Building a Home Battery Setup and Pre-Charging MultiPlus

Steps

1. 1

   Step 1: Reviewing current setup and safety components

   The three MultiPlus units, the Lynx busbar, and the Cerbo are all mounted on the wall with the cables neatly tucked into cable ducts. I installed an extra main switch at the top so I can safely cut off the power coming from the meter cupboard. Next to it is a 25 A residual current circuit breaker to protect the cable between the shed and the meter cupboard.

   The MultiPlus units are connected with 70 mm square cables, which many consider too thick for this setup, but I prefer cables a bit too thick rather than too thin. I will also use a thermal camera to check for any hot spots or warm cables beforehand.

   What I used

   Item	Amount	Notes
   MultiPlus unit	3	Mounted on the wall
   Cerbo	1	Connected
   Main switch	1	Placed at the top
   Residual current circuit breaker	1	25 A
   Cable	multiple	70 mm square

2. 2

   Step 2: Custom components and battery cabinet adjustment

   The shunt is homemade using a 3D printer, which saved a lot of money while keeping the same quality to calculate current flow. The distribution is also a modified power in unit that lacks indicator lights for blown fuses, and the Victron Mega fuses will later be replaced by EF3 fuses. The battery cabinet stores the battery packs built in earlier videos.

   However, the battery pack became too wide with the cables on top, making the BMS on the side unreachable, so I moved the BMS to the front of the box.

   What I used

   Item	Amount	Notes
   Shunt	1	3D printed
   Power in distribution	1	Modified
   Mega fuse	multiple	Victron, to be replaced by EF3 fuses
   BMS	1	Moved to the front

3. 3

   Step 3: Drilling cable holes in the steel cabinet

   I need to run the battery cables outside the closed cabinet by drilling a couple of holes in the top. To prevent the metal from cutting the cables and causing a short circuit, I will equip the holes with 3D-printed protection rings and rubber printed caps. The battery pack is already heavy and inside the cabinet, so I must be extremely careful not to let any metal splinters fall into the battery pack while drilling.

   What I used

   Item	Amount	Notes
   Protection ring	2	3D printed
   Rubber printed cap	2	For cable protection

4. 4

   Step 4: Routing negative and positive cables

   With the holes ready, I start cabling by routing the negative power cable from the bottom of the cabinet through the hole, up the cable duct, and to the bottom of the Lynx busbar. I do the exact same thing for the positive cable, running it via the other hole and behind the cabinet into the cable duct. The battery cables enter the top of the cabinet, run down the side, and connect to the battery poles at the bottom.

   My fuse holders double as battery poles for both positive and negative, which is an extra piece of safety for my peace of mind.

   What I used

   Item	Amount	Notes
   Negative cable	1	Routed through cable duct to busbar
   Positive cable	1	Routed behind cabinet to busbar

5. 5

   Step 5: Stripping and crimping cable lugs

   To connect the cables to the power in, I measure the jacket depth, strip a piece of the cable, and insert it into a claw cable lug with no stray wires sticking out. I use a hydraulic crimping tool bought from AliExpress, which is a super nice and cheap tool that does the job perfectly. I close the valve on the tool, pump it until it tightly wraps around the lug, and then open the valve to release a neat crimped lug.

   I skip using a shrink sleeve for this video demonstration and just set it up without one.

   What I used

   Item	Amount	Notes
   Cable lug	multiple	Claw type
   Hydraulic crimping tool	1	From AliExpress

6. 6

   Step 6: Connecting cables to the Lynx busbar and battery pack

   I use a 13 mm socket to loosen the bolts on the power in, place the negative cable directly on the main carrier without washers or nuts in between, and add a washer, spring washer, and nut. Viewers in the comments always debate the exact names of these washers, which led to some funny discussions. I tighten the nut with the socket and recommend using a torque wrench.

   Next, I cut the negative cable to length at the bottom of the cabinet, crimp another lug on it, and connect it to the battery pack negative terminal through the BMS. I repeat the exact same process for the positive cable.

   What I used

   Item	Amount	Notes
   Socket 13 mm	1	For loosening and tightening bolts
   Washer	multiple	Used on terminals
   Spring washer	multiple	Used on terminals
   Nut	multiple	Used on terminals
   Torque wrench	1	Recommended for final tightening

7. 7

   Step 7: Pre-charging the MultiPlus capacitors with a bulb

   The MultiPlus units currently have zero voltage because their internal capacitors are completely empty. Connecting the battery directly would send a massive energy surge, potentially damaging cables, fuses, or the BMS, so the units must be pre-charged the first time. The busbar reads 0V, while the battery reads 51.2V.

   I made a simple pre-charge tool using a small lamp fitting, two crocodile clip wires, and a 60V 10W incandescent light bulb that acts as a resistor. I connect one crocodile clip to the negative fuse and touch the positive cable with the other clip through the bulb, which makes the bulb light up and slowly charges the capacitors without causing a loud spark.

   Once the voltage rises safely, I connect the positive cable directly to the battery pack without any sparks.

   What I used

   Item	Amount	Notes
   Incandescent light bulb	1	60V, 10W
   Lamp fitting with crocodile clips	1	Homemade pre-charge tool

8. 8

   Step 8: Powering on the MultiPlus units

   Now that all the cables are securely attached without pulling any sparks, power is supplied to the MultiPlus units. I flip the front switch forward, and I see all the indicator lights start blinking to show they are turning on. Before doing anything else, I need to adjust and update the firmware, which is a great topic for the next video to keep things concise and focused.

   What I used

   Item	Amount	Notes
   MultiPlus unit	3	Powered on

9. 9

   Step 9: Takeaways

   • Always protect drilled holes in steel cabinets with rings to prevent cable damage.

   • A hydraulic crimping tool from AliExpress makes solid and clean cable lugs.

   • Pre-charging empty inverter capacitors with a 60V bulb prevents dangerous sparks and protects equipment.

   • Updating the firmware is the necessary next step before configuring the system further.