12v batt

Do a load test or have one done. Changing the 12 VDC batt on age or miles is a blind shot in the dark. A load test (typically free at an automotive shop specializing in batts) is the best way to detect when the batt is moving toward failure. I'm driving a 2004 Prius. I forgot about the 12 VDC batt and my wife was stranded. Annual load test is good insurance and most likely free. Then after the batt is 5 years old I recommend load test every 6 months. It is unlikely that you will see any indication that the batt is about to fail except with a load test. The way you know it is going to fail is when it does and you are stranded. I jumped out prius and got got started. Wife went straightway to get new batt without shutting it down till arriving at shop.

 

9 year old post good advice though

 

How much amps can I drain off the 12v battery on an 06' prius ? need to install sound system

 

someone with a gen 1 prius said you'll have hell to pay if you install an aftermarket system as many of the vehicles functions rely on that factory stereo. my 04 chevy impala has a similar issue but a pro shop can do it but its too expensive for me to want to do it.

 

btw, have you considered just keeping it and using one of those bluetooth adapters that transmit an fm signal to your factory stereo? yeah, not as cool as an aftermarket stereo but only costs $20

 

just bought a 2001 prius from the original owner. looking at all the paperwork, and they have all of it, the battery was replaced every 2 years. that tells me the battery is way to small to do the job intended. what i did was put a full size battery in the trunk and connected it to the posts of the old battery. then i installed a cheapie 20w solar panel that fit between the speakers on the back dash and a small charge controller that always keeps the battery topped off. the problem with the battery dying is that when the gas motor isnt' running, its not being recharged. when you turn off the key and leave the battery in an uncharged condition, it develops a memory. over hundreds of times, your battery will wear out and die prematurely. i've solved the problem.

 

The 12v battery sees very little load. It does not start the car. I wouldn't recommend running two batteries in parallel, this could be dangerous and cause more problems then it solves, especially since they are different capacities. You run a high risk of having an exploding battery by overcharging. You can easily modify the existing connections to accept a more traditional and cheaper AGM type battery. Dont put a wet cell battery in the prius, the traction battery pulls air from the cabin, trunk, and the outside. it is a fire/explosion hazard as well as a poisoning hazard as the gases can travel into the cabin of the vehicle.

 

thx. i appreciate that thought. the original small battery is there kind of only as an ornament. it doesn't hold a charge well and is sort of dead-ish. i only connected to it as i was lazy and it was easy for me to make good, safe, easy battery cable connections. its been a year and no problems. i have been worried about the offgasing from that battery but i've removed the exhaust tube from the old battery and its my belief that the hole serves as a vent and as i drive it has a venturi effect and draws air out of the trunk. lead batteries do produce a very small amount of hydrogen when being charged and that mostly occurs during driving when there is airflow on that exhaust tube. the amount of charging being done by the small solar panel is a trickle charge. i'm thinking very little hydrogen gas is produced then. however you are exactly correct and i will revisit this design. thx.

 

You can get all the parts needed from walmart. if using a traditional top post battery you will need some marine battery adapter, the type that adapt the post to a thread with wing nut, and a replacement negative cable that fits a top post. To make the positive fit the threaded post you will need to drill it out slightly. For the negative you just unbolt it from the body and replace it with the new one. Some walmarts also sell vented battery boxes. I have one bolted down in my trunk with an optima battery inside.

 

For clarity for future readers of the thread, that isn't the case. Whenever the car is in READY, the 12 volt battery is being charged, whether the gasoline engine is running or not.

-Chap