Col_T

Sorry, I'm not on the boat at present, but we bought the boat last July and the sales brochure tells me it's a 40 amp charger (Sterling Pro-Combi 1500Q). Hope this helps, Colin T

Thanks for the replies, chaps. I might have been able to say I was starting to get somewhere with this electrickery stuff, if I hadn't got over-confident and used the wrong term for how the batteries are connected together! Another question, if I may. There is a 200A mega-fuse between the battery charger +ve and the battery the charger connects to - should the cables connecting the batteries be 200A rated? I can see why it would be sensible, though it would also seem over-kill to me.

So, I have 5 x 110Ah sealed batteries connected in series e.g. +ve on battery 1 connects to +ve on battery 2, etc, etc, with -ves connected the same way. Connection to the Sterling Inverter Charger is from battery 5, where battery 1 is left-most battery. I know there are risks, but the batteries are left on charge whilst I am away from the boat. Some questions:- 1:- Surface charge - if the batteries are left on trickle charge for a long period, think small numbers of days rather than hours, does the surface charge get absorbed into the batteries in the same way that turning off the charger allows the surface charge to be absorbed? 2:- I think that if I take a voltage reading across the +ve and -ve terminals of any individual battery I will get a reading for the whole battery bank (because they are all connected) - correct? 3:- All the batteries in the bank have two set of posts (one threaded, one plain) and the interconnect cables use the threaded posts. Will a voltage reading, taken from the plain posts, be for that individual battery or would it still be for the whole bank? 4:- Am I right in thinking that current flowing from the charger into the batteries = the current drawn by any 12v appliances turned on plus whatever tail current is required by the batteries? 5:- I'm thinking of altering the interconnections so that the charger +ve connection goes to battery 4 and the -ve to battery 2, or vice versa - it shouldn't really make a difference - and I think that the cables to the 12v loads should attach to the same points as the battery charger cables. Presumably the +ve 12v load goes to the same battery as the +ve battery charger connection. What would be the impact of connecting the -ve 12v load to the same battery as the +ve battery charger connection - so that both the +ve and -ve on battery 2, for instance, have a total of 3 connections rather than the +ve having 4 connections and the -ve having 2 connections? Alternatively, of course, am I just fretting about nothing?!! That's probably enough to be going on with!! Colin T

Thanks all for the answers, and for furthering my education - at least I'm getting an idea of how much I don't know! A supplementary question related to current flow and electron flow, and the fact they flow in different directions. Wiring diagrams - should these be read positive to negative (direction of current flow) or negative to positive (direction of electron flow)? Thinking about it further, I guess the more relevant question is "is a wiring diagram only meant to show which components are in a particular circuit" because if so, knowing which direction stuff flows in is irrelevant?

With apologies for bringing the thread to the original topic. Just to check my understanding:- Amp is a measure of current flow over time, typically one hour. Amps per hour indicates a rate of change in a flowing current. Current flows from negative to positive. Amp.hour is a measure of capacity, hence it's use in battery ratings. A question then - if a 110 Amp.hour battery can provide 110 amps, nominal, and the amp rating already includes in the one hour time duration, why are batteries not rated as 110 amps?

I also have 5 batteries in the domestic bank, and having been trying to get my head round this with what sounds like the same result as you! The obvious solution is method 2 from the Smartgauge page linked to, though that is not optimum. I have dreamed up a much more whacky solution, though I have doubts that it will work. I'll describe here so that those who understand these things can tell me why it's a rubbish idea. Start with method 4 from the Smartgauge web-site which gives you two pairs of connected batteries, which we'll call A and B. Place the fifth battery between A and B and connect A and B together as per the diagram. Then connect the +ve from the fifth battery to the +ve of battery A, and the -ve from the fifth battery to the -ve of battery B, and then connect the cables to the load / battery charger as per the diagram. See, told you it's whacky! All comments on the above gratefully received, though I'd appreciate explanations of why it won't work so that I may try and learn a little more!

Mornin' all, Thanks for an amusing thread with laugh out loud high-lights - just what a chap needs on a cloudy Wednesday morning. You folk talk of tiling grout, I think of powder that gets mixed with water to form a paste. I also think of the dried grout getting broken up by the gentle vibration of the engine and the much more violent thuds, bangs and graunches when I hit something - pontoons, lock landing stages and the entry to locks being current favourite targets. So, is there a plasticiser one can add to the dry grout to make it a bit elastic / less prone to cracking up? Only asking as I, also, have to re-grout the shower cubicle, and it's not something I want to make a habit of! Colin T

Surely does, Tony, and provides the reasoning, so many thanks.

Apologies if this is going off on a tangent, but . . . From what I have read on this, and other threads, sulphation can be pretty much fixed by regular equalisation charges or at least the effects can be reduced if it's detected in time. For those with open cell wet batteries, water that gets evaporated off by the equalisation charges can simply be added which is not the case for those, me being one, with sealed low maintenance batteries. This raises a question in my mind - what is the balance between shortening battery life by equalisation charges and reducing the fluid levels within the batteries and reducing battery life by not performing enough equalisation charges? Put more simply, Trojan open cell wet batteries may require a monthly equalisation charge, but wouldn't that regime severely reduce the life expectancy of sealed low maintenance batteries?

Why I would want them is simple curiosity about how much CaRT know about where I've been. As for knowing where I've been of course I knew, at the time, I just might have forgotten now! That's all from me on this one, so thanks for the info and the replies. Colin T

Evenin' all, I have read, in a number of other threads, that C&RT monitor cruising patterns of boats on the canals. Is there a page on the C&RT web-site that will let me see where, when, and if I've been spotted, or is this something that requires an e-mail to them? Thanks in advance, Colin T

Thanks for the replies, folks, and apologies for not responding to them earlier. Something that wasn't clear in the OP is that the batteries being left on charge permanently is a happy by-product of leaving tube heaters on - we do winterize the boat e.g. draining water tanks and pipes, leaving taps open, etc. but the tube heaters are an attempt to prevent the boat freezing. In summary, leaving the batteries on trickle / float charge is the best thing one can do for them until one, or more, on the bank start to fail at which point leaving them unattended is potentially the worst thing one can do for 'em. There are a couple of potential work-rounds, the first being the 'disconnect' box suggested by WotEver (post 12), the other being to install a 13 amp socket between the shore-line socket and the pro-combi (actually, between the galvanic isolator and the pro-combi) - something I've dreamed up, though this might not work of course as the thought is that the pro-combi would not be switched on. The first work-round has the advantage that the batteries can be left on charge, though that'll be an unattended charge which may be a disadvantage. The other work-round has the dis-advantage that the batteries are not being charged at all! You folk have both increased my knowledge (much appreciated so many thanks) and given me something to think about (not quite so much appreciated but thanks none the less!). That's about it for now. Over and out, Colin T.

Cricket, you boys stay up late!!! The Pro Combi is one of the older models e.g. automatically switches to inverter if the shoreline power fails. Richard, The 4A you mention, is this something you have measured or is it taken from the technical specs? Only asking as it would be interesting to know what my 1500W uses - I knew that the inverter would use some power but really hadn't imagined it would be that much, to be honest, and given that info your approach looks far more sensible. Right, work calls, so I'd better drag myself away. Thanks for the replies. Colin T.

Many thanks for the responses. The Pro-Combi is set to charge sealed lead acids, via the dial selector on the front of the unit so, hopefully, they'll be getting the correct charging voltage. The resting voltage check question was purely educational, so thanks for the comments and for explaining the logic behind those comments. I didn't think I needed to do one, but didn't know how to even if I did need to, though I had seen reference to this in other battery related threads. I too have had the 'running the batteries flat' concern about the Pro Combi. I suspect that I'm being naive and/ or optimistic but I reckon there are two failure points - me running out of credit at the power distribution point on the pontoon, and the power supply to the pontoon going belly up. There are live aboards on either side of us so I'm hoping the marina would be fairly prompt in rectifying power failure to the pontoon, and should be able to fix any problem within a week. I go down to boat every 2 or 3 weeks at the moment, just to make sure it's still afloat as much as anything - it's our first boat and we only bought it last July so we're still at that worrying about it stage! I've done some fairly rudimentary calculations which make me think that the batteries should be able to cope with powering the tube heaters via the inverters for a couple of weeks, so I'm hoping that I'll get away with it. Still, nothing like tempting providence, is there?! Once again, thanks for the replies. Colin T.

Mornin' all, Our boat lives in a marina with shoreline power supply left plugged-in, and live, whilst we are away. The boat has a Sterling Pro-Combi inverter / charger which acts as a battery charger when plugged into a live shoreline connection, so is constantly charging the bank of sealed lead acid batteries. We run tube heaters, controlled by electronic timers, to try and prevent the boat freezing up. A couple of simple questions. 1:- is leaving the batteries on charge permanently doing them any harm? 2:- suppose I wanted to take a resting battery voltage reading on return to the boat - would the batteries be rested if they've been on a 'trickle charge' for a few hours, or do they need to be disconnected from all load / charge for a couple of hours before taking reading? Indeed, does each battery have to be completely isolated from everything before taking the reading? Apologies for 'numpty' questions, but though I am trying to get some understanding of electrics I know I have a huge amount still to learn. Thanks in advance, Colin T.

Sorry for the delay in replying, work getting in the way of real life! So, to answer questions / comments in the order posted:- Wotever: DC -ve hull bond looks to be the same point as the AC hull bond BUT I am not on the boat at present, I'll check next time I'm there; by'eck: thanks for the welded stud suggestion, that makes sense if I can find somewhere sensible to locate it; bottle: yup, that was either a typo or a typical example of 'muddle-head-me' - thanks to all for the benefit of the doubt !; Blackrose: thanks for the suggested location of said welded stud - again, this is something that'll need looking at next time I'm at the boat. A question - by'eck quoted a specific size / gauge for earth cable. Is there a reference where I can translate the mm2 size to a diameter - so that I can check what's been installed on the boat? I think that's about it, other than to offer thanks for the help and good advice to a novice boater - very much appreciated. Colin T.

Sorry chaps, it is indeed one of those horrid domestic wrap around bonding clamps. I'm guessing it was the pragmatic solution as I'll need something like 2 metres of earth cable to connect the shore socket to the steel engine bearer beam, which might not be ideal but I don't think it will be a problem. What will be, err, challenging, is that the earth point on that beam is slightly beyond my maximum comfortable reach, and has not much more than about 6" working room around it as it's located between the engine and the bulkhead that forms the back of the bed-room wardrobe (bedroom at stern of the boat). Still, I guess it's challenges like these that make life interesting, eh?!

Hi Tony, It's a 57' steel hull narrow-boat. It seemed a bit strange to me also, but then I don't understand electrics too well, hence the question. Colin T

Ta muchly Over n out Colin T

Many thanks for the swift replies, gents, very much appreciated. Having read the page referenced by the link, as well as a web about why the AC ground must be bonded to the hull, I think all I need to do is make sure that both earth cables terminate at the point - the steel engine bearer beam seems favourite. Colin T Sorry - meant to say "both earth cables terminate at a single point"!

Mornin' all, Joined yesterday and this'll be my first post, so I'll start with an electrical query! The boat came with a shore-line socket installed, cable to connect to a shore based power supply, but no galvanic isolator. Threads on this forum suggested this was not an ideal situation so I've bought and fitted a Safe Shore galvanic isolator. When it came to fitting the thing, I discovered there was an earth cable from the earth on the back of the shore socket that terminated on a strap fixed to a deck drain outlet. Taking advice from Safe Shore I've moved this earth cable so it runs from the boat-side of the isolator to the deck drain, not from the shore-line side of the isolator. My question is: do I actually need this earth cable at all?? For clarity, the 240v supply line runs from the socket, through the GI and then directly to a Sterling Pro-Combi inverter / charger which is earthed to a steel engine bearer beam. All answers gratefully received, but I'd be grateful if you could avoid too much electrical detail - I simply don't understand that stuff! Thanks in advance, Colin T