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11 hours ago, Peanut34 said:

I apologise to those of you who were annoyed by my 'vague' question - I see some of you were trying to help and I don't mean to be rude, there were some interesting points in there and I thank you for them.

Nobody was annoyed by your vague question... it was quite typical for someone either new to the forum, or not up to speed with batteries, alternators and controller type things..... so they/we asked some questions to clarify what you were looking for - again, quite typical for a forum.

 

What was annoying was your immediate response that you actually knew everything, and were being patronised.

 

I actually have a Victron DC to DC 30A unit waiting to be fitted, so that I can charge my lithiums from the alternator, via the LA bank.

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It is a quest for information, but not really a quest for opinion.

 

When I saw the conversation veer the wrong way, I expanded and clarified, developed my idea, and finally presented a considered hypothesis. That's quite a normal way for such a conversation to unfold. No harm in it, and it's certainly not the same as 'knowing it all'. I don't know why a couple of you got the hump. If someone said they felt patronised by you in real life, would you turn on them and abuse them? Would you call them childlike and entitled and say they were annoying?

 

I think I'll allow myself a Christmas treat and do some patronising of my own: maybe a couple of you should think about the assumptions you make, and the way you feel when those assumptions falter; the things you know, and the things you merely believe to be true but peddle as if they were gospel.

 

Thanks @Jen-in-Wellies for the very nice posts ?

Edited by Guest
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3 hours ago, Peanut34 said:

I don't know why a couple of you got the hump. If someone said they felt patronised by you in real life, would you turn on them and abuse them? Would you call them childlike and entitled and say they were annoying? 

Then there is no hope for you. If someone asked me for information etc, and on receiving it said I was patronising because it wasn’t perfectly pitched at their (unknown to the giver) level of knowledge, then I would give them a lot worse than I gave to you. I only toned it down because one can get ticked off on here for being rude. Actually I have encountered one or two like you, fortunately very very few in amongst the plethora of normal people. I left them with no confusion about my opinion of their arrogance, ungratefulness  and sense entitlement.

 

oh and by the way  Happy Christmas! You never know, Santa might bring you some humility in your stocking! Let’s hope he doesn’t bring you presents that are beneath you, otherwise you will be shouting “Patronising old git” up the chimney as he leaves.

Edited by nicknorman
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21 hours ago, Dr Bob said:

I too felt the OP post was clearly lacking in detail so very difficult to understand what he was asking. From his comment about trojians it sounds like he is looking for something to give him 14.8v on charge whereas his alternator is only putting out 14.2v.

To help, on my old boat, the alternator put out around 13.9v max so I bought a Sterling AtoB which is a doddle to fit and worked great to get the voltage up to 14.6v.....or other charging programmes which were very very useful when I swapped to Lithiums. With our new boat and a much bigger alternator, I now have experience of Sterling B2Bs which allow charging at a range of voltages and they have a custom set up that can go to 14.8v (IIRC). They are a bit wasteful on power and loose 15% of what you are making.

Perhaps if the OP came back and gave us a detailed description of what he is trying to achieve, we could provide some better advice?

15% is quite a lot of energy to throw away. The AtoB is not a total doddle to fit as it will involve making and fitting new battery cables, anything between 25 and 70mm2.

 

An alternator controller will do much the same job with almost zero power loss and will be easier to install as long as you are able to solder a wire inside the alternator, or pay someone else to do this. The controller will also have the huge advantage that it won't have a float mode ?.

 

Anyway, as its Christmas and I'm feeling generous, for a small fee (about £8,500) I will design and build an alternator controller for the OP that very closely replicates the "ideal" charge curve for the Trojans, including the little "equalisation tickle" at the end of every charge.

 

...............Dave

 

 

 

 

 

 

If the OP accepts my kind offer I plan to subcontract the project to NickNorman who already has most of the design done, and pocket and handsome profit.

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1 hour ago, nicknorman said:

Then there is no hope for you. If someone asked me for information etc, and on receiving it said I was patronising because it wasn’t perfectly pitched at their (unknown to the giver) level of knowledge, then I would give them a lot worse than I gave to you. I only toned it down because one can get ticked off on here for being rude. Actually I have encountered one or two like you, fortunately very very few in amongst the plethora of normal people. I left them with no confusion about my opinion of their arrogance, ungratefulness  and sense entitlement.

 

oh and by the way  Happy Christmas! You never know, Santa might bring you some humility in your stocking! Let’s hope he doesn’t bring you presents that are beneath you, otherwise you will be shouting “Patronising old git” up the chimney as he leaves.

 

8 minutes ago, dmr said:

15% is quite a lot of energy to throw away. The AtoB is not a total doddle to fit as it will involve making and fitting new battery cables, anything between 25 and 70mm2.

 

An alternator controller will do much the same job with almost zero power loss and will be easier to install as long as you are able to solder a wire inside the alternator, or pay someone else to do this. The controller will also have the huge advantage that it won't have a float mode ?.

 

Anyway, as its Christmas and I'm feeling generous, for a small fee (about £8,500) I will design and build an alternator controller for the OP that very closely replicates the "ideal" charge curve for the Trojans, including the little "equalisation tickle" at the end of every charge.

 

...............Dave

 

 

 

 

 

 

If the OP accepts my kind offer I plan to subcontract the project to NickNorman who already has most of the design done, and pocket and handsome profit.

OOh my goodness, I was going to just slip away, but Christmas is cancelled and you've poked me. Let's do it.

 

@nicknorman Look at the language you use - 'normal people', 'there is no hope for you'....it's so bitter. Why?

 

I don't think you have met anyone like me, clearly not in a professional capacity at least. If you had, you would be more able to deal with being challenged, you would be more open-minded, more patient, and more inquisitive. Perhaps you would even relish such a situation, because it would force you to think about your assumptions and any shortcomings in your knowledge. You might have kept reading and understood what I was actually asking, not what you thought I was asking. Instead you contribute nothing, you only attack and belittle me.

 

You may be the big swinging nick on the forum, but I wouldn't let you near a real engineering problem.

 

@dmr I had some faith in you, why join in the hack circle jerk and back your pathetic friend? 'Much the same job'. Test, analyse, quantify, report. Close only counts in horseshoes and hand grenades. And apparently in narrowboat forum 'engineering', where the bar appears quite low.

 

Well, I'd better get back to being hopeless! Bye ?

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10 minutes ago, Peanut34 said:

 

OOh my goodness, I was going to just slip away, but Christmas is cancelled and you've poked me. Let's do it.

 

@nicknorman Look at the language you use - 'normal people', 'there is no hope for you'....it's so bitter. Why?

 

I don't think you have met anyone like me, clearly not in a professional capacity at least. If you had, you would be more able to deal with being challenged, you would be more open-minded, more patient, and more inquisitive. Perhaps you would even relish such a situation, because it would force you to think about your assumptions and any shortcomings in your knowledge. You might have kept reading and understood what I was actually asking, not what you thought I was asking. Instead you contribute nothing, you only attack and belittle me.

 

You may be the big swinging nick on the forum, but I wouldn't let you near a real engineering problem.

 

@dmr I had some faith in you, why join in the hack circle jerk and back your pathetic friend? 'Much the same job'. Test, analyse, quantify, report. Close only counts in horseshoes and hand grenades. And apparently in narrowboat forum 'engineering', where the bar appears quite low.

 

Well, I'd better get back to being hopeless! Bye ?

I do suspect that your obsession with battery manufacturers charge specifications shows a lack of understanding of real world engineering.

 

There are many posters on this forum who just re-post stuff they have read previously. There are a few who are competent engineers and NickNorman is one of those, he can be a tad rude at times but that is not an uncommon trait in engineers, they do tend to say what they think. 

 

and its probably not a good idea to use the Trojan charge profile on a boat.......tell me why? ?

 

..........Dave

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4 minutes ago, Peanut34 said:

 

@nicknorman Look at the language you use - 'normal people', 'there is no hope for you'....it's so bitter. Why?

 

I don't think you have met anyone like me, clearly not in a professional capacity at least. If you had, you would be more able to deal with being challenged, you would be more open-minded, more patient, and more inquisitive. Perhaps you would even relish such a situation, because it would force you to think about your assumptions and any shortcomings in your knowledge. You might have kept reading and understood what I was actually asking, not what you thought I was asking. Instead you contribute nothing, you only attack and belittle me.

 

You may be the big swinging nick on the forum, but I wouldn't let you near a real engineering problem.

 

@dmr  

It’s not about being challenged on a technical discussion, that I relish because it makes one think, and quite often something is learned, which is always good. It’s about avoiding the nause of interacting with someone who plays the “patronising” card on the first encounter. A cheap shot and tedious beyond belief. Life is too short to deal with such people.

 

If you are any sort of engineer as you seem to be implying, you would know without even having to think about it that clear and concise communication, eg between design engineer and customer, is the vital first step in any project. Since your opening shot was classically unclear and somewhat rambling, I think it highly unlikely that you are any sort of design engineer, or if you are, you are not a naturally good one. Oh and I have been a professional electronic design engineer in my time, though I did change careers and so now electronics is only my hobby.

 

I could have been more patient, open minded and inquisitive but why should I bother to exert that energy? Why do you think you are worth that? You are not paying any of us, we don’t owe you anything, it is you who is seeking free information. This is why I call you “entitled” - you seem to think that whilst you, who are seeking free information, have no duty to present your question clearly and politely, whereas apparently we have a duty to treat you with the utmost respect and go to great pains to avoid any possibility of failing to pitch our responses to you at the exactly correct level. Yup, that is pretty much the definition of “entitled”.

 

I would have kept reading and perhaps understood what you were actually asking (though why should you make it so difficult, was it some sort of game?) but when you hit the sulky teenager button and whined that it was so unfair that we were patwonising you (aaah diddums) I lost interest.

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On 23/12/2020 at 18:08, dmr said:

I am not aware of any alternators fitted as standard to narrowboat engines that do "smart charging", a basic machine sensed low gain voltage regulator is about as good (bad?) as it gets?

 

..............Dave

 

That was my understanding too. I have a Sterling alternator controller and it increases max charge voltage from the alternator from 14.4v to 14.8v during the absorption phase, essentially turning the alternator into a smart charger. 

 

As Tony quite rightly says, it won't do an equalisation charge, but then lots of "smart chargers" don't have that facility either. Equalisation doesn't define "smart charging". From what I've read equalisation charges of wet lead/acid batteries should be conducted periodically and not at every charge cycle - which might be the case if your alternator could be made to do an equalisation charge.

 

 

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15 hours ago, dmr said:

 

 

An alternator controller will do much the same job with almost zero power loss and will be easier to install as long as you are able to solder a wire inside the alternator, or pay someone else to do this. The controller will also have the huge advantage that it won't have a float mode ?.

 

 

 

So what's the difference between my mains battery charger on float mode at 13.6v with anything from a few amps to 0.6 amps going into the batteries, and my alternator controller at 13.6v doing the same thing? Isn't that effectively float mode?

 

By the way, Merry Christmas everyone. I'm just waiting for me Christmas dinner..?

Edited by blackrose
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44 minutes ago, blackrose said:

 

So what's the difference between my mains battery charger on float mode at 13.6v with anything from a few amps to 0.6 amps going into the batteries, and my alternator controller at 13.6v doing the same thing? Isn't that effectively float mode?

 

By the way, Merry Christmas everyone. I'm just waiting for me Christmas dinner..?

Yes it is Buuuuuuuuuuuuuuuuuuuuuuuuuut.  Its fine as long as it does not drop into float before the batteries are all but fully charged and as I said before I suspect the  smart chargers and the controllers probably use similar logic in their chips so they are likely to. However even so I don't see why, apart from in a very few specific cases, an alternator needs a float charge setting because why waste fuel and engine wear charging after then batteries are full. I can see it would be an advantage on ocean going boats though that run 24/7, especially if they have 12.7/25.4 volt  regulators.

 

However as far as I can tell from the OP he thinks, until he cares to clarify what he intends to do,  he will get a longer battery life if he ruins his start battery by discharging it through a battery to battery charger presumably running 24/7. In that case it is probably a good idea to have afloat setting.

 

The only thing he will not have is an enhanced absorption voltage in the case of a 13.8 to 14.2V alternator regulator but in most cases I suspect a new regulator would go a long way to solving that at less cost.

 

Still its his money and hos boat so he can do as he wishes.

 

Edited to add, I still don't understand why someone who claims technical knowledge thinks any form of multistage charging will look after his batteries better than ensuring they are as fully charged as possible for as much of the time as is possible and avoiding deep discharging where possible.

Edited by Tony Brooks
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1 hour ago, Tony Brooks said:

Yes it is Buuuuuuuuuuuuuuuuuuuuuuuuuut.  Its fine as long as it does not drop into float before the batteries are all but fully charged and as I said before I suspect the  smart chargers and the controllers probably use similar logic in their chips so they are likely to. However even so I don't see why, apart from in a very few specific cases, an alternator needs a float charge setting because why waste fuel and engine wear charging after then batteries are full. I can see it would be an advantage on ocean going boats though that run 24/7, especially if they have 12.7/25.4 volt  regulators.

 

However as far as I can tell from the OP he thinks, until he cares to clarify what he intends to do,  he will get a longer battery life if he ruins his start battery by discharging it through a battery to battery charger presumably running 24/7. In that case it is probably a good idea to have afloat setting.

 

The only thing he will not have is an enhanced absorption voltage in the case of a 13.8 to 14.2V alternator regulator but in most cases I suspect a new regulator would go a long way to solving that at less cost.

 

Still its his money and hos boat so he can do as he wishes.

 

Edited to add, I still don't understand why someone who claims technical knowledge thinks any form of multistage charging will look after his batteries better than ensuring they are as fully charged as possible for as much of the time as is possible and avoiding deep discharging where possible.

 

Yes there's no particular advantage of having a float mode on an alternator but if the alternator is spinning anyway why not have it charging at the most suitable voltage?

 

With battery chargers like mine which isn't that smart it's fairly simple to overcome the issue of going into float too soon by switching it off and back on again - typically I do that when running the charger from the generator. The charger then goes into float a lot later in the charge cycle. Similarly, one can do that with an alternator when arriving at locks or when moored up.

 

But the main benefit of alternator controllers is the increased charge voltage in absorption mode. Any disadvantage can be worked around by controlling the controller.

 

Did the OP say that multistage charging will look after his batteries better than ensuring they are as fully charged as possible for as much of the time as is possible and avoiding deep discharging where possible? If he did then of course he's wrong.

Edited by blackrose
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1 hour ago, Tony Brooks said:

Edited to add, I still don't understand why someone who claims technical knowledge thinks any form of multistage charging will look after his batteries better than ensuring they are as fully charged as possible for as much of the time as is possible and avoiding deep discharging where possible

Quite!

I agree. He was looking for info on wether DC-DC converters existed and I responed yes......but he hasnt been back to ask for any detail. If he had I would have said that both the AtoB and the BtoB have a propensity to drop to float far too quickly so are far from being smart as the makers suggest. The one thing they are good at doing though is boosting voltage for those of us who are not happy with the 'low' voltages that some alternators produce (yes, a number of alternators do not get to the 14.0V+ that LA's require - I've had 2 of them on different boats - and Gibbo talked about the issue).

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2 hours ago, blackrose said:

That was my understanding too. I have a Sterling alternator controller and it increases max charge voltage from the alternator from 14.4v to 14.8v during the absorption phase, essentially turning the alternator into a smart charger. 

 

As Tony quite rightly says, it won't do an equalisation charge, but then lots of "smart chargers" don't have that facility either. Equalisation doesn't define "smart charging". From what I've read equalisation charges of wet lead/acid batteries should be conducted periodically and not at every charge cycle - which might be the case if your alternator could be made to do an equalisation charge.

 

 

Yes, equalisation is something that ideally should be done occasionally and only when required as its often said that it does take a bit of life out of the batteries (I am not 100% convinced of this). Some intelligent chargers do an equalisation at a fixed interval like weekly, which is maybe a good second best.  The "official" Trojan charge profile does show what I called an "equalisation tickle" at the end of every charge. This is just for a short time right at the end of the charge and is probably a good thing for the batteries.  I would think the Trojan charge profile is really aimed at giolf cart batteries getting an overnight charge (which is why the OP is going up a blind alley) and so not ideal for use on liveaboard boats. I think the Trojan tickle might be as high as 16volts (can't be arsed to find the details) and this is why I do like the concept of automatic equalisation....some stuff just might not like this voltage and so should be turned off prior to equalisation.

 

.............Dave

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Just to say things really clearly, there are only three real stages of charge, bulk, absorption and float. Bulk and absorption are really dictated by the batteries not the charger, so float is the only feature of a "smart" charger and for most off grid boaters float is undesirable most of the time.....so smart chargers are not of much use (for off grid boats).

 

Temperature compensation and the ability to adjust absorption voltage, plus an equalisation capability are good things to have.

 

......................Dave

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Just on the subject of alternator controllers, I did a couple of sketches for the other channel about this, in relation to Li batteries. But, apart from the voltage scale, the principle is the same. The first one showing a typical “ordinary” alternator regulator curve. People talk about “bulk” and “absorption” as if these were two discrete stages, whereas in reality they tend to blur into each other due to the low gain of the regulator control circuit.

 

One advantage of a modern digital add-on alternator regulator is demonstrated in the second sketch, showing much more precise control of voltage using a digital PID type regulation loop. This has clear bulk and absorption stages and the main advantage is of course that maximum output current can be maintained almost until the regulated voltage is reached, so whilst nothing is gained at the start or the end, quite a bit is gained in the middle.

 

895AA2E7-30BE-44EB-916D-286AA01EDD34.jpeg.de93bbe8afaa8e653f407e4401498ddc.jpeg

(sorry about the tippex!)

 

 

68E5E885-7DF9-432E-84AD-72E5235151FF.jpeg.3264fee16832a8076f12abe0736f8814.jpeg

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1 hour ago, dmr said:

Yes, equalisation is something that ideally should be done occasionally and only when required as its often said that it does take a bit of life out of the batteries (I am not 100% convinced of this). 

 

I'm not convinced either. The advantages of equalisation/desulphation will outweigh any disadvantages in terms of maintaining capacity and therefore battery longevity. That's the whole point surely?

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1 minute ago, blackrose said:

 

I'm not convinced either. The advantages of equalisation/desulphation will outweigh any disadvantages in terms of maintaining capacity and therefore battery longevity. That's the whole point surely?

Equalising when necessary is a good thing because it recovers capacity lost from sulphation. But it does create its own “reduction in life”. When the batteries have sulphation, the net result is a benefit. When the batteries don’t have sulphation, there is nothing to be gained and a bit to be lost. So as Dave says, only when necessary.

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1 hour ago, nicknorman said:

Equalising when necessary is a good thing because it recovers capacity lost from sulphation. But it does create its own “reduction in life”. When the batteries have sulphation, the net result is a benefit. When the batteries don’t have sulphation, there is nothing to be gained and a bit to be lost. So as Dave says, only when necessary.

Certainly not dry during every charge cycle then.

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31 minutes ago, blackrose said:

Certainly not dry during every charge cycle then.

Have a look at the charge profile specified by US battery for their version of the Trojan.

They term the high voltage bit as a finish charge and do it on every cycle.

 

This is a 3 stage charge process (unlike most chargers stage 3 is not float)

1 Constant current Bulk charge

2 Constant Voltage absorption at 14.4 down to a 3% tail current then

3 More constant current at 3% till the voltage gets up to about 15.5volt

 

An equalisation charge is then extending this 15.5v at constant voltage for a couple of hours once every 30 charge cycles.

 

............Dave

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Right, I'll see if I can give it another steer, although I really don't think forums are for me.

 

Let's keep it theoretical: It's Wednesday 23rd December 2020, I have an infinite output alternator, three 12 V flooded batteries totalling 300 Ah, and a lot more money than sense.

 

I want to charge my batteries as fast as possible. Not a little faster, or even a lot faster, AS FAST AS POSSIBLE! And I also want to achieve or their expected service life (in terms of cycles) and actually get some use out of them (because that's why I have batteries) i.e. cycle them between full and the DoD which corresponds to the cycle count I want to achieve.

 

I believe the best parameters I have to go off are the manufacturer's own, which I assume [danger] to have been arrived at from some comprehensive bench testing (or the robbing of another manufacturer's values in lieu of bench testing). Yes, they probably include a safety factor, and perhaps I could push them a little further, TBC...

 

Bulk is straightforward, but if I regulate to a single bulk voltage and the temperature of the batteries changes, I've fallen off the tightrope, I'm now sub-maximal, and I've failed in my objectives, right?

 

So I need temperature-sensing. At this point, it's grown one arm already and I have a feeling more limbs are on the horizon.

 

And so it develops, until I arrive at a point where - in order to achieve my objectives - I need temperature compensation, voltage-drop correction, a distinct absorption phase (adaptive?), equalisation (the consensus seems to be that equalisation is a good thing, if you do it right)...and so on. So many arms and legs!

 

Yes, it's diminishing returns. Yes, this thing is definitely going to be a 'gizmo'. Yes, I have more money than sense (theoretically though remember).

 

[An epiphany] Oh my goodness, this device sounds an awful lot like my solar controller. And the heart of my solar controller is a DC-DC converter! Oh, they make them for non-solar charging..oh, they don't do everything, but they certainly seem to have potential...

 

Quick (and yes, poor) post: Does anyone have one of these?

 

And the rest is not theoretical. Ah well. As I said, I don't think forums are for me.

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I think I made my point earlier and I don’t hold grudges.

 

Your two aims of charging as fast as possible and achieving the rated cycle life, are incompatible. Fast charging of LA batteries inevitably shortens their lives. But one has to look at the big picture - fast charging means less engine running and hence saving on diesel, engine wear and noise and vibration nuisance. But a need to replace the batteries more frequently. So it is a balance between battery damage/replacement cost, and the cost to run the engine for many additional hours.

 

Trojan recommend charging current of 10 to 13% of 20hr capacity. We have 450Ah of T105s, so optimum charge current for cycle life is 45 to 59A. But we have a 175A alternator and when the engine is first started in the morning, most of that goes into the batteries. The current won’t subside to 59A for several hours if the batteries are low at the start. With my new alternator controller it can hold a much higher current for longer (as per the sketches I posted earlier) which is even further away from Trojan’s recommendations. But it gets the batteries charged pretty quickly.

 

How much damage is done to the batteries? Not sure, but I’m sure it will shorten their lives (which doesn’t matter because I have 600Ah of Li batteries to fit once all the lockdown shenanigans is over).

 

A dc to dc converter is one way of doing it, people use A2Bs and B2Bs. And as you say, an MPPT solar controller incorporates a Dc-Dc converter. But that is a somewhat inefficient way of doing it because dc-dc converters tend to dissipate a fair bit of heat, and are expensive.

 

My preferred solution is to control the power generation at source, rather than to accept whatever the power source is and then massage it into what you actually want which is what an A2B or B2B does. A solar controller has to do it this way because it’s not possible to alter the way in which the power is generated. But with an alternator, it is relatively easy to control the way the power is generated.

 

If you don’t want to build your own, there is a very good alternator controller on the market, the wakespeed WS500. This started off as an open source project but unfortunately went commercial. And now very expensive, which is why I built my own.

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I assume you are aware that the bulk phase is simply the time during which the batteries will accept more charge than the charge source can provide and all inductive charge sources will drop their voltage during that period. The voltage will then gradually as the batteries charge and the BATTERIES themselves start to limit the current they will accept at whatever voltage the charge source is regulated to. Once the charge source is regulating the voltage it is called acceptance.

 

The only way you can increase the current   the batteries will accept is to increase the charging voltage but then you quickly run into the gassing voltage of the batteries. Now the gassing voltage will vary from battery design to battery design and I suspect other things as well. Now try to get a battery manufacturer what the gassing voltage is for their battery, I have yet to see it quoted. They just quote a recommended charging voltage or a maximum charging voltage.

 

Float voltage is only important to prevent damage to batteries that are left on charge for long periods so does not really matter as far as alternate charging is concerned because the engine is shut down in most cases before much damage can be done.

 

The question is how much value should be put on stuff put out by manufacturers and how cost effective add ons will turn out to be. That is the difference between the two of us. You seem happy to believe all that they say where as I am sceptical where commercial interests and profit are concerned. I certainly would not put over much credence on extensive bench testing being how the recommended charge profiles are arrived at. See the comment about the different profiles from trojan you c find on the net. I suspect its done by experience and altered to reflect what they find from warrantee claims.

 

Having got over six years out of three x 110 Ah wet lead calcium batteries by the use of solar and daily monitoring/charging as required I doubt the expense will be worth it.

 

No I do not have one but I know some people like @Dr Bob have used them or similar in hybrid LA - lithium systems and he has asked you for more information so he can answer the question. I wish you would also stop going on about DC to DC converters because they are not what you are asking about. A DC to DC converter on its own simply converts one DC voltage to another so, for an example, can run a 12V car radio in a 24v truck. You are talking about a battery to battery charger that contains as DC to DC converter an much more control electronics.

 

I think they have also been used with split domestic battery bank where for some reason a "spare" bank is charged from the working bank and then swapped over but that is another "good idea" that has caused strong comment. However neither use is what you seem to be asking about. As @nicknorman said an alternator controller will waste less energy than battery to battery chargers and thus have more available to put into the batteries.

 

I think you could be an asset to a forum if you spent some time getting to know the members and so on.

Edited by Tony Brooks
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