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Best alternator setup with lithiums?


Jay88

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Hi,

 

After some advise IRT charging a lithium leisure battery bank of 400ah. At this stage the boats 6 x 110ah leisure batteries are completely dead (boat stored on hardstand) and when we start CCing next year I'm keen to get lithium's as opposed to LA.

 

Current setup is as follows:

- Isuzu 43 engine with 2 x 80A alternators, one to starter battery, one to current leisure bank through sterling A-B charger

- 6 x 110ahr leisure batteries

- 2 x bow thruster batteries

- Sterling A-B charger for leisure batteries (broken) 

- Sterling b2b (I think from leisure or starter battery to bow thruster batteries??)

- 625w solar (to be installed next year)

 

After doing some research it appears that charging the lithium bank via the 80A alternator may cause it draw too much current or shut off suddenly, which apparently isn't so good for it. Whilst I have investigated installing a 200A alternator for the lithium's, the price is simply beyond my budget, as such looking at how I can use what equipment I have to have an effective yet simple (very important!!) system to charge the lithium with the 2 x 80a alternators. Through my research  have seen other boats / RVs with a DC-DC charger from the alternator to the lithiums but some people appear to do nothing with no ill effects on their alternators.

 

I imagine a very simple solution would be to have one alternator going to the starter battery and the other to the lithiums via a DC-DC charger. I'm guessing I could then use the existing B-B charger to link the starter and bow thruster batteries so they get a charge? (if they are already wired up this way?). Or can I somehow use the existing B-B charger between the starter and lithiums so I have 2 x alternators charging the lithium's once the starter battery is full?

 

Ideas?

 

Cheers!

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Firstly I must caveat this by saying that you will get proper answers from the experts, and this is just a personal experience that may have some similarities.

 

I also found that it was not financially viable to upgrade my alternator to a decent model, so I'm stuck with 100 amp domestic and 80 amp engine alternators. 

The problem I ran into was that these cheaper alternators cannot maintain their rated current output for a useful length of time. With lead acid batteries thats not such a big deal because after say 10 minutes of charging, the LAs internal resistance against charging starts to build up, and so that reduces the amount drawn from the alternator. 

But lithiums will draw almost everything the alternator can produce, and so if you connect them directly to the alternator, they will draw its maximum current, and within 10 minutes it will be overheating, and will be at risk of burnout. 

From what I've seen, my impression is that an 80 amp alternator will probably be able to put out about 40 amps on a continuous basis before it starts getting a bit hot, so its possible your maximum potential charging current will be somewhere between 70-90 amps, so thats not too bad. 

 

My solution to limit the current was to use two 50 amp Sterling B2B chargers (I'll explain why I use two in a bit), but these are not cheap, at £300 or more. 

A cheaper and simpler way of limiting the current is to install a long length of 16mm cable before the charge hits the lithiums. There are threads on here and youtube videos about it, with the necessary detail. 

 

One setup that people have been using is a lead acid battery in parallel between the alternator and the lithiums. This acts as a buffer and prevents damage to the alternator by continuing to accept charge if/when the lithiums stop charging abruptly. 

 

I initially tried to wire both my alternators to provide a single charge route into a lead acid battery, but it didnt work because my alternators are regulated to different voltages, and one of them ended up doing all the work whilst the other hardly ever delivered any charge. 

So check the alternators voltage to make sure they will work at the same time, and if they do, you can use a single lead acid battery and keep the setup simpler. 

What you dont want is for one or other alternator to be cutting out at some point during charging, leaving the other unit to do all the work. 

My solution to this was to set up two charging 'routes', ie one LA battery linked to each alternator (the A2B charger was ditched as I was using B2Bs, but I think you'll need an A2B charger in place- but again, someone who knows their stuff will confirm that).

So in my setup, from each LA battery the charge goes into a B2B (then a fuse), and then the B2Bs feed onto a positive bus and on into the lithiums. 

 

But anyway, hopefully the experts will be along shortly to give you a proper explanation of a suitable setup. 

You won't regret getting lithiums. 

 

ETA- just a thought here, but if your A2B is broken, and if your alternators work at different voltages like mine (which to be fair is not usual), then its decision time: do you splash out on a new A2B charger, and use cheap lengths of wire to limit the current, or do you do what I did and buy a B2B instead, and not use an A2B at all?

Bear in mind the B2Bs are inherently inefficient, and at least 10% of the energy they take is wasted as heat. Also with mine, they got so hot running at full chat (50 amps) that they kept switching into half power mode, so I wouldnt assume you'll even get the full rated 50 amps from them tbh, possibly more like 45 amps. 

And the limitation with the B2Bs is you only have two current settings: either full on charging at 45-50 amps, or half power at about 25-30 amps. 

If your alternators are good to put out a total of say 80 amps, a B2B charger wont be able to impose that precise current limit on the alternator (unless you buy two of the B2Bs, and run one at full power and another at half power- but thats getting expensive).

This where the length of thin wire method is better- you can work out how hard your alternators can safely work without overheating, and you can cut a length of wire to limit the current to exactly the safe level.  

 

In your place, I'd be tempted to buy an A2B, and use thin wire to limit the current, BUT on the proviso that both alternators work together at the same voltage- you dont want one of them stopping while the other runs, as I mentioned above. 

 

 

 

Edited by Tony1
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Have been helping some one install Lithiums. We tested the alternator to battery charging for the very first time less than one hour ago!

Connected the single alternator to the engine start battery as usual. From there used a Victron battery to battery charger, configured as a Lithium charger. This limits the charging current to the Lithiums to 30A, so shouldn't over heat the single small alternator on the engine when running for several hours. Too soon to say how this will work in the long term, as it has been running for a grand total of ten minutes so far...

Jen

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25 minutes ago, Tony1 said:

I initially tried to wire both my alternators to provide a single charge route into a lead acid battery, but it didnt work because my alternators are regulated to different voltages, and one of them ended up doing all the work whilst the other hardly ever delivered any charge. 

 

There seems to be something not right here unless you have failed to mention something else between the LA battery and lithiums or I do not understand this system.

 

As lithiums accept all the charge the alternator can throw at them so as alternators suppress the output VOLTAGE at high current loads while the lithiums are in parallel the alternators' voltage regulators should not be working. This means one can't shut down. However, when the lithiums disconnect then one may shut down but by that time I would have thought whichever it was it would not matter LA charging wise.

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15 minutes ago, Tony Brooks said:

 

There seems to be something not right here unless you have failed to mention something else between the LA battery and lithiums or I do not understand this system.

 

As lithiums accept all the charge the alternator can throw at them so as alternators suppress the output VOLTAGE at high current loads while the lithiums are in parallel the alternators' voltage regulators should not be working. This means one can't shut down. However, when the lithiums disconnect then one may shut down but by that time I would have thought whichever it was it would not matter LA charging wise.

 

I must apologise Tony, I'm probably not explaining the setup correctly, or the issue- and this was 18 months ago now.

After the first B2B was installed, I tried running a cable directly from each alternator onto a common post, and from there, a single cable went into the lead acid battery.

From the lead acid, the charge then went into the B2B. 

So at this point, there was no need for an A2B charger.

 

But what we found was that even with a charging current of about 60 amps, one of the alternators was overheating and the other stayed cool. The electrician who was doing part of the work said that the cool alternator was almost certainly not working, and was leaving the other alternator to do all the work. And for my poor alternators, 60 amps is too much over more than 15 mins, and they get too hot.

He measured the voltages of the two alternators, and one was I think about 0.4v lower than the other.

If memory serves, it was the lower voltage alternator that was not doing any work, because the higher voltage from the other alternator was overriding it in some way that I dont understand. 

Once I separated the two alternators so that they each fed into their own lead acid battery and their own B2B charger, they both ran all of the time. 

 

To have alternators regulated at such different voltages sounds like its a really poor setup and install when the boat was new, but I mentioned it because it may be an issue for the OP, if he wants to try and get both alternators charging at their safe max. 

 

ETA- as a result of separating out the two alternators into different 'routes', both now work at their individual safe maximum currents, and I can charge the lithiums at a combined 90-95 amps if I need to, although I am conscious that 95 amps is a lot of power for a V belt to handle (sadly neither of mine are poly V belts), so I dont always run the charge at its full potential. 

 

 

 

Edited by Tony1
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1 hour ago, Jen-in-Wellies said:

Have been helping some one install Lithiums. We tested the alternator to battery charging for the very first time less than one hour ago!

Connected the single alternator to the engine start battery as usual. From there used a Victron battery to battery charger, configured as a Lithium charger. This limits the charging current to the Lithiums to 30A, so shouldn't over heat the single small alternator on the engine when running for several hours. Too soon to say how this will work in the long term, as it has been running for a grand total of ten minutes so far...

Jen

 

My problem with this kind of setup is that, as an effete and decadent member of the capitalist class, I use a fair amount of electricity. I even have a fridge, with things in it.

So I want a setup that can charge at a decent rate. Typically, my oppression of the working classes requires about 140Ah per day, and charging at 30 amps (in the winter with little solar) that would need the engine running for four hours each day. 

That's a fair bit of diesel, is that. Couldn't your proletarian friend press their other alternator into service, feeding a separate lead acid and running via a separate length of cable, and maybe double the charge? 

 

(I'm available for moral guidance as well as electrical consultancy.)

 

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47 minutes ago, Tony1 said:

 

My problem with this kind of setup is that, as an effete and decadent member of the capitalist class, I use a fair amount of electricity. I even have a fridge, with things in it.

So I want a setup that can charge at a decent rate. Typically, my oppression of the working classes requires about 140Ah per day, and charging at 30 amps (in the winter with little solar) that would need the engine running for four hours each day. 

That's a fair bit of diesel, is that. Couldn't your proletarian friend press their other alternator into service, feeding a separate lead acid and running via a separate length of cable, and maybe double the charge? 

 

(I'm available for moral guidance as well as electrical consultancy.)

 

My friend is such a poverty stricken pleb that his boat only has the one alternator on the engine and a rather weedy one at that. What the boat does have, being a wide beam, is acres of roof space, which has been largely filled with a ridiculous quantity of solar panels. We are hopeful that the boat will be self sufficient from these except in the darkest couple of winter months. During the winter it is on a shore line, so the alternator is the principal source of charge for the rare mid winter trips away. We didn't think that either upgrading the alternator, or adding a second, would be worth while. Not just the costs of the alternator(s), but the addition of pulleys, conversion from V belts and so on. That money went on a humongous solar controller and panels instead. The 30A engine charge should be appropriate for his boat and his usage. For others, not so much.

The thread title is "Best Alternator Setup With Lithiums". The answer, as usual, is "It Depends"!

Edited by Jen-in-Wellies
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14 minutes ago, Jen-in-Wellies said:

My friend is such a poverty stricken pleb that his boat only has the one alternator on the engine and a rather weedy one at that. What the boat does have, being a wide beam, is acres of roof space, which has been largely filled with a ridiculous quantity of solar panels. We are hopeful that the boat will be self sufficient from these except in the darkest couple of winter months. During the winter it is on a shore line, so the alternator is the principal source of charge for the rare mid winter trips away. We didn't think that either upgrading the alternator, or adding a second, would be worth while. Not just the costs of the alternator(s), but the addition of pulleys, conversion from V belts and so on. That money went on a humongous solar controller and panels instead. The 30A engine charge should be appropriate for his boat and his usage. For others, not so much.

The thread title is "Best Alternator Setup With Lithiums". The answer, as usual, is "It Depends"!

 

Oh dear.

Oh dear oh dear. 

A wide beam, you say? And with a single alternator?

Is this really the sort of person you ought to be associating with?

Anyway, I heard widebeams are being cancelled. 

 

 

Edited by Tony1
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1 hour ago, Tony1 said:

 

Oh dear.

Oh dear oh dear. 

A wide beam, you say? And with a single alternator?

Is this really the sort of person you ought to be associating with?

Anyway, I heard widebeams are being cancelled. 

 

 

I'm always prepared to side with and be an ally of the most marginalised and discriminated against boaters in the inland waterways community. 😀

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3 hours ago, Jen-in-Wellies said:

My friend is such a poverty stricken pleb that his boat only has the one alternator on the engine and a rather weedy one at that. What the boat does have, being a wide beam, is acres of roof space, which has been largely filled with a ridiculous quantity of solar panels. We are hopeful that the boat will be self sufficient from these except in the darkest couple of winter months. During the winter it is on a shore line, so the alternator is the principal source of charge for the rare mid winter trips away. We didn't think that either upgrading the alternator, or adding a second, would be worth while. Not just the costs of the alternator(s), but the addition of pulleys, conversion from V belts and so on. That money went on a humongous solar controller and panels instead. The 30A engine charge should be appropriate for his boat and his usage. For others, not so much.

The thread title is "Best Alternator Setup With Lithiums". The answer, as usual, is "It Depends"!

How humongous an amount of solar Jen? At nearly 5kw I suspect I will be self sufficient in winter, although I ha6the genny as backup 

3 hours ago, Tony1 said:

 

Oh dear.

Oh dear oh dear. 

A wide beam, you say? And with a single alternator?

Is this really the sort of person you ought to be associating with?

Anyway, I heard widebeams are being cancelled. 

 

 

Such discrimination I don't think I can even read about it anymore! Also remember this is a proper navigation for proper size boats not floating corridors 🤪

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7 hours ago, Jay88 said:

Hi,

 

After some advise IRT charging a lithium leisure battery bank of 400ah. At this stage the boats 6 x 110ah leisure batteries are completely dead (boat stored on hardstand) and when we start CCing next year I'm keen to get lithium's as opposed to LA.

 

Current setup is as follows:

- Isuzu 43 engine with 2 x 80A alternators, one to starter battery, one to current leisure bank through sterling A-B charger

- 6 x 110ahr leisure batteries

- 2 x bow thruster batteries

- Sterling A-B charger for leisure batteries (broken) 

- Sterling b2b (I think from leisure or starter battery to bow thruster batteries??)

- 625w solar (to be installed next year)

 

After doing some research it appears that charging the lithium bank via the 80A alternator may cause it draw too much current or shut off suddenly, which apparently isn't so good for it. Whilst I have investigated installing a 200A alternator for the lithium's, the price is simply beyond my budget, as such looking at how I can use what equipment I have to have an effective yet simple (very important!!) system to charge the lithium with the 2 x 80a alternators. Through my research  have seen other boats / RVs with a DC-DC charger from the alternator to the lithiums but some people appear to do nothing with no ill effects on their alternators.

 

I imagine a very simple solution would be to have one alternator going to the starter battery and the other to the lithiums via a DC-DC charger. I'm guessing I could then use the existing B-B charger to link the starter and bow thruster batteries so they get a charge? (if they are already wired up this way?). Or can I somehow use the existing B-B charger between the starter and lithiums so I have 2 x alternators charging the lithium's once the starter battery is full?

 

Ideas?

 

Cheers!

Well the best alternator setup is to use an external smart alternator controller which does a lot of things including monitoring alternator temperature and reducing output to stop it getting too hot. Also reducing alternator output to a low float voltage (say 13.3v) to avoid holding the lithiums up at a high charge voltage after they are fully charged, which is bad for them. It would need to be linked to some sort of state of charge measurement device. The Mastervolt Alpha Pro III linked to a Mastershunt Ah counter and Masterview Easy panel would be one way of doing it - if you have £1k + to spare. Well you did ask!

 

If doing it on a budget I would have the alternator connected to a smallish LA battery, then from the LA battery via a longish bit of wire to add some resistance and hence limit current, to the Li. Via some sort of battery isolator switch so one could “turn off” charging to the Li. When you do that, the LA can absorb the otherwise damaging alternator voltage transient (in the moment that it takes for the alternator field current to subside). And something like a BMV712 to allow you to keep an eye on the Li SoC so you can shut off charging (manually) before the battery gets rammed fully charged (which is not great for its longevity when done habitually).

 

I have the former type of system, but plenty of people have the latter type of system and it seems to work ok.

Edited by nicknorman
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11 minutes ago, nicknorman said:

Well the best alternator setup is to use an external smart alternator controller which does a lot of things including monitoring alternator temperature and reducing output to stop it getting too hot. Also reducing alternator output to a low float voltage (say 13.3v) to avoid holding the lithiums up at a high charge voltage after they are fully charged, which is bad for them. It would need to be linked to some sort of state of charge measurement device. The Mastervolt Alpha Pro III linked to a Mastershunt Ah counter and Masterview Easy panel would be one way of doing it - if you have £1k + to spare. Well you did ask!

 

If doing it on a budget I would have the alternator connected to a smallish LA battery, then from the LA battery via a longish bit of wire to add some resistance and hence limit current, to the Li. Via some sort of battery isolator switch so one could “turn off” charging to the Li. When you do that, the LA can absorb the otherwise damaging alternator voltage transient (in the moment that it takes for the alternator field current to subside). And something like a BMV712 to allow you to keep an eye on the Li SoC so you can shut off charging (manually) before the battery gets rammed fully charged (which is not great for its longevity when done habitually).

 

I have the former type of system, but plenty of people have the latter type of system and it seems to work ok.

 

I don't have this long wire setup so I'm not 100% clear on the detail, but I had assumed that most people using this method would be using their existing A2B charger, and would select a charge profile that would ensure the A2B went into float at 14v or less. 

So that way they wouldn't have to manually intervene on every charge - which I assume they would do by by switching off the engine, or by disconnecting the charge to the lithiums. 

 With an A2B in place, the charging profile of the A2B could be set up to go into float at whatever voltage is reached when the lithium is roughly 80% full- have I got that right?

 

 

Edited by Tony1
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1 minute ago, Tony1 said:

 

I don't have this long wire setup so I'm not 100% clear on the detail, but I had assumed that most people using this method would be using their existing A2B charger, and would select a charge profile that would ensure the A2B went into float at 14v or less. 

So that way they wouldn't have to manually intervene on every charge - which I assume they would do by by switching off the engine, or by disconnecting the charge to the lithiums. 

 With an A2B in place, the charging profile of the A2B could be set up to go into float when the lithium is roughly 80% full (or whatever value is safe), right?

 


The long wire only solves one of the Li issues - preventing the alternator from overheating. I have never used an A2B so I don’t know if it can be configured to go to float at the appropriate time. The Sterling data sheet says the Li profile is 14.6 charge voltage and 14.4v float, so personally I wouldn’t want to go anywhere near that. At £450 or so an A2B is similarly priced to an Alpha Pro III which is what I’d go for (the latter, I mean). If you have some sort of alternator controller which monitors alternator temperature then obviously you don’t need the long wire.

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1 minute ago, nicknorman said:


The long wire only solves one of the Li issues - preventing the alternator from overheating. I have never used an A2B so I don’t know if it can be configured to go to float at the appropriate time. The Sterling data sheet says the Li profile is 14.6 charge voltage and 14.4v float, so personally I wouldn’t want to go anywhere near that. At £450 or so an A2B is similarly priced to an Alpha Pro III which is what I’d go for (the latter, I mean). If you have some sort of alternator controller which monitors alternator temperature then obviously you don’t need the long wire.

 

My thinking on this is that most boats will have an A2B (alternator to battery) chargers, because thats the standard thing to use to charge lead acids.

So for most people, there wont be a £450 purchase for an A2B, it will already be in place, and the only expense apart from the lithiums will be a BMV712 or similar, plus some cable.

If I'm understanding it right, the A2B being in place means that you can select one of its charge profiles, to make sure it goes into float at a safe voltage for the lithiums.

 

 

 

 

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8 hours ago, Tony1 said:

 

My thinking on this is that most boats will have an A2B (alternator to battery) chargers, because thats the standard thing to use to charge lead acids.

So for most people, there wont be a £450 purchase for an A2B, it will already be in place, and the only expense apart from the lithiums will be a BMV712 or similar, plus some cable.

If I'm understanding it right, the A2B being in place means that you can select one of its charge profiles, to make sure it goes into float at a safe voltage for the lithiums.

 

Sorry to comer back, but I think that you are way off the mark with "most boats" and "that is the standard thing to do". First of all I would suggest with no proof that over 50% of inland boats have no additional charging equipment apart from an alternator and maybe a charge splitter of some type.  Then of the remaining proportion they will be using all sorts of "charge enhancing" devices. Whilst Sterling did a lot to popularise B to B and A to B devices they are pretty recent devices, I think produced initially to enhance the charging of split battery banks with engine ECU controlled alternators. Then they became a way of enhancing boat charging systems, but I suspect only within the last ten years. If a boater has an A to B that can be set to the correct values then your solution is a good one. Like wise using the alternator to charge a LA start battery and then a B to B to charge the LI domestic bank.. However, it all comes down, as you say, to having the correct charging profiles.

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2 minutes ago, Tony Brooks said:

 

Sorry to comer back, but I think that you are way off the mark with "most boats" and "that is the standard thing to do". First of all I would suggest with no proof that over 50% of inland boats have no additional charging equipment apart from an alternator and maybe a charge splitter of some type.  Then of the remaining proportion they will be using all sorts of "charge enhancing" devices. Whilst Sterling did a lot to popularise B to B and A to B devices they are pretty recent devices, I think produced initially to enhance the charging of split battery banks with engine ECU controlled alternators. Then they became a way of enhancing boat charging systems, but I suspect only within the last ten years. If a boater has an A to B that can be set to the correct values then your solution is a good one. Like wise using the alternator to charge a LA start battery and then a B to B to charge the LI domestic bank.. However, it all comes down, as you say, to having the correct charging profiles.

 

Thanks for the clarification Tony- so yes, I had completely the wrong idea about common charging systems.

My boat had an A2B, so I just assumed its been the standard setup for a couple of decades. 

 

(On a side note, I sold my old A2B for about £150 if I recall, so there might be a cheaper option via ebay or similar). . 

 

 

 

 

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9 hours ago, nicknorman said:


The long wire only solves one of the Li issues - preventing the alternator from overheating. I have never used an A2B so I don’t know if it can be configured to go to float at the appropriate time. The Sterling data sheet says the Li profile is 14.6 charge voltage and 14.4v float, so personally I wouldn’t want to go anywhere near that. At £450 or so an A2B is similarly priced to an Alpha Pro III which is what I’d go for (the latter, I mean). If you have some sort of alternator controller which monitors alternator temperature then obviously you don’t need the long wire.

 

I wish I'd gone down the route of an alternator controller instead of using B2Bs, but the snag in the OPs case is the same snag I had- which is that a powerful alternator is a prerequisite, otherwise he has to buy an alpha pro for each of his two 80 amp alternators (and pay for fitting). I'm assuming one alpha pro cant control two alternators, right?

 

And if he opts for a solution that only uses one of his alternators, he'll have to settle for a charging current of 40-50amps at most, which needs him to do 2 or 3 hours charging on winter days when there's little solar available. 

 

But it would be good to hear back from the OP as to what their thoughts are at the moment about the possible options. 

There are too many threads where the OP asks a question, gets a range of replies (usually with a free argument thrown in), and is never heard from again.

 I hope this wont be one of those.

 

 

 

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32 minutes ago, Tony1 said:

I'm assuming one alpha pro cant control two alternators, right?

 


interesting question. I would have thought that two alternators of the same model driven at the same speed could be controlled by one controller provided it could cope with the maximum field current. Can’t find a spec for the Mastervolt’s max field current.

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Yes,  maybe.  I also  think two identical alternators would be OK, provided the field current is acceptable to the Controller.  However, I think manufacturing tolerances might make it impracticable  because  you are not at all  likely to have identical alternators.  One would produce a little more voltage than the other,  for the same field current in each and one would have a little more field current for the same  voltage.  That will give you different output voltages and so one alternator would do more work.

How much more I have no idea.

 

N

 

 

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38 minutes ago, nicknorman said:


interesting question. I would have thought that two alternators of the same model driven at the same speed could be controlled by one controller provided it could cope with the maximum field current. Can’t find a spec for the Mastervolt’s max field current.

 

But then in many cases thee is the practical consideration of the brush holders on the "slave" alternator. I suppose the way to deal with that would be to keep its regulator in place but bypass it with a fly lead a bit like the advanced controllers use. I think the negative regulated systems would also need a positive feed to the other brush.

 

I still can't see how a 60 amp load would not pull the voltage of Tony1's alternator down so both shared the work, but he found what he found. Too many people have successfully paralleled their alternators for his problem to be a common one.

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39 minutes ago, Tony Brooks said:

 

I still can't see how a 60 amp load would not pull the voltage of Tony1's alternator down so both shared the work, but he found what he found. Too many people have successfully paralleled their alternators for his problem to be a common one.

 

I don't want to name the electrician involved, because if there is any problem understanding this issue of one alternator not working, it will be down to my poor memory of the details he gave, plus my very poor understanding of what he was even saying, and I dont want my ignorance to give any kind of bad reflection on him.

He works on a daily basis with alternators of all sorts, and has done for years, so I don't doubt his knowledge at all. 

He would be able to explain it properly so it would make sense to you, but sadly I can't.

 

I can remember that when we observed that one alternator was not working, he tested the regulated voltages on both of them, and one was I think about 0.5v lower than the other (I think the higher alternator might have been 13.9v).

He felt this difference was the root cause for why one of them wasn't running and the other was, but the details of his explanation were beyond my understanding. 

 

I do recall doing some testing with a bigger current draw, and in that situation the non-working alternator did finally kick into action and started to produce maybe 20 amps, but the other one was by then putting out maybe 60-70 amps, which was way too much for it to stay cool, so that was a short test. 

 

I did ask him about whether the regulated voltage on the two alternators could be adjusted so that they were the same, but he was a bit pessimistic about it, and about whether it would 100% resolve the issue - I cant remember why.

 

After that, I gave it all some thought and came up with the idea of getting a second B2B and second lead acid battery, and setting up a separate charging 'route' for each alternator.

The costs ended up being not far short of a brand new powerful alternator plus an alpha pro regulator and fitting- but by then I was unfortunately committed down the B2B route.

 

Edited by Tony1
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