How I fixed my sisters non stating Journey on cold days.
First I want to say that my sister bought her 2010 Journey used in the summer of 2015, it came with a brand new battery. In the first winter the car would not start it would just click, headlights would be nice and bright.
Now I was a mechanic when I was young. I joined the military and became a RADAR technician, learning all kinds of electronics. Today I am a Computer Analyst/Programmer and I still make electronic devices. So after my sister replaced 3 batteries in 5 years, the lockout solenoid, starter, ignition switch, and neutral safety switch I new there had to be something else wrong. Anyway the only thing I replaced was her first battery, she did have the rest of the work done at a local garage and a local dealer, neither could solve the problem. Then last winter she could not start her car when leaving work and she called me. So I didn't take my jumper cables because they were broken so I took my battery charger/booster with me. I tried to use my booster but, no luck. Then one of her employees came out with a booster that they use to boost the diesel trucks and that wouldn't work. Then someone came over with a small booster that used lithium batteries and can be also used as a power pack for cell phones and it worked. So I'm thinking, how the hell does this little battery pack start her Journey when a diesel truck booster wouldn't do it.
Ok this is where my electronics training comes in. In all the times I boosted her Journey the battery voltage was at 11.5 - 11.8 volts. Now on a normal car/truck the vehicle will still start. I know my 95 Neon will start at 10.5. So I had a hunch. I use what is know as LDO voltage regulators. These regulators are used to protect electronic parts from things as brown-outs and low voltages that could damage them. Problem is these voltage regulators will not turn on if the incoming voltage is too low. Now most battery chargers and charger/boosters use what is know as half bridge or even a single diode to make what is supposed to be 12 vdc. Batteries need to charge at higher than 12 vdc usually between 12.6 and 14.3 vdc. So the battery charger/boosters that we used that late cold day did not put out 12 vdc but 15 vac and the voltage regulator in the on board computer did not think it was 12 vdc, which, is why that little battery booster with the batteries started the Journey and ours wouldn't. The guy barely touched the terminals and it started.
The Fix:
So this fall I put one of my battery maintainers on her Journey and told her too make sure she plugs in both her block heater and the battery maintainer. I connected the maintainer directly to the under hood terminals and not the battery. Now we are in our second cold snap here of where the temperature has gone below -28C/-18F with a wind-chill of -46C/-50.8F and her Journey started with the remote start no problem. She is very very grateful. So the way I see it, someone at Fiat/Chrysler screwed up on the design of the engine management computer and used a voltage regulator with a low voltage lockout that is set to high. Almost all of todays electronics work off 5vdc or even less, Sure the relays are listed at 12 vdc but they will pickup at 9 vdc I know I've tested them. The way I see it someone at Chrysler/Dodge owes a lot of people money for repairs and new computers.
Ray Richter