Can I use cordless telephone batteries in a model?

[MillenniumFalsehood]

I want an internal power supply for a model, but it's a Trek TOS Bird of Prey which has a fairly smooth surface, so no way to hide a battery hatch. We just replaced our old cordless phones with new ones, and I was wondering if there was a way to utilize the battery system in this model. I thought perhaps I could use the 'disposal tube' on the aft as a recharge port, but I wonder if there is some sort of circuit which is necessary to charge the batteries. If not, the GREAT, but if so, I'll need to come up with a better plan.

[Umi_Ryuzuki]

Utilizing it is easy, strip the wires and solder it into your ciruitry.

... However,...

If the batteries are nicad, then it may be, that the phone batteries had to
be replaced because the pack is not holding its charge. The batteries could
also have built up a memory, in which case, they will not discharge energy.
Or, the pack has been over discharged, left dead too many times, or too long,
and a cell has reversed, disabling the entire pack. Recharging the pack in
any of these cases becomes problematic, and would require access to the
battery to replace the pack.

Nickel Metal Hydride batteries would not suffer these issues, but the charging
rates are a bit more specific, and an automatic charger is usually recomended.

Lipo batteries are in every way a different animal. If it is over discharged, it
could cause a fire. If it is over charged, it could cause a fire. If it is
shorted out, it could cause a fire... Which is why very specific chargers
and sensors are required to manage Lipoly batteries.

.

[naoto]

Speaking of batteries and discharge rate... I recall how hot standard AA batteries got when running one of those mini-4WD cars (like the ones from Tamiya) for a minute or two when using one of those high-RPM motors (the ones with the heatsink). Not brave enough to see what it would be like with Lipo cells...

[MillenniumFalsehood]

We didn't replace them because they didn't hold a charge, we replaced them because we wanted new phones. I'll check out which type they are.

[JMChladek]

Just remember most nicad (and NIMH) battery cells are 1.2 volts each while alkaline batteries are 1.5 volts. So keep that in mind with the total voltage when you select your power source. As such, 5 Nicads will have the same voltage as 4 alkalines.