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Apparently regardless of whether or not the car is plugged in?Spot on. The 12V battery only cycles when the car is parked and "off". Cycles kill the 12V battery
The car can't pull DC power from the plug, it would need another separate 12v batter charger put in place.Apparently regardless of whether or not the car is plugged in?
I recently had to leave the car idle for 3 weeks but plugged into my Nema 14-50. When I returned my 7-month old 12-volt needed to be replaced. I assume those 2 events were not coincidence.
My neighbor who does not work on cars just had his 12 volt battery replaced. He does not look forward to doing this every 12-18 months. He asked me if I could hook up a Battery Tender to his 12 volt battery. It looks pretty simple to me to do this. He would like to top off his 12 volt battery for 8 hours once a month. He intends to do this while not charging the main battery. Any one have any concerns on why he should not do this ?
I guess you haven't read any of this thread, huh? The car only recharges from that wall connection at its next scheduled charging time, which will be the next day. Meanwhile, the very small 12V battery gets drained and refilled, drained and refilled, drained and refilled, repeatedly, about 4 to 5 times a day. That is a lot of stress and cycling on that 12V battery, which is what leads to these frequent replacements. If you have a tender just providing that energy directly, the 12V battery never goes low, thus significantly extending its life.I guess the real question is "why bother?" If the car is plugged in, as it should be, it will automatically be taken care of.
The first battery did go quickly, I believe they had a bad batch back then, but the current 12V has lasted four years and 100K miles. If it goes tomorrow, it won't owe me anything.I guess you haven't read any of this thread, huh? The car only recharges from that wall connection at its next scheduled charging time, which will be the next day. Meanwhile, the very small 12V battery gets drained and refilled, drained and refilled, drained and refilled, repeatedly, about 4 to 5 times a day. That is a lot of stress and cycling on that 12V battery, which is what leads to these frequent replacements. If you have a tender just providing that energy directly, the 12V battery never goes low, thus significantly extending its life.
So...yeah...that's why to bother.
After reading many posts in this thread (but by no means all), I see mostly positives to using a battery tender. I only have a few questions that may have been addressed in some of the message I did not read. Charging ICE vehicles I have never had the charger connected to the battery while the vehicle was running ie.. with the alternator AND battery charger BOTH charging the vehicle. With that i mind, I have two concerns: 1) If the tender charging wires always remain attached to the battery AND the tender is plugged in to wall power, would anything go wrong if the high voltage contactor enabled (either because a door was opened or traction battery needed a charge). In this scenario the battery tender and the DC-to-DC converter would BOTH attempt to charge the 12V battery. 2) Same question as 1 but with the tender NOT plugged into wall power but still having the charging wires attached to the 12V battery. The car could even be driven in this scenario. I could make a quick disconnect for the charging wires which would eliminate scenario 2 but would not help with scenario 1 (ie.. I still want the tender to maintain the 12v charge level). Bottom line, will anything bad happen if BOTH the tender and the DC-to-DC converter are attempting to charge the 12V battery in parallel?
Thanks in Advance for any Enlightenment!
Regards, Ron
If you are using a modern smart charger like the NOCO Genius it senses that the voltage of the 12v system it is charging is higher and stops charging based on that. So if the car decides to kick in and do the charging the external charger backs off. No problem. It will end/interrupt the desulfation/charging cycle and force the external charger to start over later but if you are leaving it plugged in for a long period there will be enough time for both systems to do their thing independently (taking turns).
If you used a dumb charger like they made in the 70s that just has a set charge rate or maybe a couple of switches then that charger would fool the car into thinking the battery is healthy and the car wouldn't do it's thing (the car wouldn't try to charge the 12v battery so long as a dumb charger is feeding it). That isn't bad on the spot, but it's not helping like having a smart charger would. If that dumb charger is undersized it could be worse than letting the car do the charging.
Long and the short get a proper smart charger that knows the difference between LA/SLA, AGM, and Li-Ion and don't worry about it, the two systems will play nice.
You can't look at your past experience with a starting battery in an ICE. That delivers a tiny fraction of its power to start the car and is recharged immediately. The battery in a Tesla is a totally different animal - sealed AGM (though still lead acid), deep cycle vs starting, and is cycled several times a day.A good 12V lead acid battery has lasted me at least 3 years many last 5 years or more)
Tesla uses a sealed AGM battery. AGM batteries must be (and remain) sealed. There is very little free acid (by design). If they are opened they will dry out and fail in short order. I've switched all my non-Tesla vehicles (boat, truck, tractor, track car) to AGM's and have had multiple years off them. My boat battery is 7 years old and shows no sign of getting tired.The main problem with so called maintenance free lead acid batteries is there NEEDS to be a way to check/add distilled water to the cells (they will dry out). I have found a way to check/add water to every 12V battery I have ever owned and almost always got more than 3 years of service. The battery in my Model 3 has what appears to be a lid glued over the front side of the battery hiding the fill ports. Can anyone verify this? If there is no access to add water, the battery will probably fail earlier due to drying out.
.. tteries is there NEEDS to be a way to check/add distilled water to the cells (they will dry out). I have found a way to check/add water to every 12V battery I have ever owned and almost always got more than 3 years of service. The battery in my Model 3 has what appears to be a lid glued over the front side of the battery hiding the fill ports. Can anyone verify this? If there is no access to add water, the battery will probably fail earlier due to drying out. That may be the main reason why many new car batteries (not just Tesla) fail at around the two year point.
That sounds like a lot. Your car needs some sleep!
The difference is in what the car does when it is "on" versus when it is "off". First off, where you say there is no alternator, that's true that there is not literally a device that is an alternator, but there is a different device that serves the same function. It is just a DC to DC voltage conversion circuit.I’m sorry in advance to not quite understand how the 12v charging system operates. If I leave my car plugged in for long periods how would the 12v be charged any differently than if driven every day? I was under the impression the traction battery charges the 12v whether driving or sitting parked as there is no alternator that I know of.