My Sena S10 comms units have recently been going flat after only a couple of hours. They're just under 4 years old and have done a fair few hours, so I'm OK with that. I'm especially happy that it is possible to replace the batteries, even though it's a daunting prospect for a klutz like me when it comes to soldering.
I found a Youtube clip (as you would expect), that sets the job out very well. They recommend using solder paste which I'd never heard of before. So I bought some- the smallest dispenser being about 100 times as much as I needed. Ditto the shrink tubing.
The batteries are on eBay, post free from China, and have the same number (602248) and size as the originals and cost $19.57 for the pair including postage. They arrived in less than two weeks. Even better, they are 650 mAh whereas the originals are 560 mAh.
https://www.ebay.com.au/itm/2pcs-3-7V-650-mAh-Li-polymer-rechargeable-Battery-Li-Po-ion-602248-for-GPS-mp4/252827890467?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649This afternoon I bit the bullet and did the job. It's minor brain surgery but not rocket science, if you get my drift. The torx bits I had were too big at T-10 and my 2 SNCM too small; you need T-8, but a 2mm straight blade removed the screws without damage.
If anyone else wants to do the job, I'll save you some bux. For $5 including postage I'll send you more than enough solder paste, shrink tubing (1.5mm) and double-sided tape to do the two sets. Or if you live in Perth, you might buy Brock a beer to lubricate the lock on his shed- worth asking...
This is the original battery with the leads cut short to make the soldering of the new ones easier. They actually plug onto the PC board but I couldn't get the plug to release so did the join
in situ.