Converter / charger
The converter turns shore power into 12V to run the rig and charge the battery. When the battery dies on shore power, check the converter's output and the path to the battery.
The short version
- Check 120V going in, then DC coming out at the converter.
- If the output is good at the converter but low at the battery, it's the wiring, a fuse or a breaker in between.
- Most converters have reverse-polarity fuses. Battery hooked up backwards = blown fuses.
- Match the charge profile to the battery type, especially after a lithium swap.
On the job
- Shore power on. Meter the battery posts: 13.2 to 14.4 V within a minute.
- No rise: 120 V at the converter input, then its reverse-polarity DC fuses (two or three 30/40 A ATC), then DC at the output terminals.
- Output present but the battery doesn't rise: drop from converter output to battery post under load, under 0.5 V. Check the disconnect.
- Stuck at 13.2 V with a low battery: force boost (PD Charge Wizard button) or set the profile. Lithium needs 14.4 to 14.6 V.
Numbers
- Converter output: ~13.2–13.6V normal, up to ~14.4–14.6V bulk
- Battery on charge: should rise above 13V
- PD Charge Wizard LED: solid 14.4 boost, fast blink 13.6 normal, blink every 6 to 8 s 13.2 storage
- Converter size: about 20% of the bank's Ah (55 A for 200 Ah lead-acid)
Shop tip
Battery reads the same voltage plugged in and unplugged? It isn't charging.
Try it on a service call
Put the lesson to work on a hands-on troubleshooting case.
Keep going on 12V and batteries
Learn it
- Volts, amps and ohms, the simple way
- Voltage drop: the test that finds bad grounds
- Practice: find the bad connection
- Batteries: lead-acid vs lithium
- Fuses, breakers and grounds
Prove it
- Back lights are dim
- Battery dies even on shore power
- Lithium won't charge on cold mornings
- Coach is dead, battery is fine
- Batteries dead after storage