Hydrometer - using it

[Piers]

Is it OK to use a hydrometer to check the SG of the acid even when the battery charger is on?

 

[TigaWave]

Yep, as long as you dont light a match to read it!

 

[snowleopard]

if you get bubbles in the acid, give it a shake before reading!

 

[VicS]

If the acid has warmed up during charging then the reading will be a little low so better to wait untill things have cooled down before taking the SG. I may have some data. If i can find them I'll post them.

Slightly different matter but if you top a battery up the distilled water floats on the top for ages so that gives false readings as well

 

[Piers]

Thanks - that would be helpful.

 

[VicS]

For every 10C rise in temperature the SG falls by 0.007.
(The standard temperature is 15C).
For the purists I assume that that should be Hydrometer reading rather than absolute SG as the glass the float is made of also expands!