Ozjourney
Member
It would be nice to monitor the Alt temp and get an idea of what’s really going on.
I like the option to turn off the alternator feed, if your on a long trip and with solar there is no need to burn diesel.
Unimogadventures - Our build and travel thread
- Thread starter Iain_U1250
- Start date
I like the option to turn off the alternator feed, if your on a long trip and with solar there is no need to burn diesel.
Iain_U1250
Explorer
Yes, that would be good, might add that to the list for a future project.
Iain_U1250
Explorer
Almost finished the latest update, since I removed the old battery box, I had space for something, so might as well fit a jerry can holder.
Takes a standard metal or a plastic jerry can. Just need to get a rubber tie down and then a chain and lock for it.
With this extra jerry can, I can now carry a total of five extra ones, all low down when they are full, and put some of them up on the roof rack when empty. This brings our total fuel capacity up to 455Lt (190+165+100) taking our overall range up to 1800km off road ( 25lt/100) and over 2000km on road. (20L/100km) . I think that should be enough.
Takes a standard metal or a plastic jerry can. Just need to get a rubber tie down and then a chain and lock for it.
With this extra jerry can, I can now carry a total of five extra ones, all low down when they are full, and put some of them up on the roof rack when empty. This brings our total fuel capacity up to 455Lt (190+165+100) taking our overall range up to 1800km off road ( 25lt/100) and over 2000km on road. (20L/100km) . I think that should be enough.
Wyuna
Observer
I think you have fuel capacity sorted now Iain
That Stop Start Lithium starter battery looks interesting, i think i'll go down that path myself if they offer a 100ah version, as my DC-DC draws 60ah.
Although i could parallel two together and put one under the passenger seat, but still not keen on seeing how the engine bay battery would handle 0 degree mornings and alternator charging.
It's good to see you updated your blog, i like the new seating and the covers came up great.
That Stop Start Lithium starter battery looks interesting, i think i'll go down that path myself if they offer a 100ah version, as my DC-DC draws 60ah.
Although i could parallel two together and put one under the passenger seat, but still not keen on seeing how the engine bay battery would handle 0 degree mornings and alternator charging.
It's good to see you updated your blog, i like the new seating and the covers came up great.
Iain_U1250
Explorer
T
The Lithium batteries don't like hot or cold, hence why I put mine under the seat.
I am just about to test the whole system, just changing the power steering pump, the one I have is 38 years old, and doesn't seem to put out the full pressure as my steering is a bit heavier than it should be. Probably could have overhauled it, but decided to get a new one as it is pretty old and I can keep the old one as a spare.
It has been a while since I updated the blog, have another update of our travels and adventures from time in Townsville in process, will post that one soon.
I think you have fuel capacity sorted now Iain
That Stop Start Lithium starter battery looks interesting, i think i'll go down that path myself if they offer a 100ah version, as my DC-DC draws 60ah.
Although i could parallel two together and put one under the passenger seat, but still not keen on seeing how the engine bay battery would handle 0 degree mornings and alternator charging.
It's good to see you updated your blog, i like the new seating and the covers came up great.
The Lithium batteries don't like hot or cold, hence why I put mine under the seat.
I am just about to test the whole system, just changing the power steering pump, the one I have is 38 years old, and doesn't seem to put out the full pressure as my steering is a bit heavier than it should be. Probably could have overhauled it, but decided to get a new one as it is pretty old and I can keep the old one as a spare.
It has been a while since I updated the blog, have another update of our travels and adventures from time in Townsville in process, will post that one soon.
joeblack5
Active member
If you are adventurous you could use the battery / environment temp sensor that is build in the voltage regulator and put it on the alternator. Higher temp result in lower voltage according with lead acid batteries... how thick is the metal on your cab mount.. it looks a little crusty?l
Also lithium phosphate is pretty safe but under the / your seat ?? May be build a steel box around it? discharge at low temperatures is somewhat acceptable.. the charging is not.
Johan
Also lithium phosphate is pretty safe but under the / your seat ?? May be build a steel box around it? discharge at low temperatures is somewhat acceptable.. the charging is not.
Johan
Iain_U1250
Explorer
Hi Johan, cab mount is solid - what you are looking at is the original sound deadening - about 12-15mm thick.
It sounds like you have experience using lithium batteries in cold temperatures? It would be great to hear how they have performed and what the real world problems are.
I decided to put the cranking battery the seat as it was a place where it will be warm ( and cool). I thought about a steel box, but that would not really help if the battery did catch fire, so I made it such at I can get the battery out of the truck in about 30 seconds if I need to. I have a cable cutter in the door pocket, welders gloves behind the seat and a fire extinguisher nearby as well. Not much use if I am not around, but from what I have read, it is most likely to have problems when charging or discharging and that battery gets isolated when the truck is parked.
We don't really have a problem with cold here in Australia, but when we eventually head off around the world, we will have to do some winterizing of the truck anyway. The grey water tank will need a heating pad, similarly the fuel system will need to be winterized as well.
The house batteries are more of a concern for cold, but if we are going some where very cold, I will get some battery heating pads. https://battlebornbatteries.com/product/heat-pad-for-bbgc2/?afmc=24. The batteries in front compartment have a 25mm layer of insulation under them to protect them from cold and heat. I have a temperature sensor on those batteries. I could run a loop from our truck heating system into that compartment as well, the necessary off takes are aleady there, would just need to get some proper hoses made up.
The rear compartment get warm air from the hot water tank system which will be heating the truck when it is cold and they also have some insulation under in the form of rubber back marine carpet. I will sort out another temperature sensor for them as well.
joeblack5
Active member
Nice that is sound deadening. appeared trouble some
Lain, i am no expert but have some experience with other lithium chemistries that we used when we build our electric cars with. we used batteries from a Nissan Leaf and Chevy Volt. They are a little more finicky . Cells used in factory electric vehicles are very well matched and battery balancing is not that critical. Especially with small cell count like 3 or 6 I would feel confident monitoring them once a month with a multimeter. low and high voltage protection is more critical... Nevertheless you are playing with a lot of energy .
Johan
Lain, i am no expert but have some experience with other lithium chemistries that we used when we build our electric cars with. we used batteries from a Nissan Leaf and Chevy Volt. They are a little more finicky . Cells used in factory electric vehicles are very well matched and battery balancing is not that critical. Especially with small cell count like 3 or 6 I would feel confident monitoring them once a month with a multimeter. low and high voltage protection is more critical... Nevertheless you are playing with a lot of energy .
Johan
Iain_U1250
Explorer
The new battery and electrical installation is all finished, I will be testing it tomorrow.
I decide to add a Victron Battery Monitor on the dash. ( BTW, the gauge cluster next to is it not pushed in yet)
I decided to test the system, and switched on every bit of electrical equipment in the truck ( except the air compressors) to see how much it all draws. I was quite surprised that is got to almost 110A.
I will test the system tomorrow morning, ( bit late to start the truck here). I've fitted a temperature sensor to the OEM alternator, so can monitor what is happening on the road. Looking forward to get things going, and seeing if the alternators can handle the Lithium batteries, and will see if both alternators work in parallel when charging these batteries. If not, then I will look at fitting a bigger second alternator, looking at the 270A one from Mechman, which is about the limit of the dual v-belts I have to turn it.
I decide to add a Victron Battery Monitor on the dash. ( BTW, the gauge cluster next to is it not pushed in yet)
I decided to test the system, and switched on every bit of electrical equipment in the truck ( except the air compressors) to see how much it all draws. I was quite surprised that is got to almost 110A.
I will test the system tomorrow morning, ( bit late to start the truck here). I've fitted a temperature sensor to the OEM alternator, so can monitor what is happening on the road. Looking forward to get things going, and seeing if the alternators can handle the Lithium batteries, and will see if both alternators work in parallel when charging these batteries. If not, then I will look at fitting a bigger second alternator, looking at the 270A one from Mechman, which is about the limit of the dual v-belts I have to turn it.
joeblack5
Active member
Lian, instead of a larger alternator I think it would be better to use your current alternator and set it up to control the max current. In theory alternator are current limiting because of the AC and the self induction of the coils.... but for long maximum current they fail from overheating. Old style DC generators with brushes so not self current limit so the voltage regulators included a max current "relay" coil that reduced the field current to not exceed the rated maximum current of the generator.
We fried a 24V 180Amp alternator on our Mercedes bus after we used our induction stove for an hour or so while we were driving .
It took some time to repair. It was also 17 years old with 420000 miles , so who knows. We were able to keep driving on the solar panels.. that is during the day.
Like any battery..large currents charge / discharge .. comes at a cost. If your current engine running pattern is long enough to charge the larger capacity Lithium then that would be better... and no doubt cheaper.
If you are electronically minded then you could modify your voltage regulator to include a real current regulation.
Lithium does not require temperature / voltage compensation like lead acid does.
I do not know if your setup has an internal or external regulator. External is easier to adapt to .
Any circuitry of a voltage stabilized power supply could control the field supply of an alternator and give it much better voltage regulation and current regulation.
Lithium chargers are way easier then lead acid... no bulk.. equalization charge and so on... just constant voltage and be somewhat confident that each cell shows about the same voltage.
In one of my early electric vehicle with lead acid at 144 volt each 12 volt battery had its own panel voltmeter so that I could monitor the decay of the individual batteries under load. I will see if I can find a pic. It looked like he space shuttle with all those gauges.
Johan
We fried a 24V 180Amp alternator on our Mercedes bus after we used our induction stove for an hour or so while we were driving .
It took some time to repair. It was also 17 years old with 420000 miles , so who knows. We were able to keep driving on the solar panels.. that is during the day.
Like any battery..large currents charge / discharge .. comes at a cost. If your current engine running pattern is long enough to charge the larger capacity Lithium then that would be better... and no doubt cheaper.
If you are electronically minded then you could modify your voltage regulator to include a real current regulation.
Lithium does not require temperature / voltage compensation like lead acid does.
I do not know if your setup has an internal or external regulator. External is easier to adapt to .
Any circuitry of a voltage stabilized power supply could control the field supply of an alternator and give it much better voltage regulation and current regulation.
Lithium chargers are way easier then lead acid... no bulk.. equalization charge and so on... just constant voltage and be somewhat confident that each cell shows about the same voltage.
In one of my early electric vehicle with lead acid at 144 volt each 12 volt battery had its own panel voltmeter so that I could monitor the decay of the individual batteries under load. I will see if I can find a pic. It looked like he space shuttle with all those gauges.
Johan
DiploStrat
Expedition Leader
Pretty dog. Is this a good time to suggest considering a B2B? Not to boost voltage as in the old days, but rather to control the amp draw?
joeblack5
Active member
Thank you diplostrat, 11-1/2 and going rescue since puppy, a good comrade.
I am not up to spec on the latest B2B abilities and it might b e harder when both starter and house are lithium. The key is current control so that the alternator does not overheat.. Here are some folks in the arduino world that seem to have a good understanding
..http://arduinoalternatorregulator.blogspot.com/
Personally I am not a fan of software controlled stuff on mission critical equipment and would rather go pure hardware with replaceable components as much as i can. Interesting read anyhow.
I do like someones suggestion to run the alternator at higher voltages / lower currents ( lower temps) and use an MPPT solar controller to control the whole thing. That way more power can be drawn out of the alternator at lower temps. Smells like a nice DIY project.
In my previous explained overheated dying alternator (Leece Neville) we had some failure and our bus did not want to engage the allison 6 speed transmission and all kind of ABS error codes that freaked me out. Just by chance I glance on the voltage display and it showed 37 volts where the system is a 24 volt system. Not sure if i ever shut down a motor faster then that moment. The regulator was burned out( ebay was my friend) fortunately no other damage to all the proprietary stuff in our bus.
Johan
I am not up to spec on the latest B2B abilities and it might b e harder when both starter and house are lithium. The key is current control so that the alternator does not overheat.. Here are some folks in the arduino world that seem to have a good understanding
..http://arduinoalternatorregulator.blogspot.com/
Personally I am not a fan of software controlled stuff on mission critical equipment and would rather go pure hardware with replaceable components as much as i can. Interesting read anyhow.
I do like someones suggestion to run the alternator at higher voltages / lower currents ( lower temps) and use an MPPT solar controller to control the whole thing. That way more power can be drawn out of the alternator at lower temps. Smells like a nice DIY project.
In my previous explained overheated dying alternator (Leece Neville) we had some failure and our bus did not want to engage the allison 6 speed transmission and all kind of ABS error codes that freaked me out. Just by chance I glance on the voltage display and it showed 37 volts where the system is a 24 volt system. Not sure if i ever shut down a motor faster then that moment. The regulator was burned out( ebay was my friend) fortunately no other damage to all the proprietary stuff in our bus.
Johan
Iain_U1250
Explorer
Hi Johan, how would I go about modifying the regulator for current limiting control. Both alternators have standard Bosch internal regulators.
joeblack5
Active member
Lain, I had to look back a little in your thread. So if I understand correctly your truck is 12 Volt. What alternators are on the truck. The F on the alternator for field does not have to mean that it actually senses the battery voltage thru it. It could be that it just provides the power to the regulator in case the alternator does not have field diodes. So an actual alternator number is required to look that all up.
Internal regulator are a little hard to modify since they are an integrated chip like many Bosch style or potted with sand and glue?..
I would think that you can program your victron BMV 712 to turn on the relay when a certain temperature is detected and with that relay switch of the F connection on you alternator. The temp sensor should be on the alternator.
Another solution would be a hall effect current sensor on your alternator output so that you can monitor the produced current .. fleabay..
WCS1800 Hall Current Sensor 70A Short Circuit Overcurrent Aegis Module
so if you go over the 70 Amp you turn off the voltage regulator... This is a rather crude solution that turns the alternator off at a certain current set point ( 70A). Then on again. you would need a relay that would wear out quickly because of the fast on off switching but would prove the concept. The voltage regulation part is taken care of by the VR. At least it can provide a good indication what current your alternator is delivering to the battery.
If you are up to experimenting.. read .. risk taking... then you could have the above over current device switch off the field directly by interupting the wire to the field brush after the voltage regulator. instead of a relay use a semiconductor to increase the switch frequency.
Maybe the most elegant method, within the cheap solution group, would be to program the BMV for the voltage you want the batteries to be and turn the output relay off when your are going over that setpoint.. eliminate the alternator VR and replace with a current regulator.
So now you alternator has become a current source and the BMV is the voltage regulator.
regarding one or two alternators .... you have to estimate your Ah usage versus engine run time to determin what current you need at a minimum to keep you batteries full.
Sorry this got somewhat lengthy and I do not know your electronic background.. so proceed at your own risk.
Johan
Internal regulator are a little hard to modify since they are an integrated chip like many Bosch style or potted with sand and glue?..
I would think that you can program your victron BMV 712 to turn on the relay when a certain temperature is detected and with that relay switch of the F connection on you alternator. The temp sensor should be on the alternator.
Another solution would be a hall effect current sensor on your alternator output so that you can monitor the produced current .. fleabay..
WCS1800 Hall Current Sensor 70A Short Circuit Overcurrent Aegis Module
so if you go over the 70 Amp you turn off the voltage regulator... This is a rather crude solution that turns the alternator off at a certain current set point ( 70A). Then on again. you would need a relay that would wear out quickly because of the fast on off switching but would prove the concept. The voltage regulation part is taken care of by the VR. At least it can provide a good indication what current your alternator is delivering to the battery.
If you are up to experimenting.. read .. risk taking... then you could have the above over current device switch off the field directly by interupting the wire to the field brush after the voltage regulator. instead of a relay use a semiconductor to increase the switch frequency.
Maybe the most elegant method, within the cheap solution group, would be to program the BMV for the voltage you want the batteries to be and turn the output relay off when your are going over that setpoint.. eliminate the alternator VR and replace with a current regulator.
So now you alternator has become a current source and the BMV is the voltage regulator.
regarding one or two alternators .... you have to estimate your Ah usage versus engine run time to determin what current you need at a minimum to keep you batteries full.
Sorry this got somewhat lengthy and I do not know your electronic background.. so proceed at your own risk.
Johan
Iain_U1250
Explorer
I have just done 45minutes of testing, easiest just to list all the tests and what the result was. I had an Auber temperature sensor on the OEM Bosch 90A alternator and used a IR heat gun on the 120A alternator measuring on the coil itself. (the brown/black bit on the picture)
I also had a clamp on meter on the 120A alternator output. The battery monitor measures the the combined input into both sets of batteries, so the output of the 90A alternator would be the difference between the total measured on the BMV712 and the clamp on meter less the normal current ( 10A) to run the truck. Inside the shed, the ambient temperature was 23C and got up to 25C after running the truck. I have been discharging the batteries for the past week, guessing they would be down to about 60-70%. They were were all down to 13.2V
1. Idle test - I started the truck and just let it idle - about 700rpm. alternators charging batteries independently
2. Truck at 1200rpm - charging batteries independently - minimal extra load
3. Truck at 1200rpm - charging both batteries in parallel - minimal extra load
4. Truck at 1800rpm - charging both batteries in parallel
5. Truck at 1800rpm - charging batteries independently - maximum load ( all spot/headlights, ,main engine fan, ac etc.)
6. Truck at 1800rpm - charging both batteries in parallel - maximum load ( all spot/headlights, ,main engine fan, ac etc.)
7. Truck at 2000rpm - charging both batteries in parallel - maximum load ( all spot/headlights, ,main engine fan, ac etc.}
On the first test, at idle the voltage jumped to 13.7V and current up to 20A. The 90A rose from 20C and stabilised at 40C after about five minutes. The 120A alternator got to a stable temp of 65C. The 120A alternator was putting out 20A, so that means only 10A was going into the main batteries, so the 90A was only putting 10A into the starter battery. This was the test the the video showed would blow up the alternator, and nothing of the sort happened. Temperatures on the alternator did not rise at all. If I lowered the idle down to less than 700rpm, the current going into both batteries dropped down to zero.
Second and third tests, the total input into the batteries was 90A and it did not make any difference being in parallel or independent. The real change was was in the output of the 120A alternator. When run in parallel with the 90A, it was putting out 60A, so that means the 90A alternator was putting out 40A. The temperatures on the 120A alternator stayed at 65C. When run independently, the 120 alternator output rose to 85A, so than means the 90A was only putting out 15A into the starting battery, which has rose to 13.85V whilst the main batteries remained at 13.7V. The temperature on the 120A alternator rose over about a minute to 95C and stabilised.
Test 4 showed no real change other than the total output going to 120A, and in parallel mode, the 120A alternator temperature dropped down to 85C and stabilsed.
Turning on all the electrical load - this is about 120A in total, and with both alternators in parallel, the current going into the batteries dropped down to 50A. The output on the 120A alternator rose to 100A, and the temperature rose up to 110C and stabilised. The battery voltage dropped down to 13.6V. The 90A alternator went up to 55C. This temp measurement was on the casing, so I checked the difference between the casing and the coil on the 120A alternator, than the casing was at 75C. So I am guessing this meant the coils on the the 90A would be around 100C. So that means the total output of both alternators was 170A, of which the 90A alternator started to take up the load of charging the batteries. I kept this test running for ten minutes, and it stayed constant.
Running the two alternators independently with maximum load, saw the output of 120A alternator go up to 110A, the temperature on the coil increased to 115C quickly then stabilise. The total input into the batteries dropped down to 20A. Voltage on the main battery was 13.6V, and increased to 13.8V on the starter battery. So, I think that means the main batteries were discharging by 10A, and the starter battery was getting charge of around 30A. I carried on this test for 10 minutes as well. Switching off the main engine fan (25A) load saw the BMV current change by the same amount.
I increased the revs to 2000rpm, and it made no difference to anything to any of the above, so I think that the alternators are running at their maximum capacity.
So, my conclusions are the if I run both alternator in parallel, then I will have no problems at all, and during the day, I will be charging the main batteries and starter at a rate of around 120A ( about 30A each) and around 13.8V. I will need to do a long run to see what will happen when the batteries get full, but I am thinking that since the alternators only put out 14.2V, I doubt that will happen. The solar system is set to no more than 14.5V, so even with that, I will never trigger the built in BMS shutdown of 15V on any of the batteries, but it also mean that I will not be charging the batteries to this full capacity, which might not be a bad thing.
So now I have to decide whether I really need to get a bigger alternator, of just used the built in feature of the Blue Sea Systems ML-ACR so that it will automatically run the two systems in parallel after about 3-5 minutes after starting and always run both alternators in parallel. I can get a 270A alternator from Mechman for around $800, so will probably get it.
https://www.bluesea.com/products/76...rging_Relay_with_Manual_Control_-_12V_DC_500A
One thing I might invest in is something like this to protect the alternators. https://sterling-power.com/products/alternator-open-circuit-protection-device and maybe I should look at getting a smaller pulley for the 120A to increase it efficiency at lower rpm, but to be honest, I hardly ever leave the truck idling, and even in off road conditions, we seldom trundle along at less then 1500rpm. The big LED spotlights on the roof draw 10A each, but we only used all of them when on dark dirt roads, I normally just have one pair on as that is more than adequate. The inner pair of spotlights are set to light up the sides of the road more than in front anyway,
The next test will need to be done on the road, and when there is a high ambient temperature over 40C to see if everything does work reliably. I think I will move the temperature sensor to the 120A alternator and epoxy it directly to the brown bit on the 120A alternator coil, as that is what seems to get the hottest. I could wire in the Auber gauge on the dash so that it would automatically make run both alternators in parallel if it got hot.
All in all, I don't seem to be having any problems at all with this new setup, time will tell I guess.
I also had a clamp on meter on the 120A alternator output. The battery monitor measures the the combined input into both sets of batteries, so the output of the 90A alternator would be the difference between the total measured on the BMV712 and the clamp on meter less the normal current ( 10A) to run the truck. Inside the shed, the ambient temperature was 23C and got up to 25C after running the truck. I have been discharging the batteries for the past week, guessing they would be down to about 60-70%. They were were all down to 13.2V
1. Idle test - I started the truck and just let it idle - about 700rpm. alternators charging batteries independently
2. Truck at 1200rpm - charging batteries independently - minimal extra load
3. Truck at 1200rpm - charging both batteries in parallel - minimal extra load
4. Truck at 1800rpm - charging both batteries in parallel
5. Truck at 1800rpm - charging batteries independently - maximum load ( all spot/headlights, ,main engine fan, ac etc.)
6. Truck at 1800rpm - charging both batteries in parallel - maximum load ( all spot/headlights, ,main engine fan, ac etc.)
7. Truck at 2000rpm - charging both batteries in parallel - maximum load ( all spot/headlights, ,main engine fan, ac etc.}
On the first test, at idle the voltage jumped to 13.7V and current up to 20A. The 90A rose from 20C and stabilised at 40C after about five minutes. The 120A alternator got to a stable temp of 65C. The 120A alternator was putting out 20A, so that means only 10A was going into the main batteries, so the 90A was only putting 10A into the starter battery. This was the test the the video showed would blow up the alternator, and nothing of the sort happened. Temperatures on the alternator did not rise at all. If I lowered the idle down to less than 700rpm, the current going into both batteries dropped down to zero.
Second and third tests, the total input into the batteries was 90A and it did not make any difference being in parallel or independent. The real change was was in the output of the 120A alternator. When run in parallel with the 90A, it was putting out 60A, so that means the 90A alternator was putting out 40A. The temperatures on the 120A alternator stayed at 65C. When run independently, the 120 alternator output rose to 85A, so than means the 90A was only putting out 15A into the starting battery, which has rose to 13.85V whilst the main batteries remained at 13.7V. The temperature on the 120A alternator rose over about a minute to 95C and stabilised.
Test 4 showed no real change other than the total output going to 120A, and in parallel mode, the 120A alternator temperature dropped down to 85C and stabilsed.
Turning on all the electrical load - this is about 120A in total, and with both alternators in parallel, the current going into the batteries dropped down to 50A. The output on the 120A alternator rose to 100A, and the temperature rose up to 110C and stabilised. The battery voltage dropped down to 13.6V. The 90A alternator went up to 55C. This temp measurement was on the casing, so I checked the difference between the casing and the coil on the 120A alternator, than the casing was at 75C. So I am guessing this meant the coils on the the 90A would be around 100C. So that means the total output of both alternators was 170A, of which the 90A alternator started to take up the load of charging the batteries. I kept this test running for ten minutes, and it stayed constant.
Running the two alternators independently with maximum load, saw the output of 120A alternator go up to 110A, the temperature on the coil increased to 115C quickly then stabilise. The total input into the batteries dropped down to 20A. Voltage on the main battery was 13.6V, and increased to 13.8V on the starter battery. So, I think that means the main batteries were discharging by 10A, and the starter battery was getting charge of around 30A. I carried on this test for 10 minutes as well. Switching off the main engine fan (25A) load saw the BMV current change by the same amount.
I increased the revs to 2000rpm, and it made no difference to anything to any of the above, so I think that the alternators are running at their maximum capacity.
So, my conclusions are the if I run both alternator in parallel, then I will have no problems at all, and during the day, I will be charging the main batteries and starter at a rate of around 120A ( about 30A each) and around 13.8V. I will need to do a long run to see what will happen when the batteries get full, but I am thinking that since the alternators only put out 14.2V, I doubt that will happen. The solar system is set to no more than 14.5V, so even with that, I will never trigger the built in BMS shutdown of 15V on any of the batteries, but it also mean that I will not be charging the batteries to this full capacity, which might not be a bad thing.
So now I have to decide whether I really need to get a bigger alternator, of just used the built in feature of the Blue Sea Systems ML-ACR so that it will automatically run the two systems in parallel after about 3-5 minutes after starting and always run both alternators in parallel. I can get a 270A alternator from Mechman for around $800, so will probably get it.
https://www.bluesea.com/products/76...rging_Relay_with_Manual_Control_-_12V_DC_500A
One thing I might invest in is something like this to protect the alternators. https://sterling-power.com/products/alternator-open-circuit-protection-device and maybe I should look at getting a smaller pulley for the 120A to increase it efficiency at lower rpm, but to be honest, I hardly ever leave the truck idling, and even in off road conditions, we seldom trundle along at less then 1500rpm. The big LED spotlights on the roof draw 10A each, but we only used all of them when on dark dirt roads, I normally just have one pair on as that is more than adequate. The inner pair of spotlights are set to light up the sides of the road more than in front anyway,
The next test will need to be done on the road, and when there is a high ambient temperature over 40C to see if everything does work reliably. I think I will move the temperature sensor to the 120A alternator and epoxy it directly to the brown bit on the 120A alternator coil, as that is what seems to get the hottest. I could wire in the Auber gauge on the dash so that it would automatically make run both alternators in parallel if it got hot.
All in all, I don't seem to be having any problems at all with this new setup, time will tell I guess.
Last edited: