Hello Allison, sorry to hear of your tribulations. So much good advice being given here so thought I'd pitch in with my ha'penny worth?
Jack mentions about how cars need to be run fairly frequently to keep the battery charged. If a normal car battery is allowed to sit dormant without being fully charged it will rapidly decline and become unable to accept a charge. Then you need a new one! However there's other "stuff" which benefits from the vehicle actually being driven, like brakes etc. Being a diesel you'll have a Diesel Particulate Filter (DPF) on your exhaust. Just to explain this is a device which catches carbon particles (soot) which the engine emits as a result of burning it's fuel. It needs to be able to reduce this to ash (which takes up much less volume and so it can store) to do this it needs to do a "Regeneration". It does this entirely automatically but needs for the engine to be fully up to temperature and to run continuously for maybe 15 to 20 minutes (it varies) If it can't do this eventually it will block up and that's a problem not easily resolved. So take it for a good drive maybe once a month or so - some say it should be every week? - and you're not so likely to have a problem. Also run your Air Con regularly or the seals will tend to dry out and you'll loose the refrigerant gasses. Often once a system starts to leak it's quite difficult to stop it. So just run the Air Con regularly (I have mine on at least once a week and don't get any problems) by the way it doesn't have to be because you want cold air from the vents! You can have it on with the heater controls at hot. Actually if you do so you'll find it demists the screen more quickly too.
Now thinking about jump starting. First off let's think about the jump leads themselves. Generally speaking the very cheap sets you see are a waste of time. With jump leads it's all about being able to pass large currents (amounts of electricity) so small diameter wires or wires made from materials which don't conduct electricity efficiently are a waste of time. Some of the cheap sets use aluminium wire - I had a set like that and it had two problems. The Aluminium wires were brittle and snapped but more of a problem was that the crimped connection between the steel spring clamps and the wire was electrically inefficient so resisted the flow of electricity! I junked them and bought a copper cored set, which, as they too were crimped connections, I then soldered the wires to the clamps for better conductivity. Cheaply crimped connections where high current is being demanded are a big limiting factor and often limit performance on cheap leads. Now soldered these have worked very well indeed on pretty much all petrol engined vehicles I've used them on but they struggled a bit on my 1.9 tdi SEAT Cordoba - just couldn't pass enough electricity (current) they were getting warm to the hand. Then I had a stroke of luck. At work I used to do the 24 hour standby on the breakdown service and our boss bought a new set of jump leads for the breakdown truck. He let me buy the old set for a pittance - Happy Days! Here's a couple of picture of the lead sets:
Just for scale I've got the car keys in the shot. The big thing though is the size of the wire. just look at the wire thickness of the "commercial" black set. You can see also that although the orange set look thick the size of the wire is tiny compared to the black set - you can see how I soldered the wires in the orange set too. Notice the black set also has "proper" bolted connections. The big black set would start commercial vehicles whereas my relatively cheap orange "DIY" set are fine for doing most of the Family cars. (I tend to use the black ones all the time though because they are longer)
Jack also mentions about making your connections (Positive to positive on the batteries then Negative on good jumper to chassis earth/engine block on "flat" vehicle - we could talk a lot about this but let's leave it at that for now) then start up the "good" vehicle and let it "feed" the flat battery for 10 minutes or so. When you see people doing a jump they very seldom do this but it's a very good thing to do. Because, the flat battery, especially if it's very flat, will "soak up" some of the electricity available from the good battery. This can have a couple of detrimental effects. Most obviously there may not be enough "left over" to crank over the vehicle with the flat battery but also the jump leads are going to have to work much harder to pass current to the flat battery and the starter motor at the same time. Although 10 minutes or so of charging before you try to crank the non starter will not charge the flat battery fully it will very greatly reduce the current the flat battery is trying to draw. By the way, always give the clamps a good "wiggle" when connecting to ensure a good electrical circuit is being established. With such heavy current being passed a poor connection can overheat and smoke. Jack advises to run the engine at a fast idle and he's, as usual, so right. Modern alternators charge well at quite moderate revs, often charging quite "enthusiastically" even at idle, so I'd say you shouldn't need to run the engine of the "good" car at much more than 2,000 to 2,500 rpm to achieve a good charging result. Basically don't sit there revving it's head off!
He also mentions Battery chargers and I'm a great advocate of periodically using a good quality charger even if the car is starting fine. If the car isn't going to be driven really regularly I'd say it's a must. If you are going to buy one then get a modern "smart" charger and you can then charge the battery on the vehicle without needing to disconnect any of the car's battery connections. Here's my little collection of chargers:
The big blue and white one I bought back in the '70's and is an old style transformer type and not at all what you want. It charges old style lead acid batteries fine but you must disconnect the main car leads on modern cars or it might damage the electronics. The one on the bottom is a cheap one bought from, as Jack mentions, Aldi/Lidl, I can't remember which, and is an excellent little modern inverter type charger. I've used it on family cars, without disconnecting the car's leads, and it's worked absolutely fine. The one on top is my premium brand CTEK which is very similar to the wee Tronic but has a higher available charge rate (7 amps as against 3.6 amps for the Tronic) and has "clever" advance functions which the Tronic does not. Something like the Tronic would be ideal for most people.
What do you do about servicing and repairs? It sounds like you don't probably do this yourself? If so have you found yourself a nice wee independent garage? Personally I'd advise against "Lightening Fit" "drive straight in" type setups. If you haven't already found somewhere like this maybe one of the Forum members can advise if you say roughly where you are based.
Sorry for the length of post! hope even a wee bit of it was useful?
Regards
Jock
