Can Anybody Positively Identify This Alternator, Please?

[David Schweizer]

I've got some old material on the AC5 somewhere, but haven't tracked it down yet, not where I thought it should be.

The best I can find on the web is that the AC5R should cut in at around 1250 rpm, though this can be reduced by fitting a larger warning light bulb, and delivers 85% of full output at around 3000 rpm. I don't know what effect the Kestrel should have on that.

The A127, or one iteration of the 70A version from Prestolite, cuts in at about 1500rpm but needs 4200 rpm for 85% of full output.

 

Edit to add that Prestolite do seem to still offer a version of the AC5, but it might only be available in 24Volt.

 

Tim

 

Those figures confirm my experience of the A127. Cut in at tickover 600x3 = 1800rpm. Full output at 1500x3 = 4500rpm.

[alan_fincher]

Your battery bank if depleted would take longere to re-charge, but I must admit that a leisure bank of 7600 Ah begs the questiion how much electrical equipment do you plan to use on board?

 

I'm not sure where 7,600 Ah has crept in - have I mistyped something earlier - that would be a lot! Currently Flamingo has what should be 5x 110 Ah, so 550 Ah in total, (plus the starter). I doubt these have a lot of life left in them - even if they did before, we have already had some "low volts" incidents with them.

 

On Chalice we have 3 x 110Ah, and I'm fairly convinced that ultimately we may need no more than that on Flamingo. However at the moment Flamingo is highly "mains" dependent, having a thirsty mains central heating pump, as well as the main cabin lights being 230 volt. I'm sure we will slowly break that dependence, as soon as I'm up to tackling real work, rather than just pottering around trying to understand how we will move forward.

 

Additionally, where it does have some 12 volt lights, they are really poor but thirsty "bus bulb" types - lots of amps, but very little light. We expected to be replacing all this over time. Plus the inverter side of the Heart Interface takes a significant 12 volt current, even if no"mains" is being drawn from it. I'm not convinced we will retain that massive (and ancien) box of tricks, (weighs half a hundredweight, apparently! ), and may opt instead for individual charger and individual inverter, each with much lower maximum ratings. There is lots to assess, and make decisions about.

[David Schweizer]

No Alan the mistype was mine (since corrrected) I meant 500 Ah., We also have bus bulbs in the saloon in Helvetia, which we actually like, and are quite bright (I think they may be 24w.) In reality there are rarely more than two on at any time, and usually only for two or three hours max. Yiou can now get LED ones with the same BA22D fitting (but expensive!)

Edited February 5, 2015 by David Schweizer

[Sir Nibble]

Most difficult part of changing a diode is getting the pulley off. Diodes can be individually tested without splitting the alternator. There was a super low speed AC5 built for Gardners, this isn't one of them.

[madcat]

 

 

On the subject of Ardverc , a number of friends have them and are well pleased. I bought a Sterling , I got it cheap ages ago. It works fine but I'd probably buy an Ardverc next time round when ever that is .

 

If you decide to replace the AC5 don't just get rid as I'd be interested in buying it from you. I've been keeping my eye out for one for ages.

[Sir Nibble]

I would suggest testing the diodes, or even taking voltage readings first. If it's a diode then split it and check the slip ring end bearing housing for wear. If that's ok change the diode or flog it to madcat.

[MtB]

I am always surprised that increasing the revs significantly above the 700 RPM tickover never seems to result in a much higher charge rate to the batteries, but at 700 RPM, we are spinning it at only half that 4,200 PRM number.

 

 

The whole point of changing from dynamos to alternators back in the late 60s was that an alternator delivers maximum output at very low revs (typically 1000rpm) but is safe to spin at far higher speed (typically up to 10,000rpm) than a dynamo. This is because the wires are static (in the body) of the alternator but spinning (in the armature) in a dynamo.

 

This means that full output can be obtained from an alternator at tickover but no damage results from revving the nuts off it (technical term), unlike a dynamo.

 

 

MtB

Edited February 5, 2015 by Mike the Boilerman

[alan_fincher]

The whole point of changing from dynamos to alternators back in the late 60s was that an alternator delivers maximum output at very low revs (typically 1000rpm) but is safe to spin at far higher speed (typically up to 10,000rpm) than a dynamo.

 

 

 

Errm,

 

Assuming you mean alternator RPM, not engine RPM, that is massively different from what is usually said on the subject, and certainly bears no correlation to graphs like this, (random one from many found with a quick Google search).....

 

 

Surely whilst some narrow boat engines can give a fairly good rate of charge at tick-over, (provided the pulley ratios are right), even with say a 3:1 ratio and a 700 RPM tick-over, the alternator is spinning at maybe 2,100 RPM, but a graph like the above would suggest it would still only be at about 80% output, (certainly not maximum).

 

That graph requires the alternator to be spinning at more like 4,000 RPM to achieve full output, so maybe 4 times what you are suggesting. (With a 3:1 pulley ratio, that would need engine to be in excess of 1,300 RPM)

 

Other randomly suggested graphs for other alternator types are not wildly different to this. I think if you could provide an alternator that gave full output with alternator RPM at just 1,000, there would be a massive marketplace for it.

 

EDITED TO ADD: I'm assuming the 12V 100 Amp line, when referring to that graph.

Edited February 5, 2015 by alan_fincher

[Timleech]

 

 

The whole point of changing from dynamos to alternators back in the late 60s was that an alternator delivers maximum output at very low revs (typically 1000rpm) but is safe to spin at far higher speed (typically up to 10,000rpm) than a dynamo. This is because the wires are static (in the body) of the alternator but spinning (in the armature) in a dynamo.

 

This means that full output can be obtained from an alternator at tickover but no damage results from revving the nuts off it (technical term), unlike a dynamo.

 

 

MtB

 

Alternators can be designed to run at much higher speeds than dynamos, so can be higher geared. The commutator on a dynamo is a weak point, can burst open if driven too fast, also expensive to make.

Dynamos were commonly made to work at low speeds.

Both machines have wires in the static and revolving parts.

 

On the subject of Ardverc , a number of friends have them and are well pleased. I bought a Sterling , I got it cheap ages ago. It works fine but I'd probably buy an Ardverc next time round when ever that is .

 

If you decide to replace the AC5 don't just get rid as I'd be interested in buying it from you. I've been keeping my eye out for one for ages.

 

If you particularly want a 12Volt AC5, try Middletons in Manchester. They took a new 12V AC5 (strap mounted) from me in part ex for a 24V Gardner type a couple of years ago, they're as likely as anyone to have old stock lurking about.

I swapped the AC5 on my engine for its big brother, the AC7, so have a nearly new Gardner type 24V AC5 available.

 

Tim

Edited February 5, 2015 by Timleech

[David Schweizer]

 

 

 

Errm,

 

Assuming you mean alternator RPM, not engine RPM, that is massively different from what is usually said on the subject, and certainly bears no correlation to graphs like this, (random one from many found with a quick Google search).....

 

 

Surely whilst some narrow boat engines can give a fairly good rate of charge at tick-over, (provided the pulley ratios are right), even with say a 3:1 ratio and a 700 RPM tick-over, the alternator is spinning at maybe 2,100 RPM, but a graph like the above would suggest it would still only be at about 80% output, (certainly not maximum).

 

That graph requires the alternator to be spinning at more like 4,000 RPM to achieve full output, so maybe 4 times what you are suggesting. (With a 3:1 pulley ratio, that would need engine to be in excess of 1,300 RPM)

 

Other randomly suggested graphs for other alternator types are not wildly different to this. I think if you could provide an alternator that gave full output with alternator RPM at just 1,000, there would be a massive marketplace for it.

 

EDITED TO ADD: I'm assuming the 12V 100 Amp line, when referring to that graph.

 

Alan, I think you are probably being optomistic if you expect any alternator to achieve an output equivalent to it's maximum rating for very long. I am sure if I am wrong someone with more technical knowledge will correct me, but my experience suggests that even with an advanced external alternator regulator, output very quickly drops to about 75% where it will hold for a while before gradually dropping to about 45%, something which can be achieved on our boat at tickover (alternator speed aprox 1800 rpm)

 

I don't know what requirements a 24hour electrical audit on Flamingo would indicate, but knowing you, I doubt that it would be that high, so I suspect that a few hours cruising even at 25% would easliy replenish your batteries, and you are renowned for long cruising days!!

[Tony Brooks]

 

Alan, I think you are probably being optomistic if you expect any alternator to achieve an output equivalent to it's maximum rating for very long. I am sure if I am wrong someone with more technical knowledge will correct me, but my experience suggests that even with an advanced external alternator regulator, output very quickly drops to about 75% where it will hold for a while before gradually dropping to about 45%, something which can be achieved on our boat at tickover (alternator speed aprox 1800 rpm)

 

I don't know what requirements a 24hour electrical audit on Flamingo would indicate, but knowing you, I doubt that it would be that high, so I suspect that a few hours cruising even at 25% would easliy replenish your batteries, and you are renowned for long cruising days!!

 

 

Alan's graph is for an alternator running into a RESTIVE load such as you will find on a test rig. You are talking about a "real life" situation where the load is far from straight resistive and if we use that term actually alters its "resistance" as the batteries charge (pedants - note the parentheses). The reason the output drops to 75% is that the "resistance" of the battery has shot up because of surface charge so the current output will fall. That is simple Ohm's law in so far as we can think resistance when talking about battery charging.

 

However I suspect your conclusions are not far from the mark.

[Timleech]

 

 

Alan's graph is for an alternator running into a RESTIVE load such as you will find on a test rig. You are talking about a "real life" situation where the load is far from straight resistive and if we use that term actually alters its "resistance" as the batteries charge (pedants - note the parentheses). The reason the output drops to 75% is that the "resistance" of the battery has shot up because of surface charge so the current output will fall. That is simple Ohm's law in so far as we can think resistance when talking about battery charging.

 

However I suspect your conclusions are not far from the mark.

 

That's true, IF the main alternator load is charging the batteries. If you put on a big load, such as microwave via inverter, the output will shoot up.

 

Tim

[alan_fincher]

 

Alan, I think you are probably being optomistic if you expect any alternator to achieve an output equivalent to it's maximum rating for very long.

No, far from it!

 

Certainly on Chalice, just charging a modest battery bank, with no external regulator, we have seldom seen large charging currents for very long, and also seldom anything vaguely like the theoretical alternator maximum output.

 

My challenge was purely in completely the opposite direction to challenge haevily Mike's assertion that "an alternator delivers maximum output at very low revs (typically 1000rpm)", because if he is talking about alternator RPM, rather than engine RPM, I think most people would recognise that statement as nonsense.

 

That's true, IF the main alternator load is charging the batteries. If you put on a big load, such as microwave via inverter, the output will shoot up.

 

Tim

 

Yes,

 

Although we have no such option on Chalice, (very small inverter), what I do note is that once you turn anything on, (lights for example, or more usually several laptops on the go at once), the current delivered by the alternator rises to more or less meet the demands of whatever is turned on. So if charging at (say) 20 amps into a relatively charged bank, and you switch on 10 amps of loading to that bank, then the alternator will provide 30 amps (ish) overall.

[alan_fincher]

 

I don't know what requirements a 24hour electrical audit on Flamingo would indicate, but knowing you, I doubt that it would be that high, so I suspect that a few hours cruising even at 25% would easliy replenish your batteries, and you are renowned for long cruising days!!

 

Yes, as I have indicated, current power requirements on Flamingo don't really enter in to it, as I would hope to move away from things like 230V domestic central heating pumps, and 12 volt 24 watt "bus" bulbs that deliver almost no light. At the moment it is far too "over-thirsty".

 

You are quite correct that when on the move with Chalice, even with a modest alternator and battery bank that we rarely have issues, but there are occasions where we end up at the same place for several days, (typically boat festivals), and although we may not be using a lot of power, a son wants to run a fairly thirsty lap top all day long. Often there are multiple laptops on, (don't ask!), and I suspect our greatest use is generally driving computer facilities. In an ideal world we would be able to survive several days without some engine running, but the reality is we often do end up with the engine on on those occasions, to stop battery volts going too low, (obviously how old, and how well looked after the batteries have been enters into this - I'm not that great at looking after them!).

[David Schweizer]

 

Yes, as I have indicated, current power requirements on Flamingo don't really enter in to it, as I would hope to move away from things like 230V domestic central heating pumps, and 12 volt 24 watt "bus" bulbs that deliver almost no light. At the moment it is far too "over-thirsty".

 

You are quite correct that when on the move with Chalice, even with a modest alternator and battery bank that we rarely have issues, but there are occasions where we end up at the same place for several days, (typically boat festivals), and although we may not be using a lot of power, a son wants to run a fairly thirsty lap top all day long. Often there are multiple laptops on, (don't ask!), and I suspect our greatest use is generally driving computer facilities. In an ideal world we would be able to survive several days without some engine running, but the reality is we often do end up with the engine on on those occasions, to stop battery volts going too low, (obviously how old, and how well looked after the batteries have been enters into this - I'm not that great at looking after them!).

 

That comment about bus bulbs concerns me, The 12v 24w bus buklbs on Helvetia dekluiver quite a good amount of light despite them being at the far end of the boat away from the batteries. If yours are not very bright, it suggests that either the batteries are not fully charged or the cable size is too small, or that our personal concepts of lamp brightness are significantly different.

 

When making observations about usage and re-charging tiome i had overlooked laptops etc which we do not have. Jan has an Ipad(?) thing, which will work through her phone, but i don't bother with anything when away from home.

[alan_fincher]

 

That comment about bus bulbs concerns me, The 12v 24w bus buklbs on Helvetia dekluiver quite a good amount of light despite them being at the far end of the boat away from the batteries. If yours are not very bright, it suggests that either the batteries are not fully charged or the cable size is too small, or that our personal concepts of lamp brightness are significantly different.

 

If I owned up to what is the state of the 12 volt cabin electrics, people would laugh themselves silly!

 

I can't actually believe just how bad they are, I won't even go there, but trust me, if anybody opens a tap, all the light flicker on and off uncontrollably.

 

I'm fully expecting to replace every inch of 12 volt cabling in the main cabin, (much of which is actually solid drawn single strand mains wiring, but some of which is even lenthened in Arctic cable, and hence is visually indistinguishable from the 230V AC side. The latter has all been replaced, and seems safe enough, other than being complete overkill, as there are individual cable runs virtually the whole cabin length not just washing machines and immersion heater, but even for a proposed dish washer! Currently the boat is fine on a landline, but how he proposed to power many of these things if it was not quite eludes me.

[Tony Brooks]

If the boat has an old Wylex type domestic re-wirable fuse board have you checked the tightness of the screws on the negative busbar that sits inside the fuse box? Just a thought.

[Sir Nibble]

 

 

Other randomly suggested graphs for other alternator types are not wildly different to this. I think if you could provide an alternator that gave full output with alternator RPM at just 1,000, there would be a massive marketplace for it.

 

EDITED TO ADD: I'm assuming the 12V 100 Amp line, when referring to that graph.

I've built alternators to deliver full whack at 500 rpm. Trade off is that the full output concerned is rather low. Typically I can get about 45A from 800 rpm. I find the fact that that is available constantly compensates for lack of amps by an increase in hours.

[alan_fincher]

Reopening this topic,now I have had my first opportunity to start looking at the issues with the alternator and / or how it is wired, (including the use of the Kestrel).

 

I stil couldn't get it to energise using just the alternator warning lamp.

 

However on strapping a 68 ohm resistor, (which I should draw about an additional 176mA at 12v) across the bulb, I did get it to energise as soon as a few revs were added.

 

HOWEVER......

 

As was happening before, some circumstance seems to be blowing the warning lamp, so some combination of circumstances must be putting well over 12 volts up it.

 

I suspect, but haven't proved it, that it is stopping the engine with the alternator still connected, because at the point the lamp should come back on, it doesn't.

 

No idea where the voltage to cause this is coming from. Coult the Kestrel be causig this in some way - I can't get my brain around it.

 

Unfortunately on a special trip to Halfords I only bought two lamps - I now have no lamps!

 

I may try temporarily bodging this by putting two 12V bulbs in series, and hoping whatever is causing it can't actually produce in excess of 24V.

 

But ideally I would prefer to understand what is going on, and, if possible, avoid the bodging!