How to test the HYBRID battery
 

I did this test on a 2007 GS450h. I borrowed a friend's laptop with Techstream software installed and tested the condition of the Hybrid battery. These steps should work for any Lexus or Toyota hybrid vehicle. This test tells you if you hybrid battery is healthy or beginning to fail. You can also gain an idea of how optimal your hybrid battery is by comparing to other people's stats. Prior to this Hybrid battery test, I tested the 12V battery to make sure it is working well.

First, some background. The hybrid battery consists of many blocks connected in series. If one block goes bad, the entire battery becomes non-functional. While your vehicle is running, the min and max voltage of each block is being monitored. If the difference between the lowest voltage of any block and the highest voltage of any block exceeds the 1.2V specification, the hybrid battery will stop working. Therefore, while a hybrid battery rarely goes bad, it does only go bad in one block. Technically, only that block is needed to be replaced rather than the whole battery, which would make it a cheap fix if you can find a place that can do this.

Second, the software. In the "Hybrid Control" section of Techstream, there is an option to test battery charging and what data to monitor. I monitored the Hybrid battery for 20 mins with charging and discharging cycles. I plotted an overlapping graph of "Batt Block Min Vol" and "Batt Block Max Vol". Attention is paid to the DISCHARGE cycles. During CHARGE cycles, the min and max voltages will be very close, even for a bad battery block. However, during DISCHARGE cycles, the min and max voltages will be far apart, indicating a failing battery block.

You're probably wondering how do you get your vehicle to charge and discharge while conducting the test. Put your handbrake on. Start your vehicle and let the gasoline engine run until it shuts off to indicate the CHARGING cycle is complete. Now press the brake pedal with one foot and put the car in REVERSE gear and press the accelerator pedal with the other foot (both pedals pressed simultaneously so car is not moving). This way, you are engaging the electric motors and DISCHARGING the hybrid battery. You can look at your Energy Monitor in your car's display screen to verify the electric motors are being run. Now, once the gasoline engine starts running again for the CHARGING cycle, release only the accelerator pedal. Keep doing this for the entire 20 minutes of live data capture (accelerator pedal pressed for DISCHARGE and released for CHARGE).

Looking at the graph, the hybrid battery is healthy since the difference in the min and max block voltages during DISCHARGE cycles is about 0.05V to 0.15V, well within the 1.2V specification. The highest voltage reached is 17.1V and the lowest is 14.45V. The DISCHARGE cycle time is about 4 minutes and 30 seconds. I had the AC running during the test. Things such as AC, sound system and possibly your 12V battery condition will change how long each CHARGE and DISCHARGE cycle is, but you will still get the important health information of your battery. The mileage and age of your hybrid battery will affect your highest and lowest voltages reached and the discharge times.

Do at your own risk as I am not responsible for any possible damages. Good luck to all and please post your test results!

that's so awesome! what's the mileage on the 450h you tested? mostly hwy or cities? any idea how much a dealer charges for this test?

i have also techstream soft and cant find this feature to measure voltage how it called under which section I have version Toyota Techstream V9.00.025

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Regards
Arvid

This is an old thread but seems to have some useful information. One thing I cannot ascertain from the pictures of the graphs is by doing this if it is possible to determine which blocks are bad? Or are you merely determining that there is a bad battery block and then you will have to find that bad block using other means?

This makes me want to try and get setup with techstream. Never heard of it before but it seems like it can do so much with our cars. I used to have something similar for programming my Audi's.

I can't believe it's already been 2 years since I posted this! In the Techstream software, there is a chart of the voltage of each of the 20 battery blocks. You can determine there which one is off.

there is an app called "hybrid assistant" that can help you test the load battery using a ODB II bluetooth reader

How do you test it and how accurate is the software? Does it really work and have you tired it personally?

nope but i just found out in their faq the battery testing doesn't work on 450h ;(, only way is to get someone with the scan tool to run it through

http://hybridassistant.blogspot.com/p/faq.html

Hybrid engines are really useful. It can save much compared to diesel and gasoline vehicles. The biggest plus is saving money as you stay in your pocket.
If you want to know what a hybrid engine is;
Link: https://bilgihanem.com/hibrit-motor-...nasil-calisir/

I have techstream and it only tells you the combined voltage per row of cells,
20 rows with 2 cells in each

Seriously.. ! gotta love DIY's like this. Nice job!

Without the reader/software, couldn't I get a decent sense of how much capacity the pack has remaining by conducting the same charge/discharge 20min experiment that OP did, and see how many cycles I run through compared to how many (~2) that OP did? I have 200k on my 2011 RX450h and am super curious how much capacity remains in the pack relative to when it was new.

Dr. Prius / Dr. Hybrid app for android with a compatible OBD adaptor (I use Carista) has a full complement of battery tests that support our cars as well.

Does anyone know if a quality OBD scanner can do this? I have an Autel hand held scanner that does live data like o2 sensors for example and fuel trim and many others, but I’ve never had it on a hybrid car. I’m wondering if I could use it in the manner described here?

Nick