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Is this ability to respond to the battery because the alternator in the 2020s is "smarter" than previous Transit alternators?
I've read nothing to indicate this. It's not just the alternator but the "vehicle charging system" of which the alternator is part of. From my understanding this smartness is about voltage (pressure). The idea is that the voltage is lowered when the battery SOC is determined to be "high" via the BMS/shunt measuring amps in and out. When the BMS thinks the battery is replenished it lowers the voltage. Voltage times amps is work (watts). Lowering the work on the alternator lowers the resistance at the belt. So the BMS is a key player in all of this which is why it can compromise things to connect directly to the battery negative terminal as that is where amps in and out are being measured. That BMS is looking at amps going out and amps going in as well as resting battery voltage to determine SOC. If you directly connect to the negative side you are going to see current from not just the cranking battery but also from the house bank. If the BMS is programed to a certain number of AH for the cranking battery then it is not going to be able to determine an accurate SOC and potentially corrupt the commands to the rest of the system.

All that being said, if you have a house bank that is depleted it will try to draw a lot of current and that will lower the voltage in the charging system regardless of a CCP connection or direct to battery positive. That voltage drop will signal the charging system to kick into gear and bring the voltage to where it thinks the battery needs it according to the BMS. That voltage level is for AGM batteries and may not be sufficient to get Li batteries above 80%. I guess if you are willing to oversize your Li house bank by 20% you are golden as long as you don't over draw whatever connection you have to the vehicle charging system.

All of this is what has me considering charging Li house batteries directly with a connection that can handle the 1C amps of the bank and then letting solar top off the last 20% when it can. Just an interesting theory at this point. With an AGM battery bank you have both a lower 1C (max charge rate) and lower voltage required to fully charge. So maybe with Li you over size by 20%. But, you still have to make sure your charge rate does not overrun your positive connection to the vehicle charging system.

Again, I am more than happy to have a real engineer blow all this up.
 

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What is the benefit of charging directly from the alternator VS using b2b or invertor and charger ?
Thanks
Pros: Cost, simplicity, efficiency. Easier to enable a direct connection for jump starting.
Cons: Less (zero) control over charge profile resulting in possible lower battery life. Possible corruption over sophisticated/unknown Ford electrical systems.

I’ll continue being the volunteer test bed for the direct connection approach, 4 years and counting, and I’ll also volunteer my $2,000 battery for this test.

As for direct connections to the starter batteries, I’ve already conceded to a better approach in another thread (direct to positive bus and direct to van structure), but see no need to change mine at this point.
 

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I've read nothing to indicate this. It's not just the alternator but the "vehicle charging system" of which the alternator is part of. From my understanding this smartness is about voltage (pressure). The idea is that the voltage is lowered when the battery SOC is determined to be "high" via the BMS/shunt measuring amps in and out. When the BMS thinks the battery is replenished it lowers the voltage. Voltage times amps is work (watts). Lowering the work on the alternator lowers the resistance at the belt. So the BMS is a key player in all of this which is why it can compromise things to connect directly to the battery negative terminal as that is where amps in and out are being measured. That BMS is looking at amps going out and amps going in as well as resting battery voltage to determine SOC. If you directly connect to the negative side you are going to see current from not just the cranking battery but also from the house bank. If the BMS is programed to a certain number of AH for the cranking battery then it is not going to be able to determine an accurate SOC and potentially corrupt the commands to the rest of the system.

All that being said, if you have a house bank that is depleted it will try to draw a lot of current and that will lower the voltage in the charging system regardless of a CCP connection or direct to battery positive. That voltage drop will signal the charging system to kick into gear and bring the voltage to where it thinks the battery needs it according to the BMS. That voltage level is for AGM batteries and may not be sufficient to get Li batteries above 80%. I guess if you are willing to oversize your Li house bank by 20% you are golden as long as you don't over draw whatever connection you have to the vehicle charging system.

All of this is what has me considering charging Li house batteries directly with a connection that can handle the 1C amps of the bank and then letting solar top off the last 20% when it can. Just an interesting theory at this point. With an AGM battery bank you have both a lower 1C (max charge rate) and lower voltage required to fully charge. So maybe with Li you over size by 20%. But, you still have to make sure your charge rate does not overrun your positive connection to the vehicle charging system.

Again, I am more than happy to have a real engineer blow all this up.
My understanding of how the alternator(s) appear to work is similar to yours. They are fundamentally voltage based vs current based, and current information is used as part of managing the system as a whole.

I am interpreting Ford's "175 amp limit" as their recommendation for maximum continuous end user load allowed- not that they are actively limiting the CCP to 175 amps using current management of the alternator(s). If they are, then I missed that in the description. Sprinters have a similar stated limit - 40 amps - which hasn't changed as they have almost tripled the alternator output rating.

If we assume for the moment that the 175 amp number is a "current regulated max number", and follow the typical LiFe battery supplier recommendation of C/2 charge rate (max) then it would indeed set a floor of ~ 400 amp-hr x 12 volt LiFe pack as the minimum.

I am not at all confident that this 175 amp number is the maximum that the CCP will deliver with a pair of 250s driving down the highway. I know that it isn't identical, but the somewhat similarly configured pick up trucks are going to have 3 ish kW inverters, which is nearly double this amount of power.

AGM batteries are somewhat self limiting unless they are pushed by specialized charging gear.

I would be very curious if someone has an indication that this 175 amp number is a regulated max, or just what can be counted on.

If it is "what can be counted on", then active battery to battery charge control is even more critical for LiFe than before.
 

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What is the benefit of charging directly from the alternator VS using b2b or invertor and charger ?
Thanks
When the battery is flat, depending on the B2B charger, you might get a more rapid charge at the beginning. For instance, my Renogy DCC50S will charge at a max 50A. Down side is you don't get the voltage buck at the end to complete the charge to 100%. My Battle Born wants 14.5 volts charge pressure to get to 100%. A charge controller with a Li charging profile will deliver that. So it is about exchanging fast recovery from flat vs. being able to get the bank to 100% over time. In real world use you have to think about what it is you really need/want.

Of course, with a 120A Sterling you likely get the best of both worlds to some extent. At a price.
 

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Important to determine how much amperage is required for your application. Many people want maximum amperage when they have no need for it. My Magnum inverter/charger/transfer switch has a 50 amp charger. I set the charger to charge at 40 amps. Charging from the vehicle powered pure sine inverter is seldom required. My single 300 watt solar panel normally provides all the power required. No need for high amperage alternator charging. I understand that other people may have a need for more alternator charging due to different loads and/or weather conditions.

So first estimate the amount of charging you will need from the vehicle 12 volt system. Then design the system to provide that.
 

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All of this is what has me considering charging Li house batteries directly with a connection that can handle the 1C amps of the bank and then letting solar top off the last 20% when it can. Just an interesting theory at this point. With an AGM battery bank you have both a lower 1C (max charge rate) and lower voltage required to fully charge. So maybe with Li you over size by 20%. But, you still have to make sure your charge rate does not overrun your positive connection to the vehicle charging system.
I can't quantify it, but it is a known quality of Li batteries that they last longer if stored less than fully charged. So if the battery is oversized 20% some of the cost will be recovered with increased longevity.

If, by charge directly, you are suggesting simply connecting the lithium battery to the vehicle charging system, that doesn't seem like a good idea to me. Avoiding draining the starter battery is easy, just put a voltage sensitive isolator on the cable connecting the Li battery to the vehicle charging system. But now you have exposed your Li battery to all of the vagaries of the "smart" charging system. And when the charging system is not just fooling around and is actually charging the battery, it is not using a profile for Li batteries. Would connecting directly to the charging system work? Maybe. But it doesn't seem like it would work very well.

The more I think about it, the more I like Orton's dual inverter approach. It seems to solve a lot of problems and offer a lot of advantages.
 

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Important to determine how much amperage is required for your application. Many people want maximum amperage when they have no need for it. My Magnum inverter/charger/transfer switch has a 50 amp charger. I set the charger to charge at 40 amps. Charging from the vehicle powered pure sine inverter is seldom required. My single 300 watt solar panel normally provides all the power required. No need for high amperage alternator charging. I understand that other people may have a need for more alternator charging due to different loads and/or weather conditions.

So first estimate the amount of charging you will need from the vehicle 12 volt system. Then design the system to provide that.
Would just one inverter and a shore power charger work? Inverter would invert either from vehicle system or house battery. Shore power charger would use the inverter only when the inverter is switched to use alternator current, or when shore power is available.
 

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Again, just learning and thinking out loud. My understanding is that the primary utility of the charge profile is to get the batteries as close to full charge as possible. The early stages of the Li profile is "bulk" which requires relative low voltage and draws high current. After 80% or so charge more voltage and less current is needed to get a Li bank up near 100%. So I don't think the down side is anything other than not being able to fully charge the bank with the alternator. The upside is to be able to relatively quickly be able to run up to that 80% level. Depending on your use cases, quick recovery (even at idle) in an hour or so might be more useful that getting that last 20% over several hours..
 

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Would just one inverter and a shore power charger work? Inverter would invert either from vehicle system or house battery. Shore power charger would use the inverter only when the inverter is switched to use alternator current, or when shore power is available.
That would work with proper switching. Only issue would be the size of the inverter needed to run the conversion. Too large an inverter may draw too much power from the vehicle system. With two inverters one could be sized to limit alternator load and the other could be larger for the house loads. I have two 1000 watt inverters. House inverter is a inverter/charger/transfer switch in one housing.

A block diagram of my system:

 

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I looked at the one inverter Orton approach. Was going to use something like:
SBD-4201G 150/200A 6-pin relay
(You can google it).
Even have a circuit diagram for it, somewhere.
You would need to run some heavy duty cables between the batteries and wherever the inverter and relay are located. You could incorporate a battery switch and have emergency jump starting and/or emergency direct charging of house battery (should the inverter or 110v charger fail).
 

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@amac ...The two Battleborns should provide me with 160AH ...
I may be mistaken, but I'm pretty sure you have 100AH usable for each of your BB batteries as I believe they are really 120AH capacity.
So you just gained 25% over 160, no charge ;)
 

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Discussion Starter #33
I may be mistaken, but I'm pretty sure you have 100AH usable for each of your BB batteries as I believe they are really 120AH capacity.
So you just gained 25% over 160, no charge ;)
That would be great. I would take some extra AH.
 

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I don't know if this will be helpful in this discussion but as an anecdotal data point:
I have 2x 100Ah AGM batteries directly connected to CCP2 in my 2020 and observed the following:
  • with Auto start stop it does not seem to charge the house battery (at least significantly by monitoring the Voltage at the house battery)
  • with ASS disabled I get full charging (I don't have a way of measuring current as we are on a cross country road trip, but the measure voltage at the house battery goes to ~14V)
  • In 2 weeks of heavy usage of house battery and charging and discharging I have not turned off my manual switch and the CCP2 shut off / load shedding appears to have protected the vehicle starter battery enough and always allowed for starting in the morning.
Hopefully when I return I can collect some more actual data to share.
 

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Again, just learning and thinking out loud. My understanding is that the primary utility of the charge profile is to get the batteries as close to full charge as possible. The early stages of the Li profile is "bulk" which requires relative low voltage and draws high current. After 80% or so charge more voltage and less current is needed to get a Li bank up near 100%. So I don't think the down side is anything other than not being able to fully charge the bank with the alternator. The upside is to be able to relatively quickly be able to run up to that 80% level. Depending on your use cases, quick recovery (even at idle) in an hour or so might be more useful that getting that last 20% over several hours..
I believe the charge times are more like this with the lifepo4...
Bulk to 90% maybe even 95% and then the amps finally start to taper and at that point it's not several hours it's more like 20 to 30 minutes

I believe that is the best feature of these batteries .
That's also why my van has a single 100 ah Battleborn , no need for any more capacity , I have a xtra brand new in the box Battleborn 100 ah battery and I have no use for it , I'm going to try and return it.
 

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Again, just learning and thinking out loud. My understanding is that the primary utility of the charge profile is to get the batteries as close to full charge as possible. The early stages of the Li profile is "bulk" which requires relative low voltage and draws high current. After 80% or so charge more voltage and less current is needed to get a Li bank up near 100%. So I don't think the down side is anything other than not being able to fully charge the bank with the alternator. The upside is to be able to relatively quickly be able to run up to that 80% level. Depending on your use cases, quick recovery (even at idle) in an hour or so might be more useful that getting that last 20% over several hours..
Battle Born has a pretty good explanation of charging profiles:

Charging LiFePO4 Batteries | Battle Born Batteries

I have long used lead acid batteries and can confirm that it can take a long time to get the last 20% charge into them. From your report, it sounds like lithium batteries suffer from the same problem, although perhaps not as much as lead acid. If that is the case, then I think you are on to something in making the battery 20% larger than loads would indicate, because the true limiting factor, the thing cramping your style, is not the loads, it's the charging time.

But in your case, with a 2020, I would think that if you connect directly to your charging alternator, because the 2020 has the smart alternator features, the voltage of your house battery (and therefore its state of charge) would be all over the map. This is because the smart alternator does not try to keep the battery fully charged. The opposite. It tries to always insure that the battery is partially depleted so that it is ready to accept a large influx from the alternator.
 

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Discussion Starter #38
I don't know if this will be helpful in this discussion but as an anecdotal data point:
I have 2x 100Ah AGM batteries directly connected to CCP2 in my 2020 and observed the following:
  • with Auto start stop it does not seem to charge the house battery (at least significantly by monitoring the Voltage at the house battery)
  • with ASS disabled I get full charging (I don't have a way of measuring current as we are on a cross country road trip, but the measure voltage at the house battery goes to ~14V)
  • In 2 weeks of heavy usage of house battery and charging and discharging I have not turned off my manual switch and the CCP2 shut off / load shedding appears to have protected the vehicle starter battery enough and always allowed for starting in the morning.
Hopefully when I return I can collect some more actual data to share.
Any more observations about charging while the ASS is active? Seems this could be a problem no matter what method you are using to charge house batteries.
 

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Any more observations about charging while the ASS is active? Seems this could be a problem no matter what method you are using to charge house batteries.
We're actually on our return trip right now somewhere in Nebraska...
Now, I will have to take back that I don't get charging with ASS on.
It seemed like that in the beginning but now I see a charging voltage with ASS enabled.
I will look into this more scientifically back home.

Now with that said my house batteries seem to have gotten weaker already. I did have a pretty deep discharge at one point, and I also have the cheapest batteries I could find on Amazon.
But the voltage at the house batteries has been lower in the same conditions then on the first leg of the trip
This I also need to look into more upon return home.
 
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