Just a further thought. You may already be aware of this, but it's possible to get a misleading voltage reading on the regulator output. If the capacitor is not doing its job properly there will be a heavy ripple on the output and unless your meter is one of the 'true RMS' variety it could well follow the peak value and therefore give an false high reading. If you can lay your hands on a 'scope to hang across the battery you will see what the voltage actually is and if the electrolytic is properly smoothing the regulator output.