Originally Posted by SpitFire6
Hi,
3 x Alkaline = 4.5v
3 x NiMH rechargeable = 3.6V
Are you allowed to run rechargeable cells in it?
There are 1.5V rechargeable out there in AA format. Costly & AHr is not great though
Cheers,
Iain.
The 1.5V vs 1.2V debate is way overblown. For high current application they don't expect voltage to stay consistently at 1.5V or 1.2V the entire duration until it suddenly drop to 0, it is a curve that gradually goes down.
Just revisiting an old thread. I used to have a Sony portable TV that used 3 AA batteries. It was a moderate drain device that was obviously a much tougher load than maybe a wall clock, but not quite as severe as a digital camera (especially with flash). I could roughly get about the same life out of a set of 3 alkaline (nominal capacity about 3000 mAh) as I could get out of a freshly charged set of 1600 mAh NiMH cells (Maxell branded by made by Sanyo) . Because of the high-ish drain of the device, I could measure the voltage across the battery to get an idea how much energy was being wasted. It was about 1.67V without a load, but with that load it was less than 1.05V. With the freshly charged NiMH batteries, it was about 1.37V (waiting a bit after coming off the charger since it can read as high as 1.43V), and with a load maybe 1.15V). When I used alkalines on that TV, the batteries got really warm, but with NiMH I'd describe it as feeling lukewarm. It was a little more complicated because alkaline tend to still have more energy before they give out in a high drain device, but it's at a point where it just won't work any more in such devices, while NiMH taps through more of its range.
I have never seen a device that didn't run fine on NiMH batteries in place of alklines. There were a few things that were different, such as LED lights or flashlights that weren't well regulated, and the higher voltage meant it was brighter.
There are a lot of devices that require a lot of peak current for a short period, such digital cameras and flashes. I never really tested that, but even back in the day of 1200 mAh NiMH batteries, they were yielding more photos in digital cameras than alkaline with more than 2.5 times the nominal capacity. But it was at a certain point where they just couldn't provide enough current for those peaks. One of the things that some people did was find another easy load because they actually had quite a bit of energy left, but just couldn't cut it.
There are still a few uses for NiCad batteries. They can generate a ridiculous amount of current for a given size, so I think there are still some power tools that use them. Still not as powerful as lead acid batteries though.
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