MPP Lightweight 12V Battery Installation Instructions

Difficulty: 3/5 – You will require a decent level of dexterity during one step of the install.

Thank you for purchasing our MPP Lightweight Battery Kit! This is a short instructional guide on installing the battery properly. You’ll love the weight reduction and getting rid of that silly lead acid battery! We spent lots of time designing and testing this kit, we hope you love it as much as we do.

Tools & Equipment Required:

1/4″ 10mm Socket
1/4″ Ratchet
1/4″ Extension
10mm Wrench
4mm Hex Key
5mm Hex Key
T25 Torx Bit
3/8″ 13mm Socket
3/8″ 15mm Socket
3/8″ Ratchet

Installation Instructions:

Discard foam rectangles included in battery packaging, it is not required for this install.

Remove Frunk:

Pop the hood (frunk) and remove the trim, exposing the stock battery. If you aren’t familiar with this procedure, please have a look at our instructional video here: https://youtu.be/ECBoNunI8z8

Disconnect LV BMS/HVIL Connector

Reference our “Hard Reset” Guide to disconnect the logic connector under the 2nd row seat

Remove Stock Battery

Using your 10mm wrench or socket, loosen and remove the negative battery cable first, setting it safely aside.
Using your 10mm wrench or socket, loosen and remove the postiive battery cable. Wrap it with electrical tape before moving it aside to prevent it from sparking on exposed metal.
Using your 10mm wrench or socket, loosen and remove the battery hold down bracket.

Pull out and set aside the battery vent hose, it is no longer needed. You can zip tie it out of the way.
Lift the battery out of the car

Using your T-25 Torx bit, loosen and remove the rear battery hold down bracket and remove it

Assembling the MPP Lightweight Battery Kit

Drop the two provided countersunk bolts into the two holes in the centre of the bracket
Using a 5mm hex key and 10mm wrench, install the thin jam nuts on the bottom side of the bracket, tighten them.

Countersunk bolts installed in bracket with thin nuts.

Important!

The thick blue washers will be installed on these through the bottom of the stock battery holder. Make sure the recess of the blue washer goes over the thin nut, and the flat side faces the ground.

Example: Blue washer installed flat side down, with serrated M6 nut (assembled out of car)

Install the hold down cord on one side of the bracket using the M5 cap screw and 4mm hex key
Place the battery in the bracket
Stretch the cord over, and install the second M5 cap screw in the bracket, securing the battery to the bracket.

Battery strapped into bracket, 4mm hex key in view

Using 5mm hex key, installed the included battery terminals on the positive and negative locations of the battery, torque to 30-35 INCH-lbs
Important – The larger terminal is installed on the positive side of the battery!

Install the Lithium Ion Battery In The Car (RWD)

Place the battery/bracket into the car. It will index in the stamping of the tray.
Make sure to orient the positive terminal with the positive cable!

Battery installed with positive and negative terminals in correct orientation

Using a 10mm wrench or socket, install the blue washers underneath the tray using the supplied M6 serrated nuts. Your arm will fit in the right side and there will be just enough room to turn your wrench or ratchet.
Note: Remember to keep the flat side of the blue washers facing down!
Tighten the M6 nuts.

Pictured: Jesse installing the blue washers and M6 serrated nuts underneath the battery tray. Try placing your left hand on the crossmember for support, and inserting your right arm as pictured.

If for some reason you drop the hardware or can’t accomplish this step, you can lift the front of the car and remove the undertray. This will give you a clear view of the battery tray and also let you recover any dropped hardware.
Install the positive battery cable first, then the negative battery cable.

It’s done! The small wire protruding for the battery is for aircraft use, tuck it out of the way or ziptie it up!

Install frunk trim

DM/Performance Model 3 Procedure

The front motor of the AWD/P Model 3 makes reaching under the tray as shown above very difficult. We have added some steps to make this possible. These steps can also be used if you are having difficulty reaching under the tray on your RWD Model 3.

Remove the two 13mm bolts holding the battery tray to the crossmember

Pictured: 13mm bolts holding the battery tray to the crossmember

Remove the 6 bolts holding the crossmember to the strut towers (15mm)
Remove the single 10mm bolt holding the bracket to the crossmember

Pictured: Hardware attaching crossmember to strut towers that must be removed.

Remove the two 10mm nuts holding the coolant reservoir to the battery tray

Pictured: View of the 10mm nuts that must be removed to separate coolant reservoir from battery tray.

Pictured: Removing the two nuts for reservoir.

Be sure not to misplace the rubber bushings after you remove the nuts

Pictured: Rubber isolation bushings for coolant reservoir. Don’t drop them!

Squeeze and remove white clip attaching clear hose to battery tray

Pictured: White clip to be removed from battery tray.

You will now be able to slide the crossmember/coolant reservoir towards the front of the car. Wedge a microfiber cloth underneath the driver’s side of the crossmember to prevent it from touching metal as you pull it forwards.
Once the studs that went through the coolant reservoir are clear, you will be able to lift up on the battery tray to access the underside

Pictured: Crossmember moved forwards to allow access to the bottom of battery tray from the front.

Pictured: Accessing hardware underneath battery tray with the newly acquired space in front.

Install the battery/bracket assembly as described in RWD instructions.
Reassemble following steps in reverse order – do not overtorque the crossmember bolts that attach to strut towers!
Torque 6 bolts holding crossmember to strut towers to 25 ft-lbs.
Torque two battery tray bolts to 25 ft-lbs.
Complete battery installation according to RWD instructions.
Install frunk trim.

You’re done!

Click here for instructions on how to perform a 12V battery reset.