12V Battery

[S.J.C.]

Hoping someone knows the answer. I use several accessories through my Motorsport hobby which connect directly to the 12 Volt Battery which over the period of a day will drain the Battery - whether enough to reduce the Battery voltage to cause starting problems I don't know. In my previous vehicles I'd start and run engine for say 20 minutes occasionally to top up battery and to get some heat into the car to warm us up! - I'm assuming this is not possible in my new Prius as it seems to turn off the engine very quickly when its not required to top up traction battery. Anyone advise - or do I need to buy a remote power pack unit?

[Grumpy Cabbie]

Hoping someone knows the answer. I use several accessories through my Motorsport hobby which connect directly to the 12 Volt battery which over the period of a day will drain the battery - whether enough to reduce the battery voltage to cause starting problems I don't know. In my previous vehicles I'd start and run engine for say 20 minutes occasionally to top up battery and to get some heat into the car to warm us up! - I'm assuming this is not possible in my new Prius as it seems to turn off the engine very quickly when its not required to top up traction battery. Anyone advise - or do I need to buy a remote power pack unit?

I can't answer exactly but I can give my experience and see if it helps.

I use my Prius as a cab and using a car as a taxi will often prematurely kill a 12v Battery in a normal car due to the extra equiptment we carry and have running whilst stationary - meter (nominal drain), sat nav (nominal drain also) and a two way radio and despatch computer (high drain). These must continue to run whilst I am sat waiting my next job. If it is a quiet night shift and I don't get a job for an hour or maybe two, this can really kill the 12v over time, let alone the embarrassment of running the Battery flat!

With the Prius you leave the car in the 'ready' state. This is the same as leaving the engine running on a normal car. In this ready state the traction Battery will be keeping the 12v charged continuously. If the traction battery gets low, the engine will kick in for as long as needed to top it up, then will switch off and leave the traction battery charging still. Assuming you're happy to leave the car unattended (a thief could jump in and nick your car!), then the car will keep the 12v topped up for as long as it has petrol. I have heard it might be possible to lock the door physically with the small key whilst leaving the car in ready mode (the remote won't work) but it is not something I have tried.

I hope this helps.

[johalareewi]

The good news is that the 12V Battery doesn't get used to turn the engine. The massive HV Battery does that. So you only need enough charge in the 12V Battery to power up the control systems. The bad news is that because of this, the gen3 battery isn't as meaty as a normal car battery.

You might also want to find where the jump terminals are in the Prius in case you need them. :)

Have read of this...

http://priuschat.com/forums/gen-iii-2010-prius-accessories-modifications/74916-adding-secondary-battery-12v-outlets.html

[S.J.C.]

Hoping someone knows the answer. I use several accessories through my Motorsport hobby which connect directly to the 12 Volt battery which over the period of a day will drain the battery - whether enough to reduce the battery voltage to cause starting problems I don't know. In my previous vehicles I'd start and run engine for say 20 minutes occasionally to top up battery and to get some heat into the car to warm us up! - I'm assuming this is not possible in my new Prius as it seems to turn off the engine very quickly when its not required to top up traction battery. Anyone advise - or do I need to buy a remote power pack unit?

I can't answer exactly but I can give my experience and see if it helps.

I use my Prius as a cab and using a car as a taxi will often prematurely kill a 12v Battery in a normal car due to the extra equiptment we carry and have running whilst stationary - meter (nominal drain), sat nav (nominal drain also) and a two way radio and despatch computer (high drain). These must continue to run whilst I am sat waiting my next job. If it is a quiet night shift and I don't get a job for an hour or maybe two, this can really kill the 12v over time, let alone the embarrassment of running the Battery flat!

With the Prius you leave the car in the 'ready' state. This is the same as leaving the engine running on a normal car. In this ready state the traction Battery will be keeping the 12v charged continuously. If the traction battery gets low, the engine will kick in for as long as needed to top it up, then will switch off and leave the traction battery charging still. Assuming you're happy to leave the car unattended (a thief could jump in and nick your car!), then the car will keep the 12v topped up for as long as it has petrol. I have heard it might be possible to lock the door physically with the small key whilst leaving the car in ready mode (the remote won't work) but it is not something I have tried.

I hope this helps.

Hope I'm doing this right, Thanks for replies, didn't appreciate that the 12V battery was charged from the traction battery.

I'm also using a two way radio, which can drain battery quickly if a lot of transmissions are made, its not too bad if its a matter of listening and I wouldn't leave the car unattended and open.

Sorry only had Prius a week so, can i clarify what you mean as 'ready' mode. Would that effectively be having 'started the vehicle' i.e pressed break pedal and pressed start button, but it still having the 'P'switch on. - as in my owners manual (Page 160 ) it says in 'N' position the petrol engine operates but electricity cannot be generated.

[Grumpy Cabbie]

Ooh I'm not going to refer to the owners manual, but I think you're on the right track regarding 'Ready' mode. It's when you get in, press the brake and then press the start button but don't engage a gear. The car is now running though the engine will only fire up if needed. You can now use the two way radio in the same way I do. You're probably best turning the heating off as this will run the Battery down a little quicker. When the traction Battery gets low (it the Battery level shown in the car icon on the screen) the car will fire the engine automatically to charge it up (though only about a third full) and then it'll cut off. It will repeat this action for as long as is needed or until you run out of fuel.

It probably sounds complicated but give it a try (turn the heating completely off) and use your radio instead of the two way and see what happens to the traction battery level. It will probably take a good 20-30 mins for it to run low enough for the engine to kick in. Also, do not leave the car unattended as someone can jump in and drive it away - even if you take the key with you!

Any other questions?

[S.J.C.]

Ooh I'm not going to refer to the owners manual, but I think you're on the right track regarding 'Ready' mode. It's when you get in, press the brake and then press the start button but don't engage a gear. The car is now running though the engine will only fire up if needed. You can now use the two way radio in the same way I do. You're probably best turning the heating off as this will run the battery down a little quicker. When the traction battery gets low (it the battery level shown in the car icon on the screen) the car will fire the engine automatically to charge it up (though only about a third full) and then it'll cut off. It will repeat this action for as long as is needed or until you run out of fuel.

It probably sounds complicated but give it a try (turn the heating completely off) and use your radio instead of the two way and see what happens to the traction battery level. It will probably take a good 20-30 mins for it to run low enough for the engine to kick in. Also, do not leave the car unattended as someone can jump in and drive it away - even if you take the key with you!

Any other questions?

Many thanks.

[timberwolf]

<snip>

Sorry only had Prius a week so, can i clarify what you mean as 'ready' mode. Would that effectively be having 'started the vehicle' i.e pressed break pedal and pressed start button, but it still having the 'P'switch on. - as in my owners manual (Page 160 ) it says in 'N' position the petrol engine operates but electricity cannot be generated.

Yes, and the word READY is lit up on the instrument panel. And a for reading the owners manual.

[priusoldy]

12 volt Battery Note;

Just in case some owners are confused with the 12 volt Battery system, here is a little info,.

If you wish to read the true voltage of the 12 volt Battery, this must be done without the main power switched on (Via button).

The reason for this is that the 12 Volt battery is not charged directly from the alternator on the petrol motor (as would be normal on other conventional autos), but is charged via the inverter from the main hi-voltage battery. The petrol motor only comes into operation when the main h-voltage battery is running low.

I found this out the hard way by testing etc.

Maybe helpful for someone out there, Regards Brian

[johalareewi]

Blimey, a 4 year old thread brought back to life.

[Grumpy Cabbie]

Blimey, a 4 year old thread brought back to life.

Usually the actions of a troll or one post wonder.