Dead 12v in my FEH.

Discussion in 'Ford Hybrids' started by 08EscapeHybrid, Jan 3, 2018.

  1. 08EscapeHybrid

    08EscapeHybrid Moderator

    So our bitter cold has taken its toll on my 12v battery. It is going on 6 years old, and without warning, today when I went to leave from work, my FEH would not start. All this past week has been relatively short trips in extreme cold. I don't think we've had one day above freezing in at least a week. This evening when I went to leave work it was about 20F and the FEH refused to start. My battery was reading 8 volts. I guess this explains my drop in mileage the past month or so. I had felt the drop was more than just bitter cold weather, and now I guess I know why. Its been trying its darnedest to charge that battery.

    So, I took this opportunity. I had been thinking about replacing my 12v with a lithium automotive battery as the efficiency of a lithium battery is much better than a lead acid battery. I took the plunge in the name of science. I just ordered the battery online. My hope is that the lighter weight combined with higher efficiency of the lithium cells over lead, that I may see an uptick in mileage.
    xcel and BillLin like this.
  2. S Keith

    S Keith Well-Known Member

    Keep expectations low. Even 70A being dumped into the 12V is only about 1hp, and it likely wasn't doing it that much for more than 1-2 drives before failure. The efficiency gains in lithium are negligible in this scope.

    Below 50°F NiMH can't take much of a charge and survive, so your hybrid function is crippled in that kind of cold until the battery warms up along with all the other inefficiencies inherent in cold weather operation.

    I live in Phoenix, and even our mild weather with dips down into the 30s can mean a 10% difference in economy between the morning drive and the evening drive at 70-75°F.
    xcel and BillLin like this.
  3. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    My 2012 Prius Plug-in 12V battery just died, too. I didn't bother checking the voltage but nothing lit up, and of course the proximity unlock function didn't work. If the driver door was not unlocked, I would have had to use the physical key. The battery recharged okay. Still, I have no trust in it working off the charger for any length of time. So... Optima yellow top battery on the way. I thought about going the lithium route, too, but no time to research and no discussions of lithium replacements for my application found in some cursory searches.

    You are fortunate that the FEH 12V battery is fairly normal and more readily available, and the lithium experiment sounds perfect. Good luck! Thanks for trying it out and promising to post the results. Should be interesting.
    08EscapeHybrid likes this.
  4. S Keith

    S Keith Well-Known Member

    Sorry, I have to make a comment on the Yellow Tops. I just replaced the original Toyota 12V in an 09 and an 08 Prius here in AZ. Replaced an original from a 2007 in 10/17 with 256K miles on it. Lots to be said for the quality of the Yuasa made Toyota battery with a 7 year warranty (2 full/5 pro). For the Gen2, at $240 OTD, they cost about $60 more than the Optima. I have never replaced a Toyota battery that was less than 5 years old.

    IMHO, along with the deterioration in the majority of Pb batteries in the U.S. over the last 5 years or so, Optima is no longer the premium brand it once was. They are made by Johnson Controls, who makes just about every 12V battery available in the U.S. - Walmart, Autozone, Etc. The overall quality seems to have settled to the bottom, regardless of brand.

    I've seen 2 catastrophic failures of Yellow Top Optimas in Gen2s in the last year: 1) violent venting in a battery less than 1 year old and 2) leaking in a 3 year old Optima, and I've replaced a dozen that were 3-4 years old.
    BillLin likes this.
  5. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    Thanks for the heads up.
  6. 08EscapeHybrid

    08EscapeHybrid Moderator

    I don't know if I had posted it here, but I had already taken the lithium plunge on another vehicle. I've been using a lithium battery in my motorcycle for almost 2 years now, and I have been extremely pleased with it. It always fires up quickly, even when sitting for extended periods. It was my great experience with the lithium battery in the motorcycle that got me thinking about possible advantages of a lithium 12v in the FEH.
    BillLin likes this.
  7. Jay

    Jay Well-Known Member

    I would not buy a lithium-ion battery for use in place of pb-acid in a motorcycle or car mainly because the two battery types have quite different charge requirements. Pb-acid is fairly tolerant to overcharging where Li-ion isn't tolerant at all. There are other differences and lots of white papers on charging Li-ion out there. Also, multi-cell Li-ion batteries need some sort of charge-balancing circuitry to maintain an even charge on all cells. Most aftermarket packs have no charge-balancing circuitry. Finally, pb-acid lasts longest when a full charge is maintained on the cells which is ideal for a starting application. Li-ion lasts longest with 40% to 70% charge--not the best for a starting application.
    RedylC94 and BillLin like this.
  8. S Keith

    S Keith Well-Known Member

    Quality Lithium (LiFePO4) 12V replacements address all of your concerns. The problem is there are a number of mediocre replacements that do not have an on-board BMS.

    Lithium replacement in a hybrid is more sensible than an actual crank-start vehicle as the current demand is substantially lower.

    If you're spending many X the cost of a Pb battery to get a quality Lithium battery with on-board BMS, then there is little to no risk associated with catastrophic failure, performance or life.

    Here's an example:

    $689.99 for a 52Ah battery.

    I would like to see what the OP ordered... :)
    BillLin likes this.
  9. Jay

    Jay Well-Known Member

    That battery claims to have cell-balancing, so +1 for that. But it has contradictory specs: Max charge/discharge current 50A and then CCA 500A. Which is it? Obviously, 50A won't cut it for starting. The battery claims to have circuitry to prevent overcharging, over-discharging, short-circuiting, and reversal. That's not the same as providing the very specific charge profile that LiFePO4 requires. Here's a white paper that shows how it should be done properly on pg 4:

    There are hundreds of white papers by the chip makers for chargers that show similar profiles. Your car's pb-acid charging doesn't match it at all.

    The "smart battery" protection circuitry sounds like just a relay to open the battery if voltage falls outside a certain range:

    Imagine you've accidentally left some electrical accessory on in the parking lot and your battery is now dead. You've got charging cables but they don't work because the "smart battery" relay is open. Now you've got to call the battery company to figure out how to close the relay?

    The warranty for the smart battery LiFePO4 sounds OK till you look at the details. You must ship the battery back to their lab in FL where they decide whether it was your fault or not that the battery is hosed. Of course, LiFePO4 is a hazardous item and requires special shipping consideration. They say that it may take >6 months to return the battery to you. (!)

    I just can't imagine paying nearly $700 for this battery when my last Centennial pb-acid battery lasted 10 years and cost about $125.
    BillLin likes this.
  10. 08EscapeHybrid

    08EscapeHybrid Moderator

    Ask and ye shall receive... I looked at several batteries, but settled on this one. The reasons are as follows:

    It is close in size to the stock battery, so it will fit the battery box.

    It has BMS

    It has top post terminals like the stock battery, most of the other lithiums use screw terminals as they're intended for motorcycles

    It wasn't absurdly expensive. There was a battery I liked better, but I'm not paying over $1,000 for a 12v battery.
    Last edited: Jan 4, 2018
    BillLin likes this.
  11. S Keith

    S Keith Well-Known Member

    I'm guessing you have little to no experience with Lithium.

    First, max discharge and CCA ratings are not mutually exclusive - they are two different ratings. When you deep dive on a properly specced Pb battery you see different capacities for different currents. CCA is a 30 second current rating. No Pb battery rated at 500CCA is going to discharge 500A reliably long term without damage. Most have dramatically lower rates on the order of 5-10A to achieve the rated Ah capacity.

    Second, Lithium doesn't give a crap about a charge profile. It cares about not being overcharged. The charge profile you linked is for the purposes of fully charging a Lithium battery to 100% to obtain maximum capacity to minimize damage and prevent overcharge. That's not what we're talking about.

    In fact Lithium likes to be charged in a highly similar way as Pb except that it has a peak voltage that can't be exceeded.

    The car's charging system is going to provide about the left 50-60% of the profile you linked, and it operates in almost exactly the same way. It will not exceed 14.4 to 14.8V in the vast majority of cases unless the charging system is malfunctioning, and the Lithium battery in question has Vmax at 15.8V, which corresponds to the peak voltage in the profile. Seeing that it will never reach it means that the battery will never get charged close to 100% SoC, which is likely by design. Once the car's charging system senses the battery is at the Pb programmed peak (14.4-14.8), it's going to do exactly what the green line does - taper current to hold voltage.

    The only valid concerns you have are:

    1) Warranty
    2) What happens when the user does something stupid
    3) cost

    All of your other concerns are unfounded.

    Well, that has all the right specs and claims. Unfortunately, I have plenty of experience with China/Taiwan made products that over-promise and under-deliver including selling cells that are claimed to be protected when they in fact aren't. For the price and the claim that they are shipping from their US stock, there is hope.

    Good luck!

    08EscapeHybrid and BillLin like this.
  12. 08EscapeHybrid

    08EscapeHybrid Moderator

    Yeah, I was a little hesitant about the China thing, but I don't have $1,000 for the American one.
    BillLin likes this.
  13. puddleglum

    puddleglum Well-Known Member

    I would suggest one other concern you may want to consider with going to lithium. Lithium LiFePO4, while better than some other lithium chemistry is still susceptible to significant voltage sag in the cold, maybe worse than lead. If 20*F is cold for you it might not be a problem, that isn't that cold and it is just for starting. If you get sub 0*F temps, I would suggest you consider a battery warmer of some sort. It will be interesting to hear how it works out for you.
    BillLin likes this.
  14. S Keith

    S Keith Well-Known Member

    Disagree. That's why there's a CCA rating. It's based on 0°F.
    BillLin likes this.
  15. seftonm

    seftonm Veteran Staff Member

    How are they at -20F or -40F compared to a lead-acid? I noticed that one of the batteries linked only has 10% usable capacity at -40. I'm not sure if that's better or worse than a lead-acid.
    BillLin likes this.
  16. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    Is the CCA rating moot in the FEH since the big traction battery supplies the starting current?
  17. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    I'm out of my depth, but have heard that higher CCA comes at the expense of amp hours, and that with Prius for example, the latter is more important. I've got an Optima Yellow Top replacement in our 2010 right now, but next time I might try this:

    Canada Tire battery:
    MotoMaster Eliminator Ultra AGM
    Product Number: #010-5122-6
    Manufacturer's Product Number: ELU-S46B24R
    (rebadged Exide battery)
    Above Canadian Tire battery is rebadged:
    Exide FP-AGM51JIS

    So far (2.5 years) the Yellow Top is performing fine, though it has an easy life. The car will sit sometimes, for multiple days, but I keep a smart charger on it when that occurs.
    BillLin likes this.
  18. RedylC94

    RedylC94 Well-Known Member

    Pretty much so, except in an indirect way. The ampere-hour capacity is more important, as regards how long the battery can survive vampire drains while the vehicle is not on ("READY" in Toyotaspeak; I don't know what Ford calls the active status.). The CCA and ampere-hour capacity of lead-acid batteries both increase in proportion to weight of active material, so bigger is generally better for both specifications. However, for any given size, batteries can be designed as starting batteries to emphasize CCA, or as deep-cycle batteries that sacrifice CCA for durability via thicker but less numerous plates .

    However, for owners who barely drive often enough to keep the battery charged, a high-CCA battery would probably accept higher recharging currents at the voltage supplied by the hybrid system, so maybe CCA does matter sometimes, after all.
  19. 08EscapeHybrid

    08EscapeHybrid Moderator

    The cold shouldn't effect me... Even though we get some cold temps, the battery I bought has just over twice the capacity of the stock battery, even if it loses some in the cold, I should still be able to start, plus once started the battery should warm up with power flowing through the system.
    puddleglum and BillLin like this.
  20. Carcus

    Carcus Well-Known Member

    I've got a Ballistic 8 cell Lithium ion motorcycle battery that turns 6 years old next month --advertised to self discharge less than 10%/year -- looks like they weren't lying.

    The bike sits A LOT, and has never been on a charger. The battery is showing 13.7v resting and cranks great. I've got a fancy balance charger I got when I bought the battery. When I hook it up it shows the cells (4 pairs of 2) at 3.59v, 3.28v, 3.28v, 3.44v. So I'm going to call ballistic tech help on monday to see if I should use the discharge/balance function.

    Pretty amazing. With lead acid I have always had to replace by year 3 (or sooner) because I never trickle charge thru the winter. I do try to start and run for 5 minutes once a month but I often forget.

    Advantages and Disadvantages of LiFePO4 Batteries
    Last edited: Jan 13, 2018
    08EscapeHybrid and BillLin like this.

Share This Page