Matt here, long time reader first time poster. So like many of you my evo 4g battery life is not satisfying. I have weighed the options, and carrying extra batteries just doesn't seem appealing to me, on the same note the seido battery is pricey and i do not trust Chinese knockoffs. I have a background in tinkering with batteries and have rigged rechargeable battery packs on all kinds of stuff, and i have an idea, i would like some feedback before i attempt it. Lithium ion batteries can be soldered together in parallel as long as they are identical, so my idea is to make a sandwich of two OEM 1500 mah batteries. that are connected. since OEM ratings can be trusted, theoretically the capacity would be 3000mah. It would be more real capacity than the seido, and at about a sixth of the price. My plan is to then buy a generic extended battery just for the case to house my creation. Here are a few issues I am curious about. Will the charging circuit of the phone be able to fully charge the beefed up battery or will an external charger be needed? will the generic extended battery housing be able to enclose two stacked oem batteries? Has anyone else attempted this? (i have searched) If you have any other comments id like to hear them, but please don't just troll and say i will die because your mom saw on the news that li-ion batteries are explosive, id like to hear real feedback. Edit: I have soldered two li-ion cell phone batteries in parallel before with an old flip phone I had just to see if i could. It worked well, i had to make a new charging circuit though and the battery indicator on the phone was not accurate anymore. I just used two random non matching 3.7 volt batteries I had (you aren't supposed to do that but this was a zero budget mod). Anyway the purpose of this edit is that I know it can be done.