[jclark003]

You may want to first verify that you have an issue with your charger. The Amp meter starting out at 10 and dropping to 3 sounds normal. Start by putting a digital volt meter on the batteries and read voltage with charger off and then on. Typically you should see around 12.2-12.8V with the charger (and engine) off and no/minimal load on the batteries. When you turn the charger back on the meter should show around 13.5-14.5V. Check both banks separately.

As always exercise caution working around batteries. Use eye protection and take care not to drop anything that could short across the terminals.