01 Prius 12 v battery replacment

The very cheapest route is to measure the dimensions available, then buy a 12V battery that will fit that space and fabricate connectors as needed. However that will take time and patience.

A cheap battery will be liquid lead acid, and Toyota does not recommend use of that type of battery. Absorbed glass mat is the battery type that is supposed to be used.

 

The main issue with the liquid acid battery is that in the event of an accident that impacts that fender, you'll have liquid acid everywhere. Not so bad with Classic that has an enclosed trunk, but might be bad with the 2G hatch.

Another concern is that the original equipment battery has a vent that allows hydrogen gas to be vented to the exterior. A regular battery will not have this, so if hydrogen gas is produced it will accumulate in the trunk.

 

The U1 size (sold mostly for electric wheel chairs) is AGM. Typically $50, and perhaps less if you dig deep. Will need connector mods. Will not have a vent, so you would be one of the experimentalists there. But my experience was that the outgassing risk was acceptably low.

If you go to an even smaller AGM, say 8 amp hours, it will be sufficient to boot up the car in the $20 price range. However, Prius is already susceptible to running down it 12 when off, and if you go with one of these 'bricks', yours will be even more so.

Some of the original NHW11 batteries were flooded cells, not AGM. Just a very small point of history

 

Now some of us have peeled off the "Do Not Remove" tape and pried up the cover to reveal the six, small plugs. Topping off the cells with distilled water can restore some battery capacity ... for a short period of time. In my case, it lasted just under a year. However, if you have a dead cell, it won't work.

You might also check the ground wire connection to the frame. A little corrosion can also give the symptoms of a weak battery. But given the battery age, it is due.

Bob Wilson

 

However, if your battery is AGM (which you can tell by seeing the fuzzy white mats between the lead plates) then you should only add around 1 oz of distilled water per cell. You are not trying to drown the cell, just give it a bit of water.

If your battery is traditional lead acid, then topping off the cells is OK.

If you are the kind of person who is willing to remove the mattress tag that says "Do Not Remove", then you'll probably be OK with taking off the top label on the battery...

Just give the battery the respect that it deserves and do not get any acid on your clothing, skin, or auto body paint.

 

Probably. If you buy the type of battery that allows you to remove the cell covers, then you should periodically check electrolyte level and replenish with distilled water as necessary.

 

Hello
You could try a carquest 51R-60 thats what I have in my Gen I it has been working fine its $90