Hi, my motorhome leisure battery doesn't charge when using engine but ok on hookup.

Number 1 tip, when changing batteries, always maintain power to the ECM and other modules using a couple of pieces of wire to the old battery, a battery charger, battery maintainer, or a special gadget that connected a 9 volt PP3 battery to the power outlet socket.

Your radio is controlled by the ignition and a timer (BCM?) and seems to be a known issue. Wire to the leisure battery? Or find a good auto-electrician with a professional grade scan tool computer.
http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Fiat-radio-linked-to-ignition/4779/

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Request the manual from Leisure Time.

A camper is usually fitted with two batteries and a split charge system that isolates the batteries from each other when the engine is switched off. One battery is the standard vehicle type and the other a leisure or semi-traction type to supply the low voltage caravan or camper fittings and appliances.

The caravan battery usually is recharged by a mains operated charging system that would be operational when an onsite mains hookup is connected and the charging/distribution unit generally has a helpful charge/battery state meter.
It is worth noting the output of integrated battery chargers is usually very modest and likely to be able only to maintain the battery charge when the 12 volt lighting and water pump/toilet flush is being used. Additional equipment such as audio, 12 volt tv and especially an inverter will discharge a battery in a fairly short time.

The laws of physics tell us we can't get something for nothing and that is especially pertinent when an inverter is being used. Commercial inverters make big promises; but drawing even a modest wattage can represent a relatively high battery drain - using a fairly ordinary colour tv on an inverter can take a 90 amp/hour battery down in a couple of evenings or less.

Connect With Battery Isolator

did it flip a breaker in the motorhome where you plug in ?

I don't have any info on a Tec2 product, but the basic setup is to put a relay in between the camper battery and the voltage source to charge it. Most of the time the aux battery has a 10 or 12 gauge wire to charge it from the engine alternator and you break the connection with the relay. The relay would be "off" until the engine is running.
Did you get a diagram with the Tec2 ?

Your motorhome should have a converter in it. It takes 120 volts from the shore power hookup and converts it to 12 volts to run your heater and coach lights as well as recharging the house battery. You should make sure it is working properly. You should also have the house battery tested to make sure it's good. The engine battery should not connected to the house battery when the key is off. If it is there is a wiring or relay problem.

have to chance the electrical part of the keyswitch.

As a rule,a trickle charge is for a normal car battery and yours are deep cycle...so one may not be enough to charge 2 batteries here..There is a bit of maths you need to do for it...

It is not your battery overcharging it is your alternater putting out to much juice to the battery. get a new alternater