Peregrine

If this is so, that's a result!

No. I've checked through both the standard Isuzu manual and the additional one for canal boat users, and there's nothing.

It's an Isuzu 42, dating from 2007. The boat's manual said it would be a Lucas 70 amp alternator, but the alternator label didn't identify the manufacturer, and was marked "80 Amp". Googling its HMI (Isuzu) part number led to the Prestolite website page for the 66021126 alternator, which gave lots of detail, but not the number of poles. However, their Contact Us page has an email address for their European operation, so I sent off an ROI and got a reply first thing Monday morning!

Many thanks to all who responded. It resulted in: Getting a very speedy email response from Prestolite confirming that the alternator is 12-pole Downloading a strobe/tachometer app for my best beloved's rather old iPhone In the end it was a "Doh!" moment. As I was fiddling with the app, I realised that I'd not measured the crankshaft pulley correctly. That is 5'', and the alternator pulley is 3", so the correct calculation is 5/3 * 12/2 = 10 pulses per revolution. I'd entered 8 first time around. Once that was in, the idling speed was shown as 800 rpm, which is a little higher than that shown by the old tachometer, but perfectly reasonable. (Of course, though now OT, that means that the engine alternator is just starting to provide charging current at tickover, while the domestic alternator with a 6" pulley is spinning at 1600 rpm, which the spec chart indicates should yield about 15 amps. Not great, but a bit better than what I'd assumed under the old regime.)

Following the discussion I started last autumn about a new tachometer (http://canalworld.net/forums/index.php?/topic/87213-replacing-a-tachometer/#comment-1882715) I bought a VDO Viewline. The calculation to calibrate it for the pulses from the alternator is straightforward, but means knowing the number of poles that the alternator has. The part number label shows it's a Prestolite AS123 80 amp, though the Aqualine's manual says it's a Lucas 70 amp. I can't find any official info on the web about the number of poles, but one forum suggested that the Lucas A127 type typically has 12, so that's what I used in the calculation. However, that's producing a reading of about 1000 rpm at tickover, whereas the old tacho read about 600, and I don't know which one is correct. Without a strobe hand-held I'm a bit stuck! Please does anyone know how many poles the AS123 has, or where I could find that info?

That's useful, Tiggs. Thank you.

I recently posted a query about replacing a tachometer on a 9 year old Aqualine with an Isuzu 42 engine. Many thanks to those who responded, especially Tony Brooks. At the same time that the tachometer failed, the ignition warning buzzer malfunctioned, but while Oxley Marine were looking at these control panel problems, it seemed to recover, so I didn't mention it. Since then it has stopped working again at start, but sometimes sounds during the stop procedure, as it should. I would like to fix this – it feels like a dodgy connection, but obviously may be a faulty device. However, I can't find any mention of the buzzer in the manual. It's not on the very clear Isuzu wiring diagram. So I don't know whether it's a separate device, or whether it's part of one of the other instruments on the control panel. I would like to be clear what I'm looking for before I dismantle the control panel again. Does anyone know, please [a] where the buzzer is located; where it fits in the wiring scheme?

Thanks, markgregoryuk2000 and Tiggs. It's always hard to know [a] what you gain or lose by going for a cheaper option, and the value of a single negative comment – which I found for another cheaper make as well. Thanks, Tony. It sounds as though the current one is like yours. The guy at Furneaux Riddall indicated that the new one comes with a wiring loom, but there is also a wiring kit to convert from the old one to the new. There's nothing on their website about it, so I need to go back and ask him for more details. What I don't know is where the buttons are that you press to programme the thing – on the back of the meter or to be mounted elsewhere. The installation instruction PDF doesn't say. I saw a YouTube video for installing one in a car that had them mounted under the dash. I'm not afraid of the theory around alternator poles, etc – but I am worried about installing something in a control panel in a less-than-watertight way!

Erin Mae is an 9 year old Aqualine boat with an Isuzu 42 engine. The VDO tachometer has stopped working and Oxley Marine have declared it dead. I can live without a tachometer for the moment, but I would still like to replace it. Suppliers to my two favourite boat yards have a replacement, but for serious, silly money. I've found a VDO Viewline for less than half the price from Furneaux Riddell in Portsmouth, which looks as though it is a thoroughly updated version. However, the helpful bloke on the phone suggested it was quite complicated to fit. Any comments, please, on things to think about in fitting a new tachometer.

Final report – if anyone's interested. Bench testing of the alternator showed both rectifier and regulator to be faulty, so they've been replaced. Along the way I learnt considerably more about internal and external alternator wiring. Thanks to Tony and Nick for helping in my education.

Thanks again to both Tony and Nick. The alternator belt is fine. I seem to be getting charge into the battery bank, which is presumably coming from the engine alternator. We're currently on our way to Skipton, and a conversation with RCR has resulted in a decision to hurry that up and book in for Pennine Cruisers to have a look at the alternator. In case it's of interest, I'll report back once that's done.

Thanks Nick. Your comment, if I understand it, clarifies for me something from Tony's response. Do I take it that the warning light is normally connected between alternator D+ and the battery +ve, but with a diode on the circuit so that it only lights if the alternator voltage is lower than the battery voltage? I understand that might indicate an alternator problem. I should have thought about the belt slipping. I'll check that first thing in the morning. One reason for being puzzled is that I could see a reasonable charging voltage at the battery with the engine running, even though the warning light indicated a problem. But that might be the effect of having both alternators connected to the A2B, even though the engine alternator is (IMO) under-pulleyed.

Thanks, Tony. 1. I have a 330W solar panel, but I don't think that can be the issue. I noticed it shortly after setting out this a.m. when the batteries were relatively low, and I was in Garrow tunnel at the time! 2. I'm not sufficiently familiar with alternator circuitry to understand all you said about D+. I googled it and found some Prestolite stuff which helped and indicated it was a warning light terminal. But I'm not sure what you mean by "difference in voltage between the battery and alternator output to D+". 3. I don't understand your reference to "both warning lamps". It's just the one that is misbehaving. But it is true that the two alternators may be interacting, since they are both connected to the input terminals of the AB12160. They are identical alternators (standard Lucas type 70 or 80 amp) but they have different sized pulleys on the crankshaft, so potentially a different output. However, I understood that alternators cope happily with being connected in parallel.

Today in a tunnel I noticed the auxiliary light on my Isuzu engine control panel was lit, though inconsistently and not to its maximum brightness. The manual says the light is a warning that the domestic batteries are not charging. Erin Mae is an Aqualine with an Isuzu 42 and what they call the Deluxe Engine Control Panel. The Auxiliary warning light sits on the panel alongside the ignition switch and lights. I have the original circuit diagram for the boat, but the wiring for this warning light is not on the diagram, so I don't know what it is checking. Two years ago I installed a Stirling AB12160 alternator to battery charging device, which takes the output from both alternators and uses it to charge both the engine battery and the domestic set (and is supposed to do some other clever stuff). This means the output from the domestic alternator is routed via this gizmo, but I don't know whether or how this will have impacted the wiring to the warning light. Anyway, I have never seen this problem until now. I'm naturally anxious that this will create havoc on the domestic side of the electric. But I don't know what the problem is. Does anyone have any ideas before I call out the engineer?

The 204 is the 203 + True RMS. You decide whether that's needed on a boat. When I got my 204 it was going for the same price as a 203. Perfectly happy with the purchase.

They're sealed, Pete.

I've no argument with this. It always seemed to me that, even if there was an issue in relation to charging, it would be small, and you confirm this. I originally wanted to see a rationale for Chris' assertion about charge and load needing to be connected to the same terminals. So far, very little on this thread has supported it. But my final point / question was not about charging at all. It was about load. As far as I can see, my boat runs the 12v circuits off one end of the bank, and the inverter off the other end. What I've gleaned suggests that's not sensible, and that's what any re-wiring would primarily address.

Doesn't this mean that what you're commenting on is having a charging source and an inverter load at opposite ends (which was certainly my original question) and concluding that it's fine? Whereas what we've moved on to discussing is whether it's OK or not to have two loads (12v circuit and inverter load) placed, one at one end and the other at the other end of the bank.

This was my initial query, based on Chris Gibbons' statement. Except in relation to how the SmartGauge actually works, that website is chock full of explanation. So coming across his final but unargued assertion, I wanted to understand the rationale. It was when I examined Erin Mae's wiring in more detail that I realised that the actual configuration means that the 12v supply is taken from one end of the bank, while the supply to the inverter is taken from the other end – one of them is not on a "diagonal". As I understand it, that's a situation which could cause an imbalance and premature battery ageing, and probably ought to be changed.

Well, well, Pete. I've been wondering how to implement Chris Gibbons' representation of your scheme, in a situation where I think it may be difficult to "stretch" the current charge lead (from my Stirling gizmo) to the +ve post on the second battery in the bank – because that's how Chris shows it. Last night in bed it suddenly occurred to me that the cables could be arranged so the take-off points are from the end batteries. I've just spent 15 minutes drawing it up, ready to post in this thread – and you've beaten me to it! I wonder why the SmartGauge site shows it as it does. Perhaps that was how you originally drew it up. Your point about extra terminals on a battery post is well taken, especially since there are some sensors attached, and some negative cables I shall have to trace when we get back to Erin Mae. But my batteries have an extra screw terminal as well as the stud, so that will help. The main thing will be to see whether, with the lead from the isolator switch moved to the "proper" end of the bank, I end up with the ladder / diagonal setup, and that will depend on what my -ve cables are actually doing. If they're OK, I may just leave them, as you suggest.

Thanks for the clarification. We've had to come away from Erin Mae for a couple of weeks, so I can't trace out an accurate diagram just now. I do know that it doesn't quite match the generally excellent official Aqualine wiring diagram, and that not all the differences are due to the installation two years ago of the AB12160 unit. I agree about the potential confusion with the wiring for the engine starter battery – cable identification is one of the issues, especially of some the negative leads – but this is only about the domestic bank. The two isolator switches are either part of a double unit or else very close together, and are sited close to one end of the battery box – the wrong end (!) if, as seems probable, I need to re-route from the domestic switch down to the far end of the bank.

Tony, I'm not sure if you meant that my current system is wrong or that Paul C's suggestion was wrong, and whether you meant a diagram from him or of the actual way my wiring has been done. I have a Stirling AB12160 alternator-battery gizmo combining the output from two alternators and governing the battery charging. So when I said "alternator and solar charging sources" I really meant the output from the AB12160's terminal, which goes to the same battery post as the inverter link, without an extra isolator. The solar controller output goes via a fuse to the AB12160's terminal, to make use of the hefty charging cable already in place.

On the SmartGauge website, Chris Gibbons has a page about connecting multiple batteries, in which he recommends a wiring arrangement he attributes to this forum's smileypete. His arguments are detailed and suitably convincing, and I'm trying to work out how to follow his advice on Erin Mae. However, he ends the article with: "And finally, finally, we keep getting asked where the chargers should be connected to. We didn't address this question because it seemed so blatantly obvious where they should be connected that it never occurred to us that anyone might be unsure. The chargers should always be connected to the same points as the loads. Without exception. " In contrast with the rest of the page, there is no argument here, just a statement. So I'd like to know the rationale for this statement. I can see why you would want the +ve and -ve charging leads connected to opposite ends of the bank, but not why they should have be to the same points as the load leads. The reason is that, as far as I can see, the +ve connection from my Victron MultiPlus inverter/charger goes to one end of my 4-battery bank, via its own isolator, and the alternator and solar charging sources are connected to the same point. However, the feed from the batteries to the 12v distribution panel is taken (via a different isolator) from the other end. Now I recognise that the Victron / battery lead is both for charging (from a landline), and for supply (to the inverter when cruising), so I think this needs to be tidied up regardless. Nevertheless, I want to be as sure as I can be about the principles here before I start getting into what I think will be quite a complex re-wiring exercise.

Nicknorman, PaulD, by'eck, Thanks for these responses. I'd not realised that the effect of the temperature coefficient would be that powerful, and hadn't taken it into account. I eventually found in the Victron's manual a graph of voltage against battery temperature for the units default setting, and it does rise to 14.7 at about 10˚C. The manual doesn't seem to give an actual coefficient, but the manual for my new solar stuff does, and the calculation shows the 0.3v rise to be perfectly normal, as nicknorman says. The battery type is set to 6 on the SmartGauge, but there seems no way of adjusting the voltage at which the E 03 error kicks in. I see I can turn it off if it becomes a distraction. Thanks again for the comments. Odd things after fitting new gear are always a bit worrying!

My boat has a Victron MultiPlus 12/3000/120 inverter/charger. My new SmartGauge alerted me that my new sealed Numax batteries (4x110) had been subject to a voltage "too high for their type". I found the meter showing 14.7 volts with the Victron indicating it was in absorption phase (though by rights it should have been in float phase since it's on a landline and the batteries are pretty much 100% charged). The manual says the Victron's default battery type is an Exide gel type, and the settings for this are pretty much what you'd want for a sealed battery – absorption voltage of 14.4 and float of 13.8/13.2. I took my life in my hands, read the manual, opened the unit, found how to read the settings via a combination of DIP switches and LEDs, and confirmed that the unit is indeed on its default. So it should have been applying a maximum of 14.4 volts. Not the 14.7 shown by the meter. I don't know whether this is something recent or not. I have also just fitted a solar panel with a Tracer 30Amp charge controller, in parallel with the other charging systems (the Victron unit, and a Sterling alternator-battery unit). The meter for the Tracer shows the panel and controller behaving themselves – they also are set for sealed batteries and the charging measurements seemed spot on when we disconnected the landline and just used solar for a few hours. So I wonder whether the Victron is troubled by having a second charging source in parallel with it. But I am especially troubled by the fact that it is exceeding its stated absorption voltage for the battery type to which it is set. Any comments on this behaviour?