spineman

Hello again,

I have been following the recent post on the Check Hybrid System Error @Hues10 as it relates to to the 12v battery and wanted to start a new thread so I don't get in trouble. So, for those who haven't read the previous thread, here is my story. I am having either too much drain on my 12v battery or it is not charging correctly. I purchased the Bluetooth battery monitor to see what the battery state is resting and driving. I am getting 12.6v at rest after driving. After putting the car into Ready mode, the monitor does not read 14.4v, instead it climbs oh so slowly. Recently I have shortened my commute to 10 mins. I do have to use a 4amp charger to get the battery back to 12.6 or higher (highest I have measured is 14.4 after trickle charging) if I let the car sit more than a few days. Today I watched the monitor as I drove home, it very slowly climbed to 12.94 v as I drove home. Why is it not showing a much higher voltage with the car in Ready as it should be charging at a much higher rate? I am going to attach some screen shots of the battery monitor if I can figure out how to get one of the longer history. Right now it is only allowing me to do a screenshot of the status page.

bclexus

I believe you're overthinking what the 12 volt battery should be reading when driving - an also after being charged by the car's charging system.

Your trickle charger is quite different from your car's charger. And your battery is a 12 volt battery, not a 14.4 volt battery!

If your 12 volt battery is delivering anything in the 12 volt range before the car is started and being charged by the car's charging system, that is acceptable. If you see anything more than about 13.5 volts when driving with the car's charging system charging the battery, that is acceptable. The 12.6 volt you see soon after driving and stopping is perfectly in the range of what you should expect - nothing higher... My 12 volt battery load tested at 12.63 volts about 15 minutes after it was being charged by the car's charging system (see the analysis directly below).No one was expecting it to be at 14 volts or more after being charged by the car's charging system!





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spineman

@bclexus You said in post #55 of the Check Hybrid Thread that it should read 14.1 or so when driving. Also, why would you say not to tend the battery when it gets so low it will not activate the HV to start the car? I've almost been stranded twice now.

I still have to change out the computer behind the glove box when I get time. Maybe that is the culprit of too much parasitic draw.

bclexus

Yes, my voltage that charges the 12 volt battery reads 14.1 volts - 14.2 volts when the ICE is running.

Your 12 volt battery should never get so low it won't power up the accessories, including activation for MG-1 to start the engine using the traction battery. Thus, you should not 'have to' ever use a battery tender.

You obviously have a battery with either a bad cell or something is draining a good battery down to a level that makes it untrustworthy and essentially worthless.

Hues10

I have created a 12V battery monster it seems. I too have the battery monitor now, and can confirm that while driving, the battery level shows over 14. Normally up to 14.5. I too have only a short 10 minute drive to the gym and back. So I check the battery level in the morning before I go. It is usually between 12.5 to 12.6 level, which I accept as being charged. If it dips below 12.4, I will put a tender on it. I guess I should measure the daily drop in it if I do not drive. It is funny to watch the battery level drop if you open the door, or even trunk, as the accessory lights kick on. But it goes back up fairly quickly.

bclexus

@Hues10 - It truly is a 12 volt battery, you know! So, it's not going to maintain the higher voltage level it has while actually being charged. Anything at or above 12.0 volts is perfect.

Don't expect the battery to maintain anything close to a 100% State of Charge level after sitting for a while. A 40% - 50% State of Charge level is perfectly okay after sitting uncharged for multiple hours, including multiple days - because a 40% - 50% State of Charge level provides 12 volts - as you know it is a 12 volt battery! Right?

Don't expect a 12 volt battery to maintain a voltage greater than its cell makeup with each of the 6 cells producing approximately 2.1 volts (a 12V battery is actually a 12.6V battery).

Expecting a 12 volt battery to maintain a voltage greater than 12 volts would be like asking a 12 ounce drink glass to adequately hold more than 12 ounces - or a tightly packed 5lb bag of sugar to adequately hold more than 5lbs. Ain't gonna happen is it?

A 12 Volt battery has six 2.1 volt single cells in series producing a 100% fully charged output voltage of 12.6 volts. Actually each cell is 2.12 volts - so times 6 cells equals 12.7 volts.

If you ever see a 12 volt battery drop below 11.5 volts it is a weakly charged battery that might be getting toward the end of its useful life - - but only if the battery drops below 11.5 volts relatively soon after having received charging that brings it up to at least a 40% - 50% State of Charge level of (wait for it) 12 volts!