The new batteries arrived, and they look nice, and tested fine. They terminate in XT90 connectors, and I've standardised everything on EC5, so I made three adaptors to convert.
I use EC5s for a few reasons. They're large, so plugging and unplugging (which I do a lot) is easy althugh it does take some effort to overcome the friction. And they can handle 100 amps (I'm putting 10 to 15 amps through them).
And there's another advantage I hadn't planned on. A couple of times when I've come off the bike, and the pannier holding the batteries separated from the bike. I'm glad to say that the EC5 connecting the batteries to the bike, separated, which is good because if it hadn't, it would have torn the wires out, making it very difficult for me to carry on. But not impossible; I did do it once before.
Also, they're a bit lighter. They weigh 800 grams, whereas the batteries I've been using weigh 528 grams for half the kilowatt-hours. So what do I lose? The old batteries were 30C, which means I can pull up to 150 amps from each them. With the new batteries, they're 20C which means I could pull up to 200 amps! Since the bike only pulls 10 amps, with maybe a peak of 15, it's not an issue.
One of my old batteries has failed; it's swelled up and broke through the hard case, so I've retired it. Batteries don't last for ever!
I also bought a new kind of charger.
The chargers I mostly use are 80W. I'm charging three lots of 14.4 volts at 5 amps total, so I do need those 80 watts. If I use a 50W charger, then they only charge ar 3.2 amps, and so charge more slowly. This charger is only 30W, but I got three of them, so I can still charge my three 14.4 volt batteries at 1.5 amps per battery, a total of 4.5 amps, so it's pretty much the same charge speed. But the big plus of these chargers, is that they charge via the balance leads, so instead of having to plug in six leads (and the EC5s need quite a bit of effort) I just plug in the balance leads, which is a lot easier.
I've only just started using these, so I'm not giving a final verdict yet, but they look promising.
I also got a new balance charger, the Turnigy MAX80W.
I've tried a number of different chargers; most of them have failed on me. The ones that I still have a little bit of faith in, are the Accucell 8150 and the Turnigy MAX80W. I got a clone iMax 50W from Ebay, and it failed after a couple of weeks; others have lasted longer, but have failed sooner than I'd expect. I'm guessing that a lot of people are using el-cheapo components.