Originally Posted by ShinyShoe
......just to be able to get his engine to start when he turns the key...
Which in my book, is pretty fundamental
. After being the subject of a "Mayday" call in the past due to a dud battery, I no longer skimp on batteries. Like I said early on, it's down to your attitude to risk & the depth of your pockets. Personally I think the OP will be fine with a decent automotive battery of the correct CCA/MCA for his engine, that will fit in the available space. I wouldn't expect to pay more than £100 to achieve this. IMHO