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Discussion Starter #1
A handful of forum members have reported unexplained problems with the 12V battery going flat. I noticed that Kia released TSB 163 in May that might be relevant. It applies to Niro PHEV, Optima PHEV, and Soul EV (Niro HEV is not in this list).

For Niro PHEV's it seems to be limited to the 2018 model year, with production dates between September 26, 2017 and March 30, 2018. I think that leaves me out, which is kind of a bummer, because I've been looking for an explanation as to why I'm now seeing the notification that battery saver plus ran almost every time I start my 2018 PHEV (meaning it runs almost every night).

For anyone who is interested, you can find the TSB on the NHTSA web site: hopefully this link will work for you: https://static.nhtsa.gov/odi/tsbs/2019/MC-10160618-0001.pdf

It talks about how a technician can investigate the possibility that the rear door latches might be putting a parasitic drain on the 12 V battery while the car is off.

For the DIYers in the crowd, unfortunately it refers to a shop manual that most of us don't have free access to. But it does make the point that if you know how to correctly connect an ammeter in the 12V circuit, then after the vehicle is in sleep mode (presumably the shop manual describes how to discover whether it's in that mode or not - I'm pretty sure that having your key-fob far away is part of the formula), then if the parasitic draw is less than 50 mA, you don't have a situation that the factory considers problematic. If you have more than 50 mA draw in sleep mode, they seem to be suggesting that the rear door latches should be replaced.

For me, the 50 mA number is new information that's good to know. Unfortunately, I still have a blind spot in that I don't have all of the other information mentioned in the shop manual about "Prepare the vehicle for a parasitic draw inspection".

Hope this info helps someone. Anyone who has a concern that this might apply to them can first check their date of manufacture, which appears on a label on the driver's door jam. If you fall into the date range specified above and if you have a concern about this, you could ask your dealer to evaluate your car for this TSB. The title of the TSB is "PARASITIC DRAW INSPECTION AND REAR DOOR LATCH REPLACEMENT"








 

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Checking for parasitic draw is as simple as hooking an ammeter in line and pulling fuses one at a time until the draw goes way down. That fuse is the offending circuit. Trace that circuit until you find the issue.

Its really common practice, especially on old cars that are subject to worn or cracked insulation.
 

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Other than a specific fault, the battery saver + found in PHEVs has issues. It actually increases "vampire" loads. Below is some quoted text and a chart from an Ioniq post - they have the same issues with PHEVs.
I have also taken current measurements (several for each series) and found:
When BS+ is enabled the current flow from battery is 225-230 mA (fluctuating between the two numbers but consistent in all measurements).
When BS+ is disabled the current flow from battery is 60-65 mA (fluctuating between the two numbers but consistent in all measurements).

Now, what can be concluded from the tests (at least with my car)?
1. Battery saver triggers in at about 12.4 V. In my car it takes about 22-24 hours of rest to happen.
2. As @Patrick suspected, BS+ is using the battery when in standby and it seems it consumes significant energy relatively (~160 mA while rest of standby features use only 60-65 mA.
3. In usual everyday use of the car when it is in rest less than a day, it make sense, in my opinion, to disable BS+.
4. I do not know for how long (over one day) the battery will stay at the plateau of 12.5-12.55 V but it may be worth not to activate BS+ even in several days rest?
 

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Checking for parasitic draw is as simple as hooking an ammeter in line and pulling fuses one at a time until the draw goes way down. That fuse is the offending circuit. Trace that circuit until you find the issue.

Its really common practice, especially on old cars that are subject to worn or cracked insulation.
The problem for modern cars is that the car is never really "Off". That's why the info posted by deltasmith talks about "sleep mode" and "preparing the vehicle for a parasitic draw inspection". On newer cars just opening the door (a requirement to access the fuse panel in most of them) causes the car to "wake up" in anticipation of being started. I've seen procedures for troubleshooting battery drain issues that include instructions to wait several minutes after closing the doors to begin the test among other requirements. Finding an extra amp or so of draw is a lot more complicated now that it was a decade or so ago.

Here's a link to a generic procedure for modern cars:

https://www.aa1car.com/library/battery_runs_down.htm

Note that the spec is to measure current draw 1 hour after shutting the car off! :eek:

The fact that some cars can continue to draw around an amp for over 20 minutes after shutdown is nuts to me. I think that alone might explain some of the issues PHEV and EV people have been having with the 12V battery. It's pretty puny, doesn't get charged continuously by the ICE and it has to power a whole bunch of stuff. It could just be a case of the battery being just a bit undersized for the load in real world conditions.
 

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Other than a specific fault, the battery saver + found in PHEVs has issues. It actually increases "vampire" loads. Below is some quoted text and a chart from an Ioniq post - they have the same issues with PHEVs.
Interesting information, thanks for posting that.

This thought seems kind of a stretch, but I wonder if it's really BS+ causing the observed drain, or if the sleep logic behaves differently when it knows that BS+ is enabled.

The way I drive my PHEV (the ICE might not run for a couple of weeks at a time), the BS+ is probably necessary. The thing is, even when I do run the ICE for three or four hours of driving, if I don't see the alert that BS+ ran the next day when I start the car, I'll usually see it two days after running the ICE.

I do wish that Kia had thought to include in addition to BS+ the mechanical switch in the PHEV that they provided to HEV owners The idea that you could have a depleted 12V battery, a fully charged traction battery, but no way to boost the 12V from the traction because BS+ already ran three times and then gave up, seems to reflect an engineering decision that could have been better thought out. If there's some technique for inducing BS+ to come on again after it's timed out, I'd love to know, but my guess is that the logic is driven by the computer running on the 12V battery and by the time you notice a problem, the computer probably won't run. This is where the mechanical switch is likely to have a significant advantage.
 

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Interesting and useful information. I was hoping that the 12v battery would be charged every time I plugged in to charge the HEV battery, but I guess not. I get this message a lot but my ICE engine is sometimes not used for a week.
My car was in for annual service about a month ago. They told me there was a recall for the door handles, I bet this was the issue. They will call me when they get the parts, but I still haven’t heard back.
I also wonder how long this small battery will last. Tesla uses a smallish 12v battery (at least on the S), and it only lasts about 18 months. Most users replace it with a special lithium battery but I have not investigated that. Tesla charges $$$ to replace, assume Kia is the same, so DIY is definitely called for.
This is a great forum - IMHO, much better than Tesla forums overrun with fanboys.
 

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This thought seems kind of a stretch, but I wonder if it's really BS+ causing the observed drain, or if the sleep logic behaves differently when it knows that BS+ is enabled.
Not sure what sleep logic you mean, but if you refer to the chart I posted, you can clearly see the drain is higher with BS+ enabled versus off.

The way I drive my PHEV (the ICE might not run for a couple of weeks at a time), the BS+ is probably necessary. The thing is, even when I do run the ICE for three or four hours of driving, if I don't see the alert that BS+ ran the next day when I start the car, I'll usually see it two days after running the ICE.
Per the post I quoted, it takes about 22 to 24 hours for BS+ to trigger a recharge of the 12 V. So your observed behavior is completely consistent with that. ICE is completely separate from the traction battery recharging the 12 v battery, irrelevant whether it runs or not.
 
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