Another simpler and cheaper way to make a charger, is to build a small triac phase controller with manual voltage control which you can then adjust until your ammeter reads 11A (C/10) or 22A (C/5) where C=amp-hour capacity of the bank which in this case remains the same as for any one of the batteries, namely 110Ah (series connection).
You do get a TRIAC rated at 800V (or even 600V) and 40 Amps. This is called BTA 40-800 and comes in a handy TO-3 pakage that can be bolted onto a heatsink.The metal part of this is also conveniently isolated and does not need any insulating washers, just a thin smear of heatsink compound (Silicone grease).
O.K. you will first have to get hold of the forementioned isolating transformer with a 240V AC output. This output is then passed through the TRIAC (WHICH IS CONTROLLED BY MEANS OF A SMALL PHASE CONTROL CIRCUIT). The phase-controlled output is then fed into a bridge rectifier, ammeter and onto the battery bank. No taps are required on the transformer, as this controller has a very wide range.
(Use fuses or DC rated circuit breakers to safeguard everything as was mentioned earlier).
The only drawback is the fact that it is not an "automatic" charger, but otherwise, it works quite well as long as you keep an eye on it. I recently built one for an automobile battery supplier (November 2007) and so far everything is still O.K.
When you do work on the batteries, just "keep one hand behind your back", so to speak! If none of the positive or negative is connected to ground, then there will not be a shock hazard if you should touch any of the terminals, but don't become too tame! Always be aware what you're busy with when high voltage is present.