Battery not charging

[taffyfester]

I have a four winns 268 vista which has a charging problem.Changed the alternator and batteries but the voltmeter on the dash only reads 11.5 volts and the new batteries appear to be discharging when the engine is running.any suggestions please

 

[sarabande]

Borrow a decent voltmeter and check the output of the new alternator, and the voltage at the batteries when they have been static for about 12 hours, and again when the engine is running.

Is there any electrical gadget between the alternator and the batteries (additional switches, charging regulator, automatic battery selector) which might need checking ?

 

[alan17]

Does the battery warning light on the control panel ljght up when you turn the ignition on. If not maybe the bulb has blown in which case the coils in the alternator are not being energised and therefore it cannot produce any output?