Battery Recommendations

Hi all.

I'm looking for a battery recommendation. I have a somewhat different set of requirements, so am looking for advice on battery type, and the associated protective, balancing, and charging circuitry.

I have a torch. It is for emergencies only. It is plugged in practically 100% of the time. The light itself may automatically turn on at certain times during this (fairly often in fact) - but the torch will be connected to mains power during these times. The bulb itself is a 12V LED car headlight job. Draws about 400mA, so that's 6W max continuous. I don't NEED 12V - I will have a boost converter in place.

Voltage: 5V+.
Power: 6W
Duration: An hour? Perhaps 2? It's only for power outages.
Battery lifetime: LONG. Batteries should also be happy to sit fully charged for long periods of time.
Battery safety: Would like a safe system. This does seem to imply not lithium-something, but I know that lithium-something could be used safely in this application.

Cheerio
Sal

What's your comfort level with electronics?
If you'd be comfortable putting everything together for it, then LiFePo4 might be interesting. It's somewhat safer than "normal" LiIon, and can be more forgiving, and can give you a longer life/more cycles. Still powerful though, so safety is still a concern, take care when charging, add fuses etc.

It does have a lower charge- and working voltage, so would need a charging circuit with specific support for it, or configurable.

Hi

I suppose the main concern with any of the lithium types is the working voltage. Since I need no less than 4.5V, that's more than one cell. So balancing is an issue.

My comfort level with electronics is reasonable. That said, I don't have the capability (or desire) to make circuit boards myself. I am hoping that there are enough little boards around that I can just connect.

LiFePo4 is more similar to what the RC people use isn't it?

A final word - I have about the size of a 6V lantern battery (4R25X) to put this in (a little bit shorter though, because circuitry). So space isn't much of an issue I don't think.

Thanks
Sal