Odd battery charging voltage

Once fully charged a lead acid is effectively o/c and terminal voltage dependent on the charger and the voltage across the plates from electrolysing the electrolyte. Since you're using electrolyte it's not a good position to be in.

Most old trickle chargers could easily get to 15V and nothing to really worry about.

It does indicate a full charge, or as full as it's going to get.

Most indicators rely on the electrolyte on a window, and the reflection dependent on level only.

I guess it might be possible for the reflection be dependent on the electrolyte refractive index which no doubt will be sensitive to SG. Perhaps someone will be along to confirm or say is nonsense?

How confident are you the electrolyte is above the plates?

I prefer the 'dumb' chargers. In fact I prefer *everything* I own to be of the 'dumb' variety. I find with the so-called 'smart' products - whatever they may be - there's far too much going on under the surface for my liking and one gets to the point where it's like a battle between me and the device to get it to do what I want. I've noticed just about everything described as "smart" seldom is from the PoV of the customer and that applies to electricity meters, those tiny cars and motorways as well as more mundane things like battery chargers and mobile phones.

You're probably right. I'd never thought about it too deeply and just assumed they use some sort of micro-power LED 'traffic light' system deep in a tube with lenses to make the dim glow more visible on the exterior. I'll check out the electrolyte level. It's supposed to be maintenance-free but...... best check in case....

With some of the trickle charger / maintenance chargers its not unusual for them to output 15 or 16 volts part way through their cycle, its part of the conditioning cycle it applies to the flat battery

I should perhaps have mentioned this is one of the old-style car battery chargers with no 'brain' at all. Manual selection of 12 or 24V and high and low charge rates. That's all there is to it.

Still got a DVM though by the sound of it. My default machine has a proper moving iron ammeter and no voltage display at all.

No DVM, Newsy. Just the same sort of analogue ammeter as yours. And I wouldn't have it any other way.

I think I need to correct myself here. It's not the "smart" device itself that's the problem, neither the hardware nor the software or firmware for that matter. The battle is against the mind of whoever programmed the damn thing and thought he knew better than the end user. OK, in very many cases, he probably does. But for those of us who like total, manual control over systems and are prepared to take the risk of breaking something if we get it wrong, it's a giant PITA to contend with.

Charge indicator built into battery is just a battery hydrometer. A float that when the battery is charged will float higher and becomes visible in the window.

Some have 2 concentric floats. A ball that shows charge and 2nd one that shows level of electrolyte.

Had one in a Delco battery ages ago. Stopped working correctly long before the battery needed replacing. Seemed to me an excellent way of selling more batteries.

Thanks. It's now become visible once more. Must have got stuck for some reason deep down in its tube.

Yes sometimes it needs vibration of a "go drive" cycle.