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Tech Primer: Why 12-Volt Batteries in Electric Cars Get Sick -- And How To Keep Yours Healthy

Discussion in 'Model S: Battery & Charging' started by Akikiki, Mar 28, 2017.

  1. Akikiki

    Akikiki A'-Lo-HA ! y'all

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    While browsing news on Transport Evolved, I spotted this video. Its not about Tesla, but just EVs in general. I thought it worthy of posting a link to it. I pasted the author's comment section to help understand the background.

    Tech Primer: Why 12-Volt Batteries in Electric Cars Get Sick -- And How To Keep Yours Healthy


    Published on Mar 13, 2017
    Today's video is inspired by a problem we had this morning at Transport Evolved's headquarters: namely a flat battery on our 2013 Nissan LEAF Staff Car. But we're not talking about the main traction battery here: we're talking about the 12-volt accessory battery that's used to provide power to lights, radio and on-board computer -- as well as start the car.

    Just like the 12-volt starter battery in an internal combustion engine car, having an issue with your electric car's 12-volt battery can be extremely frustrating. But what causes the problem -- and how can you fix it?

    Support Transport Evolved by donating to our Patreon campaign at Transport Evolved is creating a cleaner, greener smarter and safer world. | Patreon.
     
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  2. Akikiki

    Akikiki A'-Lo-HA ! y'all

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    The more that I think about how a 12 volt battery can become "sick" to the point of losing charge and not starting the EV/Tesla. I wonder if its wise to add a lightweight 12 volt battery tester. Such as one of these. Anyone have an opinion pro or con?
    The intent is simply to keep an eye on the quality of the battery and hedge the chance that its failing and avoid being stranded.

    Astro 7765 12-volt Onboard Battery and Alternator Load Tester - Circuit Testers - Amazon.com

    Amazon.com: Car Motorcycle Trucks 12V Digital Battery Alternator Tester with 6 LED Lights Display Indicates Condition Car Vehicle Diagnostic Tool: Automotive

    Amazon.com: Biopoder 12v Car Battery Tester Alternator Tester ,Test Battery Condition, Alternator Charging: Automotive

    Your thoughts?
     
  3. RDoc

    RDoc S85D

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    At least in our case, the car warned us when the battery was dying. According to Tesla Service, the car could have kept going for many more weeks after the warning. We got it replaced after about 2 weeks.
     
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  4. Dr. Smoke

    Dr. Smoke Member

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    #4 Dr. Smoke, Mar 30, 2017
    Last edited: Mar 30, 2017
    This video is very nice and all, but substantially does not apply to Tesla.

    Cold Cranking Amps are a key rating on standard automotive batteries. In contrast, Teslas use a 'deep discharge battery', which is designed not for heavy short-term amps, but a more steady load and longer charge.

    Unfortunately, Tesla installs a low-grade battery which can't last long with the repeated charge/discharge cycles it's subjected to. Thus the battery accumulates sulphates on the plates and usually gives out after a year or two.

    I'm not a fan of my car letting me down, so I've installed a LiFePO4 ('Lithium Iron') battery in mine. Yes, it doesn't hold as much charge by volume as a Lithium-Ion battery, but by its nature LiFePO4 practically can't catch fire (as opposed to L-Ion), plus it lasts 3 times the charge cycles of Lithium-Ion and 10 times that of the standard AGM battery. Of course, don't expect LiFePO4 to be cheap.

    LiFePO4 batteries are a huge improvement over lead acid in weight, capacity and shelf life. The LiFePO4 batteries are the safest type of Lithium batteries as they will not overheat, and even if punctured they will not catch on fire. The cathode material in LiFePO4 batteries is not hazardous, and so poses no negative health hazards or environmental hazards. Due to the oxygen being bonded tightly to the molecule, there is no danger of the battery erupting into flames like there is with Lithium-Ion. The chemistry is so stable that LiFePO4 batteries will accept a charge from a lead-acid configured charger. Though less energy-dense than the Lithium-Ion and Lithium Polymer,Iron and Phosphate are abundant and cheaper to extract so costs are much more reasonable.

    Lithium-Ion batteries and Lithium Polymer batteries are the most energy dense of the Lithium batteries, but they are lacking in safety. The most common type of Lithium-Ion is LiCoO2, or Lithium Cobalt Oxide. In this chemistry, the oxygen is not strongly bonded to the cobalt, so when the battery heats up, such as in rapid charging or discharging, or just heavy use, the battery can catch fire. This could be especially disastrous in high pressure environments such as airplanes, or in large applications such as electric vehicles. To help counteract this problem, devices that use Lithium-Ion and Lithium Polymer batteries are required to have extremely sensitive and often expensive electronics to monitor them. While Lithium Ion batteries have an intrinsically high energy density, after one year of use the capacity of the Lithium Ion will have fallen so much that the LiFePO4 will have the same energy density, and after two years LiFePO4 will have significantly greater energy density. Another disadvantage of these types is that Cobalt can be hazardous, raising both health concerns and environmental disposal costs.
     
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  5. rjcbox

    rjcbox Member

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    Mine was replaced after 20k miles and almost 2 years, after an early alert. No problem driving a few weeks until I booked an appt for a swap
     
  6. henderrj

    henderrj Member

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    I purchased the test vehicle from Batmobile batteries. They included one of their batteries when I bought it. How does this compare to the LiFePO4 configuration? Do I have to worry about it catching fire?!
     
  7. Allanf

    Allanf Supporting Member

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    Really interesting discussion. Just wondererimg how Tesla feels about an owner installing either of these in place of the 12v battery that comes with the car. I.e does either in any way affect the operation of the car or of course affect Tesla's warranty.
     
  8. Akikiki

    Akikiki A'-Lo-HA ! y'all

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    I don't wonder how Tesla feels about an owner installing their own battery. (Not trying to be smart a$$). My point is, I would not mess with using a different battery unless Tesla steered me towards it. Maybe none, but can't guess the consequences of doing so.
     
  9. Dr. Smoke

    Dr. Smoke Member

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    I looked up "batmobile batteries"+vehicle and this is what I came up with. Is this what you mean?
    [​IMG]
     
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  10. henderrj

    henderrj Member

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    Funny, but no. Had to look it up but Sean's web address is BattMobile Batteries, Custom Lithium Batteries. I have no affiliation with them other than that I bought the car from them. Well, and one of their batteries in my car.
     
  11. boonedocks

    boonedocks Member

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    hqdefault.jpg

    I just installed one of these and a couple of kibbles a day and my 12V battery stays fully charged:

    Very Interesting video though.
     

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