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Discussion Starter · #1 ·
I have a 2020 Niro PHEV which I absolutely love. I do mostly short trips so almost all the time drive on battery only. Once a week I have to take my daughter to a function where I have to wait for about 1.5 hours for her to finish the function. I like to read in the car while listening to that top of the line sound system. Preferably I would like to be able to run the A/C system as well during that time. Previously driving my wife's Soul I drained the battery doing that (not surprisingly) and had to ask someone to jump start me. However in the Niro it seems like its running off the traction battery and over that time depletes the battery by about 10% which is absolutely fine. But I have started reading these threads about the 12V battery being recharged up to 10 times from the main battery. After the 10th time it stops recharging which appears to mean that the car would not start unless the 12V battery is energized externally in some way. If I turn off the “remote start” button the AC goes off and the radio plays for a few minutes, and the state of charge indicator disappears. If I leave the remote start on I can run the radio and the AC indefinitely. My question is, is the 12V battery being recharged while I am running the radio. A/C, etc, and is there then a risk of reaching the charge limit and the car then being immobilized? My recharge option is turned on, but I have never seen any indication that the 12V battery is being recharged, only the gradual discharge of the main traction battery. (Obvioulsy I realize that the traction battery should never be fully discharged). It seems to me that what I am doing with the Niro just allows me to benefit from the capacity of that big battery if I leave the remote start turned on. Since the 12V battery must recharge while the car is being driven, it seems that this amounts to the same thing. Does anyone know if the 12V battery recharge system could be an issue with what I am doing? (By the way, I do turn off the headlights in this situation)
 

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You should leave the car"on" when sitting for more than a few mins. You should avoid discharging the little 12v. battery.
 

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If the car isn't left "on", the radio will turn itself off after 5-10 minutes anyway, With the PHEV, there's no issue just sitting with the car on. As long as the traction battery has more than a 16% or so charge, the engine will stay off and you can remain nice and comfortable. If the battery drops to 16%, then the engine will start on occasion to maintain the traction battery.

Just be aware that you can't run the A/C if you plug the car into a charging station. The fan will run, but the A/C compressor will not. So if it's a hot day, you can't stay cool and charge the car at the same time. I've heard that it might have changed with the 2021 model year, but that's the way my 2019 was.
 

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anyone know how much current it takes to to jump the phev? seems to me that an emergency battery pack is way overpowered for this since it can jump an ice vehicle with the high current starter motor. would my 1.5A trickle charger work? how about 8 D cells?

i got a 12V meter that plugs into the cigarette lighter thinking i could check the battery voltage before starting up. unfortunately the socket is not powered without starting the car, unlike as i recall my 63 chevy. driving the car it reads 12+ to 14+ volts. i assume this is the charging voltage applied to the battery as its SOC varies. sound right?
 

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Zero current. However if your battery is sitting at 9 volts (and possibly damaged), D cells are not going to net 12 volts to the system.
Not for nothing, but if it really took zero current a stack of watch batteries would do the job. Problem is, it's not zero current. It's likely at least a couple of amps to fire up the ECU and the rest of the hotel loads and if the 12V battery is badly drained it can't handle it. Actually, it would be interesting to try 8 D cells. Regular alkaline D's are about 5Ah which is probably enough.

Now, if the 12V battery is damaged and partially shorted, then yeah, D's aren't gonna do the job.
 

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Not for nothing, but if it really took zero current a stack of watch batteries would do the job. Problem is, it's not zero current. It's likely at least a couple of amps to fire up the ECU and the rest of the hotel loads and if the 12V battery is badly drained it can't handle it. Actually, it would be interesting to try 8 D cells. Regular alkaline D's are about 5Ah which is probably enough.

Now, if the 12V battery is damaged and partially shorted, then yeah, D's aren't gonna do the job.
Good luck...8 "D" cells is not going to do it o_O
 

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Good luck...8 "D" cells is not going to do it o_O
You'd be surprised. For the PHEV there's no need to crank the ICE (traction battery does that), the only thing you need to do is provide enough power to fire up the ECU and whatever parasitic hotel loads are present (lights, radio, etc) on the 12V bus. Would 5Ah be enough? Maybe? Dunno. A D cell can source ~4A before it starts to get seriously hot and that would take a minute or so, way longer than needed to start the computer. Would 60W be enough to get the ECU going so that it could trigger the DC-DC converter from the traction battery and bootstrap the system? I'm gonna go with shmaybe. It would be fun to try. In fact, I bet if you disconnected the 12V battery and replaced it with a stack of 8 D cells it would start right up.

Any takers?
 

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it occurs to me to ask if the D cells did work, what happens when the traction battery tries to charge them? meltdown, fire, explosion? probably this should only be attempted with rechargeable batteries (i assume that’s all the emergency battery pack uses) rather than alkalines.
 

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it occurs to me to ask if the D cells did work, what happens when the traction battery tries to charge them? meltdown, fire, explosion? probably this should only be attempted with rechargeable batteries (i assume that’s all the emergency battery pack uses) rather than alkalines.
You are correct which makes me think no one is going to try it.
 

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it occurs to me to ask if the D cells did work, what happens when the traction battery tries to charge them? meltdown, fire, explosion? probably this should only be attempted with rechargeable batteries (i assume that’s all the emergency battery pack uses) rather than alkalines.
Basically nothing in the short term. The accessory voltage is ~14V, just a little more than the ~12V for a stack of 8 D cells. A little current would flow back into the batteries but not enough to do much. Just don't leave it hooked up for a cross country road trip. 😁
 

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Has anyone tried leaving their headlights on all the time as a means to keep the 12v battery charged?

I do this all the time and have never seen the 12v battery voltage dip below 13.4 volts. So keeping your headlights on will ensure the 12v battery stays charged all the time.
 

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i’m missing something here. my phev has to be “on” or “run” to turn on the headlights, neither of which seems like a reasonable way to keep my 12V battery charged.
 

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i’m missing something here. my phev has to be “on” or “run” to turn on the headlights, neither of which seems like a reasonable way to keep my 12V battery charged.
I believe the poster is saying that turning your headlights on (like Canadians) while driving will keep your battery charged.

I'm not sure this is true, as I don't understand why it would work. It may be anecdotal, just as many owners do not experience issues (or perhaps understand that they may suffer short battery life) with just normal operation (no attention to daylight light use). The primary cause of battery issues seems to be the intermittent on/off charging. This is a complete departure from ICE standard alternator always on and batteries charging at around 14 volts. Lead acid batteries seem to like it that way better.
 

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Discussion Starter · #16 ·
You should leave the car"on" when sitting for more than a few mins. You should avoid discharging the little 12v. battery.
Well thanks for that info...That is what I thought. This means that this is an advantage of a PEHV, since you have the resources of this huge battery to power up the AC and radio while parked. In a conventional ICE auto you would only have the lead acid battery, and once you ran that down, you'd need a boost from someone to get your car started. Yet another reason why I am happy I bought the Niro PEHV! By the way, all theses posts were very interesting. I was wondering how one subscriber knew what voltage the aux battery was generating...Did he rig up a voltmeter to get that info? Another Q, as I understand it to generate voltage in a dead aux battery you can use jumper cables under the hood or in the back of the car..right? Should my aux battery ever die, i do have a small Lithium rechargeable battery that has enough capacity to start an ICE, and had used that several times to get my previous (ICE)car started.
Thanks for the info from all you guys...
 

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I believe the poster is saying that turning your headlights on (like Canadians) while driving will keep your battery charged.

I'm not sure this is true, as I don't understand why it would work. It may be anecdotal, just as many owners do not experience issues (or perhaps understand that they may suffer short battery life) with just normal operation (no attention to daylight light use). The primary cause of battery issues seems to be the intermittent on/off charging. This is a complete departure from ICE standard alternator always on and batteries charging at around 14 volts. Lead acid batteries seem to like it that way better.
If you keep your headlights turned on then the DC to DC converter will keep the battery voltage up all the time while the car is running, just like an alternator does. But when you turn the headlights off, the DC to DC converter will cycle on and off. When this happens, the battery voltage can dip into the low 12s.

This is not anecdotal. With the headlights on, it puts enough of a load on the battery that the DC to DC converter will stay on and won’t let the battery voltage dip low at all. On my Niro, the voltage stays at 13.7-13.8 all the time with the headlights on.

Don’t believe me though. Try it for yourself. Test it with a volt meter with the headlights on and off, then report back as to what you find.

Want your battery to last? Keep your headlights on.
 

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Don’t believe me though. Try it for yourself. Test it with a volt meter with the headlights on and off, then report back as to what you find.
Thanks for the additional info. Not owning a PHEV I cannot confirm your results. It would be interesting to hear from other PHEV or even BEV owners on this. Your report suggests a decent engineering solution though, perhaps with mandated headlights on, or a completely artificial electrical load while driving to preserve battery voltage and lifespan. I'm wondering if this is all correct, then it follows that Canadian owners (whose cars all run full time headlights) do not suffer the battery life issues of what is apparently happening in most countries with virtually all BEVs.

I guess the caveat is that headlights on reduces efficiency. But this drop is pretty small, and the cost probably less than early failure on the battery.
 

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BTW, my Canadian Niro does not run full time headlights. The chevron LED's in the front bottom corners are my "daytime running lights"...maybe that is enough to make a difference. Since I don't have a PHEV, I can't comment on the theory expressed here.
 

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I didn't know the Canadian specifics. Heard something once, and every time I cross the border it looks like 90% plus cars on the road have their lights on. My bad. Perhaps running lights substitute for headlights?
 
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