12 Volt Battery enhancement

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Tony 240

Well-known member
Joined
Dec 15, 2023
Messages
45
I own a 2012 Nissan Leaf which I bought used and I was wondering if I could extend the mileage on the drive battery by installing a extra 12 volt battery. The reason is I live in Canada and need heat in the wintertime which lowers the distance I can travel by at least 20 percent. I was considering putting a AGM battery in the trunk and running the cables to the existing 12 volt system
 
You could charge the under-the-hood 12 v battery via one of these Orion-Tr Smart DC-DC Charger Isolated - Victron Energy . I am considering this approach to use a (safe) lifepo4 pack to to keep the under-the-hood 12 v at about 14.0 volts. This should offload any accessory electrical use from the Leaf's DC-DC converter to the (safe) lifepo4, adding an estimated 3 miles of range to my 2013 Leafs in nice weather and quite a bit more in cases like yours. Added benefit, the large AGMs I have installed under the hood will frequently get the finishing charge they need for longevity.

As the accessory electrical use gets higher, one will need more ahrs, but you know that.

What we need is good data on how much the DC-DC converter is currently using and under what scenarios. One of the early Leaf docents on this forum stated many years ago that the gauge on the dash showing accessory energy use is bogus, and just reports different usage based on what is turned on rather than an actual current sensor somewhere. I do not know if that is true, but if any one knows where someone has already done this, or the optimal place to add one, love to hear.

Additional details. You will want a 60 amp or larger breaker in two places, a nice enclosure for the auxiliary 12 volts, and a way to charge it conveniently. They make these J1772 to 120 volt adapters which might be a solution, or just a regular inlet somewhere that is convenient.

A lot of work to save a few minutes of charging on the road, but in some cases, like yours, it could make a difference. For me, the idea is to keep the Odyssey AGMs in good condition so that I don't have to worry about their condition. And marginally reduce cycling of the main pack. The main pack s in both of my 2013s are doing well, one above the expected degradation path, and one right on that path.
 
I own a 2012 Nissan Leaf which I bought used and I was wondering if I could extend the mileage on the drive battery by installing a extra 12 volt battery. The reason is I live in Canada and need heat in the wintertime which lowers the distance I can travel by at least 20 percent. I was considering putting a AGM battery in the trunk and running the cables to the existing 12 volt system
How about using the 12 volt battery to generate the heat You need? I live in a fairly chilly area of the Pacific NW. I'm looking into this very thing right now. Air and heat really suck the range out of Your charge. I've got a 2011 Leaf and still have all the bars. I must live right.

UPDATE:
I got a 12 volt heater that sits in a cup holder for My leaf. Works great. I can use any 12 volt source to power it including an extra battery and it takes care of My range issue nicely.
 
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Dude no.
It does not work like that. You need to read up.
You need about 2-6 kW to generate any kind of cabin heat. That is about eqvivalent of what the car i drawing out of the traction battery for driving on flat.
The 12V keeps interior instruments and light on. Thats about it.

Get a bigger high voltage battery or install a webasto diesel warmer on the fresh air intake.
 
Dude no.
It does not work like that. You need to read up.
You need about 2-6 kW to generate any kind of cabin heat. That is about eqvivalent of what the car i drawing out of the traction battery for driving on flat.
The 12V keeps interior instruments and light on. Thats about it.

Get a bigger high voltage battery or install a webasto diesel warmer on the fresh air intake.
 
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The 11 & 12 don't have a heat pump, just a resistive heater and that heater is on the high voltage side. However the fans and some of the pumps are on the 12v side.

I have the 2013 S that still had a resistive heater (the SL & SV went to heat pumps in 2013). I am not suggesting this, but I had a 8A8D 12v AGM rated at 250A @ 12v or about 2kWh useable. That powered a 2000w pure sine wave inverter. I also connected a 12v charger which kept the 12v above what the Leaf floats at so it wasn't charge by the HV pack. I did try disconnecting it from the HV pack but the car didn't like that (it worked but had error lights) and if anyone else ever used the car and didn't turn on the inverter the 12v could run dead. I typically saw 250-500w being charged to the 12v while driving. I also used a 750w resistance heater connected to the inverter aimed towards my feet and didn't turn on the resistance heat from the HV pack on the car itself. Not that the 750w heater made the cabin as comfortable as the cars HV heat but tolerable for just me on my trip.

Doing all this I typically got about the same range in winter as in summer, in summer my 40 mile round trip was about 60% of my battery and in winter without my charging setup it used 90% of my battery, with the aux battery and inverter I was back to using about 60% of the HV pack or bout 10 more miles.

If your just doing this to offset the 12v loads in the car, as mentioned, that might get you a few miles, if your offsetting heating depending on the outside temps it is could be a lot more.

As my daughter drives this car now and twice a week drive about 100 miles a day away from home with no access to charging, I am tempted to put two of our older 48v 100a lifepo4's or 10kw and a 48v inverter to charge the car with a 120evse. I tried this and it works but would be messy to install in the car and not sure if my daughter would think it is "cool" to have to plug the Leaf in to itself. On those days she takes our 2012 Volt which get her ~25 miles then starts burning gas. But she doesn't have to worry about range at all.
 
You could charge the under-the-hood 12 v battery via one of these Orion-Tr Smart DC-DC Charger Isolated - Victron Energy . I am considering this approach to use a (safe) lifepo4 pack to to keep the under-the-hood 12 v at about 14.0 volts. This should offload any accessory electrical use from the Leaf's DC-DC converter to the (safe) lifepo4, adding an estimated 3 miles of range to my 2013 Leafs in nice weather and quite a bit more in cases like yours. Added benefit, the large AGMs I have installed under the hood will frequently get the finishing charge they need for longevity.

As the accessory electrical use gets higher, one will need more ahrs, but you know that.

What we need is good data on how much the DC-DC converter is currently using and under what scenarios. One of the early Leaf docents on this forum stated many years ago that the gauge on the dash showing accessory energy use is bogus, and just reports different usage based on what is turned on rather than an actual current sensor somewhere. I do not know if that is true, but if any one knows where someone has already done this, or the optimal place to add one, love to hear.

Additional details. You will want a 60 amp or larger breaker in two places, a nice enclosure for the auxiliary 12 volts, and a way to charge it conveniently. They make these J1772 to 120 volt adapters which might be a solution, or just a regular inlet somewhere that is convenient.

A lot of work to save a few minutes of charging on the road, but in some cases, like yours, it could make a difference. For me, the idea is to keep the Odyssey AGMs in good condition so that I don't have to worry about their condition. And marginally reduce cycling of the main pack. The main pack s in both of my 2013s are doing well, one above the expected degradation path, and one right on that path.
I think you are right about the energy use being bogus.
 
The 11 & 12 don't have a heat pump, just a resistive heater and that heater is on the high voltage side. However the fans and some of the pumps are on the 12v side.

I have the 2013 S that still had a resistive heater (the SL & SV went to heat pumps in 2013). I am not suggesting this, but I had a 8A8D 12v AGM rated at 250A @ 12v or about 2kWh useable. That powered a 2000w pure sine wave inverter. I also connected a 12v charger which kept the 12v above what the Leaf floats at so it wasn't charge by the HV pack. I did try disconnecting it from the HV pack but the car didn't like that (it worked but had error lights) and if anyone else ever used the car and didn't turn on the inverter the 12v could run dead. I typically saw 250-500w being charged to the 12v while driving. I also used a 750w resistance heater connected to the inverter aimed towards my feet and didn't turn on the resistance heat from the HV pack on the car itself. Not that the 750w heater made the cabin as comfortable as the cars HV heat but tolerable for just me on my trip.

Doing all this I typically got about the same range in winter as in summer, in summer my 40 mile round trip was about 60% of my battery and in winter without my charging setup it used 90% of my battery, with the aux battery and inverter I was back to using about 60% of the HV pack or bout 10 more miles.

If your just doing this to offset the 12v loads in the car, as mentioned, that might get you a few miles, if your offsetting heating depending on the outside temps it is could be a lot more.

As my daughter drives this car now and twice a week drive about 100 miles a day away from home with no access to charging, I am tempted to put two of our older 48v 100a lifepo4's or 10kw and a 48v inverter to charge the car with a 120evse. I tried this and it works but would be messy to install in the car and not sure if my daughter would think it is "cool" to have to plug the Leaf in to itself. On those days she takes our 2012 Volt which get her ~25 miles then starts burning gas. But she doesn't have to worry about range at all.
I guess the dealer lied to me when i bought the car, he told me that my car ran off a heat pump
 
The 12 Volt battery on the 2011 and 2012 Leaf runs the heat pump for these cars, in 2013 and onward the heat pump is run from the drive battery (400 Volt Dc ). So the Heat pump could be run to the the extra battery, thus not draining the Drive battery.
I stand corrected my car does not have a Heat Pump I was misled the heat pumps were installed on the 2013 Leaf Sv and Sl model
 
Don't feel that you had a uniquely bad experience. Nissan salescreatures (along with other brands) lie like rugs. They tell so many Whoppers that it's sometimes hard to separate the lies from the garden variety ignorance.

Anyway, the heat pumps also draw too much power for your idea to work, and they also stop providing noticeable heat at about 24F. You have a couple of options if you want to use a big 12 volt battery to extend your range. I once tested a setup that used a 12 volt storage battery, an 800 watt inverter (square wave works fine for this) and two little 200 watt personal heaters. I mounted the heaters on the driver's seat front frame, aimed forward, and put the rest behind the passenger's seat. By turning on both heaters while driving, I created a little 'warm bubble' around the driver's legs and feet. The cabin didn't get above 45F in 20F weather, but my legs were warm enough to make it tolerable. You could charge the battery externally - just make the capacity large enough - or wire it to the 12 volt system either as a replacement for the accessory battery or to supplement it.

Your other option, as noted, is to just get a large enough LiFePo4 or AGM battery to largely replace the accessory battery for the usual loads. That should be good for a couple of miles. You can get more than that by running the tires at about 40psi instead of the too-low 36psi recommended by Nissan.
 
The 12 Volt battery on the 2011 and 2012 Leaf runs the heat pump for these cars, in 2013 and onward the heat pump is run from the drive battery (400 Volt Dc ). So the Heat pump could be run to the the extra battery, thus not draining the Drive battery.
Ok. Good luck drawing 200 amps for hje heat pump from a standard 70-100ah lead acid starter battery for more than a few seconds.

It would be tha eqvivalent of driving your gas car on the starter engine.
I guess you would go through a lot of trouble, and a lot of expensive big atea wiring, fuses, contactors for about a minute or two of cabin heat, but go ahead. To each his own ..
 
The 12 Volt battery on the 2011 and 2012 Leaf runs the heat pump for these cars, in 2013 and onward the heat pump is run from the drive battery (400 Volt Dc ). So the Heat pump could be run to the the extra battery, thus not draining the Drive battery.
I'm pretty sure that the 2013-2023 Leafs have a PTC heater (p/n 27143-3NF1B), in addition to the heat pump. It has its own (separate) power lead that emanates from within the HV battery.
www.partsfornissans.com/oem-parts/nissan-heating-unit-271433nf1b
Unfortunately, I believe the fuse for these heaters is also inside the traction battery so you don't want to blow it. In many Leafs as the PTC heater ages it can pull more current and blow the fuse inside the HV battery case. Rather than drop the HV battery and crack it open to get at the fuse many owners have had to come up with alternate ways to heat their Leafs. There are a lot of on-line blogs that address this including this forum:

2012 - PTC heater and fuse
Is there a fuse just for the heater?
Heat options - seat, steering wheel, failed PTC heater

You'll likely need about a 1kW-2kW heater to get the cabin up to temperature and at least 500W to maintain it (unless its below -10C ). You'd need to pull a lot of amperage out of a typical SLA to get that sort of wattage. A typical 40-Ah Lead Acid battery would give you only 480Watts. You could pull more amps but peukert's law would burn you. You could build your own supply from 12V versions of LFP batteries. Or if you want to get extravagant you could make a thermal battery. You could take advantage of a select material's enthalpy of fusion and experiment with Phase Change Materiels (PCM). Melt a couple gallons of a PCM like common wax (which will hold a lot of heat energy), and build a contraption to extract the heat. Charge (melt) the PCM in something easily carried from your house to your car. Could keep you warm for an hour or so during a short commute without using any energy from your HV battery :)
 
I stand corrected my car does not have a Heat Pump I was misled the heat pumps were installed on the 2013 Leaf Sv and Sl model
I am tempted to bring along my EcoFlow LFP River 2 Pro and use its inverter to run a heating pad on low to warm my lap. The seat heater and steering wheel heater work ok for me except my legs get cold. At home I can tolerate the house being on the chilly side if I have the heating pad to turn on for a short while now and then.
 
The 12 Volt battery on the 2011 and 2012 Leaf runs the heat pump for these cars, in 2013 and onward the heat pump is run from the drive battery (400 Volt Dc ). So the Heat pump could be run to the the extra battery, thus not draining the Drive battery.
May I suggest you modify or delete this mis-information, please.
The wet PTC heater on early Leafs draws it's power from the HV battery - I have seen way over 5kw on one of mine, there's no way a 12v battery could deliver this, added to which the DC to DC unit on the ZE0 runsa at 1kw max continous.........
Thanks in advance
 
I own a 2012 Nissan Leaf which I bought used and I was wondering if I could extend the mileage on the drive battery by installing a extra 12 volt battery. The reason is I live in Canada and need heat in the wintertime which lowers the distance I can travel by at least 20 percent. I was considering putting a AGM battery in the trunk and running the cables to the existing 12 volt system
Quick fix, have same leaf, range is greatly affected as 2012 has no heat pump. In other to maximize my range I dress heavily so as not to use the heater but it's was hell, came home with frozen feets and foggy windscreen until I installed a 5 kw diesel heater in my trunk, and a 12v to power it up. Yeah people might say it's not right to drive green and burn diesel but they are not in my economic situation and moreover I burn 6liters in 3weeks of driving and my drives has been really fantastic. It's a temporary winter fix that can be removed in 10mins with no changes to the car. I use the vevor all in one heater just in case you think of going same route. It's not for everyone. Good luck with your leaf experience!
 
Quick fix, have same leaf, range is greatly affected as 2012 has no heat pump. In other to maximize my range I dress heavily so as not to use the heater but it's was hell, came home with frozen feets and foggy windscreen until I installed a 5 kw diesel heater in my trunk, and a 12v to power it up. Yeah people might say it's not right to drive green and burn diesel but they are not in my economic situation and moreover I burn 6liters in 3weeks of driving and my drives has been really fantastic. It's a temporary winter fix that can be removed in 10mins with no changes to the car. I use the vevor all in one heater just in case you think of going same route. It's not for everyone. Good luck with your leaf experience!
Eberspatcher and Webasto make good safe combustion heaters. The amount of fuel they use is negligible for the heat they give. If i were driving long distance, I would do the same. Nothing is pollution free, so get over it! Burning liquid fuel for its heat value with a conversion rate of 80-90% makes a lot more sense than burning it for motive power at 25-30%.
I lived during the work week over a Eberspatcher heater, that kept me and the truck warm at temps down to -25F. in my past working life.
Safety is a thing, and I don't know anything about the heater he mentions, but the two I mention are made for vehicle installation, and can be very safe. Combustion air and exhaust are outside of the vehicle and the heated air is from inside the vehicle.
edit: goggled Vevor, and they make several, some are a clone of the two big names I mentioned above.
I would not use an "all in one" in a moving vehicle. what you do, is up to you.
 
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Eberspatcher and Webasto make good safe combustion heaters. The amount of fuel they use is negligible for the heat they give. If i were driving long distance, I would do the same. Nothing is pollution free, so get over it! Burning liquid fuel for its heat value with a conversion rate of 80-90% makes a lot more sense than burning it for motive power at 25-30%.
I lived during the work week over a Eberspatcher heater, that kept me and the truck warm at temps down to -25F. in my past working life.
Safety is a thing, and I don't know anything about the heater he mentions, but the two I mention are made for vehicle installation, and can be very safe. Combustion air and exhaust are outside of the vehicle and the heated air is from inside the vehicle.
edit: goggled Vevor, and they make several, some are a clone of the two big names I mentioned above.
I would not use an "all in one" in a moving vehicle. what you do, is up to you.
Cornbinder89 thanks for your view on the issue, I use the all in one because its much easier to install and doesn't require drilling holes on the car floor. The early leafs has a factory hole in the trunk where I pass out the exhaust from the heater. It's very well securely tighten to a false floor, bolted and strapped. Same goes for the battery. I have install a WiFi camera as well that gives me view of what happening behind in the trunk. A handy 2 kg fire extinguisher just in case. So safety aspect has been really looked into. The heating has changed my winter driving experience in the Leaf
 
I ran my Espar (Eberspatcher) hard, every night all night in the colder weather. I owned 4-5 of them, and kept one as a back-up ready to be swapped in when the one on one of the trucks needed service.
My concern with your set-up is a hard rear end collision or a roll over. I would not be comfortable but will not tell you what you can or cannot do.
The amount of heat they throw off for the fuel burned is impressive.
 
I've pondered what would a 50Ahr LiFePO4 battery provide using a 12V heater? Enough heat for enough time? Or even a 100 Ahr battery. Simply charge that overnight.
 
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