What's the difference between NiCd and NiMH battery chargers? What if I mismatch charger and batt. types?

A nickel metal hydride (or NiMH) battery is a type of rechargeable battery similar to a nickel-cadmium (NiCad) battery but which does not contain expensive (and environmentally risky) cadmium. This is why they are sometimes called the most environmentally friendly battery type. NiMH batteries tend to have a higher capacity than NiCads and suffer far less from voltage depression. However, when compared with lithium ion batteries they have a lower energy density and a higher self-discharge rate. They are used in hybrid vehicles such as the Toyota Prius, and electric vehicle development is underway. NiMH batteries perform better with high drain electronic devices like digital cameras and other common electronic devices, while for high torque power tools and other devices that require fast discharge rates, NiCd can outperform NiMH.

NiCad stands for nickel-cadmium, the materials used in the battery packs for many notebook computers. NiCad batteries can provide considerable power, but they need to be recharged every three or four hours. Full recharging can take as much as twelve hours, although newer batteries can be recharged in just a few hours. Older NiCad batteries suffer from a phenomenon known as the memory effect. If they were only partially drained and then recharged, they lost their capacity to be fully charged. This is not such a problem with modern NiCad batteries. Even with full drainage (called deep discharging), all batteries have a limit to the number of times they can be recharged. The maximum for most NiCad batteries is about one thousand recharges. NiMH stands for Nickel-Metal Hydride, the materials used in some battery packs. Unlike NiCad batteries, NiMH batteries do not use heavy metals that may have toxic effects. In addition, they can store up to 50% more power than NiCad batteries and do not suffer from memory effects.

NiCad stands for nickel-cadmium, the materials used in the battery packs for many notebook computers. NiCad batteries can provide considerable power, but they need to be recharged every three or four hours. Full recharging can take as much as twelve hours, although newer batteries can be recharged in just a few hours. Older NiCad batteries suffer from a phenomenon known as the memory effect. If they were only partially drained and then recharged, they lost their capacity to be fully charged. This is not such a problem with modern NiCad batteries. Even with full drainage (called deep discharging), all batteries have a limit to the number of times they can be recharged. The maximum for most NiCad batteries is about one thousand recharges. NiMH stands for Nickel-Metal Hydride, the materials used in some battery packs. Unlike NiCad batteries, NiMH batteries do not use heavy metals that may have toxic effects. In addition, they can store up to 50% more power than NiCad batteries and do not suffer from memory effects.

For the best answers, search on this site https://shorturl.im/avQj1 I'd follow the recommendation on the charger. The K620 is a "dumb" charger with a current output intended for overnight charging of NiMH cells. Your NiCds have a much lower capacity and are intended to be charged at a much lower rate. I have a pile of those chargers that I won't even use on the Kodak branded "white" label (precharged) cells that they came with. The cells themselves aren't bad though. Don