Battery Electrolyte level

[LadyInBed]

How do you check your levels?

I have resorted to using a plastic dipstick.
When battery is new, I put the dipstick into the cells and watch for when it just breaks the surface of the Electrolyte.
I then note the distance to the top of the battery and record it on the battery (along with the date installed and price).

Is there a better way?

 

[JohnTH]

There will be a long debate with this one, I am sure there will be those who just have to have the SG to the last mark on the hydrometer and and and.

Clean distilled water topped up to just cover the plates and I am sure that your battery will perform well.

Oh, how to check the level? peep down the hole !

Course, if it is a nicad you won't need a hydrometer, just peep down the hole.

73s de
Johnth

 

[Sandyman]

Use Mk1 eyeball.

 

[VicS]

As said by eye.

So long as the electrolyte covers the plates there's enough.

If you use a hydrometer then just enough above the plates to suck up a hydrometer full. When you cant add distilled/deionised water.

If the battery needs topping much more than once in a blue moon (next one is 31 Dec ) its time to check the charging system or start saving for the replacement battery.

 

[vyv_cox]

All of mine came with a level mark attached to the side of the filling hole. Fill to that, when the meniscus forms against it the level is just right, a few millimetres above the plates.

Don't quite agree with VicS about frequency of topping up. Sterling regulators come with a warning that more frequent topping up will be required. With my solar panels plus Sterling I find that topping up is required about three or four times per season. This has been the case for several years now and my batteries remain in excellent condition.

 

[LadyInBed]

All of mine came with a level mark attached to the side of the filling hole.

I had one once that had translucent sides so you could see the level, but I have five batteries and even with a level mark attached to the side of the filling hole I wouldn't be able to see them all without extracting the battery.

I don't see how anyone can just look down a hole and see how much electrolyte is covering the plates. I can see if it is covering them or not, but that is it.

 

[VicS]

I don't see how anyone can just look down a hole and see how much electrolyte is covering the plates. I can see if it is covering them or not, but that is it.

Thats all you need to know. If the plates are covered its Ok if they are not add distilled water until they are then a dollop more.

 

[alahol2]

A question I've not found the answer to... If you add water to the electrolyte, does the SG change?

 

[VicS]

If you add water to the electrolyte, does the SG change?

Yes of course, it will go down slightly by an amount that depends on the volume you add.

In practise* it will probably seem to go down by quite a lot because the water tends to stay on the surface for quite a while, at least until the battery has been on a good charge that has mixed things up.

*practice ???

 

[alahol2]

That's what I thought would happen. So why is a hydrometer considered the most accurate gauge of charge level? If you measure the SG and get a 'full' charge indication then add some water, have you reduced the level of charge? Would the voltage change?
Just curious as I don't use a hydrometer anyway

 

[VicS]

I would say the voltage would change, but dont know by how much.

The thing is you top the battery back up to its original level and measure the SG with it at this level but you would have to give it a good charging to get the added water and acid throughly mixed first.

Not so sure about the statement that a hydrometer is the most accurate gauge of charge level. Mine isn't. It seems to always give the same reading whatever.

 

[Plevier]

I would say the voltage would change, but dont know by how much.

The thing is you top the battery back up to its original level and measure the SG with it at this level but you would have to give it a good charging to get the added water and acid throughly mixed first.

Not so sure about the statement that a hydrometer is the most accurate gauge of charge level. Mine isn't. It seems to always give the same reading whatever.

Voltage of a lead acid cell is near enough the specific gravity plus 0.84. Thus industrial batteries generally with 1.220 sg give 2.06vpc, wet car batteries generally with 1.260-1.280 give 2.10-2.12, some SLA batteries have sg 1.300 and give 2.14 hence their need for higher charge voltage. As a rule of thumb, min voltage to maintain charge is this plus 0.1, min to recharge is plus 0.2.

Changing the sg a bit doesn't affect the capacity, and diluting it doesn't change the state of charge, just the voltage.

Hydrometer is best indicator of charge for a healthy battery. A sick battery can give misleading readings depending on its failure mode.