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Old 06-12-2024, 06:21 AM   #127
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Would the generator then still charge the house batteries?
Of course as the Inverter/charger is charging them from shore/generator power
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Old 06-13-2024, 11:05 AM   #128
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when I first start the diesel in the mornings the engine idles for 15 mins while airing up the air bags. Just no way around that. this would be time that concerns me as far as over heating the alt and wiring to the both eng and coach batts..... using the BIM would seem to prevent the overheating, while still charging.. still waiting on the BIM from amazon to install... Vatrer batt has a blue tooth batt shunt and reports to my phone with much data. I should be able to keep an eye on the charging specifics after the install.
When starting from a 'cold' state, the charging dynamics are a little different. (In some gruesome detail), The engine is cold (ambient air temperature) as is the alternator. Engines generate little heat accumulation at idle so if idled for 15', it would just be around the 'warm' state. If it is a diesel, its even more true. An alternator at idle has only about 40% of its rated capacity (see attached alternator performance curve ....this is for a 170A rated alternator but regardless of your alternator's capacity, it will have a similar relative performance), so that kind of works for you to limit current. The alternator is also at nearly its most efficient state (~70%) so resistive heating in the alternator is at its lowest. That the good news. The bad news is that the engine fan (presuming its thermostatically controlled) is not bringing air into the engine compartment AT ALL and probably never will be at idle. The alternator cooling fan has an exponential relationship with airflow vs speed up to ~8000RPM. At idle, the engine is turning 550-600RPM so the alternator is only running 1500-1800RPM and the fan airflow is probably only 10% of peak. What you really ONLY have working for you is the massive heat sink that all the cold metal has. I mention this because the first engine start of the day followed by a 15' idle is far different from one where the engine is started at operating temp then idled.

After startup, your alternator will have the 'starting debt' from the start battery to recover as well as what is shared with the auxiliary battery that is at its lowest SOC. This means the batteries are CAPABLE of their highest potential charge rate but thankfully the alternator isn't anywhere near its max. It is beneficial to run in this condition because it allows replacement of the starting debt (usually takes less than 10') and some recovery of the auxiliary battery debt, raising its voltage to lessen the potential for high amps when engine speed is raised. Mind you, this is only true if the idle is; a) the idle charging starts from cold and b) only lasts 15'. After 15', the alternator will begin to overheat because of poor air circulation even though its operating at <40% capacity.

What is most relevant and why a BIM has a place is that there is no thermal protection in an alternator and their CONTINUOUS DUTY CAPACITY is about 50% of their rated capacity ('rated capacity' is only relevant for comparing between alternators. It is a 'factory test' number and NOT its potential capacity in the vehicle. I go into in my first alternator charging video) and lithium batteries can very easily drive generation well over the 50% level.

In my own, well-instrumented system (see prior posts), with a 220A 'Rated' alternator, I can, only get 90-100A of continuous output *(at less than 90F ambient) while keeping the alternator at less than 120C/248F. I can also verify that it takes <15' from a cold start to reach max temp because of low airflow. While all vehicles are different, I think these estimates are true enough for planning purposes without going to lengths to instrument and experiment.

this mode, the BIM will have two effects; 1) Its internal (voltage sensing) logic will keep it disconnected till the system battery voltage rises (~5-10' or so) till the completion of the recovery of the starting debt. 2) when it does connect, it will stay 'ON' for 15'. While this is beneficial around engine start, its only really beneficial at a start/idle AFTER the engine is no longer cold. This is a small benefit because I don't see a long idle following start occurring once you have air tanks replenished. The negative is still the cycling of the BIM creating voltage spikes.
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Old 06-13-2024, 05:42 PM   #129
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Anyone have any idea of links or personal knowledge of Precision Instruments LiBIM's causing failures of alternators?

Any indication it was user or install mistakes?
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Old 06-13-2024, 05:53 PM   #130
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Anyone have any idea of links or personal knowledge of Precision Instruments LiBIM's causing failures of alternators?

Any indication it was user or install mistakes?
I have not. I have asked Precision Instruments about it as well and they were not aware of issues. I even looked at Amazon reviews and although there were a few that were unhappy with the product, none mentioned issues with causing alternator problems.

Does it mean it never happens? No, but I have not heard of evidence of it. And as I mentioned before, I also asked Freightliner, and they were not aware of any alternator/Lithium battery issues.

I understand the argument against them above, as it seems logical, but does it happen very often in the wild?
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Old 06-13-2024, 06:09 PM   #131
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I have not. I have asked Precision Instruments about it as well and they were not aware of issues. I even looked at Amazon reviews and although there were a few that were unhappy with the product, none mentioned issues with causing alternator problems.

Does it mean it never happens? No, but I have not heard of evidence of it. And as I mentioned before, I also asked Freightliner, and they were not aware of any alternator/Lithium battery issues.

I understand the argument against them above, as it seems logical, but does it happen very often in the wild?
I do agree that voltage spikes could be an issue.

I have been an operator of all kinds of equipment for my while life....land, sea and air. I have often been laughed at by engineers because my perception of what equipment will or won't do or is failing for difficult to ascertain reasons has left them with egg on their face.

I am a huge believer in science and engineering and following most rules of thumb. But every once in awhile, reality trumps numbers, and calculators and oscilloscopes, etc...etc... and in this case it seems that with few known failures, the Precision Instruments LiBIM seems to work just fine.

If it fails on me to protect the alternator, then yes I will be switching to the alternate tech, but with it costing a lot more money and time for installation than my 5 minute BIM job did.
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Old 07-22-2024, 12:22 AM   #132
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(From what I read) Lithium appear as almost a short. max load to an alternator, so timed-disconnect-from-lithium-period for cooling is required, but ALT does not disconnect from chassis battery w/ a BIM. Amazon can hopefully give quick delivery, or other vendors; scroll down their multi-pages on the Li-BIM and read full content? in meantime, you can pull charge solenoid/ disconnect coil wire and just recharge Lithium from CONVERTER WHEN on GEN or plugged in?
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Old 07-23-2024, 08:07 AM   #133
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(From what I read) Lithium appear as almost a short. max load to an alternator, so timed-disconnect-from-lithium-period for cooling is required, but ALT does not disconnect from chassis battery w/ a BIM. Amazon can hopefully give quick delivery, or other vendors; scroll down their multi-pages on the Li-BIM and read full content? in meantime, you can pull charge solenoid/ disconnect coil wire and just recharge Lithium from CONVERTER WHEN on GEN or plugged in?
I watched my battery shunt when the alt shut down the amps charging the Li batt dropped to 0 while start/engine batts continued to charge. I it seems to be working correctly.
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