Solution for 12-volt battery dying after 10 days?

[Blastphemy]

When we were at the dealership to test drive a RAV4 EV, the first one we were going to drive wouldn't start up even thought it had a full charge. After we returned from driving one that worked, the technician told us that the 12-volt battery had died because the car hadn't been driven in almost two weeks. He said that the 12-volt battery only charges when the car is driven, not while it's plugged in to the charger. He joked that dealerships that are unaware of this problem could find themselves with a lot of dead RAV4 EVs on their lots!

This presents a problem for us because we usually take long vacations and our cars can sit for up to three weeks at a time when we do this. That means we're going to come home to a dead RAV EV every time we go on a long vacation. D'oh!

Has anyone dealt with this issue yet and found a solution? Perhaps Toyota has a trickle-charger that will keep the 12-volt charged without driving the car??

 

[reeler]

There are lots near the airport typically where you can plug in your car while you travel. My Nissan Leaf is charging at Canopy Parking near DIA right now.

When I bought mine, it had been inside on the showroom floor for a couple months. It didn't start either and needed a jump.

You might buy one of those 12V boosters that you plug into the cigarette lighter for your travel. I doubt you will need it, but it will give you some peace of mind.

 

[TonyWilliams]

The same problem exist in the LEAF, however it has a small solar trickle charger on most models sold.

One option at the airport is to park in a sunny spot with a solar charger you can buy for $20. Another is a plug in trickle charger. Third is disconnect the 12 volt negative post. Fourth is leave the car plugged in, however, on LEAF, it will not charge the 12 volt when plugged in long term. Tesla could have the same "feature". We don't know yet.

 

[Dsinned]

This don't sound right to me. Why wouldn't the traction motor battery be utilized to "trickle charge" the auxillary power (legacy) 12V battery when the car is "off". This would be the simplest solution. Would Toyota "knowingly" ship these new EVs to a bunch of CA dealers only to have them sit stationary for who knows how long only to have them become undrivable the first time they are presented to a prospective customer? This makes absolutely no sense, because these cars could be kept drivable for many, many months on a full (main) battery charge, or even half a charge, after shipment from the factory!

 

[Blastphemy]

There are lots near the airport typically where you can plug in your car while you travel. My Nissan Leaf is charging at Canopy Parking near DIA right now.

The problem is not the main battery, it's the 12-volt battery. The RAV4 EV specialist at the dealership consulted his internal documentation and spoke with Toyota engineers and told me that both the documentation and the engineers told him that the 12-volt battery does not charge when the RAV4 EV is plugged in. The only time the 12-volt battery charges is when the car is being driven.

Leaving the RAV4 EV plugged in for 10 days won't stop the 12-volt battery from dying, as was proven when we went to test drive a RAV4 EV that had been plugged in for 11 days straight but wouldn't start because the 12-volt battery died. The techs had to jump-start the car and then drive it around for almost an hour with the jump kit still attached!

This don't sound right to me. Why wouldn't the traction motor battery be utilized to "trickle charge" the auxillary power (legacy) 12V battery when the car is "off". This would be the simplest solution. Would Toyota "knowingly" ship these new EVs to a bunch of CA dealers only to have them sit stationary for who knows how long only to have them become undrivable the first time they are presented to a prospective customer? This makes absolutely no sense, because these cars could be kept drivable for many, many months on a full (main) battery charge, or even half a charge, after shipment from the factory!

Believe me, I ridiculed this problem right to their faces at every opportunity The fleet manager was not happy to learn about this dumb problem.

 

[TonyWilliams]

the 12-volt battery does not charge when the RAV4 EV is plugged in. The only time the 12-volt battery charges is when the car is being driven.

This is the same as the LEAF, but the exception is when the car is UNPLUGGED, it will maintain the 12 volt every 5 days.

Too many LEAF's with dead 12v batteries, so I always left it on a motorcycle trickle charger when I left for more than a week. Unplugged is the best way to leave a LEAF, however the Rav4 should have the issues resolved where you could "brick" the Tesla traction battery by no leaving the car plugged into the charger (the TMS would kill the battery).

It caused quite a stir in the Roadster crowd with $40,000 batteries becoming ruined.

 

[Dsinned]

Tony, please explain what you are talking about more clearly. Are you saying, the RAV4 EV 12V battery gets refreshed every 5 days, if the car is unplugged and left off at least that longer? If this is what your saying, why are there reports of RAV4 EV on dealers' lot with dead 12V batteries??? Or, is this only a problem when they are plugged in for that long or longer, which still makes no sense to me whatsoever?

 

[Ampster]

Leaving the RAV4 EV plugged in for 10 days won't stop the 12-volt battery from dying, as was proven when we went to test drive a RAV4 EV that had been plugged in for 11 days straight but wouldn't start because the 12-volt battery died. The techs had to jump-start the car and then drive it around for almost an hour with the jump kit still attached!

I left my RAV unattended for 15 days and it started right up. I would be interested to find out how long the 12volt battery will last if nothing is left on (I don't mean neg terminal disconnected).

I can imagine a 12v battery on a dealer showroom would get lots of use, since people are opening and closing the doors and maybe playing with the instruments. I would like to get more data before I worry about trickle charging my RAV everytime I go on vacation. LOL

 

[TonyWilliams]

Tony, please explain what you are talking about more clearly. Are you saying, the RAV4 EV 12V battery gets refreshed every 5 days, if the car is unplugged and left off at least that longer? If this is what your saying, why are there reports of RAV4 EV on dealers' lot with dead 12V batteries??? Or, is this only a problem when they are plugged in for that long or longer, which still makes no sense to me whatsoever?

No, the Nissan LEAF has a 12 volt charge cycle at:

55 minutes after shutoff

then, every 5 days.

But, that 12v charge is inhibited if the car is left plugged in. Therefore, on a LEAF, we leave the car UNPLUGGED and the 12v on a trickle charger. Communications to/from the LEAF and Nissan and from the smartphone app are all powered by that 12v battery.

-CONVERSELY-

The Rav4 may or may not have these issues. Obviously, there is some issue, as there seems to be a lot of reported dead batteries. I would probably still leave a Rav4 on a 12v battery "tender" (or trickle charger), and if the weather was hot or cold, I would leave the car plugged in so that the TMS will heat/cool the battery while I'm gone without depleting the traction battery.

In moderate San Diego weather, I suspect you could leave both a Rav4 or LEAF for many months to a year unplugged (but with the 12v on a tender).

 

[Blastphemy]

Yesterday, I had the opposite problem: my 12-volt battery was just fine and dandy, but my main battery completely lost its charge. Can't drive the car when that happens either!

OK, OK... it's because I drove 121 miles on a "Standard" charge with two intermediate 30-minute 240V charges (and mostly 65 mph highway driving), not because there was anything wrong with the RAV4 EV.

So if anyone wants to know what happens when you drive to the very last bit of battery charge, I can tell you! The "limited power" limp home mode doesn't last nearly as long as I'd expected. The entire way home my miles estimate was 2-4 miles more than the distance to my house, but around 6 miles remaining it changed to "LO" for the mileage and did not last 6 more miles.

So when you get that "low battery" warning at around 2 bars of battery left, believe it! At that point, you probably have about 10-15 miles left at the most, depending on if you're driving 25 mph flat or 40 mph up a hill. And the last 2-4 miles will be limited to 25-30 mph. If - at that point - you're going downhill, you can regen and keep on going, but forget about going up a hill.

Luckily, the car died only 1 mile from my house, so I just walked home while my wife waited for AAA to tow the car to the house. (First time I've used AAA in 9 years...gotta get my money's worth, right?)

When I plugged in the 240V 30-amp Blink charger, it gave me an estimate of about 9 hours to do an Extended charge from empty, but it took a little less time, though - about 8 hours.

This morning, after the Extended charge, the RAV4 EV still drove like a dream as if last night never even happened. I really love how much visibility there is in this car - lots of glass!

 

[Dsinned]

Wow! This is probably the most interesting post I've read here yet! And you are right, EVERYONE wants to know the "what if" when you're battery gets to "LOW"!

You say you started out on a standard charge . . . and it died at 121 miles, right? Was "121" miles anywhere near the estimated range when you initially completed that standard charge?

The accuracy of the battery range gauge is of paramount importance, but it sounds like the accuracy is not very good near the bottom of the gauge.

According to Tony's latest update to the Range Chart, every segment (of the 16 total) on the "GoM" gauge is equivalent to about 2kWh of battery capacity, or 16segs * 2kWh/seg = 34kWh total. Perhaps, the ratio is bit higher, like maybe 2.06kWh/seg, or 16segs * 2.05kWh/seg = 34.96kWh. Of course, your average driving efficiency (miles/kWH) factors into this as well. If you got 121 miles out of 35kWh to begin with, then your efficiency was ~3.46mi/kWh. (BTW, not too shabby at all!).

So, purely by the numbers, the last two bars on your range gauge should have corresponded to ??? miles, or 2segs * 2.05kWh/seg * 3.46mi/kWH = 14.2 miles.

You said, your low battery warning came on when your range gauge decremented to the last two bars, and then you got 10 to 15 miles before it died, right?

Seems to me like the RAV4 EV battery range gauge is fairly accurate! But, please confirm my assumptions for your particular case, so we all have a better idea of what that gauge is telling us. TIA.

 

[Dsinned]

. . . . I drove 121 miles on a "Standard" charge with two intermediate 30-minute 240V charges. . .

Oops, I forgot that you mentioned this also. That messed up everything regarding my previous calculations as to the accuracy of the "GoM". When we factor in this "extra" added charge capacity, to the total miles driven before your battery died (121 miles), I was way off assuming your average efficiency was 3.46mi/kWH (which can only occur as result of substantial hypermiling techniques). In actuality, your efficient must of been considerably less! Please enlighten us with that added information as it would be helpful to more fully understand what happened in your situation.

Anyway, I'm sure most of us will be riveted to more threads like this, to give us a better appreciation of why there is all this talk is about "range anxiety". :mrgreen:

 

[TonyWilliams]

Here's pictures of what happens to get to turtle mode (I've never killed it).

http://www.myrav4ev.com/forum/viewtopic.php?p=132#p132

 

[Blastphemy]

You say you started out on a standard charge . . . and it died at 121 miles, right? Was "121" miles anywhere near the estimated range when you initially completed that standard charge?

Started out with 125 miles estimated range after the overnight Standard charge. No driving in Sport mode, but definitely driving for about 45 miles of my 121 with A/C on. As noted previously, I found two 30-minute opportunities to charge at 240V (but not 40 amps). Before switching to LO for the range, the RAV4 EV estimated 6 miles left. I got 3...barely, but I was unfortunately going up some small hills. If I could have just crested that last hill where I died (I was probably 500 feet short), there would have been about 45 seconds of regen going downhill that might have just gotten me home. Oh, well.

 

[toasty]

i carry one of these in almost every car. (volt, prius) everything.

they was only $30-$40 at walmart/sears

 

[TonyWilliams]

I was way off assuming your average efficiency was 3.46mi/kWH (which can only occur as result of substantial hypermiling techniques). In actuality, your efficient must of been considerably less!

The Rav4 does just fine in level road efficiency.... 3.4 is normal at 65 mph on level, dry roads without heater or TMS heat.

The varying speed around town sure kills it, thought. I typically get mid to high 2's around town. In my LEAF(s), I could get 4 around town and 4 at 65mph.

So, for my typically driving, the Rav4 is 15% down on highway economy at 65mph and 35% down around town.

 

[Jscifres]

I was way off assuming your average efficiency was 3.46mi/kWH (which can only occur as result of substantial hypermiling techniques). In actuality, your efficient must of been considerably less!

The Rav4 does just fine in level road efficiency.... 3.4 is normal at 65 mph on level, dry roads without heater or TMS heat.

The varying speed around town sure kills it, thought. I typically get mid to high 2's around town. In my LEAF(s), I could get 4 around town and 4 at 65mph.

So, for my typically driving, the Rav4 is 15% down on highway economy at 65mph and 35% down around town.

My wife just took our Rav4 to the store tonight... It's 36 degrees outside and she only drove about 2-3 miles roundtrip... Entunes says she got 0.9 mi/kWh on the 'last drive'. I almost killed her!

 

[TonyWilliams]

My wife just took our Rav4 to the store tonight... It's 36 degrees outside and she only drove about 2-3 miles roundtrip... Entunes says she got 0.9 mi/kWh on the 'last drive'. I almost killed her!

That heater must have been blasting !!!! (both the cabin and battery heaters... there are two separate ones)