So where is this "alternator" in a 2-Mode?

 

I suspect the charging circuit is the front motor in the transmission, the same one that starts the motor. That is the only physical connection between the engine and the transmission that I am aware. For those watching this if you have answers if you are so inclined would you enlighten us instead of insulting us for not knowing. Regenerative braking engages when you apply the brake pedal lightly. In that condition I understand the only thing slowing the vehicle is the magnetic field of the motor. When braking harder then the brake system is included, but the regenerative braking rate is increased substantially. I still don't understand the economy gauge since more to the left center seems to increase the amount of stored energy substantially. I think moderately hard braking ads more available battery assist. I suggest anyone that is interested to purchase an import OBDII bluetooth reader and couple it with Torque Pro app then install the custom files for GM Hybrid PIDs if you really want to see what is going on and compare.

 

You will not meet anyone or encounter anyone on another forum that knows more about GM Hybrids than Hillbilly_Hybrid.


You have been enlightened, but you just don't accept the information because you don't like it and have an impossible perception based on the performance of a PLUG-IN hybrid with 10X the battery capacity with a completely different battery management system and chemistry. Remember, your hybrid battery has stored energy comparable to 2 large 12V batteries.


Everything you need to know is here:


https://www.greenhybrid.com/forums/f...65/#post264321


With the most important at the end "not possible and not beneficial."


You're not going to get the answer you want because reality will not bend to your will.

 

How do you get the equivalent of 2 12v batteries with 360volts of high amperage Nickel Medal Hydride banks of 20 batteries able to propel a 5 ton vehicle and trailer nearly a mile at 29mph? I'm not comparing to a plug in I'm only wondering why the engine driven charging is cut off to way below what regenerative braking is capable of. Engine will start from Auto Stop at 42% State of Charge and then shut off at 47%. While on freeway under engine power the State of Charge will only charge to a little less than 50% and will only increase beyond that when braking. Why can't the engine charge be set to charge to say 59% which leaves room for regenerative charge and still able to benefit from the battery? It's not because it can't it is because it is set not to so you don't overheat the batteries when exceeding 70% during regenerative braking.

 

capacity * # of batteries * nominal voltage = stored energy

Hybrid: 6.5Ah * 40 modules * 7.2V nominal = 1.87kWh

Large 12V: 80Ah * 2 batteries * 12V nominal = 1.92kWh

The 12V battery in the 2012 Tahoe Hybrid is 70Ah, so:

70Ah * 2 * 12V = 1.68kWh

So, the Hybrid battery stores 11% more energy than two of the under-hood 12V batteries. How's that for perspective?

You're confusing power delivery with energy. 288V (nominal) of NiMH can deliver 150A of current resulting in (288*150) 43.2kW of power or about 58hp.

Note that it can only deliver that amount of power for 2 minutes before the battery is completely empty and likely damaged.

The 12V batteries can't deliver that kind of power because they are lower voltage. In parallel, you could get 150A out of them, but they wouldn't like it, and that would only be 1.8kW or 2.4 hp, but it could do it for about 30 minutes.

Note that those don't add up to their full energy storage capacity because of Peukert's law where more current draw means less capacity is available. Times are estimated but reasonably accurate.

Yes, you are comparing it to a plug in. You are basing your opinion on the comments of an Outlander driver and expressed an expectation that they should behave similarly. Big Juicy Goldencrisp Apples vs. raisins (you're driving the raisin).

The answer to your "wondering" and "why can't" questions is because GM chose to do it differently. 50% SoC is the most efficient operating state where charge/discharge is near 100% efficient from a capacity perspective (not energy or power), and it's also the safest pivot point around with to cycle to minimize damage from depth of discharge. They likely patterned it off the highly successful Ford Escape Hybrid, which targets 50% SoC vs. the Toyota that target about 58% SoC.

Not sure where you get your overheating when exceeding 70% SoC during braking as a reason. Toyota will happily run them up to as high as 80% in certain situations. Yeah, you get some heating, but it's not a catastrophe or even adjacent to one.

 

OK folks here is some more math and facts. For ALL 2-Modes including the few Daimler-Chryslers the following holds absolutely true, always.


Engine Speed = ( Front Motor A + Rear Motor B ) /2 The only way to violate that is to break a major transmission component.


The 2-Mode drive is fully capable of both series and parallel operation and is a "Compound Split" machine. Look that up! Lots to learn there.


It has four ( 4 ) fixed gears and two infinitely variable Modes. To understand the forces and torque reactions is a bit tricky. Either motor/generator can be the electrical power source while driving. During the various fixed gear states, quite often ONLY one motor is allowed to rotate. So they take turns.


BOTH are involved in starting the engine.


If you can understand a large truck 4-way differential, you can begin to understand the 2-Mode. The hybrid drive motor generators have MORE than enough torque and power capability to STOP the engine at any time. The motor generators are NOT limiting performance.


If the hybrid and engine get into a fight, the hybrid wins!


The claims of engine charging being cut off do not make sense to me. Engine charging and Regenerative braking are BOTH limited by battery limits. SOC is supposed to be 45% + - Up To 10% under "normal operations" .


Pushing the NiMh chemistry outside the supplier's recommendations of SOC, voltage, and temperature DAMAGES the cells!


Exceed 60% SOC at the risk of buying an expensive battery in the short term.


Some here have asked about adding an "alternator". OK, but why add weight and a maybe 40% efficient device when the two permanent magnet stock motors and the AC-to-DC water cooled power control box combination is MORE than 80% efficient?


One could buy the Tow Truck/Police Dual alternator brackets and install a pair of what 250A alternators?


250A * 14V = 3.5kW Two of them 7.0kW


A single drive motor inside that transmission can make OVER 60kW


Then if you still want to modify a 2-Mode, you will need some extensive CAN communication background, far more than just reading a few PIDs.

 

Thanks for chiming in Hillbilly. With your numbers I'm suspecting the formula used in this custom PID for the SoC is not correct. Especially since the voltage on the individual battery packs are showing 16.5V to 17.9 volts between 50% and 62% SoC. What I am trying to discover is mine working correctly. I would think with gas engine running while sitting that the system would charge up to optimal SoC so you can use electric only to start off and regenerative braking bringing up to beyond optimal so you have a bonus when coming off the freeway. In town driving with frequent low speed stops doesn't bring the charge up to optimal. I would think the engine running would in that case.

Another big confusion out there is whether there is a drive connection between the engine and the motors. I've heard on youtube from SEMA show by a GM representative that there is no connection except electrical and to start and charge. Then on other websites where the transmission is described they say there is a direct connection in certain modes and the electrical motors are bypassed. If there is a physical connection why does the RPMs go high and just stay there when floored and not fluctuate like a normal transmission. I suspect there is no physical drive connection and pure electrical energy being supplied to motors like a locomotive.

 

Again, you can't equate block voltage to SoC unless you apply the current and temperature relationships as well.

In certain circumstances, a resting 16.8V can be 100% SoC.

You keep using the word "optimal" like you know what optimal is.

Your car is working correctly. Your notion of "optimal" is wrong. You've been told why it doesn't behave the way you want, but you ignore it.

 

I use the word optimal in context of what was written. I dont understand. Now that our temps are below freezing the readings are quite different. So I am clueless. I want to learm to drive this most economically as possible. Uber and Lyft doesnt pay enough to be wasteful. So now at 28 degrees outside it doesn't go into autostop unless pack temp is 53 Degrees and then only below 10mph.

The volts and soc are quite a bit different at these temps also. Sitting at 59degrees bat pack temp it is in autostop at 15.3v on each bank at 57.6% soc then starts at 14.7v and 54.5% soc.

It seems the economy gauge on dash doesn't help with monitoring best drive skills so is there any other reading to keep my eye on?