Owned my T2 for nearly 17 years (286 nights away!), and after getting through batteries at the rate of knots have found my ideal solution. Campers place unusual demands on their batteries. 1. Camper is often not used for long periods 2. Camper uses considerable power while on site. Molteni Mike's modifications. 1. Two batteries (NOT leisure ones) bought from a breakers yard for £25 each. They're huge, 70-80AH each. 2. Hardwired the +ve terminals together with heavy duty jumper lead cable. Then sent both earth cables to a heavy duty (300Amp!) "boat switch" placed in a rear cupboard. This gives a choice of OFF - batt 1 - batt2 - both. The choice of using the "earth" for this system is in case of a short circuit, the system is safe. Never ever turn the switch to OFF with the engine running, you'll fry the alternator diodes! I've never used the "both" option as charging more one than one battery in parallel results in the "better" battery only being charged to the level of the "worse" one. 3. Wired a solenoid (standard Leyland starter solenoid) so that when the starter is turning, BOTH batteries are momentarily called into action. 4. When parked in the drive, the electrics are plugged into an "Optimate" charger which safely keeps the battery charged without risk of overcharging. Protocol when away from home. As soon as the vehicle is parked for the night, the battery is "switched" to the other one. In this way the battery just charged by a long drive will be fresh for the following day. The one just connected can be used overnight without concern about the following morning's start. Touch wood, this setup/protocol has worked 100% for several years. Here's a picture of the boat switch, they're about £25 from chandlers. The Optimate charger is about £40 from various suppliers on eBay. The traditional "split charge" system has the "overnight" camper electrics wired to the leisure battery and a relay to charge both batteries together when the alternator is turning. It's a great system when everything is working! But there's a small risk that something to do with the vehicle's electrics will be left on (sidelights, courtesy lights etc), causing the engine battery to drain on site. Additionally, if the leisure battery is in poor condition, after a long drive the engine battery will become drained. It's possible to fit a gizmo which sends the alternator's charge to the battery with the greater need. But that is an expensive option. But on an old vehicle, starting needs every help we can give , hence the decision to use two engine batteries which are used in tandem when cranking. In my set up, the system has controlability in that it's me who decides where the charge goes and which battery is used overnight. Actually I don't use much power on site, in the days when I had just one battery, I could remain on site for several nights and the engine would (just about) start. For the majority of the time the camper is not used for holidays, so it can be driven without regard to charging. I like the peace of mind which comes with knowing that the fully charged battery is completely isolated overnight from any current drain. It's a bit of hassle to remember to switch over batteries but it soon becomes instinctive.
Interesting Indeed the accepted method of charging a pair of deliberately mis-matched batteries by connecting them in parallel has always seemed a little odd to me.
Interesting post. I've been thinking off a similar system for mine. I do a lot of short runs and I've flattened my main battery a few times and had to swap batteries to get going. A couple of straight isolators and one key would allow me to connect either one battery or t'other to the starting system. I like the solenoid idea but wouldnt it be better to seperate out the starter motor from the ignition using a relay to temporarilt switch the ignition over to the second battery while the starter's spinning?. One battery for ignition and one for starter to avoid voltage drop on the ignition when you least need it... Just a thought maybe.. Sterling do a good intelligent split charge system which regulates the charge to each battery entirely seperately but it's over £350 ! Here's a link: http://www.sterlingpowerproductsbam.co.uk/products-altbatt.htm I tried their split charge blocking diodes but they need a self actuating alternator to work (standard alternator isnt :-(, (That is they don't pass any current to the alternator from the battery which early alternators need to start generating.) A durite voltage sensing relay does okay for me.. How long before we get lifetime charged batteries! Cheers s
If I'm reading this right the main issue is that in a traditional split charge system when the LB is knackered it can impair the ability of the starter battery to charge. The other issue for the OP is the price of new leisure batteries So the question is how long do your leisure batteries last when camping and how many years service life do you get out of them? If you routinely flatten them while camping I guess it wont be long before they need replacing. Using an optimate or another good charger can help extend the service life because they can de=sulphate the plates to a certain degree. My power needs are quite low, only some led lights which use bugger all power and a compressor fridge, kids might watch a DVD on the stereo occasionally which has an 8" screen. Last time I went away it was for 4 days at a festival and the engine was only run briefly so we could move away from a noisy generator powering the site lights and I still had around 12.2v after 4 days which is about 50% of my 110Ah battery. I tend to put the fridge on and fill it up a day or two before I go setting the thermostat as cold as I dare so the contents are just above freezing point. Then when I get to camp I change the thermostat to a higher temperature, That way it wont need to come on again for a while. So I am hoping to get a few years service from my LB
What size wire and fuse have you joined em with must be massive cos if your main battery gets low that cable is going to get the lot during the starting cycle, and in the words of the gorgeous Hillery Devey, when the beast is hungry it needs feeding!
I never had much life from leisure batteries for some reason, and concluded that two large starter batteries were better value long term. I've had several £25 second-hand from the breakers over the years and gotten at least four years out of each of them. The cable connecting the two batteries is very heavy duty, much thicker than the camper's earth strap It's made up from an old jump lead for lorries given to me by the local garage
