Brian1 Posted January 12, 2008 Share Posted January 12, 2008 Can anyone advise. I have recently installed 3/115amp leisure batteries and need some advice. At present I have connected Pos and Neg to the first in line battery from Van.Is this correct or would it be better to connect Pos to one end and Neg to the far end. Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 12, 2008 Share Posted January 12, 2008 If you connect pos to neg at each end of the three and then connect the three batteries to each other similarly you will have them in series and the resultant 36 volts could do a LOT OF DAMAGE OR EVEN START A FIRE - DON'T DO IT! Unless you fancy a new van on the insurance but otherwise absolutely not recommended. Connect the second and third batteries to the first battery pos to pos to pos and neg to neg to neg ONLY, using proper battery terminal clamps. Use cable capable of carrying at least thirty amps to reduce voltage drop and insert an inline fuse of 20 amps in EACH positive to positive link just to be safe. Any doubts - don't do it - seek help from someone who knows like an auto electrician. Link to comment Share on other sites More sharing options...
Brian1 Posted January 12, 2008 Author Share Posted January 12, 2008 Thanks Batteries are all connected Pos to Pos and Neg to neg and min 30 amp cable has been used. Maybe I was not making myself clear, the question is will it make any difference where I connect the van electrics ,obviously Neg to Neg and Pos to pos. Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 12, 2008 Share Posted January 12, 2008 Sorry -but I am not quite sure what it is you need to know - but here goes anyway! The van electrics are generally connected to the first or original battery, and the second and third batteries added with their own connections into the first securely merged with the other existing cables. You could, if you want, take the van electrics connection from any battery and it would make no difference as they are all interconnected, so there seems to be little point in altering the existing wiring loom any more than you have to? More joints = more to go wrong and more voltage drop! Does that make sense? Link to comment Share on other sites More sharing options...
Ranger Posted January 12, 2008 Share Posted January 12, 2008 I understand that all the batteries should not only be the same capacity but also all the same age??????? I expect Clive will be on here any minute now and straighten us all out. Link to comment Share on other sites More sharing options...
Brian Kirby Posted January 12, 2008 Share Posted January 12, 2008 Ranger - 2008-01-12 6:17 PM I understand that all the batteries should not only be the same capacity but also all the same age??????? I expect Clive will be on here any minute now and straighten us all out. It seems that depends a bit on the type of battery (i.e. whether gel or not) and the type of charger.All I would say is, I just hope the generator and charger are both up to the job! If your fridge takes power while you're driving, (remember the starter battery has to be charged as well) and if it is cold, dark, and raining, your poor old genny is going to have an awful lot of work to do! Link to comment Share on other sites More sharing options...
sshortcircuit Posted January 12, 2008 Share Posted January 12, 2008 Brian "your poor old genny is going to have an awful lot of work to do!" Where did the generator come from and not exactly correct. The amount taken out, will depend on how much the generator will need to work. Brian1 What do you intend to run off the batteries and how often will you be running your MH engine which will charge batteries Link to comment Share on other sites More sharing options...
colin Posted January 12, 2008 Share Posted January 12, 2008 Brian1 - 2008-01-12 2:53 PM Can anyone advise. I have recently installed 3/115amp leisure batteries and need some advice. At present I have connected Pos and Neg to the first in line battery from Van.Is this correct or would it be better to connect Pos to one end and Neg to the far end. With all the batteries connected in parralel as you seem to have stated on later post then in theory it's better to connect pos to first and neg to last. Link to comment Share on other sites More sharing options...
trooper Posted January 12, 2008 Share Posted January 12, 2008 It would be a good idea to fit a stirling battery to battery charger as this would charge your battery bank much faster, this was designed for boats with many batteries. cheers Link to comment Share on other sites More sharing options...
davenewellhome Posted January 12, 2008 Share Posted January 12, 2008 There is an argument for connecting your load (electrics supply) across the middle of the three batteries but it is purely theoretical. As long as the wiring between the batteries is heavy enough and the connections are all good it won't make any difference where you connect the load. D. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 13, 2008 Share Posted January 13, 2008 Linking multiple leisure batteries has been covered several times in MMM's "Interchange" section. I believe Clive M-G usually recommends a 'star' wiring arrangement for more than 2 batteries, or when the batteries are physically not close to each other. (I think this equates to what Dave has just said.) There are some diagrams and wise words on Clive's website: http://www.motts.dsl.pipex.com/ Link to comment Share on other sites More sharing options...
Geoff Cole Posted January 13, 2008 Share Posted January 13, 2008 Hi Brian 1 I get your drift as long as your batteries are close coupled it makes no difference which end you connect the feed cables please make sure you use 100a cable between batteries do not put fuses between batteries it is not a good idea, you would have no indication if one blewand would not really serve any useful purpose. I would however recommend that a surface mounted 100a fuse in the positive feed cable as near to the batteries as possible and a battery isolating switch with the key within easy reach in an emergency this would give you protection in the event of a circuit overload, or accident. Please be aware that with 3 large batteries you have a lot of energy stored . Use proper battery cable with swaged or soldered ends I would recommend a 3 stage charger at least 30-40amp output stirling or true charge make a good one. also make sure you have adequate ventilation. Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 13, 2008 Share Posted January 13, 2008 Geoff Cole - 2008-01-13 1:35 PM Hi Brian 1 I get your drift as long as your batteries are close coupled it makes no difference which end you connect the feed cables please make sure you use 100a cable between batteries do not put fuses between batteries it is not a good idea, you would have no indication if one blewand would not really serve any useful purpose. I would however recommend that a surface mounted 100a fuse in the positive feed cable as near to the batteries as possible and a battery isolating switch with the key within easy reach in an emergency this would give you protection in the event of a circuit overload, or accident. Please be aware that with 3 large batteries you have a lot of energy stored . Use proper battery cable with swaged or soldered ends I would recommend a 3 stage charger at least 30-40amp output stirling or true charge make a good one. also make sure you have adequate ventilation. I am not an expert but as I see it most van leisure batteries have their alternator input limited to around 10 amps, so unless you are also installing a high output 12v charging system I would not use 100 amp fuses, although the heavier duty cable you use the better the theoretical transfer of current will be. It is difficult to see how the 12v output for pump, heating, lights, tv., etc. would ever exceed 200 watts (around 17 amps) so surely a 20 amp fuse - or 30 amp at most on the output side - should be sufficient and somewhat safer? Any inverter would of course need to be separately wired with appropriate high current cables and fuse. Link to comment Share on other sites More sharing options...
Geoff Cole Posted January 13, 2008 Share Posted January 13, 2008 Hi tracker, I take your point, I have carried out many installations both marine and vehicle applications and my post was using my many years of experience, The 100a fuse is to protect the cable and battery installation not the individual appliances, they would have there own protection and it has nothing to do with the charge rate from the alternater. As there were 3 batteries I was allowing for an inverter of up to 600w, if however the total load on the battery bank is not going to exceed a given load then a smaller fuse could be used. Brian did not give his energy requirements so I was allowing for a reasonable load given the size of his battery bank. This is only my opinion based on my own experience. each to there own. Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 13, 2008 Share Posted January 13, 2008 Fair enough Geoff - I bow to your wider experience and knowledge - I just did not want any one to get the wrong idea and use a 100 amp fuse that would, in effect, offer little protection in the event of a short circuit if they were only adding battery capacity and not altering the charging rate and methods. Link to comment Share on other sites More sharing options...
Geoff Cole Posted January 13, 2008 Share Posted January 13, 2008 Hi tracker I see where you are coming from, I agree with you that high current protection is a must on these types of installations the problem is large batteries are capable of giving out very high currents, starter motors for example can take 100s of amps. The fuse is there to protect the cable and the battery bank from excessive overload, the fuse must not have a higher rating than the cable it has to protect. I look at it as if all else fails it will protect the installation. I always use at least 100A cable between batteries and always copper not aluminium. I have used my own marine experience on my own camper and installed a 50a fuse (I only have 1 battery) and a battery isolation switch which I can get at easily in an emergency. When installing battery banks on boats I always fitted a master switch close to the batteries for emergency isolation purposes, also to stop the boat being nicked! I hope this clarifies my post I would not want to suggest anything that would not be safe,I would always advise that if in doubt go to a good auto electrician. Link to comment Share on other sites More sharing options...
Clive Posted January 13, 2008 Share Posted January 13, 2008 If BIG cables are used to parallel up the batteries then BIG fuses can be used to protect the paralleling leads. The voltage drop across fuses can be significant, especially if the running current is only marginally below the fuse rating so if you have BIG cable then use BIG fuses to protect it. This does not remove the requirement to have appropriate fuse in the outgoing wires to the van electrics. The maximum charging current on a conventional split charging system (ie just a relay) is limited by the alternator rating (typically 100 amps), the demands of the starter battery and the resistance of the wiring, relay contacts and fuses to the leisure battery. You will also get a greater charge to the leisure battery of the pick up point for the split charging is the alternator B+ terminal and not the starter battery + post. If however you have a more "inteligent" system (Sargent 325, or Sterling for example) then its a different ball game. Link to comment Share on other sites More sharing options...
Brian1 Posted January 14, 2008 Author Share Posted January 14, 2008 I have already replaced Alternator with upgraded unit and we have installed a Sterling battery to battery charger into the system.I have also replaced the original charging unit(useless)with a Victron multi stage charger/invertor. with these units I am finding no problem.For wild camping I use a 2Kw Honda generator and this is proving to be capable of recharging batteries. Link to comment Share on other sites More sharing options...
Brian1 Posted January 14, 2008 Author Share Posted January 14, 2008 Thanks Don As you may see from another reply I have installed one of these Sterling units and it works wonders Brian Link to comment Share on other sites More sharing options...
Brian1 Posted January 14, 2008 Author Share Posted January 14, 2008 Geoff I agree most of your comments, and have the 100amp cables between batteries. I do not have fuses and agree your comments. My output requirements are high but I have only installed 30 amp fuse on output side which I think is safer. At this stage I have not included an isolating switch as I cant see the point but happy to take advice Brian 1 Link to comment Share on other sites More sharing options...
Brian Kirby Posted January 14, 2008 Share Posted January 14, 2008 sshortcircuit - 2008-01-12 8:05 PM Brian "your poor old genny is going to have an awful lot of work to do!" Where did the generator come from and not exactly correct. The amount taken out, will depend on how much the generator will need to work. Brian1 What do you intend to run off the batteries and how often will you be running your MH engine which will charge batteries Just realised what you mean, Hamish. The generator I was referring to was the one on the engine which, to avoid confusion, I should have called the alternator.With that addition in the charging demand, and with its output designed to charge rather less, it will be at going full ding dong for quite a long time to keep up. I assume the reason all those batteries have been installed is to service long hook-up free stops, or a high inverter demand. Logically, it follows the batteries will become heavily depleted so will need to be fully charged. Unless I'm mistaken, with a standard alternator, and with other demands from the vehicle etc, that will require several hours of driving. I was therefore trying to suggest that an uprated alternator may be required to keep up. Sorry that wasn't clear. Link to comment Share on other sites More sharing options...
Geoff Cole Posted January 14, 2008 Share Posted January 14, 2008 Hi Brian1 I was concerned about the size of your battery bank which is the reason I suggested a battery isolation switch so you could in the case of emergency/ accident fully isolate your battery bank, its belt and braces really, and up to you. May be I am pessimistic but batteries can be dangerous in an accident, which I hope you never have . I understand your thinking on using only a 30A fuse but make sure the fuse rating is not too close to your total running load for the reason Clive pointed out. In your case I would not use less than a 50A fuse. The fuse on the battery output cable is to protect your battery bank and cable not the individual equipment which should have there own fuse protection. Hope this is helpful you seem to have it all under control. Regards Geoff Link to comment Share on other sites More sharing options...
sshortcircuit Posted January 14, 2008 Share Posted January 14, 2008 Brian K Thanks Brian matter clarified. Last time I had a generator on an engine it had a regulator in a brown bakalite box with two coils and constantly sparking contacts. Brain1 From your description you have given of what is fitted you are well kitted up. Where did your installer suggest the connections be made? Link to comment Share on other sites More sharing options...
Clive Posted January 14, 2008 Share Posted January 14, 2008 Not quite right, only one contact constantly sparked, that for the dynamo field excitation regulation. The other contact was used to connect the output from the armature when the dynamo output voltage was above battery voltage. I removed a small one of these from an old Velocette Viper Clubman and replaced it with a home made transistorised regulator. Previous to that it was on my first car, and Austin 10. Ah, that was good! Link to comment Share on other sites More sharing options...
sshortcircuit Posted January 15, 2008 Share Posted January 15, 2008 Clive If we are going to be pedantic then a set of contacts is made up of two contacts and not one contact. How it worked is still a mystery and the sparks are still in my mind where from one or tuther contact(s) Link to comment Share on other sites More sharing options...
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