House batteries, overfill?

yes they can be overfilled. So long as the plates are covered when the battery state of charge is low it is ok.

Yes, they can be over-filled which is a common occurrence leading to extensive corrosion in many instances. We use golf cart batteries when RVing and purchased a Plews auto shut-off battery filler from Amazon, perfectly fills our batteries to the proper level. Although I check our batteries monthly since we keep our rig plugged in 24/7 when stored in our side yard, they rarely need any water primarily due to the smart charging provided by our onboard Iota IQ4 converter. Many assume a battery needs to be filled close to the top, in reality the fluid must cover the plates and sit just below the bottom ring of the fill ports.

pianotuna wrote:
yes they can be overfilled. So long as the plates are covered when the battery state of charge is low it is ok.

Well it might be OK for the moment but that is NOT the recommended way to do it.

All wet cell batteries have room for an extra ounce or two in each cell; that is the space between the top of the plates and the "split ring" in the bottom of the filler hole. It is intended for that space to be filled.....to give you some room so that you don't have to give them CONSTANT attention to keep from going too low.

The OP should carefully fill each cell until the electrolyte touches the bottom of the split ring and makes a little "pooch".

If you watch closely as you add distilled water you will see that when the electrolyte reaches the bottom of the fill tube it will form what they call a cats eye.

The fill tube has slots on the sides so the cell is still able to vent when it touches. If you raise the level so high in the tube that you cover the vent slots it will gurgle and burp electrolyte all over.

I never go higher than the cats eye. That gives you the most safety net if you go a little too long on checking them. If you run them just covering the plates then they are always closer to exposing the plate if you forget to check them.

If you are not charging hard at higher voltages you won't use a lot of water. If you are just looking in the hole and saying yes it's covering the plates, how long is it until it starts to expose the plate? You can do it either way as long as the plates are always covered.

Be careful when filling because you can get acid splashing. It's sulphric acid so it's best to wear goggles and have eye flushing water near.

Never make or break any wiring near the battery after it's been charging. Any spark may ignite the hydrogen gas that's in the cells and it's like a bomb going off.

If your batteries are like mine in a tray, it's very hard to look straight down into them without a mirror. These things are the BEST!
https://www.rvupgradestore.com/Flow-Rite-Battery-Watering-System-p/55-8754.htm?gclid=CjwKCAjw68zZBRAnEiwACw0eYUebZyArkZULCHtEp9zZ-0-0GuuUHsmPtAIpkeDqncAwK7XLMCG0YhoCYaQQAvD_BwE&gdffi=d722fab84a06472899ce2a16e4d2ed3f&gdfms=DAF540DA558D40A6971E243BE904E966

garyemunson wrote:
If your batteries are like mine in a tray, it's very hard to look straight down into them without a mirror. These things are the BEST!

You are correct. It is hard to look straight down.

Thanks for the responses. I am glad I didn't add any water yet but I am still surprised that the batteries haven't needed any water added after a year. I keep the motor home plugged in 24/7 at a rented storage garage.

MetalGator wrote:

garyemunson wrote:
If your batteries are like mine in a tray, it's very hard to look straight down into them without a mirror. These things are the BEST!

You are correct. It is hard to look straight down.

Thanks for the responses. I am glad I didn't add any water yet but I am still surprised that the batteries haven't needed any water added after a year. I keep the motor home plugged in 24/7 at a rented storage garage.

They aren't using water because you are not using them. They are just idling along. When batteries are discharged and recharged they use more water.

MetalGator wrote:
but I am still surprised that the batteries haven't needed any water added after a year. I keep the motor home plugged in 24/7 at a rented storage garage.

I'd be really surprised too.....to the point of being somewhat skeptical.

The top of the plates likely will be "wet" even if they are not covered and that can be deceiving when checking.....especially if you can't see straight in with a light.

I think you need to figure out how to add some water.....soon.

P.S. When your batteries are difficult to access, that is just one more plus on the side of AGMs the next time they need to be replaced.

Fill each cell to the point that the water has a "concave" look to it.

I usually need to add about a pint of water to each of my 2gc batteries each year.