Adding Extra Battery Power to FFE

[skyguy_6153]

The Focus Electric (2012-2016 model years) uses LGX P1 cells, and more info on these cells can probably be found from the endless sphere forum page. I I'd like to make a pack out of cylindrical cells, as that would rid the issue of cell expansion that FFEs have. I wonder if you found some cells that were higher in energy density, but had the same full discharge/ full charge ratings as the OEM battery, could you still utilize the OEM BMS? Or would the boards built into the modules need to be removed and reused on the diy battery....

 

[Anti_Climax]

You'd probably need the boards or you'd have to be able to recreate the data stream the BMS expects to see.

 

[triangles]

You'd probably need the boards or you'd have to be able to recreate the data stream the BMS expects to see.

And that is my big stumbling block.

Someday if ever feasible, I will upgrade my battery. The battery part and BMS part is no problem. However I'm a complete noob when it comes to canbus or knowing what the car expects from the battery modules.

It would be awesome if there was an easy way to just ditch the OEM battery and build a custom battery that just "plugs into" the FFE.

 

[skyguy_6153]

You'd probably need the boards or you'd have to be able to recreate the data stream the BMS expects to see.

And that is my big stumbling block.

Someday if ever feasible, I will upgrade my battery. The battery part and BMS part is no problem. However I'm a complete noob when it comes to canbus or knowing what the car expects from the battery modules.

It would be awesome if there was an easy way to just ditch the OEM battery and build a custom battery that just "plugs into" the FFE.

Look into Arduino products and shields for an easy learning route to sniffing the CAN. I started with my FFE using a Arduino Uno and a Sparkfun Can Bus Shield, but as soon as I ran the code, the car threw just about every warning it could generate (SSN, ABS, Low Tire Pressure, etc.). Luckily, I have Forscan to clear the errors, which were Can Bus related. Anyway, I think it may be due to not having the fuses for the traction control/ABS and pedestrian speaker installed :lol: . I will however be trying again in me free time with fuses installed.

SparkFun CanBus Shield: https://www.sparkfun.com/products/13262

SparkFun LCD: https://www.sparkfun.com/products/9395

Arduino Uno: https://www.sparkfun.com/products/11021

OBD2 to DB9 Cable (Needed for connecting the board to the OBD2 port.): https://www.sparkfun.com/products/10087
2012 Focus Electric with DIY P0A0A fix "coolant leak inside battery" (removed coolant hoses, heat exchangers, and cooling assembly from uppe

 

[Anti_Climax]

Connecting your CAN+ and CAN- backwards will do that too, as will having a termination resistor on the loop when another is already in elsewhere.

 

[Trinhray]

How do you get Forscan to clear P0A0A? Dealer cleared it with no problem.

Repeatable. I was able to trigger the SSN warning twice with P0A0A. Just by pulling the orange interlock fuse behind the rear seats on the upper battery pack. My FFE was towed two times to the dealer just to clear this code. No other fix performed.

 

[Trinhray]

With the cost of raw Li-ion cells going down, I am considering add external batteries (86 series) suggested in the forum but concern about triggering codes I cannot reset with Forscan. When putting the pack back together, were there any codes triggered and how did you clear them?

 

[skyguy_6153]

With the cost of raw Li-ion cells going down, I am considering add external batteries (86 series) suggested in the forum but concern about triggering codes I cannot reset with Forscan. When putting the pack back together, were there any codes triggered and how did you clear them?

When I rebuilt the battery in my first FFE, I was unable to drive the car because I forgot a busbar between two modules :lol: . Once I bolted that in, I ran a self test on the BECM through Forscan, and checked/cleared any DTCs. You have to go to the DTC (left side of window in Forscan) tab to clear any DTCs in Forscan. When in the tab, there are two yellow triangles at the bottom (one for reading DTCs, and one for clearing and reading.).

 

[ivankovff]

Hello, please can you read BECM module with FORScan, I reqyire the file of configuration for the battery of 33.5 kWh to compare it with the battery of 23 kWh. Thank you in advance for your precious help

 

[Trinhray]

Thanks Skyguy_6153. Can you just attach additional batteries of the same voltage range to the rear junction / disconnect next to the rear interlock fuse on the upper battery? Why did you connect the negative to the front of vehicle? If I can clear codes, I might proceed to building my own 86s pack with raw cells and custom bms.

Clearing DTC codes:
I tried using Forscan (two months trial + ELM327 HS/MS adapter) to clear P0A0A:08 but could not. Since I know the dealer can clear it twice. Everytime I open any of the HVIL connections, it will trigger a code and in the case of the interlock fuse, it is SSN warning.

Maybe it's the cheap ELM adapter or limitations to trial version. I just purchased the extended version of Forscan and their recommended OBDLink EX FORScan OBD Adapter. Let's see if it makes a difference.

Thank Skyguy_6153 for confirming that Forscan can clear the codes when everything is reconnected back properly.

 

[Trinhray]

Motorscm1 - if you are still checking these forums, can you provide more pictures or additional steps on where you connected the additional batteries to the FFE? Any DTC codes triggered and cleared?

 

[TheChickenTendy]

How much power does the Focus motor draw? What discharge rating should I be looking for with an external pack? Also any leads on where I can get Li-ion packs? I can only find LiFePO4 packs in large sizes.

A supplementary pack would operate connected in parallel. You want to get them close to the same voltage but they don't need to be exact. They will equalize as they are being used which may make your range indicator go up if the new pack is higher and starts to "charge" the original or lower if it draws the original down. But that's just indicating the state of charge for the pack the car can directly monitor rather than the combined capacity of the two.

 

[Anti_Climax]

I believe the motor is rated for 107kW. Keep an eye on eBay and scrap yard auction pages. https://www.ebay.com/itm/315781037005

 

[TheChickenTendy]

So you're thinking the best option is to get a second set of OEM batteries and hook them up in parallel to the internal pack? I was hoping to be a bit lighter than the over 600lbs of the stock set. I did find some leads on AliExpress where I could get 4 20s 55ah packs and then build myself a 6s 55ah pack out of cylindrical cells. Probably Samsung 50s cells with their own BMS. Does this sound possible?

 

[Anti_Climax]

As long as you can match the voltage range, it shouldn't much matter how you get there. I just thought you were trying to match chemistry.

 

[TheChickenTendy]

Hmmm... A 100s LiFePO4 would have a fully charged voltage of 365V and empty of 250V. This is slightly wider than the car's 361.2V full and 258V empty. If these cells were added in parallel with their own BMS I'd assume they would work together. You would just be missing out on a tiny bit of the LiFePO4's capacity.

 

[Anti_Climax]

Considering the fact that the car pack leaves 8-10% of it's SoC outside the usable range, that might not be a bad way to go.

 

[TheChickenTendy]

Now if only I had a clearer picture of the wiring diagram. The Positive behind the back seat should be easy to get to but why does the negative need to come from under the hood? There has to be a better spot to tap it. Also it would be nice to wire the contactor for the booster pack to the same control wires as the main pack. That way they could be controlled together. Not sure where I could get that diagram.

 

[Anti_Climax]

You might be better off adding separate contactors and driving them from the main circuit. Then you can tap anywhere along the harness. I'll see about getting a picture from the wiring manual

 

[TheChickenTendy]

I should just wire the extra battery's contactor to this relay.