When you buy one of the good chargers it will usually come with a variety of connectors in addition to crocodile clips for quick uses. Mine has
1. Croc clips
2. o rings that go on the main cable clamps and have a connector (waterproof) so I can just push it on.
3. o rings that can go on the main clamps but have bare ends (fit to a socket in the main cabin to avoid lifting the bonnets. Do beware of the amp level for the socket you use etc. Not my favourite solution as it needs a lot of fiddling.
Example of connectors I got with mine
[img]
http://frazerpart.com/cdn/shop/products/MXS-5.0-Charge-o-mat_1_300x.progressive.jpg?[/img]
(Not recommending this site or charger just the first right picture i found)
One thing few people have found is that the cables can chafe around the chassis over time which can induce loss shortening the time it keeps charge for. My older S2 can run for weeks after I got the cables through the chassis to the drivers door sorted. They had worn and some electrons were clearly escaping into the wild.
I would agree re fitting a new one and using a conditioner. When choosing the battery include the warranty length in your decision and keep the receipt safe - if it does bork then you can swap it 5 years in etc.
