All the ones I have are 3.7v. I set mine up with the slow charge resistor. My LiPo's came from Sparkfun and range from 160mAh to 1000mAh with the right connector.
They have to be single cells, not multi-cell packs to charge properly, the Wiki also says the boost circuitry needs 2-4.5v - Ideally the charge chip sensibly works over a similar range. But most common LiPo's of interest are at or around 3.7v.
As for 'button top' common 3.7v LiPo cells that would need "adapted" for use:
There is a AA sized 14500 cell that is also 3.7v. They seem to be 600-800mAh - though some perhaps mislabeled (brand and capacity) claim 1200 (or more). The 18650 is a larger (fatter&taller) cell that can easily hold 2000+mAh - though often they may also not be what is on the label if it is discounted. The other common 'CR123A/16340' shorter than AA but fatter seems to top out at or under 900mAh. Amazon offers all of these - and once adapted I hope they are properly charged and maintained. I found single cell holders there for all of these - but none go to the JST pin plug. I saw Sparkfun has a 2 AA battery box unit - with switch and JST plug for only $1.50 - but would need to be rewired for one cell to work.
BTW: Blowing out the charger can be the least of the problems. Read and observe the warnings on LiPo cell handling [damaged / polarity / shorting ] as posted in the Wiki - if they get hot or start smoking that isn't right:
CAUTION: Using a damaged battery, reversing battery polarity, shorting any part of the power system while powered by battery, or in any other way using a LiPo battery improperly can cause serious injury, death, and/or fire.
