Champstar Posted January 6, 2009 Share Posted January 6, 2009 Hi I am thinking of adding an extra leisure battery and wondered about the safest way to connect them....I know it has to be parrallel (neg to neg etc)...but what grade of cable to use and where would I connect the portable solar panel..to only one battery? many thanks Link to comment Share on other sites More sharing options...
spospe Posted January 6, 2009 Share Posted January 6, 2009 The short answer is to use the heaviest gauge cable that you can and fit the batteries as close to each other as possible (aim for the shortest practical cable run). Connect the solar panel to either battery, in the case you describe, the difference between one or the other will be so small as to be negligible. Link to comment Share on other sites More sharing options...
Frankkia Posted January 6, 2009 Share Posted January 6, 2009 Hi Champstar The main thing is to site the batteries as close as possible to one another. That will meen the leads between can be kept short. I have 3 leisure batteries and have used a set of old jump leads, cutting them to just the required length between the battery posts. The leads have been fitted with the snap on type of connectors (most caravan shops have them) . With snap ons you can quickly remove a battery from the circuit for maintenance and / or exchange. For the solar panels - I have both fixed panels on the roof and a portable one for when the sun is low in winter. The fixed panels are wired to one set of the snap ons screw fixings and supply power to all of the batteries evenly. I have also connected a short length of twin cable to another set of snap ons with a "bulgin" type socket on the other end (this is a plug and socket with both the pins and the holes protected and can only be plugged in one way round). The "loose" solar panel has a lead with a "bulgin" type plug which can be plugged in or disconnected at any time. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 7, 2009 Share Posted January 7, 2009 There's some useful connection diagrams on Clive Mott-Gotobed's website http://www.motts.dsl.pipex.com/second%20leisiure%20battery.htm Link to comment Share on other sites More sharing options...
Champstar Posted January 12, 2009 Author Share Posted January 12, 2009 thanks to all for the usual good advice... Link to comment Share on other sites More sharing options...
BGD Posted January 20, 2009 Share Posted January 20, 2009 A question please for all you electrickery people: Existing leisure battery is a wet-cell 95ah. I would like to add a second battery too. I have another wet-cell 70ah battery in my garage at home that I'd like to use as well. There is space in the leisure battery compartment to fit the second battery right next to the existing one. So, questions: 1. I know that "best practice" is to have exactly matched pairs of leisure batteries. But is there any reason why ('cos I'm poor!) I cannot add the 70ah battery I've already got. I guess the additional reserve of electrical power would not be as great as if I'd used another 95ah battery, but surely it will give us some additional non-hooked-up electrical resource when wild camping? 2. And as they would be located right next to each other, is it just a question of adding very stout "bridging" cables (eg bits of cannibalised jump starter lead cables) between them....pos to pos and neg to neg? 3. I assume that once connected together, the alternator would charge them both up when the engine is running. But what happens if one battery gets fully charged before the other...does the current still simply flow through both until second leisure battery is fully charegd too? Many thanks to all lecky wizzards........ Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 20, 2009 Share Posted January 20, 2009 Not a problem Bruce, with the proviso that if one or other battery is weaker than the other it will drag t'other one down with it, so as long as you are happy that both are in fine fettle - just do it and see how you get on! No point in spending what you don't have to - as someone (can't remember who) once said - saving money is an art form! Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 20, 2009 Share Posted January 20, 2009 Not a problem Bruce, with the proviso that if one or other battery is weaker than the other it will drag t'other one down with it, so as long as you are happy that both are in fine fettle - just do it and see how you get on! No point in spending what you don't have to - as someone (can't remember who) recently said! "....... but saving money through ingenuity and awareness is indeed an art form, and for some of us a very satisfying art form, that can be developed over the years." Link to comment Share on other sites More sharing options...
BGD Posted January 20, 2009 Share Posted January 20, 2009 Rich - thanks. Were the stereo replies one for each battery?? I'm still unclear on what happens when the two are hooked up together and are charging whilst the vehicle is running, but one battery (inevitably)reaches fully charged state before the other? Does the not-yet-fully-charged battery still continue to receive a charge until it too is full? Link to comment Share on other sites More sharing options...
Geoff Cole Posted January 20, 2009 Share Posted January 20, 2009 Hi Bruce, As tracker says worth a try, Some times you get away with it some times not it really depends on the state of the two batteries.The main problem is that the internal resistance of the batteries will be different, and difference in the battery capacities will mean that there will possibly be a potential difference between the two batteries when the charging source has been swiched off, because one battery has absorbed more charge than the other. This will mean that you could still have current flowing between them, and the battery with the lowest internal resistance will draw current from the other battery until they equalise. If both batteries are in good condition then this should not be too much of a problem but you will need to keep a check on the electrolyte level, and if one battery has a tendancy to gas excessively then you will need to replace the smaller one. hope it works for you Regards Geoff Link to comment Share on other sites More sharing options...
Clive Posted January 21, 2009 Share Posted January 21, 2009 Jobs a good'n by the sound of it! C. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 21, 2009 Share Posted January 21, 2009 BGD: Exide advises that, when batteries of unequal capacity are connected in parallel, the ratio of largest to smallest should not exceed 3:1 (eg. 90Ah:30Ah), so 95Ah + 70Ah would be acceptable. Also, when new and old batteries are parallel-connected, Exide says that the oldest battery should not be more than one year old. Plainly, if battery-age is an unknown factor, the result will be rather pot lucky, but (as has already been warned) as long as each battery is in good nick you should be OK. When batteries are parallel-connected, the ensemble behaves as one large battery as far as charging and discharging is concerned. The idea that the smaller battery will become 'full' (or 'empty') before the larger one is overly simplistic. Imagine instead a number of water-tanks connected together at their bases, but with water going into and coming out of just one of the tanks. As the water enters that tank its water-level rises accordingly, but so does the water-level in the other containers as they are all inter-connected. Similarly, as water is taken from the one tank, the water-level also falls in the other containers. (I think this analogy may have come from the "Beano" comic, so it may not be 100% sound technically . No doubt Clive M-G can say.) Whatever the technical niceties, using linked unequal-capacity leisure batteries doesn't appear to be problematical in practice. Auto-Sleepers has (for several years) fitted to certain motorhome models a 145Ah set-up comprising 85Ah + 60Ah batteries in parallel. As far as I'm aware this arrangement functions painlessly. Link to comment Share on other sites More sharing options...
BGD Posted January 21, 2009 Share Posted January 21, 2009 Clive/Derek - Many thanks indeed for your comments guys.......You Da Men!....................I love you both and want to have your babies. When we get "Stanley" this Friday, I'll have a play at connecting up the two leisure batteries and see what explodes in the weeks thereafter. Course if I die, or am (even more) hideously disfigured by exploding battery acids, I'll then come and haunt you guys with consistent loudly-sung loud rock songs throughout the wee small hours....... Link to comment Share on other sites More sharing options...
fred22 Posted February 27, 2009 Share Posted February 27, 2009 I have just purchased from Discovery Leisure, two quick release battery clamps prewired with red and black cable and an inline fuse for less than £10. More than enough cable, I will have to shorten it.The fuse appears to be rated at 16amps This is less than I have seen charged for two quick release clamps on their own. I understand that Discovery Leisure buy them in ready made for use in their workshops. Other shops should stock them. Link to comment Share on other sites More sharing options...
George Collings Posted February 27, 2009 Share Posted February 27, 2009 A thought that Clive may well comment on. And bear in mind I am no sparky. As I understand it when two or more leisure batteries are close together there is no need for such heavy cables to connect them. All that is needed is a cable of cross section to match the total of those feeding from the setup. Link to comment Share on other sites More sharing options...
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