Pleasant 12V battery charging surprise for PiP

Get a decent smart charger for the 12 volt, one that'll do a tailored charge program, monitor as it goes. The Owner's Manual recommends around 4 amps range, IIRC. Besides emergency use, it's good to use periodically, and/or any time the car is sitting for a few days: just hook it up, and leave it connected for the duration.

And when leaving the car sitting for months, charge the 12 volt before leavening and then disconnect the negative lead for the duration. Keep something covering the hatch latch mechanism, to avoid having to crawl through the car when you return.

 

yes, it is old news, and is in the 7,000 page manual somewhere! in fact, everything about the pip is old news, except to those who purchase recently. but i'm glad you found out.

 

Is the 12-volt charging from the traction-battery charger a trickle charge? Certainly it's not like the "ready mode" charging, which allows drawing hundreds of watts from the jump connector under the hood.

 

it is a trickle charge, but i don't recall how toyota accomplishes it, or if anyone ever researched the service manual to find out.

 

Yes, the charger always does both batteries at once. So, what happens if another 12V charger or a battery conditioner like the BatteryMinder is connected at the same time? I could see some possibilities like frying the computer, frying the BatteryMinder, or maybe just preventing either system from working properly. Anyone have actual experience with this?

 

On page 472 of the 2012 (US) PLug-In Prius Owner's Manual, it says:

If charging with the 12-volt battery installed on the vehicle, be sure to disconnect
the ground cable. *


That would prevent the car's hybrid battery charger charging the 12 volt I think. Still, I'm out of my depth, not sure if that's lawyer speak or not, ie: if simply not charging the hybrid battery when charging the 12 volt with an external charger would suffice. It seems onerous to have to disconnect the negative lead.

Maybe @Prius Team can comment?

* FWIW, that same warning is given in the regular 2014 Prius OM pdf I've also got. And, in my 2010 manual it says to remove the battery completely from the car before charging. I never do either.

 

yeah, that's just legal stuff. what would prius team know about it? they're marketing.

 

Have you charged your 12 volt in the car, with an external charger?

 

not yet, i'm still in the mid 12's. i really think the charger circuit does a fabulous job, but i'll be interested to see how it holds up while we're in florida this year. i'm hoping to talk mrs. disco into 8 weeks.

 

Disconnect the ground when using an external charger? I missed page 472. That rule can only be because they believe pushing current back through the 12V system can turn out bad in some situations. I won't say whether I've done that or not since legal stuff can void someone's extended warranty. Anyway, my Optimus battery arrives from Amazon this week. I'll hang onto the old original and see if extended time on the BatteryMinder performs a miracle.

 

I'm going on 11 months experience so far with my PiP. Far short of what some of you have. But there has never been a hint of the 12V needing a charge.

As for disconnecting the ground before charging the 12V in the car, that's just so you don't blow yourself up. This is from page 472 of my 2013 PiP manual. I added the red for emphasis.

■ Before charging
When charging, the 12-volt battery produces hydrogen gas which is flammable and explosive. Therefore, observe the following precautions before charging:
●If charging with the 12-volt battery installed on the vehicle, be sure to dis- connect the ground cable.
●Make sure the power switch on the charger is off when connecting and disconnecting the charger cables to the 12-volt battery.
​

 

Of course, it's about the hydrogen! Odd, isn't it, that "sealed" batteries still vent gas? I found out about this when charging another sealed battery in the basement- hydrogen set off the carbon monoxide detector.

 

What a great idea Toyota had, a gas, hydrogen, plug-in, hybrid.

 

I wonder if you plugged in the car as normal with a dead 12V battery (not trying to charge the 12V separately first, like what the OP did) would it start charging at all? Does there need to be 12V power to initialize HV battery charging or anything?

 

I would think you do need 12V power to initiate charging. The charging is controlled by the car's computers which are powered by the 12V battery.

 

A dead 12V = a no start Prius, period. The primary purpose of the 12V is to put the car into READY. After that point the HV system will attempt to charge the 12V// but, not a dead 12 V

 

My take is that the car is designed to maintain status quo, not bring the 12 volt back from a deep discharge. Getting a decent smart charger, using it any time the car has protracted down time (multiple days), and whenever there's an accidental drain (door left open, whatever), you'll have things covered. A quick connect helps.

 

Agree totally.

 

I’m not totally sure on that last sentence. With my first Prius I was constantly seeking knowledge. I found that the the 12 V could be removed after Ready sign. I drove it about 8 miles W/O the 12V connected! I do like your posts tho, they are always on the mark.
Andy