smart charger for trend air shield

[allan kuntz]

I bought a smart charger for a Trend air shield. The smart charger has a red and black wire but the wrong end to plug into the air shield. I am sure the red wire is the positive. The charger that came with the air shield has a black wire and a black wire with a white stripe. Can anyone tell me is the striped wire the positive. I am thinking of cutting and splicing the right end onto the smart charger. Will I do any damage to the battery if it is backwards

[Steve Peterson]

I have an air shield pro and the charger is 4.2V at 300mA with a diagram showing positive in the center and negative on the outside. Almost all wall wart transformers list the configuration.

Steve