Hello Friends, About a year ago, at the beginning of Covid, I went around 6 weeks without driving the car. When I tried to drive it, the 12v was dead. Since then, it never held a charge, despite driving it + letting it charge. I replaced it with another 12v. I'm likely not going to drive it again for ~6 weeks. I was thinking of disconnecting the battery to prevent the same issue. Two questions for the group here: Is disconnecting the battery the best option or is there something else I should be doing? (I'd rather not keep a trickle charger plugged in.) How + What do I disconnect? Ex: Do I disconnect the negative or positive? Do I have to use special pliers when dealing with live wires? Thank you!
When dealing with car batteries always disconnect the negative first (and connect it last) so that accidentally touching any metal part of the car with the wrench will not cause a short circuit (and sparks). You can easily disconnect the negative cable where it connects to the car body. JeffD
just disconnect the neg and you'll be fine. you might have to reset a couple things on power up, but nothing important. the only other option is the trickle charger (maintainer)
You can buy a disconnect switch to install between the negative battery terminal and its associated wire. They only take a few minutes to install, and they're extremely simple/robust/reliable devices. It would make the periodic disconnect/reconnect a very quick, safe, no-tools experience. (generic example pictured)
In many Prii there is already an easy way to disconnect the battery. Gen 1 and Gen 2 had a fat cable going to the battery positive terminal clamp with a plug-in connector you could just squeeze and unplug, in a plastic housing that you don't have to worry about sparking to nearby metal. Gen 3 did not have that, but has a big fat white wire right in the underhood fuse box that can be unplugged the same way, to the same effect. I haven't looked that closely at a 2017, but I wouldn't be surprised if there's a similar way.
Yes, and then you can wrap a towel around the disconnected negative cable to further isolate it from under hood components. Also, if your goal is just to leave the battery offline, just leave the negative cable wrapped up under the hood. You'll probably have to lock the car with the metal key because door locks will be inoperative. Make sure the trunk and the other door locks are secured manually and then lock the driver's door with the key. When you get back, you can unlock the driver's door with the metal key and release the hood. Reconnect the negative battery terminal and you should be good to go.
I haven't seen enough photos of the 2017, but if it's got an unpluggable main cable somewhere like Gen 1, Gen 2, and Gen 3, then you don't even need to wrap a towel around anything.
@priuswarrior1989 what's your parking situation? If you've got secure parking and AC current outlet, consider getting a smart charger, one that can be left on indefinitely, if need be. That's our scenario: sporadic use, secure parking and AC outlets available. I use a CTEK 4.3 charger, and I've installed it's quick connect under the hood, for convenient connection. If you don't have secure parking, I'd second the disconnect/isolate of the neg battery connection.
In the just-in-case department, park the vehicle so the hood is easy to get to and (worst case) be towed out. I would also suggest fully charging the 12v before disconnecting it. Long term storage: also see rodent/pest issues. GOOD LUCK!
Thank you! Do I just leave the cable hanging or should I wrap it with electrical tape or something? Thank you! Is the towel a fire hazard? Additionally, is my goal to avoid the cable from touching the battery terminal or any other metal portion of the car? Thank you! Ahh, unfortunately I don't have an outlet nearby.
second the battery tender, but can't a prius go longer than 6 weeks w/o being driven? I'm pretty sure I've left mine undriven for that period of that time in the past...
The neg cable is typically disconnected at the post, and it's other end left connected to bare metal on the body. One issue is that the cable is pretty short, and having spent years connected to the post, has "memory", may want to relax back towards that post. If it touches it's not a short, but it will be connected intermittently, and may spark a bit. Bottom line, it doesn't hurt to take measures to isolate it. My typical scenario for disconnecting it is during brake work; what I do is stuff the loose cable end into a leather glove, and the other glove I lay over the latch mechanism on the hatch threshold, so the the hatch can't lock on me.
this being a 2017, i'd be curious to see a disconnected negative cable under the hood. on my dakota, it just falls down below the battery
