Alternator w/internal regulator & remote sense

[summer breeze]

I have a high output alternator with remote voltage sense (Eco-Tech). I have a single large bank (10x12v) of AGM batteries (Lifeline GPL-31T). The vehicle operates 12-14 hours a day (sometimes 24). The bulk and absorb stage works as expected. My question is do we need to float the voltage down to 13.x? The problem with floating the alternator is the vehicle will not operate properly at 13.x and expects 14.x. If we don't float the voltage down what happens to the capacity of the batteries?

[Gibbo]

The problem with floating the alternator is the vehicle will not operate properly at 13.x and expects 14.x.

 

We need clarification on exactly what that means before you can get any useful info.

[summer breeze]

We need clarification on exactly what that means before you can get any useful info.

 

The on board electronics require 14.x volts and things such as the AC unit will not work if the voltage is too low. The vehicle is a class 8 chassis (Freightliner)...

[Gibbo]

The on board electronics require 14.x volts

 

Which electronics?

 

I'm not trying to be obtuse, but there really isn't enough information.

 

and things such as the AC unit will not work if the voltage is too low. The vehicle is a class 8 chassis (Freightliner)...

 

Then the AC unit is either installed incorrectly or not fit for purpose. I suspect the former.

[summer breeze]

Which electronics?

 

I'm not trying to be obtuse, but there really isn't enough information.

 

Then the AC unit is either installed incorrectly or not fit for purpose. I suspect the former.

 

The vehicle is working as designed. When the voltage drops the AC goes offline until the voltage rises. The logs report a low voltage condition. This is the only system that I am aware of that goes offline but it is enough for me to keep the voltage where the stock alternators put it @14.4. Can we move on? we can't step it down to a float voltage...

[Chris Pink]

I have a high output alternator with remote voltage sense (Eco-Tech). I have a single large bank (10x12v) of AGM batteries (Lifeline GPL-31T). The vehicle operates 12-14 hours a day (sometimes 24). The bulk and absorb stage works as expected. My question is do we need to float the voltage down to 13.x? The problem with floating the alternator is the vehicle will not operate properly at 13.x and expects 14.x. If we don't float the voltage down what happens to the capacity of the batteries?

 

If I had a couple of grands worth of Lifeline batteries i'd be asking these questions of Lifeline or your suppliers not poking around on a boating forum.

[Gibbo]

The vehicle is working as designed. When the voltage drops the AC goes offline until the voltage rises. The logs report a low voltage condition. This is the only system that I am aware of that goes offline but it is enough for me to keep the voltage where the stock alternators put it @14.4. Can we move on? we can't step it down to a float voltage...

 

Right, so it's actually only the AC that doesn't work?

 

I'm assuming by "AC" that you mean air conditionning? Or do you mean an AC inverter?

[summer breeze]

Right, so it's actually only the AC that doesn't work?

 

I'm assuming by "AC" that you mean air conditionning? Or do you mean an AC inverter?

 

Sorry, you are correct, the air conditioner goes off line. There could be other systems that go off line as well but they may go unnoticed as they do not keep me comfortable on a hot summer day...

[Gibbo]

If I had a couple of grands worth of Lifeline batteries i'd be asking these questions of Lifeline or your suppliers not poking around on a boating forum.

 

He could do, and the question will work its way back the UK importer. In turn, they will ask their head of R&D. And guess who that is.

[summer breeze]

If I had a couple of grands worth of Lifeline batteries i'd be asking these questions of Lifeline or your suppliers not poking around on a boating forum.

 

I have spent a great deal of time browsing these forums and you over estimate the suppliers. And I believe the suppliers to my solution might be represented here...

[Gibbo]

Sorry, you are correct, the air conditioner goes off line. There could be other systems that go off line as well but they may go unnoticed as they do not keep me comfortable on a hot summer day...

 

Right, if it's an AC unit designed for a 12 volt system I will lay good odds that the wiring between the batteries and the AC unit is not big enough. It is therefore dropping voltage so the AC unit is seeing a lower voltage than what is actually at the batteries. That will cause exactly the symptom you are seeing. You are keeping the batteries at 14.x volts in order to hopefully keep the voltage at the AC unit above its low voltage cut out (probably about 11 volts or so).

 

Under normal vehicle use Lifelines are safe to maintain at a normal charge voltage of around 14.2 to 14.6 volts. But on the sort of use your vehicle is seeing that will wreck them. Regular 12 to 24 hours at acceptance voltage is excessive for those batteries. Disabling float would be a very bad idea.

 

ETA: Any equipment designed to operate from a 12 volt system will absolutely not need 14 volts. Never.

Edited November 27, 2012 by Gibbo

[Tony Brooks]

The vehicle is working as designed. When the voltage drops the AC goes offline until the voltage rises. The logs report a low voltage condition. This is the only system that I am aware of that goes offline but it is enough for me to keep the voltage where the stock alternators put it @14.4. Can we move on? we can't step it down to a float voltage...

 

 

If Gibbo suggest that your vehicle has a problem please take note of what he says. I doubt you will get a more knowledgeable person to respond to you in Europe, let alone the USA. He has proven his expertise many times over on this forum but he does not accept fools gladly so take care.

 

On a personal not I find it all but incomprehensible that someone from the USA should come onto a UK INLAND MARINE forum and starts asking about vehicles and then apparently reject the best source he has. Whatever this "vehicle" is it seems odd to me that it has so many batteries yet operates at 12V unless its is a motor caravan type thing.

 

On the basis of the small amount of info you have deemed to supply I would also suggest that you have voltdrop (undersized cables)on the battery supply to what I assume must be the inverter - or you have some half baked US designed bit of kit that does not know that battery systems can run down to below 12 volts. I do not see that US practise will be any better than the UK so undersized wiring is a real possibility.

 

Please, lets have a lot more detail about this thing and if you are so sure there is not a problem with the unknown AC thing then let us see the voltdrop measurements that you have made between battery and thing when it is operating on a high load - I assume that you have them because if not you can not dismiss Gibbo's suggestion.

 

 

Edit - typing while Gibbo replied.

Edited November 27, 2012 by Tony Brooks

[summer breeze]

Right, if it's an AC unit designed for a 12 volt system I will lay good odds that the wiring between the batteries and the AC unit is not big enough. It is therefore dropping voltage so the AC unit is seeing a lower voltage than what is actually at the batteries. That will cause exactly the symptom you are seeing. You are keeping the batteries at 14.x volts in order to hopefully keep the voltage at the AC unit above its low voltage cut out (probably about 11 volts or so).

 

Under normal vehicle use Lifelines are safe to maintain at a normal charge voltage of around 14.2 to 14.6 volts. But on the sort of use your vehicle is seeing that will wreck them. Regular 12 to 24 hours at acceptance voltage is excessive for those batteries. Disabling float would be a very bad idea.

 

ETA: Any equipment designed to operate from a 12 volt system will absolutely not need 14 volts. Never.

 

I know it seems odd but the only changes made to the stock chassis is the cable between the alternator and chassis fuse panel has been doubled in size. The low voltage effect on the AC unit is well known to the folks that work on it. I don't have an answer for you other that that is the way it was designed. I cannot drop to float.

 

Is my only off the shelf solution the Alternator to Battery Charger from Sterling? I would prefer to just isolate the battery bank when the amp draw was .5C to the batteries but I can't locate a product that will do this. I don't need the batteries while the vehicle is running. We have a common buss that peer the load, source and battery bank and we don't have a load that would exceed the alternator output even at idle. Could we just put a shunt in the negative lead and a solenoid in the positive lead and when the amps to the batteries dropped < 5 amps (in my case) and the voltage at the batteries was > 13.8 just open the solenoid? and if either of the criteria changed, just close the solenoid? this seems much simpler than turning everything over to the Sterling unit...

[summer breeze]

If Gibbo suggest that your vehicle has a problem please take note of what he says. I doubt you will get a more knowledgeable person to respond to you in Europe, let alone the USA. He has proven his expertise many times over on this forum but he does not accept fools gladly so take care.

 

On a personal not I find it all but incomprehensible that someone from the USA should come onto a UK INLAND MARINE forum and starts asking about vehicles and then apparently reject the best source he has. Whatever this "vehicle" is it seems odd to me that it has so many batteries yet operates at 12V unless its is a motor caravan type thing.

 

On the basis of the small amount of info you have deemed to supply I would also suggest that you have voltdrop (undersized cables)on the battery supply to what I assume must be the inverter - or you have some half baked US designed bit of kit that does not know that battery systems can run down to below 12 volts. I do not see that US practise will be any better than the UK so undersized wiring is a real possibility.

 

Please, lets have a lot more detail about this thing and if you are so sure there is not a problem with the unknown AC thing then let us see the voltdrop measurements that you have made between battery and thing when it is operating on a high load - I assume that you have them because if not you can not dismiss Gibbo's suggestion.

 

Edit - typing while Gibbo replied.

 

I apologize and do recognize the value of Gibbo's knowledge as that is why I am here. I have spent a great deal of time researching the available resources. This forum has the most respectable representation.

 

The AC problem belongs to Freightliner and we have been very careful to keep our world separate from theirs. The stock alternator behaves the same way and the EcoTech is the ONLY thing we have changed in their world. If we add a float this will change their world and I cannot go there. Their electronics are very sensitive.

Edited November 27, 2012 by summer breeze

[Gibbo]

The alternator to battery charger won't change a thing. Won't make any difference whatsoever.

 

I know you don't want to accept this but the answer is simple. There are two possibilities:-

 

1. You have volt drop between the batteries and the AC unit. Whether you believe this or not is up to you. It appears you're just guessing that you don't, but haven't actually checked.

 

2. The AC unit is not fit for purpose. If it needs 14 volts (which I doubt) it would be against the law to market over here as being suitable for a 12 volt battery system.

 

I think 1 is the answer. Whether you like it not

 

The AC problem belongs to Freightliner and we have been very careful to keep our world separate from theirs. The stock alternator behaves the same way and the EcoTech is the ONLY thing we have changed in their world. If we add a float this will change their world and I cannot go there. Their electronics are very sensitive.

 

I don't believe this. In Europe, anything designed and/or marketed for use on a 12 volt system has to, by law, operate at full spec down to 10.5 volts. Most actually work lower than this. I find it hard to believe that the USA allows people to sell shit that doesn't work in its intended application.

 

When I worked in the States (for many years) I never came across a single piece of 12 volt equipment that didn't work at 10.5 volts. Not a single one.

 

I think you have volt drop.

[Tony Brooks]

I apologize and do recognize the value of Gibbo's knowledge as that is why I am here. I have spent a great deal of time researching the available resources. This forum has the most respectable representation.

 

The AC problem belongs to Freightliner and we have been very careful to keep our world separate from theirs. The stock alternator behaves the same way and the EcoTech is the ONLY thing we have changed in their world. If we add a float this will change their world and I cannot go there. Their electronics are very sensitive.

 

 

Look, I have no idea who or what Freightliner are (apart from a vehicle ferry line in Europe) but suspect it is what in the UK we would have called body builders who put specialist bodies onto commercial chassis. This being so they are likely to follow what appears to be typical manufacturing practise where test vehicles have been built and then the components are downgraded to reach an acceptable standard or unreliability. This is all too often apparent in the electrical systems where the need to save a few 10ths of a penny/cent per vehicle leads to undersized wiring being fitted.

 

It all depends upon how your air conditioning is connected to the rest of the vehicle wiring so without a full wiring diagram with cable sizes and run lengths we are not in much of a position to help.

 

Look, get a decent multimeter set to 20 volts DC plus a long length of cable (1sq mm conductor or above) with a small crock clip on each end. Clip cable to battery positive, the other end to the meter positive wire and the other meter wire to the Air Conditioner main positive terminal. Run engine and aircon at high setting. If you have more than 0.5 volts on the meter you have found the problem. 0.3 is better. Do the same for the negative side. This should not require disturbing any wiring apart from possibly a terminal cover.

 

If both readings are 0.5 volts or less (0.3 or lower is better) then I fear that your AC unit is not fit for purpose and needs replacing with something that is. (Note - the 0.5v comes from Eberspacher who say that is their standard on their aircon installations. I would prefer 0.25 volt on each side of the unit). Even with 0.5 voltdrop on both sides that still drops the voltage by 1 volts so the unit will only see 11 volts when the battery is at 12 volts.

 

 

Edited to add:- is this a rental or lease vehicle? If so then in the UK your course of action is clear, simply return it as being unfit for purpose and insist on a vehicle that is. You could also get the lease/hire company to give you written indemnity against damage to the batteries because of their unfit for purpose system. It would not be your problem to solve. Only try to solve it if you own the vehicle. However having no knowledge of US consumer law things may be different.

Edited November 27, 2012 by Tony Brooks

[summer breeze]

I think you have volt drop.

 

 

Lets say that you are correct. I am still stuck in a no win situation. Let me tell you how I discovered this problem.

 

The EcoTech failed and I was forced to put the undersized factory alternator (36SI) back in place. It did not have the amps to charge the bank so we were stuck in bulk for a very long time. It was summer so we had the AC on but it would not blow cold air. We took it to the shop and the tech explained that the system had taken the AC unit off line because of the low voltage (I think we were in the mid 13.x). The tech said the voltage needs to be between 13.8 and 14.x. I had just picked up the EcoTech replacement so I swapped it out. We pushed through the bulk stage and when the voltage passed 13.8 the cool air blew through the vents and the tech said I was good to go.

 

Bottom line is I am not going to get any help from Freightliner as they expect the voltage to always be between 13.8-14.x and as long as it is everything work correctly. The wiring to the AC unit goes through their buss and everything is computer controlled (multiplexed even). I cannot make a change to their system as it is too delicate as it is.

 

I am asking for help and am telling you my solution must not include dropping the alternator output below 13.8. My thought was that if anyone could help it was the folks in this forum. I apologize for not wanting to spend time on this part of the problem because it is a dead horse that I have already worn my self thin on...

[Chris Pink]

Easy.

 

Get another alternator and small battery to run your air conditioning.

 

Else you have two choices; run your very expensive batteries in non-recommended condition or do without air con.

 

make and model of the aircon unit?

[Sir Nibble]

The tech said the voltage needs to be between 13.8 and 14.x.

This isn't by any chance some built in system to check that the engine is running and under charge is it? perhaps just a safety system to prevent the AC running the battery flat which can perhaps be byepassed or adjusted out. What I am implying is that perhaps the problem is not that the AC CANNOT work at lower voltages but WILL NOT.

[summer breeze]

Look, I have no idea who or what Freightliner are (apart from a vehicle ferry line in Europe) but suspect it is what in the UK we would have called body builders who put specialist bodies onto commercial chassis.

 

Tony, close. This is a class 8 vehicle that has been stretched into an RV. Unlike the normal body builders, we have elected to keep our systems separate as we have no need to access to their interface. We have however, increased the storage and charging system. We installed a high output alternator and the conductors (4/0) from the alternator to their common buss. We increased the conductors from their buss to their battery bank (also 4/0). Our point of demark is connecting our common buss with theirs (also 4/0).

 

Everything works great as long as the voltage stays between 13.8 and 14.x which is all the time. If we have sit for awhile and drawn the voltage down below 13.8 then there is a brief period of time where the Ac does not work correctly but with the EcoTech that period is very brief...

[Gibbo]

The AC unit is not fit for purpose. In Eurpope the supplier would have been sued out of business by now. He simply would no longer exist.

 

The AC unit should work down to at least 11 volts. If it doesn't, it's useless in a vehicle.

 

As you seem happy to accept a piece of shit equipment I would suggest you "sort of" leave the system as it is, but add an additional cheap battery and connect the AC unit to that. Connect that battery directly to the alternator. Then put a normal split charge diode to the Lifelines. Short that diode out with a big contactor during normal charging. Then when you want to go to float open the contactor. The diode will drop some voltage to get a more manageable float voltage on the Lifelines but the AC will still be getting full alternator voltage.

 

I'm baffled why you have such an enormous bank of batteries yet you can't run the AC (probably the biggest thing on there) from them. Seems a waste of batteries if you can't really use them.

[Tony Brooks]

Lets say that you are correct. I am still stuck in a no win situation. Let me tell you how I discovered this problem.

 

The EcoTech failed and I was forced to put the undersized factory alternator (36SI) back in place. It did not have the amps to charge the bank so we were stuck in bulk for a very long time. It was summer so we had the AC on but it would not blow cold air. We took it to the shop and the tech explained that the system had taken the AC unit off line because of the low voltage (I think we were in the mid 13.x). The tech said the voltage needs to be between 13.8 and 14.x. I had just picked up the EcoTech replacement so I swapped it out. We pushed through the bulk stage and when the voltage passed 13.8 the cool air blew through the vents and the tech said I was good to go.

 

Bottom line is I am not going to get any help from Freightliner as they expect the voltage to always be between 13.8-14.x and as long as it is everything work correctly. The wiring to the AC unit goes through their buss and everything is computer controlled (multiplexed even). I cannot make a change to their system as it is too delicate as it is.

 

I am asking for help and am telling you my solution must not include dropping the alternator output below 13.8. My thought was that if anyone could help it was the folks in this forum. I apologize for not wanting to spend time on this part of the problem because it is a dead horse that I have already worn my self thin on...

 

 

I very much doubt that the main supply to ANY of your equipment is multiplexed. It is the control systems that are and "modules" on the main units switch the supplies in and out. It must be worth half an hour just testing for voltdrop on the main supply cables.

 

As far as I know even multiplex controlled alternators all limit their current to a safe level by dropping their voltage to below the regulated level so you can do nothing in the early stage of charging. The problem with the late stages of charging when you want to switch to a float of 13.8 volts is that if an external controller of any sort tried to reduce the voltage the regulator in the stock alternator would simply take over and run the output at the higher volatge.

 

In the UK there may be a rather crude way around this involving either an adjustable "tractor" regulator or an ordinary regulator set to 13.8 volts plus and alternator modification involving a diode and switch that allows you to switch a higher charging volatge in and out. You could start off with the diode giving a high charging volatge and then after some hours switch it out to give the lower volatge. However this involves adding a diode to the regulator supply from the field diodes and the availability of a suitable low voltage regulator. If the alternator is controlled by the on-board ECU I fear that your only recourse is to having the alternator map reprogrammed, but even then I doubt it will be possible to do what you want.

[Gibbo]

I think what we've got to accept here is that OP doesn't want to find the cause of the problem and recitfy it. He wants to bodge his way round it.

[Tony Brooks]

I very much doubt that the main supply to ANY of your equipment is multiplexed. It is the control systems that are and "modules" on the main units switch the supplies in and out. It must be worth half an hour just testing for voltdrop on the main supply cables.

 

As far as I know even multiplex controlled alternators all limit their current to a safe level by dropping their voltage to below the regulated level so you can do nothing in the early stage of charging. The problem with the late stages of charging when you want to switch to a float of 13.8 volts is that if an external controller of any sort tried to reduce the voltage the regulator in the stock alternator would simply take over and run the output at the higher volatge.

 

In the UK there may be a rather crude way around this involving either an adjustable "tractor" regulator or an ordinary regulator set to 13.8 volts plus and alternator modification involving a diode and switch that allows you to switch a higher charging volatge in and out. You could start off with the diode giving a high charging volatge and then after some hours switch it out to give the lower volatge. However this involves adding a diode to the regulator supply from the field diodes and the availability of a suitable low voltage regulator. If the alternator is controlled by the on-board ECU I fear that your only recourse is to having the alternator map reprogrammed, but even then I doubt it will be possible to do what you want.

 

 

Bloody hell - just read you later post. Does this mean that a commercial outfit is asking for free advice on this forum? If so I think you need to employ a real specialist who can access and understand the onboard equipment. If you are a commercial outfit it would have helped us if you had been upfront about it because I for one would have avoided responding because of my fear of US litigation. It is one thing trying to help an ordinary US citizen but quite another advising commercial organisation who could get sued for "big bucks".

 

I am sure that with the right expert this can be solved but it likley to cost you.

[summer breeze]

The AC unit should work down to at least 11 volts. If it doesn't, it's useless in a vehicle.

 

As you seem happy to accept a piece of shit equipment I would suggest you "sort of" leave the system as it is, but add an additional cheap battery and connect the AC unit to that. Connect that battery directly to the alternator. Then put a normal split charge diode to the Lifelines. Short that diode out with a big contactor during normal charging. Then when you want to go to float open the contactor. The diode will drop some voltage to get a more manageable float voltage on the Lifelines but the AC will still be getting full alternator voltage.

 

I'm baffled why you have such an enormous bank of batteries yet you can't run the AC (probably the biggest thing on there) from them. Seems a waste of batteries if you can't really use them.

 

Okay, I finally figured out the disconnect in our thoughts. The AC unit I am referring to is the cockpit AC system. It is only usable why the engine is running because the engine powers the compressor. When the engine is off the cabin AC unit (different unit) runs off the house bank. The engine, power train and chassis all belong to Freightliner. The cabin belongs to us. Also, this is a very modern 2010 piece of equipment and and there are times when I use similar terms to describe it but I assure you it is very sophisticated piece of equipment (why I stay clear)...

Edited November 27, 2012 by summer breeze