I have a cyrix CT 120A relay between the starter battery and the service battery which is a victronenergy agm deep cycle 110 ah. Obviously the cyrix does a start with the batteries in parallel most of the time, that is, if the batteries are in solar charge or if the batteries are fully charged. In your opinion is it harmful to the agm victronenergy? I believe it is absolutely not harmful, as during start-up, the smartshuunt only marks 30A of absorption on the agm for less than 1 second. I think This is because the resistance of the positive cable in series between the batteries and starter motor means that 80% of the starting power is supplied by the starter battery.In fact starter battery have a much more short and more thick cable, that cause a lot less drop voltage and supply more amps to the motor. But some peaple say me that's is no good.... In fact, the total absorption for starting is about 120A and are divided as follows: 30A on the agm services and 90A on the starter battery. Furthermore, the data sheet of the agm victron says that it tolerates inrush currents of 500 CCA at - 18 degrees, and absorption of 880 amperes for 5 seconds. So 30 amps 2/3 times a day for less than 1 second shouldn't hurt. What do you think? However, I have equipped the cyrix with a switch on the negative of the coil to exclude it during start-up.
