Battery stamina

4 weeks shouldn't have any major impact on the traction battery. However if you have smart key, that is a pretty significant trickle drain on the auxiliary 12v battery. With smart key installed use the switch on the dash under the steering column to turn it off. You care should store well that way. If you do not have smart key just park it and don't worry.

 

HV battery should be fine. The aux battery might be another matter but probably will be OK too. Park it so the jump terminals are easily accessable by a jump source just in case. In other words, back it into the garage.

Turn off SKS and make sure the headlights are completely off and not just off because of auto-off.

 

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I've seen several references to this headlight issue, but no real explanation as to why.. what causes the 12v battery to discharge if I use the auto-off feature? [I'm one of those that wishes we had or could enable DRL in the US.]

Thanks!

 

It's all secretly hidden in the body ECU, but I would think its the same reason your TV uses power when off; so you can use the remote to turn it on.

The prius doesn't have nearly the drain for auto-off as a TV has, but the principle is similar. There are electronics that are active to keep ground away from the taillight relay coil. If you put the headlights to off, the source of the ground that needs to be blocked is removed, so the electronics that was holding it back deactivates.

 

Right. When you flip the courtesy light switch to OFF you're just interrupting the ground. The body control software is still watching for a door switch signal to provide that lovely Theatre Lighting (Gradually ramp up to full intensity, then gradually ramp down to off).

Poke the SKS Disable button and it *should* be ok for a month.

 

We're talking about the Auto-Off of the headlights/taillights. I don't think the position of the dome switches will affect drain much.

 

Oops missed that - sorry. Only the Canadian models have Auto headlights. I leave mine in Auto as the car gets driven 6 days a week, so when they turn on in my condo underground parking it isn't that big a deal.

You can bet if I'm gone for a few days I'll poke the SKS disable button and turn the headlight switch to Off.

Turning the courtesy light switches to off may only help if a door is somehow ajar. I've noticed it's easy to leave the hatch ajar and only the hatch courtesy light turns on then. If you fully open the hatch, all the courtesy lights turn on.

The electronics would still be drawing power, but nowhere near as much as an actual light bulb.

Actually, since I got my portable battery booster last fall, I don't even worry about it. It's very reassuring to know it has more than enough power to charge the 12 vdc Prius battery to boot up.