Not withstanding the great specifics on the WFCO, the reality of the LiFePO4 world are that they are very very tolerant of PSOC operation, and most batteries out there today only need an occasional top balance to 14.4 to stay completely healthy. Having one source that can do this is completely adequate, solar, charger or alternator. just pick one and be aware of the need, and make sure you have a good battery monitor to track SOC reasonably accurately.
Mike... it's not for everyone... I put relatively large cables between pickup alternator and trailer AGM batteries. I have an engine running automatic relay and a manual switch to control relay.
Connector is at a cable end in bed near back of cab. Another connector near front of trailer. The in-between cables are connected between the two.
When we arrive anywhere we have fully charged batteries.
Have auto relay to prevent connection between controller provided 12 volt and pickup provided 12 volt
Thanks Mike for answering my question. For those wanting more details...2 100AH lithium batteries and 2 100W solar panels. The 2 lithium batteries doubles the AH from our 2 lead acid batteries.. We are light power users...rarely if ever using the A/C or microwave, fridge on propane, no dedicated inverter. Just the basics as we are camping....
Mike, if a dc to DC charger is installed, how will it work to just maintain the lithium battery? How will the existing converter act, does it go to maintain mode?
DC to DC chargers can also be had to limit the current the alternator has to provide when charging lithium batteries as lithiums can absorb a charge at a much higher rate. This protects the alternator from excessive load.
In my opinion, the rule-of-thumb, and Gary's thought #1, that the regular converter will charge to 80%, is an oversimplification and over-generalized. In a harsher light, when applied specifically to the WFCO 8955 Power Center's converter, it may be a myth.
There are so many influencing factors:
What is the size of the lithium battery bank?
What is the starting status of the lithium battery bank?
What are the lithium batteries' BMS technical parameters?
How long has the WFCO converter been powered up?
Examining the WFCO theory of operation and it's charge profile (see references):
Assuming the lithium battery bank is well below 100% , upon firing up a generator or enabling the shore power breaker, in many cases the converter will soon enter bulk mode (14.4V), where it will remain for a minimum of 1 to 4 hours. During this time period, the converter may deliver up to 50AH to 200AH to the lithium battery bank.
Depending on the lithium batteries and how their BMS works, this initial 4 hour period (or less) may be sufficient to approach 100% of lithium power bank capacity.
Another factor to consider if using the standard WFCO 8955: the converter's transition to float mode (13.2V) at the 48 hour mark. While having 13.2V may be safe (depending on the battery manufacturer), it is something to be aware of, especially when determining what charge mode the solar controller should be in.
I'm sure all this highly technical explanation is correct, but WAY over my head. I have two 100ah lithium batteries in my travel trailer. They are charged by either the onboard converter or the 700 watts of solar on the roof. I have a Morningstar MPPT solar controller which Morningstar tech support helped me program to switch from my old six volt batteries to the new lithium batteries. I talked to tech support at Progressive Dynamics to see if they thought it would be alright to use my solar controller in conjunction with my 'old-fashioned' converter and they said no problem. The battery mfg (Expion 360) agreed. So, with no knowledge of all the parameters you brought up, my system works flawlessly. My truck driver brain was able to set up my system with very little technical knowledge. Just a bit of research.
Not withstanding the great specifics on the WFCO, the reality of the LiFePO4 world are that they are very very tolerant of PSOC operation, and most batteries out there today only need an occasional top balance to 14.4 to stay completely healthy. Having one source that can do this is completely adequate, solar, charger or alternator. just pick one and be aware of the need, and make sure you have a good battery monitor to track SOC reasonably accurately.
Mike... it's not for everyone... I put relatively large cables between pickup alternator and trailer AGM batteries. I have an engine running automatic relay and a manual switch to control relay.
Connector is at a cable end in bed near back of cab. Another connector near front of trailer. The in-between cables are connected between the two.
When we arrive anywhere we have fully charged batteries.
Have auto relay to prevent connection between controller provided 12 volt and pickup provided 12 volt
Voila
Thanks Mike for answering my question. For those wanting more details...2 100AH lithium batteries and 2 100W solar panels. The 2 lithium batteries doubles the AH from our 2 lead acid batteries.. We are light power users...rarely if ever using the A/C or microwave, fridge on propane, no dedicated inverter. Just the basics as we are camping....
Mike, if a dc to DC charger is installed, how will it work to just maintain the lithium battery? How will the existing converter act, does it go to maintain mode?
DC to DC chargers can also be had to limit the current the alternator has to provide when charging lithium batteries as lithiums can absorb a charge at a much higher rate. This protects the alternator from excessive load.
Great generalized response.
In my opinion, the rule-of-thumb, and Gary's thought #1, that the regular converter will charge to 80%, is an oversimplification and over-generalized. In a harsher light, when applied specifically to the WFCO 8955 Power Center's converter, it may be a myth.
There are so many influencing factors:
What is the size of the lithium battery bank?
What is the starting status of the lithium battery bank?
What are the lithium batteries' BMS technical parameters?
How long has the WFCO converter been powered up?
Examining the WFCO theory of operation and it's charge profile (see references):
Assuming the lithium battery bank is well below 100% , upon firing up a generator or enabling the shore power breaker, in many cases the converter will soon enter bulk mode (14.4V), where it will remain for a minimum of 1 to 4 hours. During this time period, the converter may deliver up to 50AH to 200AH to the lithium battery bank.
Depending on the lithium batteries and how their BMS works, this initial 4 hour period (or less) may be sufficient to approach 100% of lithium power bank capacity.
Another factor to consider if using the standard WFCO 8955: the converter's transition to float mode (13.2V) at the 48 hour mark. While having 13.2V may be safe (depending on the battery manufacturer), it is something to be aware of, especially when determining what charge mode the solar controller should be in.
References:
1. WFCO Theory of Operation, available at https://wfcoelectronics.com/theory-of-operation/
2. pgs 6-7, WFCO 8955 Converter Operation Modes, WFCO 8955 Manual, available at https://wfcoelectronics.com/wp-content/uploads/2022/11/WF-8900-Power-Center-Series-Manual.pdf
I'm sure all this highly technical explanation is correct, but WAY over my head. I have two 100ah lithium batteries in my travel trailer. They are charged by either the onboard converter or the 700 watts of solar on the roof. I have a Morningstar MPPT solar controller which Morningstar tech support helped me program to switch from my old six volt batteries to the new lithium batteries. I talked to tech support at Progressive Dynamics to see if they thought it would be alright to use my solar controller in conjunction with my 'old-fashioned' converter and they said no problem. The battery mfg (Expion 360) agreed. So, with no knowledge of all the parameters you brought up, my system works flawlessly. My truck driver brain was able to set up my system with very little technical knowledge. Just a bit of research.