12v aux battery needs water

That has been my experience with wet cells; "Maintenance Free" is not what it says

I always try to remember to pop off the caps of a MF battery to check the level, and when I forget, it usually means a replacement is around the corner. It gets expensive when you have around 9 of them to keep track of, lol

 

Can someone elaborate more on this process? Should I check my 12v battery for proper water levels? I never knew they had water... or had to be filled up. I have 22K miles/3yr

 

"Wet" or lead acid batteries are filled with electrolyte (water/acid mixture.) With time, the water evaporates, leaving behind the acid at a lower level. When the fluid level gets below the plates you fry the battery, eventually.

The "old" batteries were vented to relieve any pressure build-up when the battery was under charge. The water would "boil off," thus requiring "maintenance" and had removable caps that allowed you to easily add water (preferably distilled water).

The "new" "Maintenance-Free" batteries have a one-way vent valve and "non-removable" reservoir cap, which supposedly make the battery maintenance free, however, that is not always the case. On a Maintenance-free battery, look on the top side of the battery and you will see a plastic strip that is flush with the top and has edges meeting up with the actual battery case. You usually have to take a small flat-bladed screwdriver and gently pry up along the edges of the plastic strip, evenly and progressively to dislodge the actual plugs that seal each cell reservoir. The process is a lot easier to visualize once you have put a new wet cell battery into service (the battery is shipped dry, a removable foil tape covering the reservoir holes, and comes with a bottle of liquid electrolyte that you pour into each cell.)

 

I have not looked at my battery. 42k miles. What brand and size is the battery in 2010 IV?

 

Did the battery look like this? I didn't know how to remove the clear cover as it was flush with the black plastic.

 

From about two posts above:

"...look on the top side of the battery and you will see a plastic strip that is flush with the top and has edges meeting up with the actual battery case. You usually have to take a small flat-bladed screwdriver and gently pry up along the edges of the plastic strip, evenly and progressively to dislodge the actual plugs that seal each cell reservoir..."

Thanks for the picture. You illustrated my words perfectly

 

Thanks for this, I'll check mine.

You're supposed to use only distilled water in a battery, right?

 

Yes, distilled water only.

 

Due to these battery threads I just checked the 1 year old 25K miles battery in my car, and I'll be damned if I can find a way to check the water. The top of my battery seems sealed SOLID .... there are no strips, plugs or anything that I can see. Does anybody else have a battery that looks like that ? It looks like the one pictured above, but the top is SOLID black plastic. No yellow ... no clear .... specifically says on the battery .... 'NEVER ADD WATER' don't know how you would anyway ....

Is there something I'm not seeing ... or have they changed them ?

Thanks

REV

 

Yes, I saw that. However, there is hardly any space between the clear strip and black plastic, this is why I asked the question if this is the same type of battery.

I didn't want to visibly damage the battery is it is under warranty (3 years/36k miles, right?).

One more thing. Next time I tried to start Prius, I would not go in "D" or "R" but only "N" and displayed message: "press Park" or something similar.

I cycled power once and it went away.

Is this normal after battery disconnect? I expected loss of trip counters and radio presets but not this.

 

Mine looks the same as yours. I wonder if we could pry the black plastic top off? Wouldn't be the first thing I've destroyed by trying to get it apart!

 

Mine was made in 08/10.

How about yours tumbleweed ?? Maybe they changed the later 2010's battery.


REV

 

08/10 .... as I wrote above !!

REV

 

I didn't notice the date sticker when I looked but my car was made in 07/09.

 

Yeah .. my CAR was made in 08/10 ... no idea right now on the battery.


REV

 

My Gen 3 Prius was first sold in December 2009 and had no battery problems. The battery has a clear plastic plate that is about 1/16" thick, that is hidden beneath a yellow sticker on top of the batteryl. I was able to easily lift the short edge of the clear plastic plate using a carefilly inserted pin knife blade. Once the plate was removed, each of the 6 cells had a small rubber cap that I carefully and easily removed using my fingers. This exposed each of the 6 cell chambers that each required about one to two ounces of distiller water to cover the tops of the battery plates so the plate tops were each submerged about 1/8" to 3/16" below the surface of the replinished electrolyte/distiller water. After reattaching the rubber caps and carefully wiping off the top of the battery with a damp cloth, the clear plastic plate snapped firmly in place. Although I was careful when removing and storing the yellow decal, it did not stick nearly as well as it was before the procedure. I am no expert and just used common sence in this process, although it must be better having the battery plates fully submerged below the electrolyte than exposed at the top, as they were before.

 

The 12V battery has a one year warranty, I believe.
Yes, they are "maintenance impossible" batteries, NOT "maintenance free". When I heard the GIII runs at 14+V on the 12V system I wondered how long the battery would take to run low on water. BTW, most of the water is not "boiled off" or "evaporated", it is converted to H2 and O2 and vented. This is a normal result during charging with lead-acid. The -real- "low maintenance" batteries have a catalyst in the caps that recombines the H2 and O2 and drips the water back in. You find that as an option for "stationary cells" used at radio sites (for example).

As far as the sealed top versions, I guess the only thing I can say is "sucks to be you". I hear all sorts of nonsense on those batteries, claiming you can't add water as the chemistry is wrong. They are -lead-acid- batteries. You use sulfuric acid and water as an electrolyte. Yup, it should be a proper mixture. Yup, distilled water is best, though in a Prius, the battery life is so short I doubt anyone could show a difference if you just used tap water.

BTW, the GII runs at a 12 V system voltage of 13.8V nominal. With those, -under- charging was common. Looks like the "fix" for the GIII has resulted in mild -over- charging. At least they don't go dead on you as long as you replace them every, what, four years?