The batteries on the SQ4 are now seven years old and are coming to the end of their life, as witnessed by a complete failure to start earlier this year, remedied with the CTEK charger, and a short trip out a few days ago. This one was odd - I had left it idling on the bi-starter to warm up and all was fine (though of course at that speed it wasn't charging). I then took it out and it had no power, eventually dropping onto three cylinders within a few hundred yards of the house - I travelled 1/2 a mile in all, none of it at high enough speeds to charge the battery.
Getting home, the multimeter showed my batteries were down to 5.5 V or so. New batteries are on the horizon!
In the meantime, picking up on a thread in the AOMCC forum I had bought a battery condition monitor from Gammatronix:
I've chosen to fit it in the top of the dummy battery box. It fits in a 14mm hole which I cut with a cone drill.
I've sealed it with some silicone on the outside:
There's a further map #6, which is for low current applications and shows a slow red, yellow or green blink according to voltage level.
Here is a very exciting video of a LED flashing green. Tell your friends, it is riveting stuff:Eagle eyed readers will see the CTEK charging connector I have fitted in the background.