Infrequent Use of Car

If you have the capability, I like to recommend a trickle charger. In my area (South Florida) we see a lot of people who don't do a lot of driving, hybrids and normal gasoline cars, and the biggest issue seems to be premature battery failure. (12v battery for Hybrids) The batteries never get enough time to fully recharge when used only for short trips or when left sitting for long periods. An inexpensive trickle charger ($10-20) can help prevent this.

And of course regular maintenance is ALWAYS recommended.

 

If the car is going to sit in the garage for 2-4 weeks at a stretch, it's only a matter of time before the tiny 12 vdc battery in the hatch is kaput. I had trouble the first winter with my Prius just driving around at -40 with Max Heat and the electric defrost on all the time

Consider investing in a battery tender. It will automatically keep the 12 vdc battery at float charge level, some also "condition" or desulfate the battery.

I have an older model of this VDC Electronics Battery Minder:

http://www.vdcelectronics.com/batteryminder_12117.htm

The maintainer comes with several harnesses (Quick clamps, ring terminals) so I wired mine directly to the 12 vdc battery. I plug it in whenever my Prius is parked in the garage. I have previously posted photos of the harness on my 12 vdc battery

Note, this maintainer really isn't a charger. If the battery is dead, it doesn't have the amps to charge. You need a conventional battery charger in 10 amp position or higher to charge a dead battery

I've used the VDC Battery Minder for over 3 years and it works great. I also use them on my tractor and plow truck at the hobby farm, and on my FJ

No need to worry about the NiMH traction battery. When the Prius is powered off, relays are opened so there is no parasitic drain on the NiMH battey. Apparently the NiMH battery is good for 6 months

 

Before I got the Battery Minders for my hobby farm equipment, I tried those garbage trickle chargers. Problem is, they just keep charging and that will also ruin a battery.

I speak from experience because the Case tractor at my hobby farm doesn't get much use during Spring or Fall, so it can sit for a month or longer in the shop. Battery kept going so low it would barely crank and needed a jump

I got a cheap trickle charger from Canadian Tire and after leaving it on for a week, acid was spraying out the vents. So I had to cough up $280 for a new tractor battery, and clean up all the damage the acid caused.

I took the charger back to Canadian Tire and they were quite quick to point out in the instructions "Not intended for long term unattended use, or battery damage will result. This is not an automatic battery charger ... etc etc" For long term use of unattended equipment, you MUST use a float charger.

If a person doesn't want or need the desulfation capability, and quite frankly I don't see why not, VDC also has a basic float charger that doesn't desulfate:

http://www.vdcelectronics.com/batterykeeper.htm

 

Since the Battery Tender is mentioned here, I do have a battery conditioner and it has a lighter plug adapter. Can I just plug in the battery conditioner through the cigarette lighter plug located below the dash to charge the 12V battery if needed?

 

I'm not certain, but I think you may not be able to do this.

The 12V plug beneath the dash is not "live" until the car is in accessory mode or Ready mode, so you will not be able to connect to the battery through that plug unless you leave the car on. Probably not the best way to manage the battery.

 

As I prefer to ride my bicycle as primary transportation... and then our EV is the next choice in line - My Prius stays parked in the garage for about a month at a time on average. Usually goes three weeks minimum, up to six weeks between drives. All I do is turn off the SKS button. Two years now, and I've not had any issues.

 

Others have already answered your question, short reply: NO

This is not just a PRius quirk. My FJ Cruiser also kills the lighter circuit when off, so if the battery went dead a cig lighter jump start gadget would not work for the FJ either

Either wire it up to the underhood jump point, or directly to the 12 vdc battery in the hatch. My VDC harnes intended for hard wiring has an inline 10A fuse

 

and what about the HV bat.. and leaving that discharing itselfs for weeks...

 

Fred,

Looks like you've been doing fine for 2 1/2 years. I wouldn't change a thing. Your use is very similar to mine on my 06, and I have had no problems either (knock wood).

sul

p.s. Quit posting so much, huh?

 

So... i have this update on the way the 12v Cigarette lighter plug functions.

It turns out you can use the 12v lines to jump the car. the radio and other such units are tied directly onto that line while the main computers used to start the car are "locked" on to the ignition circuit. what this mean is that you can jump the car with the 12v cigarette line. once you plug it in, the radio will turn on instantly... every time.... it's odd.. but verification that you have enough voltage to jump.

 

I'm a bit confused by that. So you're saying that you can "backfeed" into the radio, which will then power the relay to backfeed into the rest of the 12v system?