how to check battery fluid level?

add some distilled water to left cell

and check the right cell

I didn't find difference by checking the shadow of using flash light at back of the battery

By check the actually fluid level in the hole, it's normal?
but why the shadow of flash light is far below the min level?

how to use the max and min line to check the battery fluid level correctly?

 

Just fill them all up. I haven't seen a battery like that in decades. Where the hell did that come from?

 

my confusion is by looking at the shadow of flash light, it is too low
but by checking fluid level in the hole it's normal

the shadow is just from metal plate not the actual fluid level?
Thanks

https://www.youtube.com/watch?v=Tfgf0euQrIk

 

Yeah. You can only get so much liquid into each cell. Fill them up and call it a day. If I remember correctly, because it's been so long since I've seen a battery like this, there should be some space at the top with a little tab that sits below the bottom of the hole. Fill to that tab.

 

Thanks for your input
It's hard to identify the fluid level by using flash light without shaking the battery
see 3:18 in the following video
https://www.youtube.com/watch?v=zwiL4ApjDMM

 

Typical flooded battery with round caps instead of the rectangular ones. Probably OEM judging by the Panasonic logo molded in the case.

Picture in the 2024 4Runner owner's manual:



Section in the 2011 Subaru owner's manual (made in Japan, with Panasonic battery):

 

Thanks for your reply

my confusion is by looking at the shadow of flash light, it is too low in the first photo
but by checking fluid level in the hole it's normal in second and third photo

the shadow in first photo is projected from metal plate not the actual fluid level?

 

^Most other battery cases are opaque, so the only way is to check by the ports lol.

For street use, the acid level won't change appreciably over the life of the battery. Like the Subaru manual says, "It is unnecessary to periodically check the battery fluid level or periodically refill with distilled water." If you go off-road a lot, the acid can spill out of the vents, in which case change to an AGM battery to save your inner fender.

 

Get the water above the plates and your good. And use distilled water.

 

If you live in hot desert climates, you best check the level frequently, or your battery will not survive.

 

Do the stock panasonic batteries have vents tubes? I don’t recall seeing any. Or does it just spill out of a hole somewhere on the side of the battery?

 

The water can evaporate out of sulfuric acid solution due to heat. Like if your charging system is over charging (a failing alternator), or if the battery is failing or is shorted. Many years ago when people used the old school battery chargers that didn’t taper off the charging voltage like modern battery maintainers do, they’d often wind up over charging and boiling off the water faster.

Spilling the battery electrolyte due to normal driving or 4 wheeling would be pretty rare. You’d probably have to be nearly upside down.

 

Is this battery the one you asked about earlier? https://www.4runners.com/threads/is-this-battery-the-original-one-for-new-2023-4runner.33062/

What sort of conditions is it driven and stored in?

 

"Meniscus" is the key! https://tentangautomotive.blogspot.com/2014/12/how-to-check-car-battery-water-levels_7.html

 

yes. it's good regardless I'm wrong to tell fluid level by using solid shadow of flash light without removing it from truck and shaking

The correct method to identify fluid level is through those tubes directly

 

OK, so my question is whether you operate or store it in extreme heat or have had other problems that would have led you to suspect that the battery fluid levels needed checking this soon. Didn't you buy this vehicle new just six or seven months ago?

 

Typically the batteries with vent caps on top, either round or rectangular, have vents built into the caps. They're tiny on the Panasonic caps (GR86 battery shown):

I've had batteries leak from the vent holes just transporting them in the footwell driving 4 city blocks. Left a distinct smell on my Weathertechs. They had vents on the side, much bigger (~1/4") than the Panasonic battery vents, to be compatible with vent tube connections for trunk-mounted applications (Prius, Rav4 Hybrid, etc.).

My 4Runner came with a flooded Costco battery dated 2021. I'll get an AGM to replace it in 2026.

 

Yeah, it depends on the particular style or battery application. I’ve had motorcycle batteries that have a side vent tube pointing down that you actually are supposed to attach a nylon tube routed it down below the frame, for any spilling.

I’ve never had an automobile battery with such a vent.

AGMs would definitely be better to prevent any leakage. But then you have to make a mod to be sure you charge it with a higher voltage.

 

I’ll have to take a look at mine. Hopefully holes that small would keep the fluid from coming out (thinking that the surface tension of the liquid would make it hard to get through the holes). But maybe that’s wishful thinking. It’s good to know though, this will have to go on the post wheeling-trip check list.