Yes, the more some things stay the same. Batteries.
Last year at this time I was all torn about running what everyone else was running – Thundersky – and maybe trying Headways. Headways were the big unknown, and seemed to be more stable, capable of higher discharge rates, and overall cooler looking than the blocky, slow Thundersky. As winter moved into spring, it became clear that the newly branded CALB were slightly better than Thundersky, and that the Headways were getting used, proving reliable, if problematic from a BMS standpoint. My big anguish was where to put my money, and a not inconsiderable amount of money. This anguish spawned my second big anguish- how to build a battery mount.
Thus, my idea to build a bracket arrangement that would allow me to use several different sizes and styles of battery. Here’s one of the early photos of that.
When it came time to buy the batteries, I made the decision to go with cheap lead-acid AGM 22ah mobility batteries. I did this for a few reasons. First, they were cheap, at about $300 for the whole thing, second, they were about the same weight as what I wanted to run in lithium. I also felt that prices and technology were moving pretty fast in batteries and whatever I bought would be obsolete pretty soon, and that since this was my first build, the chances of blowing up or melting whatever I had were pretty high.
All of those reasons turned out to be pretty much on target.
Even Brammo, with the release of the Enertia 2, has introduced a new battery with twice the range. Enter LiPo- lithium polymer, around for a while in the RC and robot circles. LiPo seems to be right where Headway was last year, a little new, not really tried and proven, but with such compelling advantages they seem certainly worth considering. So. I’m back to not being quite sure exactly what packs I’m running, so torn about how to configure the mounting system.
The good news is, as you can see in the previous post, I could fit the same capacity of LiPo in half the space of the Headways. The weight savings is considerable- almost a third. So it’s a lot less of a challenge, but still. I’d love to be certain of what the technology will look like by May, and know how to build the packs.
But then, what fun is certainty?