CVT552 High Power Mobile Chargers

The Prepair CVT552 mobile battery charger is designed to be used for charging of heavy-duty batteries on rail and other plant where a standard workshop unit cannot be brought to the battery or where a fixed workshop charger is not available. The charger is designed for use outdoors in bad weather but should then be brought indoors to allow any accumulated moisture to dry out. One hours running off load inside a dry workshop will normally be sufficient.

The photographs on the previous page show a pair of units and the main features of the bodies. Other arrangements are available to order, we can offer a high degree of customisation on this sort of equipment.


The CVT552 mobile charger comprises a high-power, fully rated constant voltage charger, contained in a rugged chassis and casing which is designed to stand up to railway use, probably the most severe test of any equipment.

The charger section is rated continuously at 30 Deg C ambient, and is a half-controlled thyristor system for single-phase or fully controlled thyristor for three-phase operation. A further control unit provides overvolt and alarmed shut-off of the charger should the output voltage go over a preset limit, the output circuit being disconnected at the output contactor. A top-mounted lamp shows whether the charger is connected and charging or shut off, it also flashes if the disconnect function has been activated.

Output smoothing is standard on all our chargers, and the units will operate without battery if required, as stand alone power supplies. Wiring is heavy-duty flexible stranded type with hexagon-crimped copper-tube terminals onto bolted connections throughout. Because the operating control systems are different on the three-phase units, the PCB's are wired differently but generally they are recognisably similar to the single-phase units.

Indicators are provided for AC ON, CHARGE, INHIBIT and FAULT. The mains isolator and output control switches are all grouped on the front panel, and the AC input MCB is also located behind a small Makrolon® cover alongside the input isolator.


The system is built around a 3mm sheet steel chassis, to which all the main components are bolted. (We do not use anything other than threaded fasteners, and all are either stainless steel or zinc plated) A 32mm diameter axle is bolted underneath the main chassis, and this is braced by a rugged mounting bracket. Steel wheels with solid rubber tyres finish off the underframe.

On top, the main components including the transformer, choke, capacitors, thyristor stack and heatsink are all grouped inside the main chassis for protection, and the whole assembly is covered by a 16g/1.5mm sheet steel body and cover. Two 12mm stainless-steel rods pass through the chassis and body and are taken out to the lifting eyes on top. All forces are taken directly to the chassis frame, the body does not take any of the weight when lifting the unit. Cooling of the unit is by two fans, both ball-bearing types for long life, one on the thyristor heatsink and the other evacuating the body area to the outside.


The chargers are available with either single phase or three phase inputs as standard , or we can offer 110V or 415V AC inputs as options. Note that operation at 110V input effectively more than doubles the required AC supply current compared with 240V input.


The chargers will operate on any type of battery that will accept the rated output of the charger. Typically, vented Lead-Acid and Nickel-Cadmium types are usual, but we have had specialised versions of this charger system operating on Lithium-Ion batteries in series-parallel assemblies.

We recommend that batteries have no more than 4 X the rated output of the charger for a fast charge, or up to 10 X the rated output for slow and overnight charging (200AH and 500AH for a 50A output charger.)


The standard units have approximately 20 metres of 3 or 4-core HOFR Tough Rubber Sheathed flexible cable for the mains input, and approximately 5 metres of 2-core 16mm sq HOFR cable. Input connectors can be supplied, and most of the standard output connectors can be supplied to suit, or we can design and manufacture special outdoor connectors.


The CVT552 Mobiles are used mainly on Rail applications, and are the standard charger for the Class 66 Freight locomotive, and the Virgin Voyager train set. Other applications have included electricity substation battery support, and underwater/subsea battery charging.


The chargers are available with the following standard outputs:
29V 100A
29V 200A with dual-current control (100/200A)
72V 50A (Class 66 and 67)
90V 50A
110V 50A
Dual 90/110V 50A

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Contact us: Phone: +44 (0)1582 455000 Fax: +44 (0)1582 416000 Email:
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