Hybrid (HV) battery test proposed

Battery temperature will affect discharge rate. To normalize that you'll have to drive for X number of minutes with an outside temperature of Y to ensure the battery temperature has been brought up to roughly the same value from car to car.

 

That test is about as good as you can do without using OBD port equipment. The unknown in your test is battery temperature as this will make a difference.

If you have a laptop you could buy a cheap ELM327 reader "about $15" and download Priidash free software.to monitor it more closely. This also gives you much information on what is going on under the hood with, rev counter,battery, inverter and MG temps and much more.

Even better still a Mini VCI reader comes with Techstream software "about $35" and have access to every parameter of the battery including module resistance, DTC reading and clearing, brake bleeding and so much more.

John (Britprius)

 

That "free software" link is to a video gambling site

 

Google "Priidash(tm) The windows version is the quickest to install.

John (Britprius)

 

The battery voltage is the best indicator of its' health. Here is a graph at various temperatures of V vs DoD (Degree of Discharge):


The battery will lose capacity as it ages and goes through charge/discharge cycles. This will result in lower voltages than shown in the chart. It is best to look at the Battery Block voltages (will need an OBDII device). You should watch the MaxV and the MinV as the battery is discharged. A new battery will have a few tenths difference, while a battery with problems will have several volts. Toyota specs are a maximum of 1.2 volts.

 

The voltages shown on that chart are way off - minimum and maximum - according to measurements made by me and others on their own Prii. Mine shows a max of 244 and minimum of 200, with a brief drop to 190 when the engine starts.

 

The graph shows the battery voltage vs charge state, not load. Here is a graph of V vs I:


Your 244-190 range seems correct depending on charge state.

 

Your dealer can read the data for you for about $100 and give you a full report for your records. You would only need to do this every once in a while or unless you had concerns.

Openelectron.com is developing a module that plugs into the OBD2 port and records this battery data. I have a beta test device and it works great.

 

Yup, mucho experience with large battery banks and SOC/DOD graphs. Both charts are way low at 80% SOC and 20% SOC (the max/min used by the Prius). The 1500 watt load I used in my tests, slightly more than the 6.5 amp line in your 2nd graph, would put me at about 210 volts and 180 volts, not 244 and 200.

Edit: and I just realized since my measurements weren't even at 80% SOC, since the Prius keeps the battery right around 20% all the time while it is sitting still.

 

Hi Lewis, nice simple test. Sadly I only got 4 min 25 sec (4.4 minutes). My battery is definitely a weakling.

Come on everyone, do this test when you get a spare 10 minutes, it's very easy. Sure it won't be 100% consistent, some people will have more loading than others from things beyond their direct control, such as the power drain of the DC-DC converter for charging the 12V battery, or in my case the rear battery fan which was running throughout my test (though only on low). I suggest doing it after a drive, when your engine will be warm enough to sit without wanting to start, and the HV battery will probably be warmed up a little too.

If values are to be compared then it's important that anyone trying this does it the same way. So note that we're measuring the time take from when the SOC display first drops to 5 bars to when it drops to 4 bars. Car in "D" mode, park brake applied, all accessories off.

 

As I said in post #2, until you've added a temperature equalization element to the test the results will be meaningless. Results from a battery that has been sitting in a 150 F degree car in the middle of summer will be different from one that has been sitting at -10 F in the middle of winter.

 

Doing the test after a moderate length drive will help minimize the problem, but I agree there will still be discrepancies. Personally I'd still like to see the results though. Posters could mention what was the ambient temperature and how far they'd driven when they report the test. In my case it was 21C and I'd driven quite a few hills beforehand as the battery was warm enough for the rear fan to be running at low speed.

 

>>> Bump <<<

Come guys, someone give this a try, it only takes 10 min of sitting. So far I'm coming last by a long shot. I'd really like to see a few data points here.

 

I'll give it a go in the next day or so and report back.

John (Britprius)

 

^ Thanks John.

 

I can give battery temperature, any rise in temperature at the time of test by monitoring with Techstream.

John (Britprius)

 

I did not read the entire thread, but Midtronics recently launched a tester for hybrid battery packs that will give you a health report on your battery.


iPhone ?

 

I had some time today, so I tried to run the test so uart would have some data.

Info on car: 2009 Prius Package #2 12 volt battery condition fully charged and was installed 60 days ago. Ambient temperature 72 degrees F

Conditions prior to test: I drove the car approximately 25 miles. Most of it was highway, so the car was in S4 mode at the time of the test and fully warmed up. I powered down everything that I could. I also made sure that the traction battery was charged by doing a force charge prior to running the test.

Conditions and time of test along with results noted. Began test with 7 bars (green) due to force charge. I set the parking brake and placed the transaxle in D. I waited until the 6th bar appeared.

When the 6th bar appeared the time was 3:06 P.M.
When the 5th bar appeared the time was 3:16 P.M.
When the 4th bar appeared the time was 3:20 P.M.

This Prius was placed in service on December 28th, 2008 and it currently has 65,8XX on the odometer.

I guess mine is considered a weakling...

That's the data I was able to compile and I hope it helps.