Now that I have some more time with the "a3s" pump I bought..... works great, but the battery is total garbage. If left unused for a week the battery will be dead. I'm tempted to crack it open and see if I can replace the battery with a higher quality cell. I bet it is a pretty standard part in there.
I knew it was a gamble when I bought it, and overall it actually works better than expected, but this isn't something you can rely on being ready for action when you need it.