Low 12V battery

[jgruiz]

New to this forum. Just got a new NAH on 4/27/2009 and 2 days latter had starting trouble and just kept doing about every other day. On 5/12/2009 it would not start at all and had it towed to Nissan dealer. Dealer ses we are not driving car enough to keep 12V battery charged; to much idle. My wife drives this car to work at about 10 miles a day, so I guess its stop and go and apparently the car sees a lot of idle time. So what's the use of getting a hybrid to save gas if we'll be having this problem constantly! Any suggestions.On 5/14/2009 Talked to sales mngr and according to him there is 4 ways that the hi-voltage battery gets charged;1: any time car is above 40 miles;2: by an alternator; 3: by braking;4: or when car is coasting. He ses I should take car out for a freeway drive maybe once a month 4 about 100 miles!!! Today I got up at 5:30am and made a 100.3 mile drive. Never saw the battery getting charged other when braking or coasting. There is a 6 % grade clime about 25 miles from us so I drove all the way and turned back and the battery got a full charge since I did a lot of coasting. But to keep 65 miles the car needs the electric motor to keep up that speed so when I got back home the battery had a little more than 50% charge. I didn't use any of my accesories. So is this sales mngr knows what his talking about.

May18,2009 car would not start so had to jump start and droped it off at nissan dealer. Tech found a defective brake switch and says this is common and was also shorted and therefor draining my 12v battery. But car would not start so left it overnight since it looks like problem is more common in mornings. No problem next day so I drove car home. I noticed charge gauge is indicating about a quarter charge but by time I got home it was indicating about half charge. My wife did a couple errands and by the time she got back charge gauge is back to quarter charge. It seems the charge is not holding much.Modified by jgruiz at 12:31 PM 5/15/2009

Modified by jgruiz at 12:52 PM 5/15/2009
Modified by jgruiz at 6:35 PM 5/19/2009

[banshee08]

I am wondering if you are reffering to the 244V battery that is used by the electric motor or the 12V battery used to power things like you radio and accessories?

I have had my hybrid altima for exactly one year today and about 20K miles on it and have never seen the 244V battery fully charged. It would get to about 80% charged according to the meter but never full. You may have a defective battery or charging circuit if you constantly have a charging issue.

[jgruiz]

I meant the 12v battery. It gets it's charge from the hi vltage battery via a dc to dc converter. The car is at the dealer now and apperently NISSAN tech has suggested three things; the 12v battery be replaced, the ignition switch be replaced and either replace the BCM module or reprogram it. I got a call from NISSAN rep about what they think is the fix. Apperently the Hi voltage battery is not holding the charge either. Only one time have I seen the charge at full charge and that is after coasting down a six mile grade. If we run the A/C, which the compressor is electric, then it will drain the battery. The temperature here is in the three digits (Imperial County); we are in the middle of the dessert.

[banshee08]

Wow, that is pretty bad. I have been lucky and I go Full EV mode everyday for about a 2 miles stretch on flat road. I have never seen my EV battery at full charge. I noticed the DC to DC charge keeps my 12V system at 14V and I have a pretty major audio system in my Altima. I have not had a problem yet and keep my fingers crossed. Hope all goes well for you and welcome to the forums. Keep us informed of what Nissan does next.

[jgruiz]

Finally got our car back on June 1st. Dealer replaced the 12v battery, the push start button and the BCM. The BCM is the module that controls the start sequence among other things. The dealer also found a shorted ignition switch which was causing the voltage to drain from both the Hi-Voltage battery as well as the 12v battery. One thing I notice is that the charge on the Hi-Voltage battery doesn't last very long if we are using the A/C and while on EV mode. I know that the A/C compressor is electric so I guess that's why it drains the charge, but once I get the gas engine back on and up to speed the battery gets charged again. It wasn't doing that before. Hope our problems are over now because we really like the HYBRID. I guess we can't idle for too long while using the A/C and on stop-n-go traffic like on rush hour on the freeway!!!

[banshee08]

You are right about the A/C and the Hi voltage battery. It does drain it quite fast. I try not to use the A/C if a can but in the summer you have to use the A/C else the battery starts losing the ability to recharge fast enough due to heat. A/C affect the hybrids more I think in terms of MPG but with my driving habits that is not much of an issue. I hope your troubles are over and you enjoy your altima. I love mine. I am wondering what kind of MPG are you achieving currently? With just over 21K miles I have a running average of 39.6 MPG calculated from miles to gallons of gas purchased.

-Chan

[jgruiz]

Its too soon to tell, but our city mpg is about 27-28. A lot better than our old Maxima at 16 mpg. The best I've done on the hi-way has been 35-36 mpg with A/C, but like I said before its too soon since we've only got about 900 miles on the car. I'm wondering how the system (battery)will do on rush hour traffic (stop-n-go) conditions with the A/C on. Has any body ran into this condition with EV mode and the A/C on? I'm sure something is built-in into the system to handle such. I've asked my case rep at NissanUSA and they haven't got back to me on this.

[banshee08]

I drive in A/C and EV mode many times. The battery does drain faster and you will notice the gas engine kick in much more often. To maximize the battery. I usually let the gas engine get the car moving with the A/C on and then coast in EV mode until I have to stop. I try not to stop and go too much instead I will leave plenty of room ahead of me in traffic and coast as much as possible. I would suggest that if you want to maximize your MPG then just google hypermiling and learn some hybrid friendly techniques.

Just a hint on flat highway driving try to keep the car at about 68 mph to get the best mpg.

Its too soon to tell, but our city mpg is about 27-28. A lot better than our old Maxima at 16 mpg. The best I've done on the hi-way has been 35-36 mpg with A/C, but like I said before its too soon since we've only got about 900 miles on the car. I'm wondering how the system (battery)will do on rush hour traffic (stop-n-go) conditions with the A/C on. Has any body ran into this condition with EV mode and the A/C on? I'm sure something is built-in into the system to handle such. I've asked my case rep at NissanUSA and they haven't got back to me on this.

[jgruiz]

Oh yea; I know what u mean. I have gotten a full charge but only after coasting down a six mile grade, but after driving home for 25 miles with the A/C on its back to half charge. One question I have n maybe u can answer. Do the Hybrids have a alternator just like normal cars do. According to a mechanic at the dealer they do but I have doubts on that

[banshee08]

Actually the Toyota Hybrid design does not have an alternator in the traditional sense. There is actually two electric motors in the system one generator and the other is the drive motor/starter for the gas motor. They call this a full hybrid due to the fact that the system can charge and drive the car at the same time with the gasoline and electric motor.

The 12V system is charged thru a DC to DC converter. You will notice if you measure the 12V system when the car is on, the system seems to maintain a good 13.9V.

Here is a interesting link to see how the system works if you are interested. You will see why the system can not maintain EV mode beyond the 42mph point.

http://eahart.com/prius/psd/

[jgruiz]

Wow; very intersting. I save some of those links and I'll have to look at them closely. Hope NissanUSA comes back to me with some help and when ever they do I'll pass along the info. I'am just trying to get as much info as possible on this Hybrid to learn how to drive it. Although its my wife's car I do get to drive it once-n-while. Whenever it needs washing and gassing-up!!!

[banshee08]

I just saw for the first time my battery full charged. I was going down hill at about a 5% grade hitting traffic. I just let the car regen the battery and applied no brake at all. With a full charge at the bottom of the hill, I was able to wrestle about 5 miles of stop and go traffic. Note though I never really stopped I just coasted as much as possible.

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