Amateur (Ham) Radio ?

Well, if you are talking about 50W transmitter output, then the radio will probably draw < 10A when transmitting. This is no problem when the car is READY. The 12V battery will not last too long under these conditions if the car is not READY.

 

I use an IC-208H, power tapped off the battery under trunk floor, never had any problem with that hookup. fyi, nuts on battery are metric. I almost never run full power, usually just need low power here in town. Remember also if you leave car in the mode where its powered up but ice will not come on (push on button twice without foot on brake?) the 12v battery will charge from the HV battery if it gets low. This link is one of the better ones regarding ham radio install....73!
http://priuschat.com/forums/prius-t...installing-ham-radio-side-car-run-wiring.html

 

There are four possible states that you can set the Prius to:

• IG-OFF where the car is turned off
• ACC-ON where the MFD lights up but the dashboard lights are off. This is good for playing the stereo for an extended period of time.
• IG-ON where the MFD is on and the dashboard warning lights are on. This state is OK for a few minutes, say if you need to raise/lower the power windows; however you should not leave the car in this state for an extended period since the current draw is relatively high and the 12V battery is not being charged
• READY where the powertrain is ready to move the car, and the DC to DC converter is maintaining 12V bus voltage at ~13.8V

Hence, if you are suggesting IG-ON as a state to be used when operating your radio, I recommend that you not operate the car like that for an extended period, or risk losing the 12V battery due to deep discharge.

 

You can safely draw up to about 40 Amps from the Prius 12V system when in "ready". Do connect to the 12V battery, do put fuses as close as possible to the battery, and best to use a relay there as well, controlled from the "accy" 12VDC, which can be found on the dash aux power connector and in the console (so you don't leave the radio on accidentally).

Remember, the Prius 12V battery is only about 38 Amp-hr, so conduct your draws accordingly (all puns intentional).

 

Thanks for the refresher Patrick!

 

One other thing to remember. The charger in the inverter can put out as much as 40 Amps.

From this 40 Amps you must:
1. Charge the 12 V battery - perhaps 1-2 Amps after a few minutes.
2. Power the cars electronics (I haven't done the measurements) - perhaps 5-10 Amps.
3. Power the headlamps and any other lights that may be on - headlamps will be 10-14 Amps, half that for HIDs. Add 3-4 Amps for the rest.
4. Run the cabin fan and battery cooling fan - perhaps 7 Amps max.
5. Run your amateur radio - 1 Amp on standby, 2-3 Amp on receive, 5-15 Amp on transmit.

So you see it's easy to draw more than 40 Amps from the 12V system. Moral - don't transmit for more than a minute at a time, or for those installing "killer audio", don't run it at full volume for extended periods. You WILL draw down the 12V battery if you do.

 

Hi David,

IIRC, Bob Wilson has drawn at least 80A from the 12VDC bus, to power his 12VDC to 120VAC inverter (for emergency purposes). The fuses on the bus are 100A and 120A, so that represents the upper limit...