IOTA DLS 12 V Converter/Chargers with IQ4 & IQ-AGM Smart Controllers — Charge Stages, Configuration & Troubleshooting

Overview

The IOTA DLS is the workhorse converter/charger in a coach 12 V system. Fed 120 Vac (108–132 Vac input range) from shore, generator, or inverter bypass, it regulates 13.6 Vdc for the DC loads and charges the house bank up to the model's rated current: 15 A (DLS-15), 30 A (DLS-30), 45 A (DLS-45), 55 A (DLS-55), 75 A (DLS-75), or 90 A (DLS-90). Full-load output stays above 13.4 V. It is a power supply first: with a healthy battery attached it carries the loads and floats the bank; with a discharged bank it delivers full rated current until the battery comes up. Fan cooling is proportional to internal temperature, and the unit protects itself with reverse-polarity fuses, brown-out protection, cycle-by-cycle current limiting, and thermal shutdown.

Installation and connections

Mount indoors in a ventilated compartment with at least 4 inches of clearance at the fan — never zero-clearance, never in a compartment shared with batteries or gasoline, and never directly above a battery where vent gases can corrode it. Connect the AC input before the battery to minimize arcing. DC lugs take 4–6 AWG at 45 in-lb or 8 AWG at 40 in-lb; RV installations require a type III circuit breaker within 18 inches of the battery, and the chassis bonding lug must be strapped to vehicle ground. The DLS-90 needs a 30 A AC branch circuit (21.8 A max draw); the DLS-75 draws up to 18.2 A and ships with a NEMA 5-20P plug.

Configuration: dual-voltage plug vs. IQ controller

The DLS has no dip switches; its behavior is set by what is plugged into the Dual Voltage Jack. Nothing plugged in: fixed 13.6 V float — safe for storage, slow for recharging. The included dual-voltage plug (a jumper) raises output to 14.2 V for occasional fast charging; it must be removed when the fast charge is done or the bank will gas and lose water. Plugging in an IQ4 or IQ-AGM controller (or ordering a DLS with the IQ4 built in) replaces both modes with automatic multi-stage charging; on units with an internal IQ4 the jack is disabled. Use only the cord supplied with the IQ unit, and zip-tie the controller to the DLS case.

IQ4 charge stages (12 V values)

• Bulk — 14.8 V target: full current into the bank, constant-current at first, transitioning to constant-voltage. Runs 225 minutes or until 14.6 V (high trigger), then 15 more minutes, then drops to Absorption.
• Absorption — 14.2 V: up to 480 minutes to top the bank off completely.
• Float — 13.6 V: holds the bank and simultaneously carries load current up to the unit rating. Exits to Bulk if the battery drops below 12.8 V (low trigger) or after 7 days, when the IQ4 runs an equalization pass to break up plate sulfate.
• Overvoltage fault: 15.2 V.

IQ-AGM differences

The IQ-AGM is the same idea tuned for AGM banks: a combined Bulk/Finish stage at 14.7 V for up to 480 minutes, then Float at 13.6 V; low trigger 12.8 V. Instead of equalizing (which AGMs generally cannot tolerate), its 7-day maintenance cycle simply re-runs a bulk charge. Always compare against the battery maker's allowable charge voltages.

Reading the LED

At power-up the LED flashes out the battery cell count (6 flashes = 12 V). Current three-color LED (white when off): solid green = Float; flashing amber = Soak/Absorption (Finish on the AGM); flashing red = Bulk; red triple-flash every 2 s = fault. Legacy single-color green LED (green when off): solid on = Float; slow flash = Absorption; rapid flash (about 2/s) = Bulk; single flash at more than 1 s intervals, or irregular flashing = fault. The LED keeps operating from battery power even with AC unplugged — the IQ continues monitoring and will start a smart cycle when AC returns if the bank has sagged below the low trigger.

Fault state and reset

A voltage irregularity puts the IQ into FAULT: its logic disables itself and the DLS falls back to a plain 13.6 V float, and it will stay there until reset. To reset: unplug AC, disconnect the positive battery cable, wait 30 seconds, then reconnect — AC first, battery second, to avoid arcing at the battery post.

Field diagnosis (IOTA's published steps)

No output/not charging: first verify 110–120 Vac at the outlet. Then isolate the DC side — unplug AC, lift the positive battery cable (do not let it touch chassis), restore AC, and measure the output terminals with the dual-voltage plug removed. 13.6 V means the converter is fine: look for bad crimps, high-resistance connections, or a failing battery pulling voltage down. 0 V means check the reverse-polarity fuses — blown fuses mean the unit saw reversed battery cables; correct the wiring and replace fuses with the identical type and rating (8 in-lb max on the fuse screws; some models use one fuse plus a fiberglass spacer). Below 13 V with good fuses means the converter has failed. Surging or inconsistent output is almost always heat: confirm 4 inches of fan clearance, clear the vents, and verify the fan spins when the case is warm — a warm unit with a dead fan is a failed unit.