracell-c… I can't post it here because their last 5 went into my orange OzBargain bag.
There is no particular risk… they just don't last as long as Alkalines. The alarm will beep when the batteries get below a certain voltage, just like with Alkalines…. so, buy 6 for $1 and change them when prompted.
LoopyLou - You should have just left it where you found it, since it is a stupid and totally irrelevant graph. A smoke alarm doesn't draw that kind of current. What you linked to has a AA Alkaline lasting 2.9 days (at normal smoke alarm cut-off of about 0.8V).
Smoke alarms with 9V batteries inside don't work off AA's, and even a pissy little 9V carbon zinc will last over a year in a smoke alarm. All smoke alarms came with Carbon Zinc batteries in them until quite recently, and that is why the "normal recommendation" is to change the batteries every 12 months. DOH.
@LoopyLou: OK smart arse - please tell us what the cut-off voltage is for the AA batteries inside the 9V smoke alarm.
Good job on the post however rubbish batteries don't bother wasting your time.
Im after some rechargeable 9v, any recommendation ? For a hand tool