Just record it under a constant discharge with the A/C running. There is a lot of lag in the data logging, and you want the current as constant as possible.

Shouldn't take more than about 5 minutes.

 

The long part seems to be getting the SoC over 60.
it’s easy if I find a big hill. Lots of charge by the bottom. lol.

 

If you can only get to 55-ish, that's fine. What's most important is how it looks when it's under load and approaching 40-ish.

 

pop the hood and let it idle, it will charge to 70%


there's a also a tsb where you charge it to 70%, turn it off, remove the battery cable for 3 mins, replace the battery cable, start the truck back up. it will now be at 60%, leave it running and it will charge back to 70%. the tsb says you can do this 2 or 3 times to raise over all batteries charge.

Keith will know more about if that's actually good for the batterys or not. but since you don't know the trucks life. it might help.

 

12V reset simply makes the battery computer forget the actual SoC and assume 60%.

I forgot about the hood trick, so for the purposes of evaluating the battery, it is useful; however, multiple consecutive uses are misleading. SoC is based on a lookup table that uses Voltage, Temperature AND current to estimate SoC. Yes, disconnecting the 12V will reset to 60%, but the recharge to 70% is not reflective of adding 10% more charge to the battery. The car rapidly figures out that the battery is at higher than 60% SoC after reset, and quickly returns to 70%. Conceptually, the first time you do it, you might add another 3-4% instead of 10%. The second time, 1-2%, etc., so you're not adding 10% every time. The car actively avoids charging over 70-80% SoC as it becomes very inefficient, and produces a lot of heat/pressure/swelling that is detrimental to the NiMH chemistry/modules.

In this case, I would certainly recommend the "pop the hood" trick ONCE and WITHOUT a 12V reset, i.e., pop hood, charge to 70%. Turn off. Close hood, Turn on. Allow car to run until it turns off the engine, then conduct the discharge test.

The 12V reset can skew the test results as the SoC estimation is iterative, and the SoC calculated many minutes/hours since the last reset is more accurate.

 

Very interesting! I hope this thread is helping others as well or will help others in the future.

I will be able to do the test tomorrow. Possibly tonight.
last weeeknd I had it up to 62% a couple of times so I know it will get there.
I’m stuck in Toronto traffic during the week and every red light runs the SoC down so getting over 50 is rare.

 

If this is typical operation, and you're not getting codes, then the likelihood of the battery being healthy is higher.

Toyota hybrids tend to target about 57-60% SoC. This battery is made by Toyota, so I expect the same target. Charging to higher SoC becomes progressively more INefficient, so don't expect to see anything significantly over 60% unless coming down a long hill or gentle slowing from a high speed on level ground.

 

Okay, let’s see if this worked….

 

I didn’t do the hood open method, I had a good charge when I pulled into my driveway after work.

 

Did you run the A/C on full blast? If so, and it's warm enough to want it, you may need to have it serviced. For the discharge portion to last 12 minutes is very atypical unless you aren't pulling much load.



Plotted entire dataset.

V01-V20 are the 20 block voltages, and they are basically all on top of each other most of the time represented most by the purple line in the chart.

SoC = state of charge; started high, engine restarted at min, climbed during charge.

dV = voltage delta between the HIGHEST and LOWEST of the 20 block voltages, i.e., all 20 blocks fall in this range. Note that GM only reports voltage to 0.1V accuracy even though they include a lot more digits. Anything under 0.2V is good.

The only times dV exceeded 0.2V is at engine start or when the engine stopped, and that's likely more about sampling than an actual deviation. GM polls the values in sequence individually. Changes in current can result in falsely high dV values because the blocks are read at different times and may be experiencing different currents when read.

This battery is showing no signs of pervasive degradation in these data. Unfortunately, at low discharge current, it's not very conclusive, BUT we do know that charging currents were high, and dV remained tight even under charging.

I would not expect this battery to fail any time soon, though individual cells failures can happen at any time. At 15 years of age, the risk relatively high, but there are no impending signs in the output.

Assuming this is the original 2010 battery, it's in fantastic shape based on these limited data.

Conservative driving and thermal management will maximize battery life. Keep all occupants in the truck cool and comfortable, and the battery will be happy.