Start with a warning about the words themselves. Battery University uses trickle charge, float charge and maintenance charge largely as synonyms — names for the small charge that compensates a battery's self-discharge. They are not three different products. The consumer distinction between a 'trickle charger' and a 'smart maintainer' comes from the charger makers, principally Deltran (Battery Tender). A guide that pretended Battery University defines the retail categories would be making it up.

One Battery University rule covers the in-between cases: if your charger stays at the topping voltage and does not drop below 2.30V/cell, take it off after 48 hours.

Battery University's name for the standard lead-acid method is CCCV — constant current, constant voltage. A regulated current raises the terminal voltage until the charge-voltage limit is reached; the current then falls away as the battery saturates. Power-Sonic's technical manual describes the same three-stage approach for its sealed lead-acid range.

The charge-voltage limit is 2.30–2.45V per cell; Battery University's three-stage summary limits charge to 2.40V/cell (14.40V on a 12V battery), then lowers it to a float of about 2.30V/cell (13.8V). Total charge time on this profile is 12–16 hours. Charge voltage is temperature-compensated at −3mV/°C per cell, and once a battery is saturated it should not dwell at the topping voltage for more than 48 hours before dropping to float.

Makers count 'stages' differently, and the counts are not comparable: Battery University's model has 3, Deltran's ISM program has 4, Clore publishes 7 phases, CTEK 8 steps — and NOCO, Schumacher and OPTIMA publish no stage count at all. A bigger stage number is a different slicing of the same process, not a quality ranking.

For a single automotive or deep-cycle lead-acid battery, the published guidance clusters around 0.1C–0.3C — on those rules a 100Ah battery points to roughly 10–30A, with Trojan's tighter deep-cycle rule at the low end (10–13A). Bigger is faster, not better: the topping stage still takes the time it takes.

Maintainers are a different sizing problem: they only have to offset self-discharge at float. Deltran rates its 0.75A Junior for batteries of 3–30Ah, and points to its 1.25A Plus for batteries larger than 30Ah or vehicles with high parasitic draws — both figures are in the model tables below.

Battery University's storage rules are the whole argument: lead-acid batteries must always be stored in a charged state, with a topping charge every 6 months to stop voltage falling below 2.05V/cell and causing sulfation (the requirements can be relaxed somewhat for AGM). A sealed lead-acid battery can be stored up to 2 years, recharging when it falls to 70% state-of-charge — about 2.07V/cell, or 12.42V for a 12V pack. Trojan's storage guidance agrees in substance: flooded batteries fully charged before and during storage, never stored discharged, kept in a cool, dry place, and recharged before returning to service.

• Seasonal machines: motorcycles, ATVs and side-by-sides, personal watercraft, snowmobiles, boats.
• Stored vehicles: classic and collector cars, RVs, spare and standby batteries.
• Seasonal equipment: electric-start lawn tractors and zero-turn mowers — Deltran's list, and it matches the storage problem exactly.
• Chronic underchargers: city-driven cars whose engines idle at low speed and never saturate the battery, and solar or wind banks that do not always provide a full charge.

A maintainer simply automates Battery University's six-month topping charge — that is the entire product category, honestly described.

NOCO's guides describe chargers that can be left connected indefinitely: after a full charge the unit keeps monitoring and provides 'ongoing maintenance and optimization', with auto-memory returning to the last selected mode. The chargers detect batteries as low as 1 volt; Force Mode (press and hold five seconds) starts charging when voltage is too low to detect — and NOCO's own guides warn that Force Mode disables safety features, with live power present at the connectors. An integrated thermal sensor adjusts charging for ambient temperature. Every lithium mode below is for batteries with a Battery Management System (BMS) only. One honest absence, stated plainly: NOCO publishes no charging-stage count, no spark-proof claim, and no UL/ETL safety listing for this line in the documents we reviewed (its guides carry an FCC Part 15 statement). That is an absence in the published material — not a judgement on the products.

The current North American model is the MXS 5.0 NA (item 40-206). The MUS 4.3 TEST&CHARGE is a separate, older model that is easy to confuse with it; the two are listed separately here and never merged. CTEK's 8-step program ends in its patented Float/Pulse maintenance. Regional warning: the European MXS 5.0 carrying the same name is a 5A unit — the North American one is 4.3A, and North American readers should shop the NA specification. CTEK sells lithium charging as a separate model (LITHIUM US) or in the dual-chemistry NXT 5; the MXS 5.0 NA does not charge lithium.

The SC series is Schumacher's current microprocessor-controlled line (the older Ship 'N Shore SpeedCharge SSC models no longer appear on its site; the Ship 'n Shore name survives on the SC1360). Three line-wide cautions. No model checked publishes a charging-stage count — only 'multi-stage'. No spark-proof claim is published for any model checked; reverse hook-up protection is the published protection. And 'float mode monitoring' is published only for the SC1308L, SC1361 and SC1360 — the maintainer-class models below say 'smart trickle charge' instead, so the two phrases are kept separate in the table. Watch the specs tables: on several models the specs table's battery-compatibility field reads only 'AGM' while the same page's description lists more types; both are shown where they differ.

Pro-Logix chargers are fully automatic and microprocessor-controlled. Where a phase count is published, it is 7 charging phases, ending in an Enhanced Maintenance Mode: after a full charge the unit rests and monitors the battery, then exercises it — applies a load to simulate active use — and restores it to full charge. Clore does not call this 'float', and neither does this guide. The Recondition Mode and the ability to charge a battery reading zero volts are maker claims, weighed in the desulfation section.

OPTIMA's current lineup page lists only the '+' generation — D200+, D400+ and D1200+ — which adds 12V lithium (LiFePO4) charging. The original Digital 400 and Digital 1200 have no product pages in the current lineup and appear to have been superseded; their specifications below come from OPTIMA's official support page and blog, and the two generations are listed separately so their specs are never merged. Line-wide: OPTIMA publishes no charging-stage count and no UL/ETL safety listing on the pages checked, and no OPTIMA charger page checked lists gel as compatible.

Every Battery Tender below runs Deltran's ISM (Infinite Sequential Monitoring) program — four stages: Initialization, Bulk Charge, Absorption, then Float Maintenance, in which a precisely regulated micro-current holds the battery at peak voltage indefinitely, 24/7. Deltran publishes no numeric float voltage for any model. The classic Plus and Junior are lead-acid only; lithium (LiFePO4) support appears only on the selectable Multi-Chemistry models, via a manual chemistry selector. Deltran publishes no desulfation mode — its stated position is prevention, quoted in the desulfation section. Models publish spark-proof connection technology, reverse-polarity protection and ETL/CETL certification unless a row says otherwise.

Every BatteryMINDer is sold as a charger–maintainer–desulfator; the desulfation wording in its row is the maker's claim and is weighed in the desulfation section below. The maker publishes no numeric float or maintenance voltage for any model, and no UL/ETL listing on the pages checked (FCC certification and California CEC items are published per model). All four models carry temperature-compensated maintenance and the same warranty pattern: a 1 Year 100% Money Back Guarantee plus a 5 Year 'No Hassle' Warranty.

Both sides agree on the chemistry. Battery University: sulfation occurs when a lead-acid battery is deprived of a full charge. Small sulfate crystals form in normal use and are not harmful; during prolonged charge deprivation, the amorphous lead sulfate converts to a stable crystalline form that deposits on the negative plates, growing large crystals that reduce the battery's active material — and with it, performance.

What makers claim. Every item below is a maker's claim, in the maker's own framing. Inclusion is not endorsement.

• CTEK — a “patented desulphation” first step that pulses current and voltage to remove sulfate from the plates and restore capacity; its separate RECOND step raises voltage to create controlled gassing that mixes the acid.
• NOCO — Repair Mode for “old, idle, damaged, stratified or sulfated batteries”; a support page describes the mechanism as high voltage and low current melting down sulfation; conditioning runs up to 16.5V for up to four hours. NOCO's own hedges travel with the claim: “Not all batteries can be recovered,” and its caution that this mode uses high charging voltage, may cause water loss in flooded batteries, and the battery should be disconnected before using it. (Note: high voltage + low current resembles Battery University's controlled-overcharge remedy for early soft sulfation far more than it resembles pulse desulfation — the word “repair” covers different mechanisms from different brands.)
• BatteryMINDer — the strongest claims here: “100% Full-Time U.S. Patented Pulse-type Desulfation” that keeps lead-acid batteries free of sulfate or “dissolves sulfate completely in older batteries”; the 1500 adds that its desulfation “can help extend a battery's life up to 4 times its normal life.”
• Schumacher — a desulfation feature that “detects and removes sulfation” (SC1355) and reconditioning functions on the engine-start combos.
• Clore — a Recondition Mode, activated when sulfation is detected, that “rejuvenates distressed batteries”; also the claim that its chargers can charge even zero-volt (totally dead) batteries.
• OPTIMA — support-page claims that its chargers recover deeply discharged batteries “discharged to as low as 1.25 volts” ⚠ (another OPTIMA page says 2.5 volts — the maker contradicts itself) and extend battery life “by inhibiting and breaking up sulfation.”
• Deltran — the counter-position, from a maker: it publishes no desulfation mode, and states that sulfation in stored vehicles, once significant, “cannot be dissolved or reversed by any charger”; its products work by preventing sulfation from forming, through continuous float maintenance.

What independent sources say.

• Battery University, BU-804b, on pulse anti-sulfation devices: 'Such technologies will lower the sulfation on a healthy battery, but they cannot effectively reverse the condition once present. It's a 'one size fits all' approach and the method is unscientific.'
• Battery University, BU-403, on pulse charging generally: 'The results are inconclusive and manufacturers as well as service technicians are divided on the benefit.'
• The same source warns that applying random pulses or blindly inducing an overcharge can harm the battery by promoting grid corrosion; that some battery manufacturers do not recommend the treatment because it tends to create soft shorts that increase self-discharge; and that the pulses contain ripple voltage that heats the battery.
• The published test literature is thin. The most directly on-point study (Ohajianya et al., 2021) ran a high-frequency pulse desulfator on four 100Ah gel batteries for ten weeks and reported capacity improvements of 89.5%, 75.9%, 1.6% and 1.4% — two batteries barely changed; the bank was being charged by a photovoltaic system at the same time, with no pulse-free control bank, so the gains cannot be cleanly credited to the pulses; and the authors themselves open by noting there are 'little or no systematic studies' evaluating whether these products do what their makers claim. No standards body — IEEE, BCI, SAE or UL — test protocol or endorsement of pulse desulfation was found.

• BMS only: NOCO's lithium modes are explicitly 'for use on batteries with Battery Management Systems (BMS) only' — the caveat is NOCO's own and applies across its line.
• Lithium does not take lead-acid float: Deltran builds its Multi-Chemistry models with a separate lithium maintenance protocol precisely because, in its reasoning, lithium does not tolerate the float maintenance lead-acid requires; Battery University agrees in principle — li-ion cannot absorb overcharge and receives no trickle charge.
• Never RECOND a lithium battery: CTEK warns against applying RECOND to lithium (NXT 5) and to GEL or AGM lead-acid (MXS 5.0) — RECOND is a controlled-gassing lead-acid step.

The lay of the land in these tables: lithium-capable — the NOCO line, CTEK NXT 5, Schumacher SC1282L/SC1339L/SC1308L (per their descriptions), all three Clore models, OPTIMA's '+' models, Deltran's Multi-Chemistry models, BatteryMINDer 128CEC2. Lead-acid only — CTEK MXS 5.0 NA and EU, MUS 4.3, Deltran's classic Plus and Junior, BatteryMINDer 1500/2012/2012-AGM, OPTIMA's legacy models. Lithium-only — CTEK LITHIUM US. Unresolved — Deltran's Weather Resistant 800mA, whose own page contradicts itself (see its row).

Schumacher publishes UL/cUL listings for the SC1339L, SC1361 and SC1308L (File E32074) and DOE/FCC certifications across the line. Deltran publishes ETL/CETL certification line-wide, with CEC and DOE listings published on some models (e.g. the Power Tender 5 Amp). BatteryMINDer publishes FCC certification and California CEC approval or certification on individual models, but no UL/ETL listing on the pages checked. NOCO, Clore and OPTIMA publish no UL/ETL safety listing on the pages and documents checked — NOCO's guides carry an FCC Part 15 statement, and Clore's shared manual carries FCC Part 15 and ICES-003 statements, which are electromagnetic-compatibility statements, not safety listings. 'Not published' means the maker does not state it in the material reviewed. It is not a claim that a product is unsafe.

Spark-proof and reverse-polarity claims are also unevenly published. CTEK (MXS 5.0 NA, LITHIUM US), Deltran, OPTIMA and BatteryMINDer publish spark-free or spark-proof claims. Schumacher and Clore publish reverse-polarity protection but no spark-proof claim. NOCO publishes neither as a claim: in its guides, reverse polarity appears only as an error diagnostic (an error LED). We report the publishing, not the engineering.

• Daily driver that sits a few days at a time — a 4–5A smart charger that also maintains: NOCO GENIUS5 (5A, charges to 120Ah), CTEK MXS 5.0 NA (4.3A), Deltran Power Tender 4 Amp or 5 Amp, OPTIMA D400+ (4A).
• Winter storage, motorcycle or powersports — the ≤1.25A maintainer class, sized for small batteries: Battery Tender Junior 0.75A (3–30Ah), Battery Tender Plus 1.25A (14–80Ah), BatteryMINDer 1500 or 2012, Clore PL2112 (1A), NOCO GENIUS1 or GENIUS2.
• Winter storage, car or boat — Plus 1.25A, GENIUS2 or GENIUS5, MXS 5.0 NA (maintenance charging to 160Ah), or the BatteryMINDer 128CEC2 if several batteries share one bench (maintains up to 8).
• Deep-cycle bank — RV, marine or golf — size by the 0.1C–0.3C cluster, then pick from the verified higher-output units: Deltran PowerPlus 12V (26A, for 40–400Ah), NOCO GENIUSPRO25 (to 1,000Ah), Clore PL2320 (20A), GENIUSPRO50 (to 2,000Ah).
• Charging plus engine starting — only two profiled lines offer engine-start functions: Schumacher SC1361 (50A start) and SC1308L (100A start), with their spec-sheet conflicts shown in the Schumacher table.
• Several batteries in storage — NOCO GENIUS2X2 or GENIUS2X4 for independent banks, or BatteryMINDer's parallel maintenance: up to 4 batteries (1500), 6 (2012 / 2012-AGM) or 8 (128CEC2), with Y-connectors sold separately.
• Workshop and power-supply work — Clore PL2310 (0–10A supply) and PL2320 (0–20A supply, published for holding voltage during ADAS recalibrations); NOCO GENIUS10's Supply mode and the GENIUSPRO Supply modes — with the PRO supply-rating conflicts footnoted in the NOCO table.

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• Stage counts: NOCO, Schumacher and OPTIMA publish no charging-stage count at all, and BatteryMINDer's Model 1500 page doesn't state one either (a sibling page calls it a seven-stage charger). Where a count appears in these tables, it is the maker's.
• NOCO publishes no spark-proof claim and no UL/ETL listing for the GENIUS line in its official documents (an FCC Part 15 statement only).
• Float voltages: Deltran and BatteryMINDer publish no numeric float or maintenance voltage for any model — their behaviour is described in words only.
• Maker pages that contradict themselves, all flagged in the tables: OPTIMA D1200+ charge current (15A vs 12A); Schumacher SC1339L (10A vs 2A) and the Schumacher specs tables that list only 'AGM'; NOCO GENIUS2/GENIUS5 input voltage (datasheet vs guide) and the GENIUSPRO supply ratings (product page vs guide); CTEK's NXT 5 manual file named 'NA' containing EU specifications; Deltran's Weather Resistant 800mA (lithium yes/no, IP67 vs IP65) and Deltran page titles that name the wrong models — we went by body text and SKU; NOCO's GENIUS2X4 product page body naming the GENIUS2X2; BatteryMINDer temperature-sensor ranges that differ between a page's features text and its own spec table.
• Desulfation and recovery modes are unproven — the full evidence is in the desulfation section above.

Sources: manufacturers' official product pages, datasheets and user guides (no.co, ctek.com, schumacherelectric.com, cloreautomotive.com, optimabatteries.com, batterytender.com, batteryminders.com) and Battery University (BU-401, BU-403, BU-415, BU-702, BU-706, BU-804b), checked 2026-11-02.