reads90 Posted January 16, 2007 Share Posted January 16, 2007 I want to power up my camper trailer I have a power cable from the battery to the rear of the 90. It takes power from the spare battery to the trailer. Conects to the trailer with a anderson plug. Now i want to put a couple of deep charge cycle batteries in the trailer . (so the trailer will have power to run lights , fridge Tv and stuff when the car is not pluged to the front) Question is will this cable alone charge the batteries in the trailer. (i thinking it will when it has charged the car batterys) The spare battery is charged though the split charge system, so will it still charge the other two in the trailer I know i will have to put in a bigger amp alternator , but need to know how the best way to plug the trailer batteries into the car and thought the cable ARB put in might do the job Or will i have to conect it direct to the back of the alternator I am going to put a 240V wiring system in and a 12 v system , for when i am at a camp site with power i can plug in the 240v (and maybe charge the batteries with a battery charger, at the same time if they need them) but when where there is no power i can use the 12v system Another question is what is the best higher amp alternator that you get for a 300 Tdi. was thinking of a 3.9 disco one which will fit and have used on a 200 Tdi in the past as they are 100 amp , but was wondering if there are any others that people use Quote Link to comment Share on other sites More sharing options...
MogLite Posted January 16, 2007 Share Posted January 16, 2007 Hmm interesting one. I'm no expert - but here is my take. The power cable that currently goes to trailer, you can't just connect this to the batteries in the trailer, or you'll be trying to charge dis-similar batteries in the vehicle and the trailer at the same time - and thats a no-no. I think what you'll have to do, is run a split charge in the vehicle - which you've already got. Then you'll have to run a 2nd split charge for the trailer. Exactly how this is done - I'm not sure. Maybe it could sense when the 2nd battery in the vehicle is charged, and then start charging up the trailer batteries - if thats the preference you want. For wiring up the trailer for a 240V and 12V supply - consider the Aussie equivalent of a Zig Panel. This will give you 12V charging when on a mains-hook up, also circuit breakers and stuff will make the rest of the wiring much easier and safer - important for you I know Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 16, 2007 Share Posted January 16, 2007 What Andy said - just because you're using a long bit of cable it's no different than sitting the two batteries next to each other and joining them in parallel. Unless they're designed to be run this way, they won't like it and may discharge each other over time. A second split-charge unit feeding the trailer is what you need, a Zig panel could be a neat way of combining everything. One from a boat could be a bit more robust / less caravanny Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 16, 2007 Share Posted January 16, 2007 Zig panel could be a neat way of combining everything. One from a boat could be a bit more robust / less caravanny A lot of the marine and caravan stuff is exactly the same, except caravan stuff is expensive and marine stuff bloody expensive. Quote Link to comment Share on other sites More sharing options...
reads90 Posted January 16, 2007 Author Share Posted January 16, 2007 ok then no so stupid a question as i thought it was going to be . need to look into some stuff over here then. BTW caravan stuff here is cheap as most people have them (supply and demand thing) will look into this split charge stuff and take it from there. Thought just connecting the cable would be far too easy. What about alternator what is the most used these days Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 16, 2007 Share Posted January 16, 2007 E34 BMW 525 - 140 Amps for £25 can't be bad (eBay) although you may have to adjust some bracketry to get it to fit, IMHO it's worth it. Quote Link to comment Share on other sites More sharing options...
Les Brock Posted January 16, 2007 Share Posted January 16, 2007 I "think" that in Aus only an Electrician is allowed to work on ANY mains installation or circuit likely to be connected to the mains, I may be wrong but worth checking out ! Quote Link to comment Share on other sites More sharing options...
will_warne Posted January 16, 2007 Share Posted January 16, 2007 Ali, as you're going to be charging several betteries you probably want to use a battery management system like national luna or pirahana otherwise it might end up alittle complicted with a split charge running off a split charge. I know Frogs have done several vehicles with 3 or more battries using these sort of systems but they're not that cheap (£150 - £200 but probably a little cheap out with you.) but they charge intelligently and give you an LED display showing how each battery is doing. How much current do you really think you'll be pulling? If a 100amp job did fine on your old 90 then shouldn't it be up to the job again? Even better idea, how about a second alternator above the injector pump that just does the trailer? That way you've got a spare for the truck if the first one fails and the wiring's simpler. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 16, 2007 Share Posted January 16, 2007 but they charge intelligently and give you an LED display showing how each battery is doing. Intelligently? not really. they've just got a voltage controlled relay in them. They're a huge rip off if you ask me. A VSR does exactly the same job, and costs about £50.Proper battery managment systems cost a lot more than £200, but then they do actually manage the batteries, by controlling the alternator. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 16, 2007 Share Posted January 16, 2007 Fair point on the alt - it's not the number of batteries you have but the amount of power you're using. A TDi doesn't exactly take much leccy to run, and you're not winch-challenging it so you should be fine with a stock alt. And yes, those Luna things are a rip, a cheapo caravan split charge relay (or an X-Charge if you want overkill) should do you fine. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 16, 2007 Share Posted January 16, 2007 The advantage of a VSR is it will see that the cranking battery gets a decent charge before connecting any auxilary batteries in parallel. Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 16, 2007 Share Posted January 16, 2007 But once the engine is running and the alt is chucking out 14.whatever volts won't the VSR just see the alt voltage and activate the split charge anyway regardless of how much charge the starter battery is talking? Quote Link to comment Share on other sites More sharing options...
reads90 Posted January 16, 2007 Author Share Posted January 16, 2007 I "think" that in Aus only an Electrician is allowed to work on ANY mains installation or circuit likely to be connected to the mains, I may be wrong but worth checking out ! Nah your right , can't tiddle around with electrics, have to get an electriction to do it all , can't even buy new light fitting for the house in B&Q Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 16, 2007 Share Posted January 16, 2007 But once the engine is running and the alt is chucking out 14.whatever volts won't the VSR just see the alt voltage and activate the split charge anyway regardless of how much charge the starter battery is talking? If the alternator is charging at 14 volts, yes the VSR will be closed, however the assumption is that if the battery and alternator are at 14v, the battery is pretty well charged. The other advantage of a VSR, over an ignition switch relay is relevant in overlanding(etc) conditions. if you have a flat aux battery (with or without a load shedder to protect it) that has been discharged over night by a fridge,lights etc, an ignition switched relay will parallel the batteries before cranking. this means the healthy cranking battery and flat aux battery will share their charge before cranking, this isn't healthy for the batteries, or the ability to start the engine. A VSR will crank the engine on the cranking battery, then parallel the aux battery once the engine is running and the voltage has risen. Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 16, 2007 Share Posted January 16, 2007 I thought the alt would put out 14V and hence the voltage of the battery terminal would be 14V irrespective of the battery charge condition. Isn't that how that battery is charged, by having a higher voltage applied across the terminals. To avoid connecting discharged aux battery to starter battery before starting you can use the alt charge light wire to trigger the split charge rather than using ignition switched live. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 16, 2007 Share Posted January 16, 2007 I see what you're saying, but it works, has done for the last couple of years. my battery doesn't hit ~14.4 straight away, the voltage rises shortly after the engine has started. Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 16, 2007 Share Posted January 16, 2007 Fair enough, if it works it work I was just trying to get my head around how it didn't kick in straight away when the alt starts charging. I've been giving overland type split charge setups (for there are many ways to skin this cat, one being battery to battery chargers)some thought for my camper van conversion that I'm (slowly) working on, and couldn't see any real advantage to using a VSR. Planning on simple split charge using a relay switched from alt charge light. As it's the aux batteries that wil be ran low the starter battery should still have a decent charge anyway. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 16, 2007 Share Posted January 16, 2007 One advantage, however small it might be, is that the VSR and it's wiring is self contained within the battery box. The other is maybe down to me playing it safe, but, with the lights turned on, the engine note changes significantly, that means that current is coming from the alternator, via the VSR which is rated at 100A. A standard relay would only be 30A, and tbh, i wasn't aware of Si's relay at the time. Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 16, 2007 Share Posted January 16, 2007 Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 16, 2007 Share Posted January 16, 2007 Yeh I can see the advantage of keeping it all contained in the battery box. I'm gonna have to do a fair bit of wiring anyway as my aux batteries will be about 5m from the starter battery and the alt is near that. Will be using big relay 70-100A (or an contactor from a winch, but that is overkill), fat cable and suitable fuses. Quote Link to comment Share on other sites More sharing options...
simonr Posted January 16, 2007 Share Posted January 16, 2007 One advantage, however small it might be, is that the VSR and it's wiring is self contained within the battery box. The other is maybe down to me playing it safe, but, with the lights turned on, the engine note changes significantly, that means that current is coming from the alternator, via the VSR which is rated at 100A. A standard relay would only be 30A, and tbh, i wasn't aware of Si's relay at the time. VSR's are a good bit of kit, but I've found them less than totally reliable unless encased in something waterproof. I'm not keen on adding electronics where a simple relay will do a good job. I like technology you can fix with a hammer! All of what you say above about ignition switched relays is true - except that most split charges are not ignition switched! They are either on the sense output of the alternator or on an ignition supply which is dead during cranking (such as the feed to your radio). Thus, even if the aux batteries are flat, it will not affect your cranking. They will only start to draw down the main battery when the alternator is charging. Whether connected using a National Luna or a regular split charge, the battery with the lowest terminal voltage will get the bulk of the charge. The distribution between any number of batteries self-regulates. Car batteries and alternators were each designed for the other. Sticking an additional charge management system inbetween does very little to prolong the life of the batteries. It does however discharge your wallet a bit faster! Si Quote Link to comment Share on other sites More sharing options...
jwriyadh Posted January 16, 2007 Share Posted January 16, 2007 Mark, can't recommend using winch contactors for split charge systems, they tend to die rather quickly when used as continuously rated. BTDT with tee-shirts on both mine and Streakies. Stick with one of Si's kits. jw Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 16, 2007 Share Posted January 16, 2007 Thanks for the tip JW, probably go for one of Si's then, was only thinking of the winch contactors as I have a few spares kicking around the garage. Quote Link to comment Share on other sites More sharing options...
reads90 Posted January 17, 2007 Author Share Posted January 17, 2007 Ok thanks for all you help and surgestion. Think i have found an alternator. Of a vetra 120amp Alternator But if i want to be like Andy (moglite) could get one of these Bling Bling As for the battery boxes . The have kits here that seem to do a bit to what you are talking about . But will have to look into it a bit more. These are the sort of battery box. Makes it all sealed and safe along with they also come with a meter on the outside so you know what power they have left in them. They are also acid proof so if they do leak then no mayor problem. (btw these boxes are everywhere here but they are in the Uk as this is from Towsure webb site. In aus and can't find a pic of one but found a company 5 miles from where is used to live in the Uk to kncik a pic off, mmm ) Quote Link to comment Share on other sites More sharing options...
reads90 Posted January 21, 2007 Author Share Posted January 21, 2007 Thanks for all you replys. taken on board now to start ripping apart and sanding down . Then putting in all the electrics Here it is in the garage ready#, so wish me luck, two things that scare some , me with electrics and paint Quote Link to comment Share on other sites More sharing options...
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