maintaining 12v Batt while using Techstream

You need to output 13.6 V @ 2.5 - 4 A to effectively create a trickle charger.

4 A is the maximum recommended current for the 12 V OEM AGM battery.

 

Just buy a battery charger there not expensive and it's a good idea to maintain the 12 volt battery. I put mine on my 12 volt battery at least once a month to check its health.

 

Maintaining at least 12.8 Volts will prevent the battery from discharging. That is not high enough to do any significant charging, but high enough to maintain the existing state of charge.

 

^ This. Any half decent smart charger can be left on indefinitely. It'll run through a charging session, then revert to giving just slight, periodic charging, if and when needed.

 

12.8v per fred h in post #4?

 

How come you can mod power supplies but you don't know what voltage it takes to charge a 12 volt battery?
That's a 5 second google if you really don't know.

It takes 13.8 volts. Either at trickle 2 amp or fast charge 4 amp.

 

What I don't get: a smart charger will do the job, and is good to have around, but that's not good enough?

 

Ned,

It's known that the 2nd gen Prius in IG-ON (foot off brake, power button twice) mode will draw about ~200-250W to drive all of the car's ECU's (with all accessories off - obviously if you have headlights or other things on this goes up). I'm not sure what is in ACC-ON mode (foot off brake, power button once), but it should be the same or lower. So to stay in ACC-ON mode continuously, you'd need minimum 20A; I'd go for at least 25 or 30A to be safe. Anything from 12.8 to 13.8V should work great. Your 13V, 65A power supply is ideal really.

 

That's because you asked a trick question, and nobody noticed.

Nothing will happen to the HV battery, which is fully isolated in not-ready mode, and isn't charging anything.

You already got answers about the minimum output needed to prevent the 12 volt battery depleting (i.e. anything higher than its own open-circuit voltage) and that's all there is to worry about.

-Chap

 

Oh yeah 65 amps is very ideal.

 

You really don't understand anything about a 12 volt battery. Your only maintaining if it's at it's full 13.8 volts...fully charged. That's maintenance mode. Any other state below that voltage and it's charging.....it's drawing current.

 

I wonder how long additional posts will keep piling up without noticing the question was about the HV battery.

 

Paraphrased:
What is the the minimum voltage I need to prevent the 12v battery from being discharged, while the car is in ACC mode? (not in ready mode)

again: 12.8 Volts


https://priuschat.com/attachments/battery-soc-chart-jpg.59644/

 

If you read the question properly:

The answer is the HV battery does not get depleted charging the 12 V battery when it is in ACC or IG-ON mode. So any trickle charger at 13.6 V @ 2 A will do the job as current drain in either of those modes will be minimal while playing with Techstream.

 

was this one of those 'when did you stop beating your wife?' questions?

 

Well at least it wasn't another: "Go get your codes read" repeated x100 threads.