You swap the lead-acid batteries in your golf cart for a lithium pack. Then the lights, the radio and the USB ports go dead, and the 48 to 12 volt reducer under the seat has blown its fuse, or blown itself. On Cartaholics, the busiest golf-cart forum in the US, this comes up again and again after a lithium conversion. Here is why it happens and how to pick a converter that lasts.
Why the old reducer dies
A lithium golf-cart pack built from 16 LiFePO4 cells is sold as 48 volt, but its nominal voltage is 51.2 volts. At the end of every charge, each cell reaches about 3.65 volts, so the pack sits near 58.4 volts while the charger finishes. After the charger stops, it settles in the low 50s and stays there for most of its range.
Many budget reducers are built around a 48 volt battery. Their maximum input is too low for that. Owners keep reporting the same pattern:
- In a Cartaholics thread, a member's Amazon reducers were rated for about 55 volts in, and they kept blowing fuses after the lithium swap.
- A Yamaha Drive owner reported that a 20 amp step-down from his battery vendor failed twice on a fully charged pack.
- An old Endless Sphere thread pointed a builder to small buck converters rated for 50 volts.
It is the same failure every time. The pack's full-charge voltage is above what the converter can take. A lithium pack also spends far more of its time near the top of its range than lead-acid does, so a marginal converter lives near its limit.
The rule: the converter's maximum input voltage must be above your pack's full-charge voltage, with margin. For a 16-cell LiFePO4 pack, that means well above 58.4 volts. For any other pack, read the maximum output voltage on the charger's label.
Three Victron converters that cover a 58.4 volt pack
These input ranges are from Victron's own datasheets and manuals.
| Converter | Input range | Margin over 58.4 V | Output | Isolated |
|---|---|---|---|---|
| Orion-Tr 48/12-9, -20 or -30 | 32 to 70 V | 11.6 V | 9, 20 or 30 A; 12.2 V, adjustable 10 to 15 V | Yes |
| Orion-Tr Smart 48/12-20 or -30 | 32 to 70 V | 11.6 V | 20 or 30 A; Bluetooth battery charger | Yes |
| Orion 48/12-60 | 38 to 66 V | 7.6 V | 60 A; factory set 13.2 V, adjustable 10 to 15 V | No |
At the low end, the Orion-Tr models shut down at 28 volts and restart at 30. The 48/12-60 shuts down at 38 volts and restarts at 40. Either way, the converter keeps running as the pack drains.
Which one fits your cart:
- Accessories only, no 12 volt battery: an Orion-Tr 48/12 in the size that fits your load.
- A 12 volt accessory battery you want charged properly: the Orion-Tr Smart. Victron says the plain Orion-Tr is not meant for battery charging and points to the Smart for that job.
- More than 30 amps of 12 volt load: the Orion 48/12-60, if you wire it as described below.
Isolated or non-isolated
In a non-isolated converter, the 48 volt side and the 12 volt side share one negative. In an isolated converter they are separate. Victron rates the Orion-Tr isolation at 200 volts DC between input, output and case.
Why that matters on a cart:
- Negative wiring. A non-isolated converter's negative must land on the load side of your battery monitor shunt and of any BMS that switches the negative. Otherwise the 12 volt current bypasses them. Many carts also ground 12 volt accessories to the frame, which ties the frame to the pack negative through the converter.
- A loose negative. Victron's manual for the 48/12-60 says to connect the negative cables first and warns that a bad negative connection could cause output overvoltage.
An isolated converter avoids both. That makes the Orion-Tr the default for most carts. Choose the 48/12-60 when you need more than 30 amps. Wire its negative first, and use a solid connection on the load side of the shunt.
Size it to the 12 volt load
Add up everything on 12 volts that can run at the same time. Use the amp rating on each device's label or its fuse size. For example:
- LED light kit: 8 A
- Bluetooth sound bar: 6 A
- Two USB chargers: 3 A
- Fan: 2 A
That is 19 amps. A 20 amp converter would run at its limit all evening. Choose the 30 amp model. Leave about a quarter of headroom as a habit.
Mind the heat. Victron rates the 20 and 30 amp Orion-Tr at 40 °C (104 °F) and derates them 3 percent per degree above that. Under a seat in a desert summer, mount the converter where air can move around it.
What it costs the pack is small next to the drive motor. An Orion-Tr 48/12-30 at full output draws about 8 amps from a 51.2 volt pack. A 48/12-60 at full output draws about 17 amps. Wire the remote on/off terminal to the key switch so the converter sleeps when the cart is parked. Victron lists the Orion-Tr at under 200 microamps when it is switched off that way.
Fuse both sides
The 48 volt input. Fuse the converter's positive lead at the pack, close to the battery. The fuse must be rated for more than 58.4 volts DC. Many common automotive fuses are rated for 32 volts, which is not enough. Our MEGA-fuses are rated 80 volts, from 40 amps up, and mount in the MEGA-fuse holder. Victron also sells 58 volt MIDI fuses marked for 48 volt products. We still use the 80 volt MEGA-fuse here, because 58 volts is below a 16-cell pack's 58.4 volt end of charge.
The 12 volt output. Fuse the converter's output lead where it meets your 12 volt fuse block, then fuse each accessory circuit. On a 48/12-60, an 80 amp MIDI-fuse in a MIDI-fuse holder on cable rated above 80 amps covers its 60 amp continuous output.
The cable. The 20 and 30 amp Orion-Tr terminals take up to 6 AWG. The 9 amp model takes up to 10 AWG. Size each run with our cable and fuse sizing chart, and remember the fuse protects the wire, so it must never be larger than the wire can carry.
Know your real state of charge
Lithium voltage barely moves across most of the pack's range, so a voltage gauge tells you little about what is left. Cartaholics has a string of threads from owners fighting cheap shunt monitors.
The Victron SmartShunt runs on 6.5 to 70 volts, so it reads a 51.2 volt pack directly. It shows state of charge, current and time remaining in the VictronConnect app over Bluetooth. Install it on the pack negative, with the motor controller and the converter on its load side. Choose the 500, 1,000 or 2,000 amp version above your controller's peak current rating. Our SmartShunt install guide walks through the wiring and settings.
If your cart has Club Car's factory lithium
Club Car's factory lithium carts charge through Club Car's own Smart Charging System, which works with the cart's vehicle control module. Owners on the golf-cart boards report that those factory packs need Club Car's own charger, and Club Car's pages do not say other chargers are approved, so check with your dealer before swapping in an aftermarket charger. Everything above about 12 volt converters, fusing and monitoring still applies to the accessory side.
Quick picks
- LED lights and USB only: Orion-Tr 48/12-9 or 48/12-20.
- Lights, a sound bar and fans: Orion-Tr 48/12-30.
- A separate 12 volt battery: Orion-Tr Smart 48/12-20 or 48/12-30.
- More than 30 amps: Orion 48/12-60, negative wired first and on the load side of the shunt.
Related guides
- 12V vs 24V vs 48V electrical systems
- Why a 12V fuse keeps blowing
- Victron DC cable and fuse sizing
- A SmartShunt on a pontoon boat's lithium battery
Send us your cart's make and year, the pack's cell count and the charger's output voltage, and a list of your 12 volt accessories. We will tell you which converter fits. Everything ships from Upland, California, and local cart owners from Laguna Woods to the Coachella Valley can pick up at the counter.