Dual battery, s

[BigRAWesty]

One thing you need to consider is the loads that will be running off your second battery. If you are running device which pull more than 25A (the 1225 maximum output current) your battery will never charge or will very slowly as the BCDC1225 can't give out enough current.
For example my second battery runs my amplifier, head unit and fridge, which on average draws around 20-25A so with BCDC1225 there would be no current left to charge the battery. Also the BCDC1225 will reduce it's output current if the ambient temperature goes above 55 degrees C which can happen if mounted under the bonnet on a hot day.

You cant just say your applications are drawing 25A and the 1225 is to small.
The fridge for example may draw a maximum of 5a/h but how many amps per hour?? Might have a duty cycle of 20% so in reality it's only 1a/h.. (example only)
Same with amplifiers. They state maximum amp draw. If your only listening to soft music the draw will be much less.

Anyway imo the ctek 1225 is a good choice with a good battery, mounted in the back.
I wouldn't worry about dual battery while winching, you winch with motor running so the alternator is doing most the work..