Yes, ripple is normal, but the question is how much? You will get REAL high ripple from a home battery charger. DC generators are three-phase units and as a result, ripple is very low, until one of the six internal diodes becomes shorted, then ripple goes very high and can cause radio noise interference, and illusive engine running problems. That also reduces the generator's maximum output to exactly one third of its rated current capacity which is not enough to run the entire electrical system under all conditions.