A maintainer is not a charger in a hurry · review

Dino KRAFTPAKET 4 A 6/12 V automatic charger review

A maintainer with a battery tester built in: it names the chemistries it supports, holds a float charge, and remembers its programme after a power cut.

By Jean-Benoit Buisson

The bottom line The maintainer to leave on a standing car. Slow on purpose, and it names what it supports.

What lands on the bench

A 4 A automatic charger covering 6 V and 12 V, with a float stage, a voltage tester and a memory function.

Why 4 A is the right number here

A maintainer is not a charger in a hurry. Its job is to hold a parked battery at rest for months, and a low current does that without heat. For a flat 90 Ah battery it will be slow — which is the correct trade for the job it is bought to do.

The chemistry list is the specification

Lead-acid, wet, MF, gel and AGM, including start-stop batteries. A charger that does not name AGM should not be used on one, and this is exactly the sentence to look for on any model.

The small feature that matters most

Memory after a power cut. A garage socket on the same circuit as a freezer is not a hypothetical, and a charger that resumes by itself is one you can genuinely leave.

Availability

On sale from 29 € to 42 € on the German, French, Italian and Spanish Amazon stores at the time of checking.

Listed but with no offer on the American Amazon store — the reference exists there and nobody is currently selling it.

Not found on the British Amazon store, where the buy link falls back to a local search rather than to a page that does not exist.

Prices and availability are what Keepa reported on the date this page was updated; both move.

Prices quoted in this text were read on 4 September 2026. The live price is at the top of the page.

What we like, and what we don't

Strengths

Names its chemistries individually, including AGM and start-stop — the specification that decides suitability
Float charge, which makes it a maintainer rather than only a charger
Memory after a power cut: a charger that resumes rather than stopping silently overnight

Compromises

4 A is slow for a large battery — this is a maintainer first
No 24 V
The built-in tester shows voltage only, not state of health

Specifications

Voltages	6 V and 12 V, stated
Current	4 A, stated
Chemistries	Lead-acid, wet, MF, gel and AGM — stated, including start-stop batteries
Battery tester	Displays battery voltage; works on 12 V batteries without mains power, stated
Float charge	Stated
Memory	Restarts in the last used programme after a power cut, stated
Amazon reference	B07KSFBMXF (same reference on 5 Amazon marketplaces)
EAN	4003342177962

Questions people actually ask

Can I leave it connected all winter?

That is what a float stage is for, and the maker states one. A charger without float should not be left connected; this is the distinction worth checking on any model.

Why does memory after a power cut matter?

Because a charger that stops and waits after a brief outage leaves a battery uncharged for a week without telling anyone. Resuming automatically is the behaviour you want on a car in storage.