Technical Diesel Alternator upgrade

[ccsalway]

I'm installing a lithium leisure battery in the van with a 50A dc-dc charger so I want to install a 200Amp alternator to supply the extra 50Amp the charger will use. Is it a straight swap out with the current alternator which I think is 140Amp or do I have to upgrade the big 3 cables and do anything to the ECU?

 

[jackwhoo]

Dont bother your existing alternator will almost certainly provide more than enough power

 

[Communicator]

I'm installing a leisure battery in the van with an 50A dc-dc charger so I want to install a 200Amp alternator to supply the extra 50Amp the charger will use. Is it a straight swap out with the current alternator which I think is 140Amp or do I have to upgrade the big 3 cables and do anything to the ECU?

Are you installing a leisure battery (FLA battery suitable for deep cyclic discharge), or perhaps a lithium battery in the habitation role? In either case as @jackwhoo has stated your existing alternator should suffice, also an alternator change in later models can be a complicated task. (See guides section).

For illustration my 2006 2.8jtd has a 90A alternator, 2 x 105Ahr FLA batteries and a smallish 20A B2B. It copes, If I were to change to lithium, and park off grid for extended periods the I would have to consider a larger alternator, as lithium batteries can recharge at a high rate for extended periods.

 

[ccsalway]

Dont bother your existing alternator will almost certainly provide more than enough power

My concern is when I drive up to north Norway where I will most definitely have the headlights on at night along with full heating as I'm driving. Which is then when I'd consider needing the extra amperage.

 

[jackwhoo]

My concern is when I drive up to north Norway where I will most definitely have the headlights on at night along with full heating as I'm driving. Which is then when I'd consider needing the extra amperage.

If You calculate the amps drawn under those circumstances I expect you will find the alternator has plenty of extra capacity.

As @Communicator mentioned a major factor will be the chemistry of your leisure batteries/capacity etc etc

 

[ccsalway]

If You calculate the amps drawn under those circumstances I expect you will find the alternator has plenty of extra capacity.

As @Communicator mentioned a major factor will be the chemistry of your leisure batteries/capacity etc etc

I suppose I could put a shunt on the van battery to read the amperage drawn and turn on all the systems...

 

[deejays]

The standard alternator factory fitted my 2018 2.3L Ducato has the following specifications on the nameplate:

5802170711

17-10-23

F 000 BL0 7CB

C5 -> 14V 70-150A

Made in Hungary



According to the Bosch test data sheet, the 70-150A refers to 70A at 1800rpm and 150A at 6000rpm alternator speed, which equates approximately to 750rpm and 2500rpm engine speed.

The house batteries I have are 400AH LiFePo4 and the DC2DC can deliver 50A over the 25mm^2 copper supply cables.

The alternator voltage is regulating correctly suppling that load as well as the standard vehicle loading - including full headlighting and A/C, so the peak current is not an issue.

The issue I see, regardless of what alternator you are running is that I have never been able to find a manufacturer’s specification on what the maximum continuous current capacity of a particular alternator is. The specifications state peak maximum achievable, not continuous.

With my 2018 2.3L the alternator is sandwiched between the rear of the engine block and the DPF/exhaust system – not a very friendly environment for heat loss! If we assume that the alternator is around 60% efficient, then 40% is dissipated internally as heat. For just the 50A alone, the output power will be 14.2 x 50 = 710W. This means the alternator will be dissipating around 473W in heat internally which it has to dissipate. If the batteries are half discharged, then the duration for full recharge is 4 hours at 50A continuous. Because of the above, I have set my DC2DC to a more conservative 30A if driving in hot conditions and or low speed driving. If the weather is cool and open road driving, then I will switch back to 50A if required.

Is anyone able to source what a particular alternator continuous current rating is?

 

[ccsalway]

The standard alternator factory fitted my 2018 2.3L Ducato has the following specifications on the nameplate:

5802170711

17-10-23

F 000 BL0 7CB

C5 -> 14V 70-150A

Made in Hungary



According to the Bosch test data sheet, the 70-150A refers to 70A at 1800rpm and 150A at 6000rpm alternator speed, which equates approximately to 750rpm and 2500rpm engine speed.

The house batteries I have are 400AH LiFePo4 and the DC2DC can deliver 50A over the 25mm^2 copper supply cables.

The alternator voltage is regulating correctly suppling that load as well as the standard vehicle loading - including full headlighting and A/C, so the peak current is not an issue.

The issue I see, regardless of what alternator you are running is that I have never been able to find a manufacturer’s specification on what the maximum continuous current capacity of a particular alternator is. The specifications state peak maximum achievable, not continuous.

With my 2018 2.3L the alternator is sandwiched between the rear of the engine block and the DPF/exhaust system – not a very friendly environment for heat loss! If we assume that the alternator is around 60% efficient, then 40% of the useable output is dissipated internally as heat. For just the 50A alone, the output power will be 14.2 x 50 = 710W. This means the alternator will be dissipating around 473W in heat internally which it has to dissipate. If the batteries are half discharged, then the duration for full recharge is 4 hours at 50A continuous. Because of the above, I have set my DC2DC to a more conservative 30A if driving in hot conditions and or low speed driving. If the weather is cool and open road driving, then I will switch back to 50A if required.

Is anyone able to source what a particular alternator continuous current rating is?

This 150 A rating is what manufacturers spec as the continuous charging current. The technical spec sheets are only available via the professional portal, but I did find information from Bosch's motorsport website

Bosch Alternator 150 A Output vs RPM (example from an official Bosch PDF)

• At ~3,000 rpm alternator speed → ~95 A
• At ~4,000 rpm → ~129 A
• At ~5,000 rpm → ~143 A
• At ~6,000 rpm → ~153 A
• Above ~7,000 rpm → output continues rising slightly (but engine/belt limits apply)

 

[deejays]

This 150 A rating is what manufacturers spec as the continuous charging current. The technical spec sheets are only available via the professional portal, but I did find information from Bosch's motorsport website

Bosch Alternator 150 A Output vs RPM (example from an official Bosch PDF)

• At ~3,000 rpm alternator speed → ~95 A
• At ~4,000 rpm → ~129 A
• At ~5,000 rpm → ~143 A
• At ~6,000 rpm → ~153 A
• Above ~7,000 rpm → output continues rising slightly (but engine/belt limits apply)

I will challenge your statement "This 150 A rating is what manufacturers spec as the continuous charging current." Where are they stating it is continuous rating? The only specs I have ever seen is an unqualified "x" amount of amps - with no qualification of maximum or continuous, let alone a specified ambient temperature for that declared rating. Nor do they specify efficiency or maximum power dissipation or output derating for ambient temperature. The specifications I have seen mean nothing. I would so like to believe those ratings are continuous, but without any qualifying related data they are quite meaningless, and at best can only be interpreted as a maximum output before the field coils are saturated.

 

[Reg 65]

I think you have answered your own question
Manufacturers can't give a figure for continuous rating because they don't know how much the environment its installed in will restrict its ability to dissipate the heat.
Fiat cover their arses by saying don't add secondary batteries bigger that 20% of the capacity of the original battery, which is clearly absurd for a vehicle they market as a base for motorhomes (taken from Fiat's 2017 converters manual) So if you ask them you will probably wish you hadn't bothered.
I suppose we can only say how much we have overloaded the alternator and whether we have got away with it.
FWIW I have had 4x019 100ah lead acid batteries (2 under each seat) connected in parallel to the main battery for many years with no problems. Both with the X2/50 150amp alternator, and the later X2/90 Euro6d 180 amp smart alternator.
But I am not advising anyone else to do it - if you do it you do it at your own risk same as me.

 

[deejays]

I think you have answered your own question
Manufacturers can't give a figure for continuous rating because they don't know how much the environment its installed in will restrict its ability to dissipate the heat.
Fiat cover their arses by saying don't add secondary batteries bigger that 20% of the capacity of the original battery, which is clearly absurd for a vehicle they market as a base for motorhomes (taken from Fiat's 2017 converters manual) So if you ask them you will probably wish you hadn't bothered.
I suppose we can only say how much we have overloaded the alternator and whether we have got away with it.
FWIW I have had 4x019 100ah lead acid batteries (2 under each seat) connected in parallel to the main battery for many years with no problems. Both with the X2/50 150amp alternator, and the later X2/90 Euro6d 180 amp smart alternator.
But I am not advising anyone else to do it - if you do it you do it at your own risk same as me.

Hi Reg, My background is electronics and electrical engineering, and the manufacturers can indeed specify and produce a set of data for the continuous current rating for a given operating ambient temperature. Certainly they cannot know the environment it will ultimately be operating in, so that is why it is common practice to specify the condition of operating ambient temperature. It may well be they do not disclose that set of data to the public - which is why I was asking if anyone has come across any such data set.

Regarding your lead acid battery set up - they have a relatively high charging impedance and will not present that high a continuous load to the alternator compared to lithium batteries, so much kinder on the alternator, specially if there is no DC2DC and the supply cable impedance is also relatively high compared to 25mm^2.

Is anyone able to source what a particular alternator continuous current rating is?

 

[deejays]

This 150 A rating is what manufacturers spec as the continuous charging current. The technical spec sheets are only available via the professional portal, but I did find information from Bosch's motorsport website

Bosch Alternator 150 A Output vs RPM (example from an official Bosch PDF)

• At ~3,000 rpm alternator speed → ~95 A
• At ~4,000 rpm → ~129 A
• At ~5,000 rpm → ~143 A
• At ~6,000 rpm → ~153 A
• Above ~7,000 rpm → output continues rising slightly (but engine/belt limits apply)

One thing you may want to ponder - if 150A is as you say, a continuous rating, then that means the full output power is 150 x 14.2 = 2.13kW continuous. At 60% efficiency, that means that 1.42kW is being dissipated as heat within the alternator. That is a serious amount of heat energy to dissipate continuously!

 

[Reg 65]

Hi Reg, My background is electronics and electrical engineering, and the manufacturers can indeed specify and produce a set of data for the continuous current rating for a given operating ambient temperature. Certainly they cannot know the environment it will ultimately be operating in, so that is why it is common practice to specify the condition of operating ambient temperature. It may well be they do not disclose that set of data to the public - which is why I was asking if anyone has come across any such data set.

Regarding your lead acid battery set up - they have a relatively high charging impedance and will not present that high a continuous load to the alternator compared to lithium batteries, so much kinder on the alternator, specially if there is no DC2DC and the supply cable impedance is also relatively high compared to 25mm^2.

Is anyone able to source what a particular alternator continuous current rating is?

Interesting reply thanks. But how can you know what the ambient temperature will be in the confined space of the alternator trapped behind the hot engine with unknown airflow?
Incidentally my 4x019 100ah lead acid batteries are connected in parallel to the main battery with 25mm2 tinned copper twin wall welding cable further protected by running inside reinforced 'rubber' water hose where they might touch metal because they are unfused to minimise resistance. (Some people will baulk at the lack of fuses and I am aware of the danger, thats why I have made sure the cables are very well protected.) As well as avoiding the losses in the B2B this makes use of the free electricity in smart alternator regenerative braking, - the battery bank regularly reaches 15 volts whilst slowing down or going downhill.
(I routed all the battery earths through the quick release factory fitted earth lead so they can all be disconnected easily as normal)

 

[deejays]

Interesting reply thanks. But how can you know what the ambient temperature will be in the confined space of the alternator trapped behind the hot engine with unknown airflow?
Incidentally my 4x019 100ah lead acid batteries are connected in parallel to the main battery with 25mm2 tinned copper twin wall welding cable further protected by running inside reinforced 'rubber' water hose where they might touch metal because they are unfused to minimise resistance. (Some people will baulk at the lack of fuses and I am aware of the danger, thats why I have made sure the cables are very well protected.) As well as avoiding the losses in the B2B this makes use of the free electricity in smart alternator regenerative braking, - the battery bank regularly reaches 15 volts whilst slowing down or going downhill.

The answer is we don't - but that is not the point I am trying to make - and that is the alternator manufacturer would know what the maximum continuous current would be for a given ambient temperature. They just don't publish it. If that information was available, then it would be relatively simple to place a temp sense probe near the alternator during typical operating conditions to observe the ambient temp and then know what the maximum safe continuous current would be. Regarding your lack of fuse - you do seem to want to live dangerously - not a good idea. Re the overvoltage - not a good idea for deep cycle batteries once they have been fully charged.. The problem with no DC2DC is that once the ECU determines the starter battery is sufficiently charged, the smart alternator voltage will drop and your house batteries will not receive any charge even if they are severely depleted. The very reason DC2DC charge regulators were invented was because of smart alternators. Even without a smart alternator it is best design practice to run a DC2DC. Even if your house batteries are lead acid, the correct charge regime for a high discharge, low capacity starter battery is not the same as the high capacity, deep cycle house battery. You will get a longer life span and faster and better regulated charge regime for your house battery if you use a DC2DC.

 

[Reg 65]

The problem with no DC2DC is that once the ECU determines the starter battery is sufficiently charged, the smart alternator voltage will drop and your house batteries will not receive any charge even if they are severely depleted. The very reason DC2DC charge regulators were invented was because of smart alternators. Even without a smart alternator it is best design practice to run a DC2DC. Even if your house batteries are lead acid, the correct charge regime for a high discharge, low capacity starter battery is not the same as the high capacity, deep cycle house battery. You will get a longer life span and faster and better regulated charge regime for your house battery if you use a DC2DC.

Didn't we have DC to DC battery chargers before smart alternators?
(I don't know because I have never had one)
The batteries are connected in parallel so the ECU cannot separate the starter battery and the others
The voltage doesn't always reach 15 volts on the over run, apparently only when the batteries need charging. I just mentioned that as an example of what he alternator can do.
I heard it re programmes itself when you disconnect and reconnect the batteries and sets itself up for the new battery bank?
They are all the same age and type of battery Varta silver lead acid except the main battery is an 020 with about 10 more ah. (the space under Ducato seat is only wide enough for 2x019) I carry the original start stop battery in case they all go flat which they never have
This arrangement is still working fine after 5 years with the 180amp smart alternator (X2/90), and for 12 years before that on the 150amp standard alternator (X2/50)

 

[deejays]

DC2DC technology is not new, but it came into its own in the RV industry with the introduction of the “smart alternator”.

I have an Audi S4 which has a smart alternator. Seven years ago, I disconnected the sense wire from the negative battery terminal as I was sick of the start/stop mechanism. Before I did that, I observed the charge mechanism and initially the charge voltage was around 14.2V, peaking to over 15V on overrun, and once the ECU had deemed the battery sufficiently charged, it reduced the voltage to result in near zero charge current. This was done in coordination with the local AUDI workshop. This resulted in deleting the Start/Stop as well as preventing the ECU from knowing the charge status of the battery – leaving it as a normal “dumb” fixed 14.2V alternator. That battery is now 8 years old and still going strong. The AUDI techs tell me the usual life of the S4 battery is around 4 -5 years. So, a Win-Win for me there.

When it comes time to replace the battery in a “smart” system, it is normally required to connect to the ECU with an appropriate scan tool to reset the battery data, so the ECU is informed of the new battery and the associated battery data. This does not occur just by simply disconnecting the battery. Your ECU would be programmed only for the standard starter battery it came with. The algorithm built into the ECU modifies the charge regime based on that battery data, start/stop cycles, age charge/discharge current etc.

The system you have will work of course, just not as efficient if the correct charge voltages and regime was set. That is the way most house batteries were set up in the old days. But now with the relatively cheap price of a decent DC2DC the game has changed – particularly if lithium batteries are used. A strict maximum of 14.2V to 14.4V for bulk charge, and a fixed 13.5V once they have fully charged - otherwise cell damage can occur. If sticking with lead acid and employing the necessary deep cycle (not starter) batteries then the correct charge regime is 14.7V bulk, with a reduction to anywhere between 13.5V to 13.8V on float. By using a DC2DC physically located at the house battery bank, you will get a much faster charge rate as the voltage will be at 14.7V at the battery resulting in an efficient charge regime, regardless of the alternator output voltage. Most people, particularly those living off grid require an efficient charge cycle to recharge the house battery as quickly and safely as possible. Your load demands may be different/lower and so not to concerned about efficient charge methods or battery life.

 

[Reg 65]

DC2DC technology is not new, but it came into its own in the RV industry with the introduction of the “smart alternator”.

I have an Audi S4 which has a smart alternator. Seven years ago, I disconnected the sense wire from the negative battery terminal as I was sick of the start/stop mechanism. Before I did that, I observed the charge mechanism and initially the charge voltage was around 14.2V, peaking to over 15V on overrun, and once the ECU had deemed the battery sufficiently charged, it reduced the voltage to result in near zero charge current. This was done in coordination with the local AUDI workshop. This resulted in deleting the Start/Stop as well as preventing the ECU from knowing the charge status of the battery – leaving it as a normal “dumb” fixed 14.2V alternator. That battery is now 8 years old and still going strong. The AUDI techs tell me the usual life of the S4 battery is around 4 -5 years. So, a Win-Win for me there.

When it comes time to replace the battery in a “smart” system, it is normally required to connect to the ECU with an appropriate scan tool to reset the battery data, so the ECU is informed of the new battery and the associated battery data. This does not occur just by simply disconnecting the battery. Your ECU would be programmed only for the standard starter battery it came with. The algorithm built into the ECU modifies the charge regime based on that battery data, start/stop cycles, age charge/discharge current etc.

The system you have will work of course, just not as efficient if the correct charge voltages and regime was set. That is the way most house batteries were set up in the old days. But now with the relatively cheap price of a decent DC2DC the game has changed – particularly if lithium batteries are used. A strict maximum of 14.2V to 14.4V for bulk charge, and a fixed 13.5V once they have fully charged - otherwise cell damage can occur. If sticking with lead acid and employing the necessary deep cycle (not starter) batteries then the correct charge regime is 14.7V bulk, with a reduction to anywhere between 13.5V to 13.8V on float. By using a DC2DC physically located at the house battery bank, you will get a much faster charge rate as the voltage will be at 14.7V at the battery resulting in an efficient charge regime, regardless of the alternator output voltage. Most people, particularly those living off grid require an efficient charge cycle to recharge the house battery as quickly and safely as possible. Your load demands may be different/lower and so not to concerned about efficient charge methods or battery life.

Thats interesting thanks
Years ago I tried unplugging the 'shunt / sensor thing' on top of the battery and the engine management light came on so I put it back- but that might have been caused by the DPF pressure sensor that I later discovered was failing.
In any case the start stop does not work whilst the extra batteries are connected.
I have just fitted a solar kit (600watts with victron charger) because I have just got 12v fridge and a separate 12v freezer. Am yet to discover how that works out.

 

[deejays]

Not a problem Reg. Every time I start the AUDI I get a momentary text warning stating the stop/start has an issue and to take the vehicle to AUDI service, but that is all it does – no other issue. I would suspect the FIAT should do similar, but to turn on the EML sounds a bit over the top – mind you, it is a FIAT. I am not surprised the stop/start does not work with the set up you have – the ECU most likely senses the battery is not near fully charged due to it now being 400AH plus, instead of just the single starter battery.

Victron make some good gear at very reasonable prices. Have a look at the Orion XS 12/12 – 50, it is one of the better DC2DC’s out there. I have fitted my ADRIA SP600 with all Victron gear, including two of their 200AH lithium batteries. If you ever do fit a DC2DC it would be worth trying to disconnect the starter battery negative sense wire to force the alternator to a fixed output. This will improve the efficiency of the system and give the DC2DC an easier time. I have read that others have disconnected the sense wire without any major issues – it might be worth testing that again perhaps? Fortunately for me I have a 2018 without any of that rubbish.

 

[Reg 65]

Yes I was impressed with the victron solar controller so sent for a victron voltage inverter. Its only 375 watts but I was surprised by how big and heavy it was - much more than the cheap chinese one I got on ebay thats supposed to be 2,000 watts . The victron output is much more accurate and stable than any of the other inverters I have had, and its pure sine wave so it works with the controller on my 160 watt Dreamland blanket (I had to cut out the controller and wire the modified sine wave direct to the blanket. Incidentally the wattage drawn by the blanket when connected direct drops as it heats up - I can only guess the resistance of the heating wires increase as they get warm?)
This is the solar kit I got link
The panel fits the corrugations of the X2/50 onwards panel van perfectly. The panel wasn't doing a lot with so little sun, so I sent for another 300 watt panel the same (from the suppliers own website where I discovered the stuff was cheaper than their site on ebay ) Their 2 panel kit comes with a 50 amp victron solar controller and mine is only 30amp as its supposed to be for one panel. But the instructions say an oversized PV array can be safely connected. I guess it just means that in the highly unlikely event of more power being produced it will be wasted, which it would have been anyway if the batteries were fully charged.?

 

[deejays]

Oversizing works because the solar panels drop in efficiency with the rise in temperature of the panel. Typically in Australia with a blazing sun, the panel can get really hot and the efficiency can drop to around 60% to 70% depending on the panel. The coefficient is approximately -0.4%/C - depending on the panel. The quoted output is with a laboratory controlled panel temp of 25C. Also the quoted output is for a certain fixed maximum solar radiation, which you are not likely to achieve in the UK. Speaking of Victron, if you don't already have a https://www.victronenergy.com.au/battery-monitors/smart-battery-shunt then you should consider it. Takes all the guesswork out of the equation and less stress - particularly if you are running off grid for any length of time.