Lithium Battery BMS Behavior

[Sweeney]

Yup - I did it. After I killed my high end deep cycle battery, I jumped into the pool of lithium batteries. Mostly becuase of cost savings -- it was less expensive and a BMS would keep me from being dumb for the 4'th time. This combined was enough to push me over the top and entice me to jump into lithium batteries for the first time. The cost is lower (finally) and the apparent problems of cold charging are resolved, and finally there is just the overall "on paper" improvements that I still need to be convinced of.

The battery I purchased was a Li Time Battery - I would have rathered follow the nest in their brand selection, but I needed one faster than I could get one so I went with Li Time. I upgraded my onboard charger a couple years ago, going from the standard at the time 5amp charger to a 10. I also have the Victron Smart Shunt

Observation and Questions:

ONE:​

The victron controller (The Smart Shunt) using the same settings as for lead acid is wildly off from the battery BMS. Like huge differences. I have adjusted parameters suggested by technical documentation - we'll see if this improves it. How does yours compare with the battery BMS if you have one?

TWO:​

The 10 amp onboard charger falls of in amperage as the battery gets fuller. The BMS on the battery drops into 'standby' when it amperage gets down to the 2 amps range. The BMS has 3 modes: Charging, Discharging and Standby. Once it goes into standby, the only way I can 'push' the charge higher to attach a 50 amp converter (from the RV service truck) to put it back into charging mode to get it up to 100% --- The onboard 'stalls out' at around 80% SOC. I need to verify this number. This is fine for testing, but surely something that is not a great solution. For batteyr longjevity thi smight be a plus, and it still gives me a geater Ah capacity than lead acid.

I just charged to 100%, and am now 'running down' the battery by running lights without the onboard charger, simulating a trip I am hoping to make next week.

THREE:​

Once I reach 'discharging' status -- I am not sure when the battery will again request charge - I assume it will oscilate between low and high range. I am curious how this will work in the world.

What I mean by that is si, if I am charging with solar (or shore power) and the battery decides at 8am its done charging, and my refrigerator pulls it down to 40%. There a chance or likelyhood that I'll now run out over power overnight. I wonder if the behavior on 'solar' is different -- if the solar charge controller kicks up 8-10 amps at "sunrise" will the battery respond differently than being on shore power. Will I just need to power cycle the charger at waking?

---

This is why I love this forum - I'm sure somone is going to answer this without the typical internet snark!!! Oh crap, I just set up for snarky answers.

 

[Van_and_Terri]

Yup - I did it. After I killed my high end deep cycle battery, I jumped into the pool of lithium batteries. Mostly becuase of cost savings -- it was less expensive and a BMS would keep me from being dumb for the 4'th time. This combined was enough to push me over the top and entice me to jump into lithium batteries for the first time. The cost is lower (finally) and the apparent problems of cold charging are resolved, and finally there is just the overall "on paper" improvements that I still need to be convinced of.

The battery I purchased was a Li Time Battery - I would have rathered follow the nest in their brand selection, but I needed one faster than I could get one so I went with Li Time. I upgraded my onboard charger a couple years ago, going from the standard at the time 5amp charger to a 10. I also have the Victron Smart Shunt

Observation and Questions:

ONE:​

The victron controller (The Smart Shunt) using the same settings as for lead acid is wildly off from the battery BMS. Like huge differences. I have adjusted parameters suggested by technical documentation - we'll see if this improves it. How does yours compare with the battery BMS if you have one?

TWO:​

The 10 amp onboard charger falls of in amperage as the battery gets fuller. The BMS on the battery drops into 'standby' when it amperage gets down to the 2 amps range. The BMS has 3 modes: Charging, Discharging and Standby. Once it goes into standby, the only way I can 'push' the charge higher to attach a 50 amp converter (from the RV service truck) to put it back into charging mode to get it up to 100% --- The onboard 'stalls out' at around 80% SOC. I need to verify this number. This is fine for testing, but surely something that is not a great solution. For batteyr longjevity thi smight be a plus, and it still gives me a geater Ah capacity than lead acid.

I just charged to 100%, and am now 'running down' the battery by running lights without the onboard charger, simulating a trip I am hoping to make next week.

THREE:​

Once I reach 'discharging' status -- I am not sure when the battery will again request charge - I assume it will oscilate between low and high range. I am curious how this will work in the world.

What I mean by that is si, if I am charging with solar (or shore power) and the battery decides at 8am its done charging, and my refrigerator pulls it down to 40%. There a chance or likelyhood that I'll now run out over power overnight. I wonder if the behavior on 'solar' is different -- if the solar charge controller kicks up 8-10 amps at "sunrise" will the battery respond differently than being on shore power. Will I just need to power cycle the charger at waking?

---

This is why I love this forum - I'm sure somone is going to answer this without the typical internet snark!!! Oh crap, I just set up for snarky answers.

I’ll try to contribute with my limited knowledge in what I have observed with my 560. Every time, solar will take my lithium battery to 100%. On AC power, the charger will initially kick in but will quickly terminate charging if the lithium battery is over 85% to 88% charge. The charger will start charging again when the battery gets down in the upper 70% to lower 80% of charge. But it rarely will take it back to 100%. While hooked up to my tow vehicle, I seem to experience good charging.

 

[SethB]

TWO:
The 10 amp onboard charger falls of in amperage as the battery gets fuller. The BMS on the battery drops into 'standby' when it amperage gets down to the 2 amps range. The BMS has 3 modes: Charging, Discharging and Standby. Once it goes into standby, the only way I can 'push' the charge higher to attach a 50 amp converter (from the RV service truck) to put it back into charging mode to get it up to 100% --- The onboard 'stalls out' at around 80% SOC. I need to verify this number. This is fine for testing, but surely something that is not a great solution. For batteyr longjevity thi smight be a plus, and it still gives me a geater Ah capacity than lead acid.

I just charged to 100%, and am now 'running down' the battery by running lights without the onboard charger, simulating a trip I am hoping to make next week.
...

Following with interest!

Regarding #2 above, a few years ago I bought a 50ah Li Time (pre BMS) to serve as my “pony” CPAP battery. It’s gotten me through many nights of off grid camping and a few power outages at home - absolutely great results.

My 10a Victron charger’s lithium profile did NOT match what L-T docs said!

I emailed L-T, possibly through their web site or perhaps Amazon mfr support link and got clarification on best charging for the battery. I was very pleased with their customer service, and set up a custom profile on the charger that I use to this day.

So that’s my recommendation; the documentation that came with your battery may be outdated due to firmware update, (or maybe there’s new firmware? Is it updatable?), or manufacturing defect…

It’s worth an email to Li Time!

 

[taranis17]

I have some limited knowledge just based on my own lithium research:

1. Does your charger specifically support LIfePO4 batteries? The charging profile for LifePO4 is different from lead-acid. At one point I looked at upgrading my previous camper to lithium from lead-acid, and was told I also needed a newer charger that supported lithium battery charging.
2. Have you synchronized the Vitron Smartshunt to the battery after the battery has been fully changed to 100%? (Tap Synchronize SOC to 100% in the app)
3. Have you reached out to the LI-Time manufacturer and asked them the proper config for your Vitron smartshunt?
Research shows these settings for a LI-Time LifePO4 battery on a Vitron Smartshunt, but I would verify with them:

Setting	Recommended

Battery Capacity

Your battery Ah rating (ex: 100Ah, 230Ah, etc.)

Charged Voltage

14.2V

Tail Current

4%

Peukert Exponent

1.05

Charge Efficiency

99%

Current Threshold

0.10A

Time-to-go averaging

3 min

Reading what you said about your charger, it seems like it does not support a lithium charging profile, which is why you're seeing the battery get to ~80%, then dropping too early to the "float" charge profile. Lithium voltage behaves differently, which is why that happens. If you're using a non-lithium charger, you also risk inadvertently activating a "Desulfation/equalization mode" that many lead-acid-only chargers have that briefly pushes the voltage too high (15v+) trying to equalize the charge across what it "thinks" are lead-acid cells, which you don't have and lithium batteries don't like.

I'd strongly recommend reaching out to both the charger manufacturer and LI-Time and go over your configuration. I'm happy to be wrong on any of this - no ego here.

 

[Old_Prospector]

Most LiFePO4 batteries can be monitored from a phone APP. In addition to percent charged, storage voltage, change in each cell bank, and balance on the APP, there is the ability to turn off the discharge mode and charging mode from your phone. During winter storage or any time the trailer is not in use, I turn these modes (especially the discharge) to off. Yes, you have a master switch to isolate the battery, but if you turn off the discharge mode an electrical meter will not pick up any voltage when touching the battery terminals. The is a better solution to ensure no parasitic electrical drain.

I live in Phoenix where the temperatures rarely go before 32F, but I finally checked on my trailer a week ago after having being outdoors in storage since December. I parked it with 100% storage and the battery is still at 100% at 13.3 volts. This is the most "peace of mind" I have ever experienced with a 12V battery.

I had Craig, Carey, and company install the LiFePO4 battery last summer when at the Mother Ship. My 560 is a 2015 model, which is the year before CampInn modified the battery compartment to accommodate the Lithium option with minimal effort. Best decision so far. I am not a lithium guru.

Edit: Remember to turn on the discharge mode from your phone during a trip with the trailer, or you'll be scratching your head why the fantastic fan doesn't have power.

 

[dustinp]

... but I finally checked on my trailer a week ago after having being outdoors in storage since December. I parked it with 100% storage and the battery is still at 100% at 13.3 volts. This is the most "peace of mind" I have ever experienced with a 12V battery.

FWIW The manufacturer of the LiFePo4 batteries we have recommend that when you are storing the batteries for long periods, that they be charged only to about 60% before storing, which is what we do with our EcoFlow sogen units, and bike batteries when we head to the southwest during the winter months.

 

[Henry]

My 10a Victron charger’s lithium profile did NOT match what L-T docs said!

I emailed L-T, possibly through their web site or perhaps Amazon mfr support link and got clarification on best charging for the battery. I was very pleased with their customer service, and set up a custom profile on the charger that I use to this day.

Can you share the victron charger settings that you are using? I purchased a LiTime group 24 (heated) and am not happy with the way the new victron charger works. The lithium battery setting in the charger does not fully charge the battery. Last fall I had played around with the custom settings, but not sure I got to where I wanted to be.

 

[Sweeney]

I’ll try to contribute with my limited knowledge in what I have observed with my 560. Every time, solar will take my lithium battery to 100%. On AC power, the charger will initially kick in but will quickly terminate charging if the lithium battery is over 85% to 88% charge. The charger will start charging again when the battery gets down in the upper 70% to lower 80% of charge. But it rarely will take it back to 100%. While hooked up to my tow vehicle, I seem to experience good charging.

OK -- I havn't attempted to attach my solar panel, but my charger seems to have the same results as your. I suspect its the charing profile on the onboard -- I think it is still ramping down its output for some reason? But at least I'm in the same situation...

Following with interest!

Regarding #2 above, a few years ago I bought a 50ah Li Time (pre BMS) to serve as my “pony” CPAP battery. It’s gotten me through many nights of off grid camping and a few power outages at home - absolutely great results.

My 10a Victron charger’s lithium profile did NOT match what L-T docs said!

I emailed L-T, possibly through their web site or perhaps Amazon mfr support link and got clarification on best charging for the battery. I was very pleased with their customer service, and set up a custom profile on the charger that I use to this day.

So that’s my recommendation; the documentation that came with your battery may be outdated due to firmware update, (or maybe there’s new firmware? Is it updatable?), or manufacturing defect…

It’s worth an email to Li Time!

I'll do that -- I have most of the specs in the manual that came with the battery, excpet the phukette (?) which just about made me spit out my coffee the first time I read that...The internal bluetooth BMS screen gives better information than the shunt does - plus - its range is a lot better. I can use it in the camper. The Victron Shunt is a little weak.

Most LiFePO4 batteries can be monitored from a phone APP. In addition to percent charged, storage voltage, change in each cell bank, and balance on the APP, there is the ability to turn off the discharge mode and charging mode from your phone. During winter storage or any time the trailer is not in use, I turn these modes (especially the discharge) to off. Yes, you have a master switch to isolate the battery, but if you turn off the discharge mode an electrical meter will not pick up any voltage when touching the battery terminals. The is a better solution to ensure no parasitic electrical drain.

I live in Phoenix where the temperatures rarely go before 32F, but I finally checked on my trailer a week ago after having being outdoors in storage since December. I parked it with 100% storage and the battery is still at 100% at 13.3 volts. This is the most "peace of mind" I have ever experienced with a 12V battery.

I had Craig, Carey, and company install the LiFePO4 battery last summer when at the Mother Ship. My 560 is a 2015 model, which is the year before CampInn modified the battery compartment to accommodate the Lithium option with minimal effort. Best decision so far. I am not a lithium guru.

Edit: Remember to turn on the discharge mode from your phone during a trip with the trailer, or you'll be scratching your head why the fantastic fan doesn't have power.

I"m not a guru either but I have a feeling this will take me down the rabbit hole eventually I'm still concerned about some things which would be much more of an issue if I were full-time living on one - but, as a recreational weekend warrior I'll be fine - and I can see already the HUGE amount of power in the batter over lead acid. Pretty impressive actually.

FWIW The manufacturer of the LiFePo4 batteries we have recommend that when you are storing the batteries for long periods, that they be charged only to about 60% before storing, which is what we do with our EcoFlow sogen units, and bike batteries when we head to the southwest during the winter months.

Yup - I may have to break the rules and put a power switch on the brakeing system - the phantom draw on the the Autow brake is small, but still there. I'd like to just flip the master switch and not worry about it. Though the BMS will shut down the battey to keep me from being a total idiot again :\

I have some limited knowledge just based on my own lithium research:

1. Does your charger specifically support LIfePO4 batteries? The charging profile for LifePO4 is different from lead-acid. At one point I looked at upgrading my previous camper to lithium from lead-acid, and was told I also needed a newer charger that supported lithium battery charging.
2. Have you synchronized the Vitron Smartshunt to the battery after the battery has been fully changed to 100%? (Tap Synchronize SOC to 100% in the app)
3. Have you reached out to the LI-Time manufacturer and asked them the proper config for your Vitron smartshunt?
Research shows these settings for a LI-Time LifePO4 battery on a Vitron Smartshunt, but I would verify with them:

Setting	Recommended

Battery Capacity

Your battery Ah rating (ex: 100Ah, 230Ah, etc.)

Charged Voltage

14.2V

Tail Current

4%

Peukert Exponent

1.05

Charge Efficiency

99%

Current Threshold

0.10A

Time-to-go averaging

3 min

Reading what you said about your charger, it seems like it does not support a lithium charging profile, which is why you're seeing the battery get to ~80%, then dropping too early to the "float" charge profile. Lithium voltage behaves differently, which is why that happens. If you're using a non-lithium charger, you also risk inadvertently activating a "Desulfation/equalization mode" that many lead-acid-only chargers have that briefly pushes the voltage too high (15v+) trying to equalize the charge across what it "thinks" are lead-acid cells, which you don't have and lithium batteries don't like.

I'd strongly recommend reaching out to both the charger manufacturer and LI-Time and go over your configuration. I'm happy to be wrong on any of this - no ego here.

The charger we use does have a lithium mode. As well as AGM and Lead Acid, and thats what I have it in -- Honestly, if it foats between 20 and 80% SOC - that actaully fine with me! its keeps the battery it its happy place. I just want to make sure I'm not having a problem that is an outlier. Where did you find the Peukert Exponent? That name still makes my inner 12 year old giggle.

 

[Van_and_Terri]

Yup - I may have to break the rules and put a power switch on the brakeing system - the phantom draw on the the Autow brake is small, but still there. I'd like to just flip the master switch and not worry about it. Though the BMS will shut down the battey to keep me from being a total idiot

I just remove the fuse on the bottom of the Autobrake in the galley to de-power it and limit my power loss when not towing.

 

[taranis17]

The charger we use does have a lithium mode. As well as AGM and Lead Acid, and thats what I have it in -- Honestly, if it foats between 20 and 80% SOC - that actaully fine with me! its keeps the battery it its happy place. I just want to make sure I'm not having a problem that is an outlier. Where did you find the Peukert Exponent? That name still makes my inner 12 year old giggle.

It's mentioned in the documentation online. I just did a search for the term in the PDF, which I'm sure you already have. I completely nerd out on stuff like this, but had to use AI to understand what it means/what it's for.

 

[Sweeney]

It's mentioned in the documentation online. I just did a search for the term in the PDF, which I'm sure you already have. I completely nerd out on stuff like this, but had to use AI to understand what it means/what it's for.

Me too -- actualy right now I'm geeking out on an AI project as i write this. Openclaw is the greatest tool ever....

 

[SethB]

Can you share the victron charger settings that you are using? I purchased a LiTime group 24 (heated) and am not happy with the way the new victron charger works. The lithium battery setting in the charger does not fully charge the battery. Last fall I had played around with the custom settings, but not sure I got to where I wanted to be.

I’d be happy to, the next time my phone, battery and charger are in the same place I’ll fire it up and check. We had a short power outage a few days ago, and I pulled the battery into the house, but not the charger.

However, my battery is probably two generations back and half the size of a group 24, with no BMS. I think you’d do better to look into what your specific batt wants to see from the charger.

 

[taranis17]

@Sweeney Sooo…. What’s the status on the lithium apparatus, Gladys?

 

[TheSongDogHouse]

Can you share the victron charger settings that you are using? I purchased a LiTime group 24 (heated) and am not happy with the way the new victron charger works. The lithium battery setting in the charger does not fully charge the battery. Last fall I had played around with the custom settings, but not sure I got to where I wanted to be.

@Henry one tip to share if you haven't already: contact Victron tech support on the item you bought which will find you someone in the channel purchased- for example I got a Victron shunt and Victron shore charger separately; so I have to talk to different people who support the sales channel assigned by victron tech support, but once you get to the victron person they are pretty knowledgeable, and can give basic understanding of how it works with a none victron supplied lion battery, one level deeper than the manual.

 

[TheSongDogHouse]

PS: another lesson learned: if you go to the Victron local recommended RV installer website you will see 2-3 depending on area you search, and you'll want someone who knows about RVs in general, with ability to flex to the tight quarters of the CI, and analyze deeper than brand new certified in victron certificate.
I'd highly recommend finding someone like Sweeney, see his RV Geek network. These are people with a lot of experience often in previous professional life, and a couple steps uo from the young kid starting out, or say an independent contractor at Camping World.

They have to be able to read wiring diagrams and tgink a couple levels deeper than plug and chug, try this, swap this part in...

Basically, once we start to freestyle away from OEM parts and need to experiment vs just driving to CI for upgrades, it gets deep fast, for me anyway.

There are some seriously smart people here in forums and Cary and Craig help a LOT, but filling in the blanks on different gear can be tricky...at least for me.