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Discussion Starter #1 (Edited)
WARNING: This is a long read. I've preempted a lot of questions though, so if this sort of stuff is of any interest you really should take your time to read it through to the end.



A while back I posted a quick thread showing some data logging I was working on. I looked for that thread to perform a revival but it's so old I couldn't quickly locate it. Alas, I'm starting a new one. It's probably a good idea too since my electrical setup has changed a lot since then.

Some "back of the envelope" calculations by interpolating tell me that from 0% SOC to 100% SOC should take less than 2.8 hours of highway driving. Typically I'm only replacing 25% to 50% in a day, so in the neighbourhood of 45 minutes to 1.5 hours. This can be broken up into multiple shorter drives throughout the day. I may consider a folding solar panel at some point to augment the driving if I'm in a place where it can be used.

I'm presently running 2 Sterling BB1260's in parallel (started as a test, but I really like it!) and have 2 Battleborn 100Ah LiFePO4 in parallel. Monitoring is done by a BMV-700 which I only recently integrated into my data logging setup.

The Victron (BMV) 500A shunt is between the house battery and my negative bus. This one ONLY measures current in/out of the house battery.
There's a 200A shunt from the negative bus to my inverter
Also a 200A shunt from the negative bus bar to the vehicle ground
And a 50A shunt from negative bus to my load centre grounds (not included in plots below)

Calibration of my shunt readings may be slightly off still, but not by a significant amount for my purposes here.

While driving at speed, I pull about 100A from the vehicle and almost 80A goes into the battery. While idling, there's only around 60A available to be drawn, which yields about 45A into the batteries.

Enough preamble. Here's a snippet from my logging that shows a drive cycle (multiple, actually) and the charging that happens along the way. There's a problem somewhere that I'll get to in my discussion of the graph.

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BLUE = Vehicle
RED = House (same as you'd seen on the BMV display, but obtained through the data port at 2s intervals)
Grey = Inverter

The BB1260 is about 86% efficient, so current in does not equal current out.

Following the green numbers from left to right I'll comment on what's happening. From the time the van is first started (1) to when it's turned off (9), about 2.75 hours have elapsed. There are two starts. The first is at (1) and the engine is shut off again at (2). The second is at (3) and it runs until (9).

From engine start at (3) I drove a short distance then idled until (4). From (4), I drove a little while through the city then got on the highway until (5) when I pulled into where I was staying for the night. Knowing that I wanted to do more charging, I let the van run while I made a little snack. At (6) I ran the microwave for about 8 minutes until (7). From (7) to (8) you can see a consistent but much lower charge rate while I'm idling (and surfing the 'net).

Here's what I think is the interesting part: At (8) you see the battery voltage start to quickly rise and the current ramps down even quicker. This is the tell-tale sign that your lithium battery is full. I shut the van off at (9) because there was very little current going into the battery and I was fairly sure it was charged. Also notable is that at (8) the SOC begins to slowly drop even though the engine is still running - probably the BB1260's have gone into "float" here, which is set at the BMS-compatible voltage recommended by Battleborn.

Also between (8) and (9), you can see that the vehicle battery voltage quickly recovers to over 14V as the load from the BB1260 is tapered off. This tells me that the vehicle battery is not supplementing the power from the alternator with my charging setup. If it was, then the vehicle battery voltage would rise much more slowly as it charged.

I was surprised that the BMV was only showing about 80% and that it didn't sync automatically. Perhaps I didn't wait quite long enough, as I have seen it sync on other occasions but still quite a bit shy of 100% when it does.

SO, the question remains as to why it wasn't very accurate in following the actual state of charge. I've set it up with the recommended settings for lithium, including changing the charged voltage and Peukert constant of 1.05. I've even set a slightly lower charged voltage so that it will automatically sync slightly sooner. Tail current is set to 4%, and charge detect time I think is 3 min.

It isn't just in this logged case where this is happening. I'm consistently seeing evidence of nearly charged batteries but the BMV says significantly less.

Note: The somewhat square wave you see in the currents is probably either the Sterling modulating it's power to control heat, or the vehicle doing the same with the alternator. I plan to look into this further just because I find it interesting.
 
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Discussion Starter #2
Oh, and for anyone that hasn't fallen asleep yet, this is what the discharge looked like prior to the above plot. The two big spikes are my microwave use for breakfast and lunch. The vehicle battery does some funny stuff related to opening the van's doors while getting in and out. This is from when I went to bed around midnight until around supper time when I went to charge my batteries. The engine wasn't started any time in between and I had been working with my laptop plugged into the inverter before going to bed.

The square wave you see superimposed onto the current and voltage plots is the result of the fridge cycling.

139791
 
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Gulp!
That was a big bite. You're obviously into it and probably know more than I do Sparky.

I'm wondering if you are in any way satisfied with how the system is working? Are you looking to get to 100% SOC? I ask because I have seen in the past articles that say the LiFePo4 batteries do best for the long run when not discharged 100% and not charged to 100%.

Ultimately, the important factor is whether you are getting to use the electrical consumers day in and day out the way you want to, and there is always sufficient SOC to allow that with the charge that is applied during every charging cycle.
 

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Gulp!
That was a big bite. You're obviously into it and probably know more than I do Sparky.

I'm wondering if you are in any way satisfied with how the system is working? Are you looking to get to 100% SOC? I ask because I have seen in the past articles that say the LiFePo4 batteries do best for the long run when not discharged 100% and not charged to 100%.

Ultimately, the important factor is whether you are getting to use the electrical consumers day in and day out the way you want to, and there is always sufficient SOC to allow that with the charge that is applied during every charging cycle.
Well, it's a huge leap forward from the two GC2 batteries I was using. I was idling a LOT more to try to get those fully charged. Because of my old habits I've found myself driving more than I need to and discovering that my batteries are already charged. I've been able to use my microwave much more often and not worry about the old FLAs not supplying quite enough current.

I'm aware of the potential longevity gains by cycling in a specific range. Right now I'm trusting that Battleborn has done a good job designing their BMS to match their 8-10 year warranty. In the future, if I can keep an accurate running SOC without hitting 100% very often then I might be able to control this with better precision. That's part of what this exercise is all about. I need to collect and analyze the data before I can do anything intelligent with it.
 

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Thanks for posting your data!

Very interesting to look at this and compare to the behavior of my system. I am using a Renogy DCC50S charging from both solar and CCP2 and set up for the LiFePo profile (1 - 100ah Battleborn). In the graph below you can see the charge cycles over several days of not really being used and just "system level" loads (internet, charging system, gateway, etc.). The solar charger is pressing more voltage onto the battery when the sun is available. It appears to be 1.4v during charge and 13.3v during slight discharge. As you can see I am quickly getting back up to 100% SOC when the sun comes back up. The data presented here is all from the Victron SmartShunt at the negative battery lead to the negative bus bar. It also has connections for direct battery voltage and vehicle battery voltage so you can see the times I drive the van when the CCP2 wakes up and the IGN signal tells the Renogy unit it is OK to draw current.
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Below is a day where we had a normal usage cycle. We arrive at our campsite in the evening and then you can see the consumption from the fan, the fridge cycling, and my CPAP and some lights. You can see about 4am I got up to pee and let the dogs out so the CCP2 woke up and held for a while but since IGN was off there was no charging of the system. Then you can see us depart and drive 100 miles or so home and the system charging again.
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I have no idea if the LiFePo profile of the Renogy is optimal for the Battleborn or not so I am still collecting information and data. Always learning something.
 

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I've set it up with the recommended settings for lithium, including changing the charged voltage and Peukert constant of 1.05. I've even set a slightly lower charged voltage so that it will automatically sync slightly sooner. Tail current is set to 4%, and charge detect time I think is 3 min.
I'm curious what settings you have made in the Sterling for your Battleborn batteries.
 

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Discussion Starter #7
I'm curious what settings you have made in the Sterling for your Battleborn batteries.
Thanks for sharing your data as well. I like to get information from as many sources as possible to help move things forward.

Do you know what the logging interval (time between data points) is on your data?

I've made a note for the next time I'm working on this to get a dump of the configuration settings and post them here for you. My changes are based on the Lithium settings in the BMV manual, a post I found from Battleborn on the subject, and some reading about others experiencing the lack of sync issue. There's still work to be done on that one.
 

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Discussion Starter #8
Adding to the comment about charging to 100% potentially shortening the battery lifespan, Battleborn's BMS performs "top balancing" and needs to be fully charged at least every so often (can't recall exactly what they recommend) so that the BMS can take care of this task.

Cycling for an extended period between say 20% and 80% could lead to an internal cell imbalance. The BMS would likely detect this but it has no way to indicate it. It can only prevent charging and/or discharging in order to protect itself.
 

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Discussion Starter #9
Here's a much more typical looking plot. This one follows where the first one I posted left off - so probably about two days worth. I've been running around a lot in the past two days, so unfortunately some of my charging potential goes to "waste" near the end of the plot. It made me think I need to add a dump load, like an electric water heater...

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There are a few places where the red lines go flat for a while. I'm chasing down a bug in my software that's causing this but it isn't hard to see where it should be when things are reset.

I'm really liking seeing the slow discharge slope vs. the very steep charge curve. This is the main reason why I spent the money on LiFePO4's.

Also note that since it's been cooler these past few days I've been using my propane stove more than the microwave. That helps to easily keep me over 50% without as much driving/idling as I used to do.

Notice again that both times I'm approaching 100% SOC, it jumps from 80 or 90-something to 100% instead of accurately ramping up closer. I might be contacting Victron with this question/observation.
 

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Discussion Starter #10
I'm curious what settings you have made in the Sterling for your Battleborn batteries.
'tail_current': 4.0,
'current_threshold': 0.05,
'charge_efficiency': 99,
'peukert_coefficient': 1.05,
'battery_capacity': 198,
'charged_voltage': 14.2,
'charged_detection_time': 2

i believe these are the ones that matter for accurate display and sync
 

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What was the source for these Sterling settings? I have 2 x 100ah Battleborn and a Sterling 1260 which I haven't installed and configured yet. Frankly a bit intimidated by the whole process and having to remove the seat and do some sort of battery direct connectivity or something since with a 1260 I can't really use the 60amp CCP safely. I only have the single 150 amp alternator.
 

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Actually now that I re-read the question, I see that it was asking about the Sterling settings rather than the Victron settings that I gave.

For the Sterling I did try some custom settings for a while but I've been using the built-in LiFePO4 setting because it does seem to match what Battleborn calls for.
 
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Actually now that I re-read the question, I see that it was asking about the Sterling settings rather than the Victron settings that I gave.
Yeah, I was after the charging parameters for comparison to what the Li stock parameters are for my Renogy DCC50S. It uses these for both alternator and solar charging (for reference).
139942
 

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Although now that I'm looking at it, I'm wondering about going back to custom... There's a slight change I think may help with my sync issue.
 

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2017, cargo, 130inch, mr, dbl sliders, 3.2 dsl, 3.31 rear end, used 13.5k mi.
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All discussions above very interesting. As a near-novice in relation to electrical componentry for van conversions, I had to trust the builder's judgement. Installed was Sterling BBW12120 120 ampere battery to battery charger for charging 4 X 100 ampere BattleBorn LiFePO4 batteries. Charging parameters are determined by Sterling pre-programmed settings. The charging algorithm set within the Sterling unit for lithium chemistry has been tested by BattleBorn in Nevada, USA, as reported via voice calls to tech support for BattleBorn. Jessee, at BattleBorn tech support, stated the optimal charging for their battery design-providing efficiency, longevity of batteries...-is found in Sterling's lithium pre-programmed parameters. It is wonderful to see real-life measurements taking place and conducted by folks on this forum. I applaud you all, will continue to follow and learn and share as I am able. As a note, always double check anything I may claim to know. Jessee at BattleBorn/Dragonfly Energy is available for consultation he personally told me. Tell him Dr. Parker sent you, but watch out, he might try to transfer your call over to sales! Not really...

Addendum: the Sterling has been functioning without fault but no significant loads to date as it has been online only 10 days. Attempted applying significant loads four days ago in western Washington whilst at 6400 foot elevation of Mt. Ranier in the Cascade mountains. PV panels wattage total of 360 watts on this system never went below 92 % state of charge (SOC) ,for three days via mppt solar controller daytime charging. This included operating two small volume fridges (ICECO 12 liter and 20liter) continuously, 700 watt microwave, 700 watt tea kettle, led lighting and interior fans, and constant charging phones, notebooks, camera gear. Before sunrise each morning, 92 to 94% SOC was always measured. Obviously, cooking and tea breaks were utilized too little. Before I could even drive off to test the Sterling, the unit started up, evaluated electrical SOC, determined battery to battery charging was not required and went to sleep. I was hoping for colder weather-preferrably snow or at least frost-to test the Sterling. No luck. Solar panels charged the last less than 10% or less of BattleBorn batteries rather quickly. It indicates to me that going total electric i.e. no propane is feasible. I certainly am going to add a single induction electric cooking surface in conjunction with a 5 to 8.5 ampere electric space heater into the mix for the occasional winter/cold weather use. Commencing with the drive after drawing battery storage to 20% SOC is the goal after heavy electrical loads. As a backup, a Honda generator is set to charge the batteries ( 40 amp charging capacity) and provide space heat in very cold situations. Winter where art thou; we hardly knew each other....

I am now going to go bulk my abs, remain in good condition and float along to the next meal to max out on carbies. Plum pudding, here I come!
 
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