I haven't gotten around to testing this, but I was just wondering if the guys at PMDG modeled this characteristic of the Ni-Cad battery? I read somewhere that if a Ni-Cad battery is kept near full charge all the time, it tends to lose some of its ability to meet more demanding situations. Sort of like an electric razor, in which you must drain he battery after the first time you use it and then re-charge it.

The battery must meet all the designed requirements all the time, this in hard winter, hot summer, always fully charged or always used from fully charged to ALMOST completely discharged.

The battery charger is here to charge and to limit battery usage when not required, at periodic intervals the battery is sent to the repair shops for a full discharge and charge cycle and in this occasion it will be tested for quality and eventually internal cells will be replaced.

If someone leave the battery on and the battery will fully discharge to 0V, it must be removed and sent to repair as it will be damaged.

Also emergency exit battery packs are used in the same way, they are also most of the time fully charged and rarely used till discharge. The emergency battery packs are nicd batteries.

I think 737 batteries are a little bit more sofisticated than an electric razor :lol:

That makes sense. The book I was reading was referring to smaller turbine aircraft with Ni-Cad batteries. It recommended doing an electric engine start every now and then to avoid the Ni-Cad battery memory issue. Haha I must have forgotten that in the 737, the engines are started pneumatically. Anyways, if anyone is interested in the book I was reading, it's called The Turbine Pilot's Flight Manual by Gregory Brown and Mark Holt. It's a great read. I am referencing pg. 50.

I think 737 batteries are a little bit more sofisticated than an electric razor :lol:

Not true, just heavy and with temperature switch inside.

The big battery used in the 737 is pretty "old" technology, it is a metal sealed case with a cover wich contains all the cells needed to have 26VDC and over 30 AMps/hour of capacity.

Inside the battery a thermal switch connected with battery charger protect the aircraft (and secondarily the battery) from overheating and this avoiding explosions, fire, smoke or acid loss.

 

The engines are pneumatically started but APU could be started using the battery in a cold & dark situation, this letting you to use the battery if you want.