12V Lithium-Ion Battery

Given my understanding of the role the 12V battery in the Ford Focus Electric performs, I think I'm going to replace the lead-acid battery with two LiFePO4 motorcycle batteries in parallel arrangement. I use these batteries in my motorcycle; they're lighter and truly maintenance free. Anyone know any reason why this might cause a criticality incident that will torch my FFE on its way to upsetting the matter/anti-matter balance and obliterate life as we know it?

Definitely doable, but I'd make sure that there is a built in charger protection in the battery...like many cell phone batteries have. if the voltage on a lithium battery goes too low or too high, it will go bad. And, as I mentioned in another thread, be sure that the charge and discharge properties of the 12V battery can handle the charge and discharge that the car presents to it.

12V lead acid batteries are very forgiving. As the battery voltage approaches the charging voltage, the current to the battery naturally reduces. Once charged, the current is low and becomes a trickle charge. If the battery has no capacity to take the charge anymore, it simply turnes to heat...which is harmless. In a lithium battery, unless there is something to control the charging, the battery will just go over-voltage and die.

I agree with davideos. Be careful and check to make sure that the charger will not over-voltage the LiFePO4 cells.

These cells like a nominal voltage (aka trickle voltage) around 3.2-3.3V. That means the trickle charging voltage shouldn't exceed ~13.2V (assuming 4 series cells) for safety. Also, the max charge voltage for these cells is 3.6-3.8V so you definitely do not want to exceed 14.5V.

Also, since we know there is some parasitic load on the FFE, you want to be careful to not deeply discharge any lithium ion battery (including the iron-phosphates). If your FFE sits for too long and the battery dips below 2.8V/cell then you might end up with some real trouble.

.... these discussions make me impatient to receive my FFE .... in a few more weeks I can poke around at this stuff myself...

I'm thinking of looking into this battery...the deep discharge one. The intended car is a ford focus, but I don't if there is a difference between the FFE and a regular focus when it comes to fit and function...
http://www.optimabatteries.com/us/en/find-a-battery/?year=2012&make=Ford&model=Focus&engine=&find_button=Search

But for now, my standard battery is working just fine. I put a voltmeter in the accessory outlet and measured:
12.03V with the car off and not plugged in
14.1V with the car on,
12.8 with the car off and charging on 120V

I did measure with the car on but not ready to drive, but I can't remember if it was 12.3 or 13.2V. I'll check again later. My typical commute is 14miles one way. I haven't had any battery issues yet. Date of Manufacture is June 2012, 1.5 years old.

@davideos here's another battery that I really like and have used many times... http://www.odysseybattery.com/batteries.html

The odyssey battery does look like another good battery. I'll have some shopping to do when it comes time to replace mine.

So I've had my car on the 120V charger now for about an hour and a half. I've noticed that the voltage on the battery is up from 12.8 when I originally plugged it in, to 13.3V. Which indicates that the car is charging the 12V battery with a constant current source. I saw someone report that their battery was charging at 12.6V when plugged in and that the charger could be bad. Actually, it probably isn't and they should check the battery after a few hours to see what the voltage is at. If the battery is taking a charge, the voltage should rise. If not, then there may be a battery or charger issue; but more likely a battery issue.

purpleporsche said:

Given my understanding of the role the 12V battery in the Ford Focus Electric performs, I think I'm going to replace the lead-acid battery with two LiFePO4 motorcycle batteries in parallel arrangement. I use these batteries in my motorcycle; they're lighter and truly maintenance free. Anyone know any reason why this might cause a criticality incident that will torch my FFE on its way to upsetting the matter/anti-matter balance and obliterate life as we know it?

Click to expand...

Which Lithium batteries were you looking at? I saw some 12V versions for LeadAcid replacement, but those were around $1000 with less capacity. They may discarge deeper, but the cost is too high for an experiment...well, for me at least

There are severe safety concerns with the existing lithium-ion batteries that are used in electric and hybrid vehicles. However, a research firm claims that it has discovered a way to make a safer battery that can produce a longer driving range by utilizing a solid electrolyte instead of a liquid one. Technical solutions and applications were presented. The innovation can not only be applied to alternative power automobile batteries. It also has the potential to make safer, longer-lasting batteries for a variety of uses, including consumer electronics.

"bump" Has anyone tried this and with what results?