What Brand of Battery do you like ? (Auxiliary)

For years I've had good luck with the interstate middle of the road or the higher end AGM batteries from the same company other brands that I used to use are long gone like Deka. And of course if you're in a foreign country I don't even have the names of the batteries I used to use in Germany and Spain years ago and I'm sure it wouldn't matter anyway. You'll find some guys here running universal battery type batteries they're a lot cheaper and they should last about as long

 

These are the best price and best quality... If you decide to buy one I can explain an easy way to mount the terminals... I got 9 years out of a battery similar to this one in my Prius: https://ebay.us/5n8222

 

Yes! Most auto parts stores will be up in the $300 range for a 12v with way less than 55amp-hours

 

oem true start

 

Most of them have around 38 amp-hours... Basically, a regular car's 12v has to start the engine, but a Prius has a high voltage battery and an electric motor inside the transmission to start the engine. So a 12v "cold cranking amps" rating is not relevant so you can instead invest in the battery most likely to keep working if you leave your headlights on, forget to close the door all the way / longest lifespan which is a mobility battery. These batteries are used in wheelchairs and back up home computer power supplies so the amount of them that are sold and the nature of the market keeps prices low.

We've been arguing over this way of doing things on Prius chat for a decade... The main thread discussing all the different opinions is here: Fitting mobility 12volt AGM battery. | PriusChat

 

I mostly agree with your post.

A "mobility battery" is only one of many potential applications for a general-purpose AGM battery. I've been using a "U-1" sized utility AGM for nearly 7½ years with no problems. It required a little more effort to adapt, and has slightly lower ampere-hour capacity, but otherwise, as far as I can tell, has served equally as well as a dealer battery that cost 3 or 4 times as much would've. A larger "mobility battery" than mine can also be made to fit. So can a Group 51 AGM for non-hybrids, which is conveniently the same physical size as a Prius battery, but needs different terminal connections.

 

I got it through Amazon from a battery specialist site in Minnesota. I later bought another one as back-up at a slightly higher price from Harbor Freight (which markets them as a component for low-power solar systems). Those batteries are available from numerous other vendors.

No, I didn't change the terminals, but simply clamped the original cable clamps directly onto the flag terminals of the U-1. That looks clumsy, but functions well, and is easily reversible in case someday I switch back to a battery with JIS terminals like the original. I checked a few times to be certain the clamps stayed tight. There may be a better way. Fortunately, 12-v battery terminals in a Prius must carry only a small fraction of the current necessary to crank an engine. Some otherwise identical batteries have a less common terminal configuration that might be less clumsy to mate to the Prius cable clamps.

I also added spacers above and behind the U-1 to locate it securely with the mounting original clamps, and added a vent system to direct any gas from the battery (unlikely) out through the original venting hose.

 

OEM

 

Fairly easy... You have to add a longer bolt on the cross bar mounting bracket and slightly longer bolts than it comes with and some washers to sandwich the terminals into place.

 

Yes, 55amp-hours means it lasts longer if you leave the door open or headlights on. Most of the auto store bought ones are closer to 35amp-hours. And because this battery fits in the back corner of the inside of the car, not the engine compartment, you can safely use this type of 12v, which is less expensive because they sell huge numbers of them to power wheelchairs and back up power supplies for personal computers.

 

maybe you could get a bolt, nut and washers, and sandwich it together over bare wire, or put a crimp loop (eyelet) on the wire