Auxilliary Battery/ Substitute

Yes, the outlets are fused with 15A fuse each.

 

Well, you're undoubtedly right about not being able to jump it from there, but it's only almost true that it's "not connected".

I ran into a funny situtation this weekend, when I was charging a Vector 12 V portable jump-start battery from the center console outlet. I pulled into a store parking lot, turned the car off, and.... it was still on.

Well, it was not on, but the radio, outboard GPS, and MFD were still running. I had no clue what it was at first, and sat there pushing the Power button a dozen times trying to find the "Off" position. My mind is trying to run down all the symptoms I've read here about oddball behavior of the IGN-ON mode, and all sorts of other scenarios.

Then I had the "D'Oh!" experience, and realized I had been floating that extra 12 V battery on the center outlet, and it just started feeding right back in, keeping all the accessories running.

So, apparently, you can play the radio in a Prius if you bring your own battery and plug it into one of the power outle..., er inlet/outlets?

Who knows what other accessories will run? I didn't push it, as I wasn't entirely comfortable that this wouldn't fry something.

Meanwhile, this jumpstart battery has a 12V input that's used by the A/C charger. It only draws half an amp through there, even if the battery is discharged, and it can't overcharge by that route, unlike the way I was doing it. So, I can power that so-called A/C input right from the car battery and it can't feed back through that port.

I may wire up something permanent to keep the thing always charged.

 

I see what you did. The 15A console outlet fuse and the 7.5A ACC fuse are controlled by the ACC relay. The ACC fuse feeds all the ACC power to all the accessories. The ACC line is really a remote much like amps have to turn on the accessories, that's why it's only 7.5A. The accessories get their main power from the B+ line, so if the aux battery were dead, the accessories would probably not power up. Because of the ACC relay being open when not really in ACC or higher mode, your alternate power would not backfeed to the main B+ through the ACC-B fuse.

So, if you jump the ACC relay temporarily, you could fire up the car throught the console outlet. If you use a SPDT pushbutton, you could close the brakelamp switch too, so that pressing the power button would bring the car to ready.

Ah, but looking at the wiring diagram, emulating the stop lamp switch would not work or set a DTC, as there is a failsafe in the switch sense. One contact opens while the other closes.

 

If by Dan you meant me, no I don't believe I mentioned charging currents. I do know the DC/DC converter can output 80A, and I can always look up fuse ratings. Power outlets are fused at 15A. Allowing for headroom, and looking at the warning label in front of the outlet in the console, they are supposed to support 10A. More can be drawn, but if you get too close to 15A, you'll blow the fuse.

 

On a related issue, the drivers' manual says not to charge the Aux Bat at more than 3.5 amps, else overheating may occur. I have a 6 amp charger. Is there a way I could turn on some lamps or other loads while charging to shunt 2.5 amps of the 6 amp charger output, leaving 3.5 amps charging the Aux Bat?

 

Check the meter of the charger. If it shows 3.5 amps, then you should be OK, charge current should go down as battery charges. If it starts out highter, then maybe adding a load might help, but you won't know if it is enough without a dedicated ammeter going to the battery only.

 

Thanks, "Danman". I'm trying to avoid disconnecting (temporarily) the aux battery to insert an ammeter. Anyhow, I thought of an alternate solution: I'm looking into installing the shunt in my charger, so that the charger ammeter shows only the current going to the battery. I'm hoping I can buy a suitable 12 volt lamp and a socket. I'll mount the socket so the lamp can be inserted from the outside of the charger. Then I can try different lamps (different wattages) and see what they do to the battery charging current.
I'll let you know how things turn out!

 

Basically adding a resistor in series, which effectively creates a current limiter. That will work.