Alternator and LiFePo battery question
What percentage of an alternator's rated output is it safe to run at a steady charge rate? 50%?
Forum Discussion
I've now got two externally regulated 120 amp alternators feeding two separate battery banks over thick cabling.
I pick and choose the voltage with external adjustable regulators with potentiometers on my dashboard, and have ammeters showing not only total alternator output but amperage the battery banks are accepting, and of course dual decimal voltmeters with sense leads on battery terminals.
I've also have voltmeters on the Field wires from regulator to alternator, and K type thermocouples on the alternators casings.
Maxed out at 50 amps hot idle, parked and the alternators get HOT quickly, as does the external voltage regulator, however at 75 amps output when moving above 25mph, they stay far cooler. Below 25mph and low engine rpms is not much better than idling parked. At 65 mph, both alternators can be nearly maxed out in the 120 amp range, and stay 155f or below, but stop at a traffic light, 50 amps max, and 220 f happens in 30 seconds or less and I have frantically lowered voltage to keep them from exceeding this, as My thermoucouples are on the exterior casing, the rectifier/ Diodes likely much hotter
Obviously underhood airflow, and alternator fan rpm have HUGE effects on alternator temperature, as of course does the load, and these are all huge variables on vehicles making direct comparisons without supporting data, and blanket statements devoid of specifics, filled with unknowns, unwise.
The voltage regulators, which are behind my dashoard, with extra heatsinking and 60mm fans attached get hottest at hot idle, low rpms. thats when field voltagwe is just shy of battery voltage. Maxing out at higher rpms field voltage is not as high and the regulators do not get as hot.
Those alternators with voltage regulators inside the alternator have that added heat load, and idling maxed out is likely even harder on them.
In the past, before I have had failed alternators which smelled like burnt varnish.
I've got a plans to force feed my alternators cold air from outside engine compartment, for when I need their full output, when parked, which admittedly would be infrequent, unless.........
I pick and choose the voltage with external adjustable regulators with potentiometers on my dashboard, and have ammeters showing not only total alternator output but amperage the battery banks are accepting, and of course dual decimal voltmeters with sense leads on battery terminals.
I've also have voltmeters on the Field wires from regulator to alternator, and K type thermocouples on the alternators casings.
Maxed out at 50 amps hot idle, parked and the alternators get HOT quickly, as does the external voltage regulator, however at 75 amps output when moving above 25mph, they stay far cooler. Below 25mph and low engine rpms is not much better than idling parked. At 65 mph, both alternators can be nearly maxed out in the 120 amp range, and stay 155f or below, but stop at a traffic light, 50 amps max, and 220 f happens in 30 seconds or less and I have frantically lowered voltage to keep them from exceeding this, as My thermoucouples are on the exterior casing, the rectifier/ Diodes likely much hotter
Obviously underhood airflow, and alternator fan rpm have HUGE effects on alternator temperature, as of course does the load, and these are all huge variables on vehicles making direct comparisons without supporting data, and blanket statements devoid of specifics, filled with unknowns, unwise.
The voltage regulators, which are behind my dashoard, with extra heatsinking and 60mm fans attached get hottest at hot idle, low rpms. thats when field voltagwe is just shy of battery voltage. Maxing out at higher rpms field voltage is not as high and the regulators do not get as hot.
Those alternators with voltage regulators inside the alternator have that added heat load, and idling maxed out is likely even harder on them.
In the past, before I have had failed alternators which smelled like burnt varnish.
I've got a plans to force feed my alternators cold air from outside engine compartment, for when I need their full output, when parked, which admittedly would be infrequent, unless.........
