2004 Prius 12V battery replacement options

[Daox]

Alright, so we've been driving next to... well hardly ever now with the pandemic stuff. The other day my wife went to use the Prius and the now ~4-5 year old battery had been sitting long enough to die. I'd rather not have to order a ~$200 AGM Toyota battery. So, naturally I am looking for replacement options and I'm wondering what others have used? My car does have the smart key feature, so it would be nice to not go to a tiny new battery.

[redpoint5]

I've mentioned this elsewhere, but I've been running a LiFePO4 in my 2012 Prius for 4 years now. Since PDX is fairly mild, and the battery lives inside the cabin, it seems to work well.

Not sure if it would be appropriate for Wisconsin if the cabin gets well below freezing for longish periods of time. If it were me, I'd probably be willing to try it just as an experiment. That's essentially what I did considering I had no other examples of people doing what I had done.

https://www.batteryspace.com/lifepo4...assed-dgr.aspx

Search for coupon codes for things like 10% off.

[oil pan 4]

Did you try using a $50, 10 to 15 amp digital battery charger to bring it back, or taking the batt to an auto parts store to be charged?
If it's got an AGM and only 5 or 6 years old, it may still be good for a few more years once it gets charged.

LiFePO4 sucks in the cold, even in new mexico.

[Vman455]

The cold issue is what's stopped me from trying a LiFePO4 battery. We have weeks-long stretches every winter where it doesn't get above freezing, and I'm a couple hundred miles south of Wisconsin.

If it were me--and I'll probably do this when the battery goes--I would just get a Toyota replacement. Mine's lasted 6 1/2 years and still going strong.

I'm not sure about the Gen 2, but the Gen 3 turns off the SKS after a certain period of time of inactivity, a couple days or something like that.

[rmay635703]

I use an old 2 amp dummy charger to restore dead batteries.

In my Insight I use a $19.99 cent lawn mower battery.

I would recommend a battery disconnect or a battery trickle/maintainer for a sitting car or your battery will be dead every time

[Daox]

Originally Posted by Vman455

I'm not sure about the Gen 2, but the Gen 3 turns off the SKS after a certain period of time of inactivity, a couple days or something like that.

The 2nd gen has a switch to turn off the SKS under the steering wheel. I did not use it. In fact I totally forgot about it until the battery was dead.

Originally Posted by rmay635703

I use an old 2 amp dummy charger to restore dead batteries.

Yeah, I tried that. Unfortunately it didn't work.

[ksa8907]

Simple replacement is definitely the easiest and shortest duration. I would replace with a lithium ion battery and a charge controller if time were of no concern.

[redpoint5]

You could always risk $45 instead to see how it holds up:

https://hobbyking.com/en_us/zippy-co...en_us_products



Relatively cheap experiment and it will at least get you through the next 3 seasons, but I bet it will hold up over time.

[Ecky]

Originally Posted by redpoint5

I've mentioned this elsewhere, but I've been running a LiFePO4 in my 2012 Prius for 4 years now. Since PDX is fairly mild, and the battery lives inside the cabin, it seems to work well.

Not sure if it would be appropriate for Wisconsin if the cabin gets well below freezing for longish periods of time. If it were me, I'd probably be willing to try it just as an experiment. That's essentially what I did considering I had no other examples of people doing what I had done.

https://www.batteryspace.com/lifepo4...assed-dgr.aspx

Search for coupon codes for things like 10% off.

I actually ran this exact battery for 2 winters in Vermont. The first winter I had supercaps starting the engine and the battery sat behind a very low ohm resistor, just to keep the caps topped off. Second winter I just used it as a starter battery, and it held up.

Not that I advise this.

LiFePO4 isn't going to explode from mis-treating it, but it's an expensive battery to kill.

[redpoint5]

Good data point.

The expense is why I followed up with the cheaper option. The Prius has no huge start load, so it could easily handle the job. You just wouldn't want to keep the car in accessory mode for more than a minute, or leave the dome lights on while parked. LED dome lights can help with that aspect.

If I still had the Prius I'd be tempted to run the smaller battery simply to free up the 20Ah one to run other more demanding things.