Tips for controlling the charging/discharging of the traction pack

I have found that during normal driving, almost no matter what the charge is, in "B" position a true "float/neutral" is possible with very little current to mg1 or mg2 it is at the tip in on the accelerator pedal. I have seen it a few times with techstream and with the custom PIDs made for torque. You just have to remember to put it back in drive at about 4-5 mph during decel. I'll try some different conditions and SOC with the scantool and get back here. It is normal for MG2 to generate even during cruising speed.

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A/C use seems to throw another variable in there. When I'm using my A/C, at steady cruise, I will always show charging the battery at 5-6 bars. Always.

 

I've observed that when cruising at street speeds (<40mph) the battery will continue to drive the motor with the ICE off, discharging down to 4 bars before starting to recharge. This is on a three month old OEM battery.

 

Yes. MG2 by it's permag nature HAS to generate current at cruise. If it is moving (any time the vehicle moves forward or backward), or it is producing acceleration torque, it rarely goes neutral. (Except seemingly during that "floating" state, which mentioned above is harder to do at different SOC. Then the inverter passes that current into the HV bus or not. MG2 produces current into the bus almost always during cruise. Part of that current passes into mg1 which drives the engine during cruise to keep the engine at a desired rpm for torque or power, the AC, or the HV battery if needed. At some point during acceleration MG1 starts to generate, and supplies the bus for the battery, AC, but most importantly MG2 (or MGR for the Lexus 400h or Highlander) to assist with acceleration. Below is the Torque gauges I put together to watch powerflow.

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Using a ScanGauge with Battery Current X Gauge, RPM, and GPH(Gallons per hour), I have found that when at 45~MPH, on level ground, holding that speed, the car will charge the battery while at low pedal pressure. The engine will spin at a relatively low speed and GPH (0.85~ indicated), and letting off the pedal will not slow the fuel flow or RPMs, but instead will increase the rate of charge. Depressing the pedal further will result in charging switching off and either the battery assisting, or an increase in fuel flow. This is with 6/8 bars (Top of the blue range) indicated. The car will happily continue to charge the battery at as many as 25 amps until the battery is well within the green zone (7/8 bars), then will switch to warp stealth (no fuel flow, engine spinning, electric motor working) if I do not increase pedal pressure. If I lift off the pedal further, instead of charging at above 25 amps, the car will reduce fuel flow or switch to warp stealth.

If you want to stop the car from discharging the battery and use engine assist, press the pedal down until you hear/feel/see the engine kick on, then slowly release the pedal. If you release too far, your car will switch back to EV or warp stealth depending on your speed. At low speed, especially with the AC on, you will see your battery discharge faster. And with my car, when I am at 5 bars or less, it is nearly impossible to prevent the engine from running and charging the battery unless I am at parking lot speeds. The only time my car will continue on EV power only when below 6 bars is if I have already been cruising in EV for some time. It seems to get "stuck" in EV mode until I increase pedal pressure just a hair, or the battery drains to 4 bars. If yours is continuing to discharge the battery at speed when at 5 bars, even when you increase pedal pressure, that behavior does not match my observations.

 

That method of float will not work always depending on soc. In B, you get a true neutral float at pedal tip-in regardless of SOC as you said. If you don't drop it back in drive at 4-5mph or the engine may continue to use fuel/stay running. There are many times the engine sounds like it is running, but actually isn't. You can watch fuel cut, it is used quite often and there is a good reason for it. MG1 will over speed if the engine turns off (no rpm) at high speeds. Again, the engine HAS to spin at highway speeds or mg1 will overspin and will come apart. Watch the RPMs on your scan gauge,( which is really too slow to poll sensors correctly) this is why they cannot EV at high speeds, with the engine off, mg1 rpms go through the roof.

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Here are the other Torque gauges I use. I have to go back in and remove some of the PIDs on my gen 2 profile, since there are a lot of generic PIDs and Gen 3s that I have to find equivalent addresses for. Im still working out engine specific info. A couple of those gauges give information, but don't have any values to them that I can make sense of. I started messing with random PIDs that gave responses on the CAN bus during a torque scan.
If anyone can help with this, I would really like to do further work developing gauges for the PID list I have. I still haven't done any data logging, just haven't had the time.

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