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Been away from my Niro PHEV for several months. Dealer and factory had no idea what to do, but it was simple. First, I ran the traction battery down to about 50%, or 13 miles of range. Then, there is an on-off switch in the fuse panel which disconnects the traction battery. Last, the 12 volt battery in the passenger side rear was disconnected. When I got back, I just reversed the procedure and the Niro came back to life with battery SOC exactly like I left it. However, I did forget how everything worked!
 

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That is what Apple says as well, but I've never seen a recommendation to discharge to that level, merely to check every few months and charge it back up to 50%. I think it will self discharge fine.
 

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quick question about the 12 volt battery in the PHEV cargo area...


what does it do ? I have an 2018 HEV and it does not have one because it is placed next to the full battery under the back seat.


Thanks.!
 

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Normal 12 v systems battery like most cars. The HEV has 12 v lithium battery under the rear seat - it may be the only production car made with no lead acid battery.
 

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Normal 12 v systems battery like most cars. The HEV has 12 v lithium battery under the rear seat - it may be the only production car made with no lead acid battery.

so there is no "battery reset" in a PHEV to boost the car if needed ?
 

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The PHEV will recharge the 12 v automatically - and give you a warning when you return that it has done so. The process is limited to a certain number of times so the traction battery doesn't do a deep discharge (which would make the car immobile). Not sure if there is a reset button after those recharges have ended, but I'm pretty sure you can get going. The reset button in the HEV just closes a relay that had disconnected the 12 v battery because of excessive discharge by the way - it doesn't directly recharge it, just allows you to start the car which will recharge it.
 

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Thanks all for the info.!


It's kind of funny to have an HEV 2018 and there is no battery at that "spot" where you can keep your windshield washer fluid gallon., And on the PHEV 2019, same "spot", you have a battery... You kind of loosing that "spot" for the 12v battery.


It's like if the engineering team told them self: "Hey, we forgot something ?? .. - What dude ? - The 12v battery !! - ohh molly .... - let's take the small spot in the cargo area, and put it there! " LOL
 

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quick question about the 12 volt battery in the PHEV cargo area...


what does it do ? I have an 2018 HEV and it does not have one because it is placed next to the full battery under the back seat.


Thanks.!
It does everything that a 12V would do in a normal car. virtually every switch or piece of electronics in the world for a car is 12v so the car needs to have a 12v power source. In the HEV version a first ever integrated 12v lithium ion 'battery' (which is just a partition of the big battery) is there but on the phev they wanted all the lion battery space for range. All other hybrids and EVs up to now have always had a 12v battery separate from the main battery.

A big revolution in electronics is happening though in cars. 48v hybrids are coming. Several are already rolling out in things such as US made pickup trucks. Huge advantages and cost savings for these 'mild' hybrids. Why?

1. 12v systems are being stretched to the max as far as power supplied as more and more stuff becomes electronic.
2. The extra power available via 48v systems allows numerous things to be done that will create higher efficiency at a low price point. e.g. electronic superchargers, electronic oil and water pumps, smart alternators/regen that provide about 15HP boost at low RPM which is a double whammy increase to power/efficiency because this also means during acceleration, the parasitic losses from belt/mechanical driven items is removed and run off stored power...water pumps, oil pumps, etc. Same thing for electrical loads (hvac, headlights, etc) during acceleration. So remove parasitic losses (several horsepower) while adding in 15-20hp of boost by switching to motor not generator (and even more torque) is a huge net plus which allows smaller engines as well as different engine cycles (such as Atkinson cycle) and leaner fuel mixtures. But wait....isn't that the same principal as a regular hybrid? yes but......
3. 48v systems are not considered 'high voltage'. A 'regular' HEV is considered high voltage. As such numerous special precations are taken by regulation which add large amounts of expense and weight. For example the cabling in high voltage is much heavier. 48v systems can provide a tamed down hybrid without the weight and price penalties associated with high voltage systems.
4. the increased power from the 48v systems can make for much smoother start/stop systems. The motor replaces the standard starter and can spin up the engine quicker/more smoothly and combined with the power assist make a seemless launch whereas start/stop systems to date have been annoying at best.

There are several coming on the market in 2019. The articles from the LA auto show are a bit fuzzy on details but it looks like the new Mazda 3 later in the year will combine this with also first ever compression ignition to get a car that is as efficient as a Prius without having a full blown hybrid. The articles are a bit contradictory sometimes though and some speak of i-eloop which is an ultracapacitor system previously used and in other places the articles refer to the new lithium ion light hybrid 48v system. It's not obvious to me if the car will have both or whether the 48v hybrid is the replacement to the i-eloop. Both would be cool.

I've read that a 48v hybrid system gets you about $500 net increase in cost but can add a very large amount to combined mileage. Top bang for the buck.
 

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Hi Brandent, Thank for the info! ;)



Nope. Had to jump start mine. Straight up regular old normal 12V. If it's dead, the car won't start regardless of the state of charge of the big battery.

but, what is recharging that 12v battery ? the thermal engine (alternator) or the full battery pack under the back seat ?...
 

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Hi Brandent, Thank for the info! ;)






but, what is recharging that 12v battery ? the thermal engine (alternator) or the full battery pack under the back seat ?...
Well there's no 'alternator' so it's the big battery while the car is 'on'. There is a curious 'feature' to the 12v/high voltage song and dance. If while the car is 'off' there is a drain to the 12v battery, the big battery will indeed recharge the 12v automatically. When you start it after that, a notice will appear in your display that tells you it happened. It says something like (too lazy to look up in the manual) 'warning: 12v battery recharged while parked'. So how did mine go dead? Still not sure what caused the drain (my presumption is something left on), but the big battery will only cycle through that recharge process (which I think runs a max of 20 minutes each time) a couple times before it gives up and calls it a day. i.e. it won't drain the big battery down just to feed juice to the little battery that has some kind of draining load. The specifics are in the manual.

The 'disconnect it' advice at the beginning of this thread sounds good for long term storage. What I can find no information on at all is what kind and how much are vampire drain/parasitic losses while parked if any and whether or not they run while unplugged. For example some PHEVs maintain battery temp while plugged in which requires cooling or heating. Will this thing try heating the battery if plugged in overnight in the cold winter? zippo info one way or the other. Nothing in the manual. Anyone know anything about the thermal controls (if any) on this thing?
 

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I thought 48 v systems was primarily to make efficient start/stop work on ICE only systems perhaps a couple mpg gain. Yup, removing belts could add a similar gain, still a long way from hybrid efficiency. But surely there is still a 12 v system to run all the electronics? At least a very good transformer.
 
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