I must get round to jenning-up on battery resistance. You can then use the output side of this to trigger a standard 30 Amp relay. Do you have any idea what could be the problem or is this normal? For connecting to the battery, there are crimp terminals that are designed for 2.5mm cable and have oversize “O” ends specifically for fitting under the nut that holds battery terminal clamps. Only when you start the engine does the fridge circuit become energised, therefore operating the habitation relay and allowing the leisure battery to be charged. 5. Fitting a tow bar is not that complex. Sometimes this is on the main fuse panel but often it is on the positive lead coming from the battery box into the charger/main 12 volt electrical fuse panel. It also energises the habitation relay, disconnecting the caravan leisure battery from the caravan and reconnecting it to the tow vehicle charging circuit only. I’ve written this to try to remove some of the mystery (or should that be misery?) The caravan has a 100 Ah battery and, by today’s standards little 12 V equipment. and AL-CO ATC.I don’t mind the fridge going on and off but I think I could do damage to the ATC unit.Is there a voltage controlled relay that is adjustable to say 12.8 volts.Can you help please,Mike. 2.5mm sq (15 Amp) or 4mm sq (20 Amp) is usual. To help with out dismantling it I’ve done a drawing showing the pin connection from the socket side…. The actual output voltage produced by the alternator will vary depending on temperature and load, but will typically be about 1-1/2 to 2 volts higher than battery voltage. To replace your bushings: If you are interested in replacing the four air conditioning compressor bushings, see the FAQ file. This noble engineering feat was fraught with troubles though as the sensor could (and most times did) get attacked by acid and the temp value would be wrong. Some alternators can be damaged by full fielding for instance, others have a pulse width modulated field controlling charging. On further investigation of the car electrics it would appear that the system is running from a single supply from the battery via a 15amp fuse without any relays that are obvious, unless they are located to the rear of the vehicle. Remember I said that there was a rely controlled by the engines ECU and only turned it on when the engine was running… well there is a circuit that runs from this relay to the caravan via pin 10 (13 pin socket) or pin 6 (on a 12S). PS… don’t forget that your tow vehicle if less 6 or 7 years old will probably require a main dealer software re-program if your tow bar fitter can’t do it. Now this is not a ‘split charge relay’. [Tips from Rich:] Being involved in the telecommunications power business since Mr. Bell was a pup, I have some knowledge about batteries. Don't buy a motorcycle battery to start your Volvo, the starter pulls too many amps, the alternator will cook it from charging too fast and the starter will poop out from not enough current to get the job done because of heat $$$$$. Scrape battery posts and the inside of cable terminals with special brushes or scrapers. So I tested the output on pin 9/13 and got zero volts. We are new to caravanning and can’t quite get our heads around the leisure battery. Use a clip as shown in the photo to hold the brush gently against the spring. My trailer is for a vintage – 1930s – car and my understanding of car electrics hasn’t had to extend much beyond three brush dynamos and cut outs (no regulators!). Don't trust your volt meter in the instrument panel ! Hi David Also the fridge doesn’t get very cold while travelling. only when the engine is off and the habitation relay has disengaged will the van-off-vehicle override selector work. If the voltage starts to fall below the target voltage, the current increases allowing the voltage to remain the same. However, all of the panel lights, the battery level and starter assembly are good. A good alternator should measure less than 500 mV (.5 VAC). All has been good for a year on the road until recently….12v system in the van operating fine while travelling. This caused the pump to nearly empty a full barrel of water and discharge the battery. They also heat faster under a load. A nice square contact (should be rounded and smooth--the other one was) point due to wear and a relaxed copper alloy arm...the car wouldn't start unless the switch was compressed by hand (a get-home crutch, BTW!). Checked with a meter and the only live fuse was the 20amp basically this was live at the relay. [Noel DeSouza]In my case, the grounding wire going from the battery to the engine was bad, so check the obvious first. A simple 30 amp automotive relay can be used. All now working, the answer is that Ford appear to be cheapskates! At 30 F, minimum voltage drops to 9.1 volts; at 0 F, it's 8.5 volts. Fuse was ok and the water heater was functioning perfectly ok on gas. In your situation I would make sure that Pin 9 from the plug is connected to the caravan’s habitation relay and I would connect Pin 10 to the fridge, with a spur to the coil side of the habitation relay. 1) Battery cables. Unless you are using a lot of extensions and a universal joint, you are going to have a hard time with this bolt. The water heater switch also works off the 12v and when that is switched on they blink but not too much. It shows it is impossible for the tow vehicle to use the caravan battery for engine starting. And diagrams of relays I have found don’t show a wire on 87a. Instead of spinning a coil inside a magnet to produce electricity, they spin a magnet inside a coil, however, this magnet is actually a small ‘electro magnet’ (sometimes called the ‘rotor’) which is powered (or ‘excited’) from your battery. Don't assume that a crimp connection of a terminal on the cable is good. Current was flowing between + and -- through the insulation. I can buy a 24volt DC/DC 30amp converter which I could mount in the boot to supply 13.8 volts to the pin 10. I apply paste flux to the lead of each brush. Because the load is so small, the DMM will show a very low resistance reading, as long as even just a few of the strands in the battery cable are still good. One is the ‘forward’ resistance that when you discharge a battery the internal makeup and chemistry limits the current if it was a direct short – it’s a lot of amps but the energy is released over a few seconds. Then I read if I have my road lights on, I should get a voltage. Orange – +ve from 13 pin plug for battery charging I’ve heard of this before with Knaus…. What tests can you do? Where Is the Best Ground? [Editor] This suggests you use Loctite on these screws before installation. You would only do this if the circuit on the back of the flexible instrument cluster PCB failed. So when you plug your van in, there is a voltage from the tow vehicle present in the caravan all the time…. Although the same result could presumably be achieved by wiring the trailer so that pin 6 did the charging rather than pin 4. Also make sure the engine is grounded - it should have a big earthing strap, or sometimes the battery - terminal is connected directly to the block - either way, make sure the contacts are good. Avoid it by engaging a load. That is the circuit which is grounding your battery and causing the drain. This would be worth a check too. removed the starter B+ (positive cable) and brush the lug and the stud it attaches to plus all washers and mounting points. Never, ever had a corroded battery terminal or wire set. Additionally, you don’t want to modify the existing tow vehicle so it is non standard… which could become problematical with current or future vehicle testing procedures. I been looking at your circuit showing the relay operation showing with engine off/engine on it looks and works so simple it seems allmost to good to be true, but after studing it I think it is true and the landrover article seems to confirm it ture. The 12 V side is extremely simple. Vehicles over the last few years have become very clever… A few years ago Land Rover owners first started noticing issues when Land Rover programmed their alternators to turn off when the vehicle battery was fully charged and effectively took away the vehicles ability to charge leisure batteries. My towcar has a split charge relay fitted on the cable between the alternator and pin 10. See battery cable connector repair for procedures. If you have checked the charger manufacturers instructions and there is no mention of the charger being OK if connected to a battery that is recieving a charge from an alternator, personally I’d make the assumption that it’s not OK. It’s a simple thing to correct however. All has been fine until last week on a trip to Fakenham. It might help to work out what fuse relates to which circuit if you look in the handbook. The caravan is a Caravelair from 1999, the wiring appears to be original. I ‘might’ be a voltage sensing relay that has been adjusted so that it is on all the time, in which case it needs adjusting to the correct setting. If it’s an old installation, you might be able to find instructions for the relay on the internet via Google if you haven’t got them. So I’d concentrate checking out the fridge circuit first. Two phrases I hear most often are "my battery won't take a charge," and "my battery won't hold a charge." I now feel I can talk to the towbar fitter next week in the knowledge that I know what I needs to be done to give me the trailer battery charging that I’ll need. Any automotive 20 amp changeover relay is OK. I think I need to follow up on a couple of different things. The lower the temperature the higher the charging voltage, and conversely, a higher temperature requires a lower charging voltage. Note: You can print these instructions out, xerox onto a plastic sheet, and mount it near your car battery for on-site reference. I don't know what heat range iron (Wattage) is in your keet, but you might need a soldering gun (150-250 Watts) to deliver the heat. Lets face it, $50 in the scheme of things is not a lot of money. was producing enough voltage it would extinguish the old ‘ign’ light. Very comprehensive article, I have read this with pleasure. At idle, most charging systems will produce 13.8 to 14.2 volts with no lights or accessories on. I had initially intended to only pull the positive cable since it was showing signs of wear and cracking at the crimps on either end, but now I've got to get a new negative cable as well. The biggest battery you can fit has a chance of having more space below the plates and a better seal. so you would not gt any leisure battery charging either. Rotting Battery Wiring Harness or Insulation. A new battery and cables cured the problem. The placement near the crossmember allows you room to use the breaker bar. The later alternators use a larger stud on the output terminal, and you'll have to carefully ream out the lug on the earlier cars, or replace the lug. If there were any additives that are useful in the long term they would be commonly used. That broke on me, resulting in my running off the battery with the same symptoms you have. 2) Get a multi-meter and measure the voltage between the battery terminals with the engine off. the uni-joint and the extensions just right, position yourself so This will happen if the small wire leading to the back of the alternator is grounded. As underhood temperatures increase, charging voltage drops down to about 13.8 volts. This excites the coils (electromagnet) and the alternator gets the magnetic field it needs to start charging as soon as the engine runs. If you connect a free standing solar panel to the battery, the existing regulator for the current panel might ‘think’ that the battery is fully charged because the free standing panel is supplying a sufficiently high voltage to the battery so it seem like the battery is charged, and the regulator will reduce it’s output, effectively leaving you with only the free standing panel charging the battery. Eventually it piles up enough to short out the plates. If the tow pack was fitted by an independent agent – does it require a reprogram of the ECU to allow all the services to work? Tasca Volvo can confirm numbers; price likely will be below MSRP. Could I ask, if my vehicles alternator is rated at 80 amps, would this be sufficient to use the modern wiring of having pin 9 permanent live, and the habitation relay activated from pin 10 to switch over to the charging circuit, and connecting both batteries for charging? Hi, Use the Vehicle's Radio to Check Alternator Diodes 5 or 6 years at $65. I do have one question though that I have not found an answer to anywhere, and maybe you can help? So despite the fact that the charging circuit could pull around 30A at peak moments (ATC @ 15A + Charging @ 15A), a 2.5mm cable should still be OK over the 3m or so because it will only peak at 30A for a brief period? However, your question was will the charger be OK while the engine is running and not on EHU. Apparently, most cars were caught, but the odd unmodified one must still be about. Before installing the VR assembly, I cleaned the internal contacts with a pencil eraser as well as cleaning the contact in the alternator. Change ), You are commenting using your Facebook account. The result was the owner was without his vehicle for three weeks and it cost over £2600 for a new ECU, master electronics control module and sensor module. large intermittent voltage drops across the positive battery cable, so I Batteries have two internal resistances… a forward resistance and reverse resistance, these different resistances are what limit the discharge current and charging current. You are right in your conclusion. A load test places a specific current load on the battery to indicate how it will perform under heavier demands, such as cranking. Then I threaded the spring over the pigtail. Sounds like you have one of the ‘better’ voltage sensing relay’s. SCR’s now (and I don’t mean the trade name acronym used by General Electric to describe Thyristors!) On most relays terminal 85 and terminal 86 are the energising coil contacts. Turns out was a direct short where cables pass under engine. Terminal 30 is referred to as “common’ as it can either connect to terminal 87a or to terminal 87, so it is the ‘common’ connection between them… it connects to one or the other. However, I do not know how much longer the electronics in the regulator will last. If this is grounded or disconnected (as, for example, through a loose instrument panel or chassis connector), your alternator will not charge. Charging voltage varies according to underhood temperatures. A simple digital multimeter from Maplins (£5 to £10) would be good enough. So a simple £5 relay with the coil switched by the charging circuit, controling the habtation relay, the ECU or the charging circuit just sees one battery. From the sounds of it, I would guess that the previous owner did not use the fridge while towing therefore pin 10 was never connected. Flaky insulation may be at work. I have taken on board your comments, which reflect where I was heading, I just needed some expert opinion. You need to get the habitation relay back correctly then continue testing. The habitation relay is put there for a reason and it is controlled by the vehicle in the way it is for a reason. Not sure what year your van is but those colours should be OK. Sargent have diagrams going back to 2003 here: http://sargentshop.co.uk/Technical-Data/System-Schematics/Swift-Group-Schematics. it will definitely see of the diode trio in the alternator. They distort, shed some of the lead and it settles to the bottom of the container of the low cells. A fave one on these is the actually connections to the back of the override switch. I’m not 100% familiar with the Ace Supreme Twinstar, however as I understand it if the engine is running, the habitation relay should activate and render the van-off-vehicle override switch inop. Voltage sensing relays should ideally always be installed close to the battery for correct operation. With a little looking, I found a shop in my area that repaired the alternators (new bearings, brushes, leads, whatever else was needed) for about $70. With engine off while connected the 12v system is fine. [Editor] To initiate charging upon startup, the small wire going into the rear of the voltage regulator must be at 12 volts. I guess the previous owner had ‘modified’ the wiring to suit.. along with the plug! Would a charger directly from the 240v effectively bypass the habitation relay, and/or the selector switch in the van?. The caravan has now taken a step into the 21st century. If you don't have a carbon pile, load the alternator by turning on as many accessories as you can. My 2006 Freelander factory fitted electrics are 2.5mm sq and work fine with our 2011 Sterling Celebration 550. Where does it go? MicroC exists everywhere and is aggravated by substantial temperature changes. Attach the positive DMM lead to the starter motor body or the engine block. If you check on line you should be able to find the wiring diagram for the OEM wiring harness for the manufacturer’s tow bar electrics, this should tell you if you can connect to the ECU. Result: INSTANT $865.00 DAMAGE, blowing five relays, radio and other electrical equip. good access to pushing the brushes back to get the right placement. Caravanners who have installed it speak warmly of it. Tony. Change ), You are commenting using your Google account. [Dave Stevens] Wood Auto Supplies Ltd. in the Huddersfield, Yorkshire, UK has an excellent on-line alternator and starter reference tool for parts. The white hood slides off for installation giving The fridge is a standard model and used by several van manufacturers who do connect it. The leisure battery in the caravan is also connected to everything including the fridge. I relalise I’m well in front of myself for fitting this towbar etc but I’m just trying to get it all sorted in my mind beforehand. Is this feasible and has anyone else experienced a similar scenario? I'm reminded of incidents with my RX-7 last year, when I was able to crank it strongly and it wouldn't start. On some caravans the battery charger is connected to the mains via a 3 pin euro-plug into the back of the unit… I believe this can come loose and sometimes causes issues when it makes intermittent contact. With all the heat under the hood, the electronics will eventually fail. It was an old battery, so I though nothing of it and replaced it. My query is this… I bought an Ace Supreme Twinstar 2004, and I am having terrible problems with the electrics and charging the Leisure battery… If the 12n and 12s have been connected and engine running, would this override the selector in the van? So I conclude that the power is going so low as to allow the battery light to come on, but I don’t understand why the relay won’t work? I switched on every electrical device in the car and checked the voltage over pin 10 & 11 with the car idling. I think it will be worth it in the end. Have you ever heard a whine from the radio that changes with engine rpm and isn't rap music? All my research tells me my CV R shouldn’t have this but it would explain my symptoms. Hi Simon, I have fitted a vehicle specific wiring kit to my 2014 Rave4 with a voltage controlled relay that switches about 13.2 volts.The problem is when stopped with engine running if I have headlights on the voltage drops below 13.2 which drops power off pin 9 which drops relays fittied in my Bailey caravan for fridge etc. Food for thought. A difference of more than one volt would indicate faulty diodes and the need to replace the regulator unit. This now makes pin 10 (13 pin) pin 6 (12S) live and provides power to the fridge in the caravan. Now we need to add something else into the mix….. This is done by the van’s electrics and relays. ( Log Out /  Some early Land Rover Discovery OEM units had this “feature”. It wasn’t very efficient though. I cannot find any power consumption details for the ATC Systems, and I’m not entirely clear on how much current the typical leisure battery draws (on average) when it’s charging. Follow Caravan Chronicles and receive notifications of new posts by email. Most 2.5mm2 cable is rated at around 25 amps, which will usually be sufficient to carry the load in the leisure battery charging circuit. when the problem happens) measure the following: Voltage Regulator. Once connected I will be able to assess if I have a further issue in terms of smart alternator behaviour, in which case I will follow your good self and install a Wildside. [BatteryTips from Tim Curry:] I talked to Exide here in Tucson a while ago and found out a bunch about batteries. is there a separate fuse or MCB for the 240 volt side of the charger? You don't even need to pull the alternator. Many thanks again for your time and efforts on this page! The battery does not seem to have an inline fuse. I had a problem on a Ford Taurus once where the voltage regulator had shorted, and was the cause of the drain. The car's acceleration was impressive, not just ''good''. apply the proper leverage to get a firm grip on the bolt head. Problem i am having is when connecting 13 pin. So as you rightly say this should be a permanent feed not switched, but it seems that this might not always be the case. I’d put an ignition controlled relay on the 24 volt side of the unit supplying pin 10. With the engine off, plug it in to each circuit in turn at the fuse panel and find the one that illuminates it. Then I stuck the end of the leader through the narrow hole, from the brush side, and used it to pull the pigtail through. When the caravan sees a voltage on this pin, it switches the caravan habitation relay over, disconnecting the caravan leisure battery from the caravan and connecting it to the charging circuit (pin 9 -13 pin socket, pin 4 on the 12S).