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Reverse polarity protection, named outright

Osram 20 W BATTERYcharge SOLAR, aluminium frame, 3 m lead, reverse polarity protection

A 20 W solar battery maintainer for 12 V batteries in an aluminium frame, with reverse polarity protection, a 3 metre lead, a 12 V plug and battery clips.

Osram BATTERYcharge SOLAR 20 W panel in an aluminium frame

Osram 20 W BATTERYcharge SOLAR, aluminium frame, 3 m lead, reverse polarity protection

A 20 W solar battery maintainer for 12 V batteries in an aluminium frame, with reverse polarity protection, a 3 metre lead, a 12 V plug and battery clips.

Panel wattage
Up to 20 W from micro-crystalline solar cells in a robust aluminium frame, first and second bullets
Regulation
Nowhere in the listing — no controller or regulation is described
Reverse-current protection
Reverse polarity protection prevents damage if the clips are connected to the wrong terminals, fourth bullet — named explicitly, which no other charger here does
Connection method
Either a 12 V DC plug or battery clips, both supplied, third and fifth bullets
Mounting
Nowhere in the listing — no bracket is described
Cable length
3 m, fifth bullet. It works best in direct sun and will also work in sufficient daylight under cloud, fifth bullet
Amazon reference
B0DG37LMDN (same reference on 6 Amazon marketplaces)
EAN
4062172404570
  • Reverse polarity protection named outright — the mistake everyone makes once
  • Two connection methods supplied, a 12 V plug and clips
  • No regulation or controller described, on a device left connected for months

Best for: A classic car, a caravan or a motorcycle stored over a winter.

≈ £43 / €50
Check price on Amazon

Specifications

Panel wattage
Up to 20 W from micro-crystalline solar cells in a robust aluminium frame, first and second bullets
Regulation
Nowhere in the listing — no controller or regulation is described
Reverse-current protection
Reverse polarity protection prevents damage if the clips are connected to the wrong terminals, fourth bullet — named explicitly, which no other charger here does
Connection method
Either a 12 V DC plug or battery clips, both supplied, third and fifth bullets
Mounting
Nowhere in the listing — no bracket is described
Cable length
3 m, fifth bullet. It works best in direct sun and will also work in sufficient daylight under cloud, fifth bullet
Amazon reference
B0DG37LMDN (same reference on 6 Amazon marketplaces)
EAN
4062172404570

Twenty watts for a vehicle that is not going anywhere.

The protection that gets named

Reverse polarity protection, in the fourth bullet: connecting the clips to the wrong terminals does not damage anything.

Everyone does this once. Usually at dusk, usually in a hurry. Four chargers in this family and one addresses it.

Two ways in

A 12 V DC plug, for a vehicle with a permanently live accessory socket. Or battery clips, straight onto the terminals. Both supplied, and which to use depends on whether the socket stays live with the ignition off.

The frame

Robust aluminium with micro-crystalline cells. A panel that lives on a dashboard or a windscreen through a winter is exposed to frost, condensation and ultraviolet, and an aluminium frame is what is still intact in March.

Honest about the light

Works best in direct sun; also works in sufficient daylight under cloud. Not a promise of full output on an overcast day — a statement that it keeps working, which is the accurate version.

No controller, on a panel left connected for months

Any regulation or controller.

A twenty-watt panel on a car battery sits near the boundary where unregulated charging is tolerable, and this device is meant to stay connected for months. It is the question to ask before leaving it on a classic car over a winter.

And no mounting bracket, so the panel lies where you put it.

Availability

German, French, Italian and Spanish Amazon stores quoted 50 € to 56 € when this page was compiled.

American and British Amazon stores carry it too, priced in their own currency, which the euro range above deliberately omits.

These figures are what Keepa reported on the day this page was last updated. Availability and pricing move without notice.

Prices quoted in this text were read on 16 September 2026. The live price is at the top of the page.

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