Anything we didn’t know already? It is nice that the Gen 5 12-V battery charges when you charge the traction battery with the AC charger. The Gen 4 12-V battery does not. That seems to be only improvement from Gen 4 to Gen 5.
Here is what caught my interest that I am struggling to understand. The aux battery voltage was 12.18 volts with the car awake. I believe the current was a bit less than 1 amp when he first read the amp clamp. Then I recall when car was on, the charging voltage was 14.1 and the current was around 15-18 amps. And the charge current stayed above 10-12 amps for duration of video. I would have to rewatch video to get actual amp values but the amp readings he was recording got my attention ! Those charging amp values are not what I have seen on my car. Yes it has an AGM so the values are going to be different. From my most recent data on 6 December, after 2 minutes car being on, the aux voltage was 14.4 volts and aux battery current 3.6 amps. Battery temperature 46F. I am unable to record initial amps at car on since it takes several minutes for scan tool to link and then for me to select values to record. 26 minutes later at trip end, aux voltage 14.4 volts and aux battery current 2.4 amps. FYI, with the colder weather here in 30’s and 40’s, the charge voltage has been constant at 14.3-14.4 volts. This was not the case when temps were above the high 50’s range. A few weeks ago, I used the Noco charger to charge the battery overnite to ensure a full charge. The next day with the OAT low 40’s, the charge voltage per the voltmeter in the console port stayed at a constant 14.3 volts for all trips. With the charging amps as shown in the video for the length of a good portion of the video, why then the multiple reports of dead 12 volt batteries. I believe it was Hyundai hybrids that were experiencing a dead 12 volt battery. I may be in error on memory but I thought the eventual fix was a software upgrade to the DC-DC converter. So now I wonder if the Prius has a potential anomaly with the DC-DC converter after watching this video. Something just doesn’t seem to add up with the charging on the aux battery. I have thought about filing a complaint with NHSTA but really can’t make the case it’s safety. The car is actually safer with a dead battery since it can’t move…… Cheers
He was observing around 18 A through the 12-V battery, which is I believe what you and I observe when the SOC is low and the DC–DC-converter voltage is around the 14.1-V (sometimes as high as 14.3 V) full charging voltage. You need to keep in mind that the current will depend on the battery SOC. When the battery is closer to 100% SOC, the current will be a lot less. So, I am guessing that the battery in the video was discharged quite a bit at the start. The open-circuit voltage before start was the most important thing for the professor to check and report, which he did not, and as a result, it made the video less useful.
The onboard charger is air cooled - I have noticed a fan noise at the back, especially when using 120 volt outlet. And I have noticed some warmth at the very back cargo area, drivers side, when charging. I’m wondering if there is any filter or anything to plug up long term?
Yes, the 12 volt charging seems to be pretty aggressive - he starts the car at 12:35 pm and the voltage stays over 14 volts the entire time and the amps are pretty high until he shuts it down at about 1:06 pm. Then we see the battery voltage at 12.77 volts which is pretty much fully charged.
This is exactly why it is much easier to spread misinformation than true information on the Internet. No, you do not know what you said from this video. The video is only a single data point. The professor would have to drive the car for at least a month if not longer and make observations to reach any conclusions about the aggressiveness of the 12-V charging system or the lack of it. What we know from our observations is that the 12-V charging system is not aggressive at all to say the least. Yes, it will be aggressive at times when the SOC is too low or it is too cold or the 12-V system load is too high or the stars are aligned in some other way, but more than 90% of the time, the DC–DC-converter voltage stays at 12.89 V, which does not charge the 12-V battery. Again, the video is a single data point that corresponds to one of those rare aggressive charging events. AGM battery for Gen 4/Gen 5 Prius/Prius Prime and observations on the 12-V charging system | PriusChat
He reported an initial oc voltage of 12.18 v . The battery was Definitely well discharged and he commented on that.
The video shows the OB traction battery charger. A close look at the charger reveals some black (ABS) air duction going toward the fan housing (appropriately labeled). I don't see a filter in this view. I don't remember the ducting on my '24 PP XSE when I investigated the traction battery charger months ago. maybe I can find that original pic.
That was far from being open-circuit, as it showed a drain current of about an ampere. If you bring the key fob near the car, the car wakes up from deep sleep and starts draining the 12-V battery.
That is an exhaust duct anyway, and there wouldn't be a filter in it as a result. I doubt there is a filter at the intake holes, which cannot be seen in the photo. Therefore, the filtering is likely only done by the cabin-air filter. All that said, there has been zero dust in my Gen 4 battery-fan filters in 4 years/40,000 miles, as the cabin filter keeps the inside of the car dust-free.
I found this most interesting at 32.15 minutes into the video (This link will take you to 32.15 minute point)
Yes, I mentioned that in my previous comments. It is a new Gen 5 feature, which was already discovered and reported by @Roy Peterson in the AGM-battery thread. Unfortunately, this feature (charging of the 12-V battery during AC traction-battery charging) does not exist in Gen 4.
OOH I SEE (OIC), the fact that the dc-to-dc converter used to keep the 12v battery in service and charge it during Traction battery 120v AC charging was the same DC-DC charger located in the front of the vehicle is an integral part of the Inverter adjacent to the ICE engine, and not an integral part of the Traction battery charger located in the rear of the vehicle, was already discovered. I did not know that. And this happens when the vehicle is NOT in the READY mode was not known by me. Toyota documents give different info on this.
yes the black duct is labeled a cooling air discharge. It looks like the intake is coming from underneath.
There is no DC–DC converter in the AC charger in either Gen 4 or Gen 5. The DC–DC converter is built into the inverter, not the charger. The DC–DC converter turns on during AC charging both in Gen 4 and Gen 5. However, in Gen 4, the voltage stays at a float voltage only to keep the 12-V battery from discharging but not enough to charge it. When the AC charging is complete, the DC–DC converter turns off in either generation, and the 12-V battery starts draining—faster with the AC-charger cable connected.
