Coolcaringer Engineering - Batteries and Chargers for LED Caving Lamps.

Battery technology has come on in leaps and bounds in recent years. Oldham cells are rugged but heavy (about 7lb) and use Lead Acid technology. Their initial capacity is about 20Ah, dropping to anbout 16Ah after some use. This gives about 16 hours duration on a full charge. Nickel Cadmium cells became popular as they dropped into the space vacated by a defunct cell. These were again of about 20Ah capacity but had a lower couple voltage of 1.25v - a pair in series giving 2.5v.

Dry batteries were never really up to the job until Alkaline cells came along. These offered good duration with small torch bulbs and the Petzl headlamps became an alternative to the Oldham setup. Anyway, enough history...

Today we have rechargeable Nickel Metal Hydride (NiMH) cells with capacities that rival if not exceed that of Alkaline and also Lithium Ion (Li-Ion) batteries which tend to be lighter if a little more volatile. Both types lend themselves to powering LED based lighting.

The NiMH batteries are made up from 2.4 to 2.7Ah AA cells - 3 of them wired in series gives a battery of nominally 3.6v that weighs about 100g. This lasts about 7 hours with a 1 Watt lamp and about 4 hours with a 2W lamp (more if the lamp is run at lower brightness - see the 2W lamp page).

The Li-Ion batteries are slightly longer and use 2 x 1.8Ah cells connected in parallel giving a battery of nominally 3.6Ah and 3.7v that weighs about 82g. These last about 10 hours with a 1W lamp and 5 with a 2W lamp (more if the lamp is run at lower brightness - see the 2W lamp page).

The best bit about these batteries is their weight - 100g or less, allowing the battery to be comfortable mounted on the caving helmet - freeing the user from the constraints of a a waist mounted power source (unless, of course, you want a large capacity battery, in which case, waist mounting becomes attractive again - see the custom batteries page). The picture above right shows a selection of helmet mountable Li-Ion and NiMH batteries (centre, some yellow), and waist mounted batteries in cut-down Oldham and Exide Lead-acid housings.

Chargers...

We have chargers for both NiMH and Li-Ion batteries with both mains and 12v vehicle supplies. Here is a selection of Li-Ion and NiMH chargers. The lower three are for Li-Ion and the upper charger is a smart charger for NimH batteries. Lower right is a custom charger for a waist mounter 11Ah + 2.1Ah combination Li-Ion battery. All thase chargers have charge state indication and automatically charge the batteries.

We also manufacture a more cost effective charger for NiMH batteries built around a plug-top transformer.

The vehicle supply (top) will supply either the NiMH or standard Li-Ion charger.

Left: Top right in this picture is the lower cost NiMH charger and below that, another vehicle supply.

Right: Li-Ion and NiMH helmet mount batteries

Below: Close up of NiMH smart charger and Li-Ion charger.

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