mtb9153 Posted February 6, 2013 Report Share Posted February 6, 2013 Hi, I wanted to throw out a question regarding jumping my CMAX with jumpers cables. First off I haven't needed to do this as my battery seems to work faithfully with 6500 miles on the car and I would hope for much more than that. I was wondering when you connect jumper cables to the charging terminals which are located under the hood. Is it going to start the gas engine and I would assume so since that would be the only way to get the car moving. I assume the engine would remain running until there was sufficent power in the Li-Ion batteries to run without the gas engine? Just wondered since this gas/battery technology is all new to me. Quote Link to comment Share on other sites More sharing options...
zhackwyatt Posted February 6, 2013 Report Share Posted February 6, 2013 You have to remember that the two batteries are completely different. If the Li-on batteries are full and the 12v is dead, then the gas engine doesn't need to come on to move the vehicle. We just need the 12v to open the relays to connect the Li-on to the rest of the system. One thing I have not tested, is if the car is on, and you open the hood, does it always force the gas engine to come on no matter what? The Chevy Volt does this and is an important safety feature. I wouldn't like it if someone had the button pushed and I didn't know it and started mucking about under the hood and the thing turned over w/ no warning. Quote Link to comment Share on other sites More sharing options...
RedLdr1 Posted February 7, 2013 Report Share Posted February 7, 2013 One thing I have not tested, is if the car is on, and you open the hood, does it always force the gas engine to come on no matter what? When I had my battery problems jumping the car did not immediately start the ICE, it initially came "On" in EV mode. I had to tell the Road Service guy to go ahead and disconnect the jumpers as I was "On" in EV mode. The Road Service guy was totally confused when I told him to disconnect and even more confused when the ICE started about a minute or so later... Quote Link to comment Share on other sites More sharing options...
roninsd Posted February 7, 2013 Report Share Posted February 7, 2013 Funny! Quote Link to comment Share on other sites More sharing options...
mtberman Posted February 7, 2013 Report Share Posted February 7, 2013 The engine doesn't come on when I open my hood. The same was true with my former Toyota Prius: You could have the hood open and be poking around and the engine would fire up. The only warning was an electronic hum and then a clicking like a relay. Then, Bam, engine on. You can sometimes tell the car is on when you stick your head under the hood because of the puttering of the A/C compressor and the hum of the climate fan. But if those items are off, it can be difficult to tell whether or not the car is onwhen you open the hood. Fortunately, there's no belt-driven alternator or belt-driven compressor or belt-driven power steering pump to worry about. Moving parts are well hidden. You have to remember that the two batteries are completely different. If the Li-on batteries are full and the 12v is dead, then the gas engine doesn't need to come on to move the vehicle. We just need the 12v to open the relays to connect the Li-on to the rest of the system. One thing I have not tested, is if the car is on, and you open the hood, does it always force the gas engine to come on no matter what? The Chevy Volt does this and is an important safety feature. I wouldn't like it if someone had the button pushed and I didn't know it and started mucking about under the hood and the thing turned over w/ no warning. Quote Link to comment Share on other sites More sharing options...
zhackwyatt Posted February 7, 2013 Report Share Posted February 7, 2013 (edited) Fortunately, there's no belt-driven alternator or belt-driven compressor or belt-driven power steering pump to worry about. Moving parts are well hidden.That is true. Edited February 7, 2013 by zhackwyatt Quote Link to comment Share on other sites More sharing options...
mtb9153 Posted February 15, 2013 Author Report Share Posted February 15, 2013 So your saying if you have sufficent Li-Ion power to start the car then once it is running then even if the 12v is dead the engine will start when needed? I don't see how if the 12v is dead or too low power. THen I guess if the engine doesn't start and your run out of Li-Ion power the car will stop moving? Sorry I'm just not savy with this electric stuff. Quote Link to comment Share on other sites More sharing options...
MikeB Posted February 15, 2013 Report Share Posted February 15, 2013 mtb, you have to remember that the high voltage battery powers a DC/DC converter to produce 12v power. This 12 power charges the 12v battery, and also provides juice for the computer, lights, and other 12v systems. So as long as the high voltage battery has juice, the car can run without a 12v battery. And of course the high voltage battery is charged off the engine or from regen. The only real need for the 12v battery is to start the computer when the vehicle is off, because there are relays that disconnect the high voltage battery. You just need to start the computer to close the relays, and then the 12v battery has done it's job and can go away. Of course, there's a little more than this, since the 12v battery needs to handle several things when the car is off, like listening to signals from the remotes and opening the doors. ANDY 1 Quote Link to comment Share on other sites More sharing options...
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