12v Battery Is Discharging, Re-Charge Now !

Is 11.5 volt considered "deep discharge"? Rob's chart shows that's slightly below 20% SOC.

 

Interesting video on Prius 12-volt battery, my 5.1 km, EV only, trip added 0.38V to my battery

 

Yeah, I watched the video on Gen4 threads. I want three Fluke 87 V multimeter @$395 each. My $20 Craftsman multimeter is not going to cut it. lol

 

why wouldn't a jump, recharge or new battery fix that?

 

I saw on a Gen4 thread Low 12 Volt Battery warning shown on dash. I can't find the thread. Does PRIME have similar warning display when 12v is low but not dead? I looked up the manual, but could not find it.

 

OK, I will stop the test before the voltage reaches 12.0 volt. I have set my Battery Monitor Power Alarm to 70% first and then again at 40%. If the 0.1 v/day discharge continues, it should be near 12v at a week mark. But, the fact that I had my car parked for a week at a time for the past month, and the battery before this testing began was never charged before, yet still showing ~12.5 v makes me think, it may not reach that low of SOC in a week.

 

this thread reminded me to put the tricle charger on my wifes hycam. 6 hours later, it's still charging. thanks for the reminder before we had a no start.

 

Yeah, I will go at least two more days. That's a full week since I drove my PRIME last time, but 6 days since a full charge last Sunday. A weekly ~30 miles drive on Sunday is my current routine COVID-19 schedule.

 

I ordered the Battery Tender 4A charger. It’s going to take a couple of weeks to get it. In the meantime I’m going to monitor the battery and try to keep it fairly close to a full charge by taking it for a drive a couple of times a week and charging the traction battery when it gets down to about 30%.

Yesterday, after no traction battery charging for a couple of weeks and no driving since Monday, I checked tha 12v battery with a voltmeter and got 12.55 volts. I checked it today and got 12.44 volts. Took it for about a 30 minute drive (half EV to run the traction battery down some and half HV to burn some gas from the original tank full) and the 12v was at 12.67 volts, which was a bigger gain than I had expected.

I will test again tomorrow and if it is back down to around 12.5 I will charge the traction battery (got it down to 31% today) and see how much that brings up the 12v.

 

Fresh after a drive the battery will have a bit of surface charge (read high). Sitting overnight it'll settle back some. Still, driving helps.

 

damn, add some distilled water , so called sealed batteries pfffft (I'm gonna get it) don't do this at home

 

5th day after a full charge. The 12v battery is now at 12.58V or 95%. During 24 hours period on day 4, it changed from 12.64v to 12.62v, only 0.02v loss. But, during day 4, the battery monitor is reporting some increase of 12v SOC up to 12.67v. The battery may have stabilized.

I don't think it is going to get much lower than the initial pre-full charge 12.56v 91% SOC. I will let it park longer by not driving the PRIME tomorrow. I just want to see, if it goes below 12.56v.

 

The battery used in this video is European, according to the professor. My 2020 does not have the EN indication which he claimed indicated Europe, while mine is partially obscured by a sticker placed on top, most of the indication appears to be USA.

 

My understanding is that EN is for the size group specification of Gen4 and Prime 12v battery. At the time Gen4 first came out on the US market, this size group 12v flooded lead-acid battery was very hard to find. But now, there are size spec available in aftermarket batteries. In any case, it is the same good old flooded lead-acid 12v battery.

BTW, I just checked the photo I took of my 2020 Prime 12v battery. Mine is EN specification battery made in Japan by GS Yuasa. See the photo 20HR 45Ah CCA295A(EN).