Aircraft Batteries

[flyer07]

Anyone happen to know which would be the better battery...the lead-acid, or the nickel-cadmium? The application would be for a light corporate jet aircraft flying approx. 25-30 hours per month. Temperatures in the aircraft's based region fluctuate anywhere from 30+ Centigrade in the summer to -30 in the winter months.

I've heard of some operators taking out their NiCd batteries and replacing their fleets with lead-acid ones? Just curious why this might be the case.

Thanks for anyone's help!

 

[Mason]

Disclaimer---I'm not a mechanic but here is what I've been told.

Some Ni-Cad batteries have experienced runaway overheating situations..you can draw conclusions what can happen in that situation.

However I've been told that Ni-cads will produce a very steady and stable output but then drop off sharply as they are discharged.

 

[avbug]

Flyer07,

NiCad batteries are much more expensive than lead acid, require more expensive maintenance and more complex maintenance, are susceptible to thermal runaway (a continuous self-perpetuating overheating process that can become critical enough to cause the battery to explode or melt, without control), develop internal memories, and are very much out of favor with most operators.

NiCad's aren't as affected by freezing temperatures, and they die suddenly, not gradally, which can be a limited benifit. Lead Acid batteries tend to wear down at a linear rate; you can see them die as the voltage drops. NiCad will stay at rated voltage until they're nearly depleted, then die off quickly. If this happens during a turbine start cycle, you're going to have to cut it off before you get a hot start. With a Lead Acid, you know what you have before you start cranking as a rule.

Most will advise you to go Lead Acid or newer gel cell types of sealed batteries, such as gas-recomb.

 

[skydivinguy]

Fedex 208 fleet was/is being switched to the Hawker lead acid battery from the ni cads. Lots of cranking power in the Hawkers vs. ni cads (18-19% NG vs 13-15%). It was a good idea to get rid of the ni cads.

 

[flyer07]

Thanks for everyone's help, greatly appreciate it!