Batteries

[Moodysailor]

I am far from an expert on the matter but isn't this what a DVSR is supposed to sort?

To a point, but not quite. Assuming the vessel in question has this fitted, all it will do is kick in when the voltage in the start batt reaches the threshold. It won't affect or impact the charging current.
I am certainly not an expert either, so it could be fine. I'm just not a fan of mixing technologies that have different charging requirements when the charging systems are really quite simple and can't differentiate.
There are more knowledgeable than me on this subject matter on this forum, so please take my opinion as exactly that.

 

[BabaYaga]

Different battery types absorb charge at different rates so whilst one charger maybe within the voltage range for both types the charging profiles will be slightly different for each.

Anyone concerned with potential damage or shorter lifespan from mixing batteries with different charging profiles may also consider the drawbacks of charging in parallel battery banks of vastly different size/Ah capacity – even with the same technology.
For instance a small or medium sized starter battery and a house bank of several hundred Ah's.
If the charger uses tail current as part of the calculation for deciding when to go from absorption to float, then the starter battery (often only very lightly discharged) will spend an unhealthily long time at high voltage. Especially so, if the charger is a bit undersized in relation to the house bank.

I am far from an expert on the matter but isn't this what a DVSR is supposed to sort?

A VSR will certainly help to fan the problem outlined in this post.

All this is also just one persons opinion, of course.

FWIW, I used for 11 years a small AGM starter battery together with a wet sealed leisure battery bank of 240 Ah. These were only ever charged in parallel by engine alternator, usually for an hour or less.
I renewed the AGM starter battery earlier this year as a precaution, as the resting voltage had begun to sink towards 12.5V. It never failed to start the engine.