12V 20A DC-DC Battery Charger - Lithium and Lead-Acid, RV, Van, Marine

The entry point in Rich Solar's DC-DC range, and the right choice when the limiting factor is the alternator rather than the battery. It converts alternator output into a correct charge profile for a 12V house bank and acts as the isolator between starter and house batteries, so one box does two jobs.

Why this charger

• 20A output, 250W nominal, working range 18-22A.
• A physical mode switch selects 12V AGM, flooded, gel or lithium — no app, no configuration software.
• Two-stage charging for lithium, which will safely reactivate an over-discharged LiFePO4 pack and take it to full. Three-stage for lead-acid.
• Handles both traditional and smart variable-voltage alternators, the latter being the reason a plain isolator relay no longer works on modern vehicles.
• Battery isolation blocks reverse current, so drawing the house bank flat cannot leave you unable to start the engine.
• D+ ignition terminal restricts charging to engine-running conditions.
• LC low-current terminal is genuinely useful on this model in particular — 20A is already gentle, and LC mode lets you go gentler still for a weak or small alternator.
• Over-voltage, over-temperature and reverse polarity protection, with standby draw under 0.6A.

Be aware before you buy

• The D+ cable, LC cable and temperature sensor are not included and must be bought separately if you want those functions.
• The RJ11 temperature sensor adjusts charge voltage for hot or cold weather, but applies to lead-acid only, not lithium.
• Efficiency is stated as above 85% measured at 14VDC and 30% load, which is the manufacturer's most favourable test point.
• At 20A, a 200Ah lithium bank taken to 50% will need roughly five hours of driving to refill. If your drives are short, step up to the 40A.

Choosing between 20A, 40A and 60A

• All three are functionally identical apart from current, physical size and weight. Same 10-16VDC input window, same charge logic, same protections.
• This 20A model suits banks up to roughly 100Ah, older or smaller alternators, and builds where solar does most of the work and the alternator is a backup.
• The 40A (500W) is the common choice for 200-300Ah lithium builds; the 60A (750W) is for large banks with short drive times and an alternator sized to match.

Installation

• 8.4 x 7.4 x 3.1 inches and 4.0 lb — the smallest of the three, which matters in a tight van cabinet.
• Input operating range is 10-16VDC.
• Size cable and fusing for the full 20A on both input and output.
• Mount with clear airflow around the heatsink.

Warranty

• Covered by Rich Solar's standard limited warranty. No specific term is published on the product page; contact us to confirm the current coverage period.