AGM battery charging question

[Harry Bloomfield]

Damian brought next idea :

Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a good
maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years ago
and use as a battery charger as well. By manually manipulating the volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two batteries
are identical in size, condition, etc it's bad news for both batteries. But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks

The only difference between a pair of matching 6v batteries and a
single 12v battery, is that the latter is in one package, basically the
cell links are internal. If both are matched with age, present state of
charge, general usage - then no reason why they shouldn't be linked and
charged as a 12v unit.