car wouldn't start

Your technician hit the nail on the head it's reading zero amps and 11 some odd volts and if you tried to use that battery say to turn on a 12 volt light bulb I bet it would turn on and turn right off or something similar like there's no amps in the battery to move through the wire to light the filament in the bulb and then go back simple I think. It's time for a new 12 volt running a small slime air pump for 5 minutes should not render your battery not able to unlock the car. I'm assuming we're talking about readying the car because you're 12 volt battery doesn't start the engine It reads the car gets the computers up to snuff etc. The engine starting is done by the HV setup. So I'll assume we're talking about readying and then driving backing out whatever.

 

If this is true the battery is probably in poor shape. The car needs to be driven regularly to main a good charge in both batteries.

As has been mentioned, the 12 V battery does not crank the engine, so does not need cold-cranking amps, just enough voltage and current to get the systems up and running. The HV (hybrid vehicle) battery then turns the engine over to start it.

 

No. Either your battery is needing to be replaced or the test was faulty.

A few hundred miles over a few years is 3 ½ miles a day. That is not nearly enough to keep the 12 V battery charged.

A good option for low miles is investing in a 4 or 5 A (forget a trickle charger) multistage automatic battery charger and connecting it to the car's 12 V battery any time the car is not being driven.

 

generally, an auto parts store will charge it up for you and load test it for free to see if it is good, or needs to be replaced.
have you checked to see if it is under warranty?

either way, i would get a battery maintainer as dolj suggests above. you don't drive nearly enough.

 

You can't get the car to ready properly because you're 12 volts has 11 point something volts and 0 amps according to the person running the test so therefore you have barely enough juice in the battery to make the warning lights on the dash go crazy. Your mechanic or battery testing people told you this You wrote it in the previous group of text. So that's all I can go by I bet once you put a 12 volt in there that's new and has some cold cranking amps and is the proper voltage this problem is instantly gone.

 

What you likely have is the battery tester couldn't compute a Cold Cranking Amps value with the voltage that low (my tester would read "voltage low - charge and retest"). Or your battery is just that weak.

Get a maintenance charger or drive the car for a few hours each week.

Posted via the PriusChat mobile app.

 

When the car was running the compressor was it in Ready mode and also in Park? If not all the power for the compressor came straight from the 12V battery, and that is not a very big battery on a Prius. So you ran that down. When you tried to start the car immediately the voltage/charge was too low. When a depleted lead acid battery sits for a long time with no load it can mysteriously "recover" somewhat. That is why when an attempt was made to start the car later it worked. Note that it only worked because all the battery had to do was power some electronics, it didn't need to spin a starter motor. The power for the equivalent of that on the Prius came from the HV battery, which was apparently in OK shape. You can recharge the 12V and test it. However, running one down to the point the car won't start is likely to damage it, so that it will not be able to store as much energy as before. Also, it may be old. Either way, you may want to replace that 12V battery.

The 0 cranking amps result is probably just another way of saying that the tester employed refused to test it because the voltage was too low. Alternatively, it may mean the tester failed it immediately when the voltage crashed when a resistive load was applied.

 

good point!

 

There are two general categories of battery testers.

First is the inductance - capacitance type. It has electronics to send a small AC voltage signal through the battery then uses some "mad science" to calculate the theoretical capacity. This test can work if the battery isn't fully charged - and it's easy - hook up the leads and push some buttons.

Second is the resistive type. A big adjustable resistor is connected and used to load the battery while the voltage is monitored. Usually a load that's half of the battery's CCA rating for 15 seconds. If the voltage is above a minimum spec (which is dependant on the battery temperature), then it passes. Here the battery MUST be mostly / fully charged and some more skill required. This measures actual capacity.

When done properly with good equipment, both tests are valid but aren't 100% foolproof.

Posted via the PriusChat mobile app.

 

Prii do not have an alternator.

The inverter will supply both DC and AC power as required. It does not need the motor to be running except when it does.

When using accessories like a tire compressor, it is advised to do that with the car in READY so that the 12 V is supplied by the inverter and also so that the engine can run as required to keep the hybrid vehicle (HV) battery at a good level of charge.

 

it doesn't matter what order you do things in. plug in the compressor, make the car 'ready' or vice versa.
whatever trouble you're having is either the 12v or the compressors, or something altogether different in the charging circuit or wiring