What sort of battery charger? Is it a regulated one? ie; 'switchmode' or an unregulated one? If unreg, it may supply more voltage at low loads than required. Some of these units can supply anything up to 17 ~ 20 volts with no load so just be a little careful when buying/using them. Just ask for a 'Switchmode' type. They are a little more expensive but well worth it.
Not sure re; the amount of noise it's supposed to make but it's gotta be quieter than a Meade SCT!
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.HTH.
L.