Battery State Indicator.can You Trust It?

[friar tuck]

i recently removed a leisiure battery that was performing well but the little indicator window was black,meaning dead battery!i took it off and put it under a small load for 12hours drawing 1 amp it held up fine losing a miniscule amount of voltage.
What are these little windows and how do they work?

 

[PhilandMena]

They are a visual indicator of battery state. To measure battery, best use a volt meter. To test battery, fully charge, remove external power/charging source,allow to settle, put known load on for x number of hours, remove load, allow to settle. measure battery again with Volt meter.

 

[andy63]

hi friar, I think the indicators built into the battery are small hydrometers .. they tell you the state of charge by measuring the specific gravity of the electrolyte and also give an indication of the electrolyte level..
its sometimes possible to top up the battery with a little distilled water if its indicating its low...
I thought dark of black indicated it needs a charge, but not sure...
charge it up and run a good load on it and see how its held a charge... if that proves good recharge and continue to use, or at least I would...
ta andy

 

[friar tuck]

Hi Andy thanks for the reply.electrlyte was a little low on all cells so i topped it up i wonder if the hydrometer part had drained? seemed to work ok on a load so its gone back on the mh now and the solar is bringing it back up to full.

 

[andy63]

Hi Andy thanks for the reply.electrlyte was a little low on all cells so i topped it up i wonder if the hydrometer part had drained? seemed to work ok on a load so its gone back on the mh now and the solar is bringing it back up to full.

it will only have drained if the electrolyte level dropped which you have confirmed... very simple device... its just a little coloured ball floating in an open tube which is immersed in the electrolyte..
hope its good for a long time to come... check and see if it returns to green when the battery is charged..
ta andy

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[mike mcglynn]

My 2 Batteries showed ok on the green indicator but were as dead as a dodo

 

[Techno]

The indicator only measures one of the six cells. It can look perfectly healthy whilst still having a dead cell.

 

[friar tuck]

Techno100 hi,if i have a dead cell would my battery still read 12.8- 12.9 and run a small load (1 amp) for 12 hours with negligible volts drop.im hoping not so i can conclude the batteyr is healthy.

 

[Techno]

No a dead cell would lose 2.5 volts off any reading and be quite obvious. Generally a battery with a cell down is reading little over 10 volts

 

[pappajohn]

My thoughts are as others have said......its both a hydrometer and electrolyte level indicator.

If the water level is correct and the battery charged it will show green (usually) But....if the level is low but fully charged it will probably show black as the ball is too far down the tube to gather enough light to be fully visible.

The specific gravity of electrolyte changes with charge state so taking a reading with a proper hydrometer is the only accurate way to determine charge state.

Obviously not practical on many installations such as battery under seat etc so regular, seat off, maintenance is a must.

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[s20hymer]

with a sealed wet battery you can unscrew the sight glass with a pair long nose pliers and add distilled water which turns it from black to green as some batteries loose water over years and it gives a false reading yet the battery is ok

 

[Don Quixote]

In a nut shell they are a waste of time, but for many it's something else to look at because it looks pretty...............