Gen 2 Prius Troubleshooting

Rough notes for edit later

A big no-no for cars, especially hybrids, is to jump start it backwards, like black to red (negative to positive) instead of black to black /red to red (negative to negative/positive to positive). This can blew some main fuse or a fusable link, DC/DC fusible link. This may be a part that plugs in or a grey fuse assembly with an embedded wire that can burn out, underneath the main fuse box under the hood, or a fuse on top of the 12 volt battery in the back in a Prius. Still looking it up. Concept is same for other cars as well.


Prius 12v batteries are more expensive than most other car batteries because they are Absorbed Glass Mat (AGM) car batteries, referred to as dry cell batteries, instead of the more common and traditional lead-acid based battery. Toyota uses dry cell batteries in hybrids because it's safer to not have hydrochloric acid a few feet away from the ~26 NiMH (Nickel-metal Hydride) hybrid batteries under the rear seat used for the actual hybrid power part of the car, because apparently there could be an explosion if there was a rear end crash and the HCl and NiMH batteries mixed. Being dry cell may be why AAA and Walmart don't carry Prius 12 v batteries. They may stock only lead-acid batteries.



Tools - Voltmeter.

https://priuschat.com/threads/how-to-change-fusible-link-under-hood.96616/


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Misinformation I was told
False - If your Prius 12 v battery has no sloshing, it's probably frozen. Once it's frozen, it's dead. --Got that from Autozone. There is no sloshing because it is dry cell. Test it with a voltmeter. There is some truth to the idea though.

-https://www.cars.com/articles/2014/02/can-a-car-battery-freeze/
A quote from the link above. 
"A 100 percent fully charged battery will not freeze until approximately minus 76 degrees Fahrenheit. A fully discharged battery can freeze at or around 32 degrees," Kimbrough said in a telephone interview. The difference between a fully charged and discharged 12-volt battery is not that big.
Related: How to Store Your Car for Winter
"When I'm talking about a fully discharged battery, I'm not talking about zero volts. A fully discharged battery is just below 12 volts. There's only about eight-tenths of a volt difference between a fully charged battery and a discharged battery," Kimbrough said.
A 12-volt battery has six cells, and Kimbrough said that if one cell is damaged, the voltage will drop below 12. Cells are connected in series, like Christmas lights, he added, and "you're never going to be any stronger than the weakest."
The electrolyte inside the car battery is made up of about 25 percent sulfuric acid and 75 percent water. The acid interacts chemically with lead plates to create electricity, leaving mainly water in a discharged condition that is more susceptible to freezing.