I wouldn't. They need to be charged in different ways. The best you could hope for is reduced battery life and the worst is exploding batteries.
Why risk it just get another charger
"One of the Nickel-Cadmium's biggest disadvantages was that the battery exhibited a very marked negative temperature coefficient. This meant that as the cell temperature rose, the internal resistance fell. This could pose considerable charging problems particularly with the relatively simple charging systems employed for lead-acid type batteries. Whilst lead-acid batteries could be charged by simply connecting a dynamo to it, with a simple electromagnetic cut out system for when the dynamo is stationary, or an over current occurs, the nickel-cadmium under a similar charging scheme would exhibit thermal runaway, where the charging current would continue to rise until the over current cut out operated or the battery destroyed itself. This was the principal factor that prevented its use for engine starting batteries. Today with alternator based charging systems with solid state regulators, the construction of a suitable charging system would be relatively simple, but the car manufacturers are reluctant to abandon tried and tested technology. In any event, nickel-cadmium technology is falling out of favour."