How can I calculate how much potential I can get from a lipo cell?

[NaDobraNich]

I have a sensor that gets dropped into a hole. It's size contained. I might be able to recover it, but might not, so I need pretty cheap costs.

I plan on feeding it with a lipo cell, but I need a lot more than the 3.7V of a fresh cell and momentarily, I need .5W spikes of power for short amounts of time. So I need a boost circuit to get the voltage up, but then I get a little lost.

I think on a LiPo cell, that those typically "short" pretty well. That if I have a 3.7V 100mAh cell, that I "could" get 48V and 10mA from that, but it would be the ESR that is the main limiter.

Then the boost circuit's response and efficiency.

Then that the battery will quickly drop from 3.7V.

Am I missing anything? It seems like it's fairly straight forward things, but there has to be some extra difficulty. For example, what are the chances I could get .5W instantly from some China 3.7V? If I want to figure this out for a specific battery will I need an ESR meter?

[shapirus]

Any respectable rechargeable lithium cell's datasheet specifies maximum continuous discharge current and maximum peak current for a given pulse duration. When you know these and your boost circuit's efficiency, you can calculate whether the cell will be able to output what you want.

Start with checking the datasheets of some cells that fit in your size constraints.

p.s. boosting 3-4V to 48V isn't going to be an easy job.

[NaDobraNich]

I'll get right on asking suppliers on AliExpress for proper datasheets

Yea, I don't really need 48V specifically. And I do need it quickly when I need it. It was just an example, I'd probably be fine with the requirements at 24V. So I'll start there. I haven't made a boost circuit yet, what is the limiting factor for gain? Inductor/capacitor size quality?

[james_s]

It's fairly easy to boost 12V to 170V for nixie tubes so it shouldn't be too hard to boost 3.7V to 48V. Disposable camera flash circuits get around 200V from a single 1.5V AA cell. Fancier xenon camera flashes get more than that from usually 4 AA cells. It's not trivial but it's not super hard either.