redarc 1220 bcdc duel battery system

[tappethead]

hey team does anyone have any experience with a redarc product known as the redarc 1220 bcdc duel battery charger & isolator DC to DC as we are fitting our troll with a duel battery system and using another redarc product known to many as the SBI12.
the problem is i have been told that the sbi12 wont charge a agm type aux battery properly as the charging characteristics differ from the calcium cranker battery i have. and the solution is to go to the 1220 bcdc or similar.
i find this line of thinking fairly believable but also an expensive option compared to the SBI12.
will the SBI12 damage the expensive agm battery?
thanking you all in advance for your words of wisdom....

[zmaster]

Hi tappethead

I have been using the sbi12 for two years with an agm 100Ah battery in the back of the patrol. It charges with no problem, but it never reaches 100% charge, who cares, it reaches 95%, doesn't bother the battery, it might last 4 1/2 years instead of 5 years, you just need to get a decent agm like a deka marine, it will handle fast charge and deep discharge, some don't like fast charge. It is true that the DC to DC charger is better, but not $500 bucks better, it is designed for long cable runs with small 50amp cables in caravans. The other problem is DC to DC, is it is charging the second battery constantly, OK for long caravan trips, but daily driving could be a worry. I find after a long trip, I take out the agm and run it through a decent 5 stage charger.