Lithium settings for my new system. What voltages?

[serpa4]

Good day. I just received my 4 Lion Energy 1300 UT batteries today. They will be in parallel for 12v at 420Ahr bank. They will go in my boat as house batteries. I have 870 watts of solar, Victron BMV 712 battery monitor, Victron SmartSolar Charge Controller for lithium (150v/70amp) with temp probe on battery, and Xantrex Freedom Pro XC, 3000 watt/150amp charger with a lithium setting (and battery temp probe).

On the Lion website, I found 3 documents, but I don't think they agree with each other.

1) LION Energy info on website (Lion_Energy_Safari_UT_1300_FAQ_2020514 PDF) says: FAQ question #09. What are the recommend charge settings for the Safari UT 1300?

It will take up to 14.6V in charging voltage and settle between 13.9V and 13.6V. Set your charger to its highest setting closest to 14.6V and at least 13.9V.

2) Other information on the Lion Website (Lion_Energy_Safari_1300_Manual_2019)

Says max charge voltage 14.6 volts.

3) The big conflicting information from their website (Lion-safari-config-for-victron-bmv-battery-monitor) says to setup your Victron BMV and Victron MPPT as follows:

Charged voltage for BMV: 13.90 volts

Charged voltage for Absorption voltage MPPT: 13.90 volts

Float voltage for MPPT: 13.90 volts.



Questions I have for you please:

1) I’m not sure what voltage to put into my Victron 150/70? 13.90 volts or 14.6 volts?

Is “charging voltage of 14.6” not the same as “Charged voltage of 13.9”?

My Xantrex Inverter/charger on my boat has a Lithium setting and Custom setting.

Xantrex Lithium setting is Bulk (Volts not stated), Absorption: 14.6 volts, Float: 13.6.

Custom charge settings: Absorption: 12.0 volt to 18.0 volts.

Custom charge settings: Float: 12.0 volts to 18.0 volts.

Custom charge setting: Equalize for Flooded battery (enable/disable).

Also for custom settings I can set the following:

Low voltage shutdown (with timer). i.e. 10.5 volts for 5 seconds. From 10.5 – 12.8 volts and timer 1 to 300 seconds.

Instant low voltage shutdown. Put in 10.5

Low voltage recovery (when inverter will turn back on and continue to operate). From 12.0 to 16.0 or off.

High voltage shutdown.

Thank you. I’m eagerly awaiting to dump my 4 sagging 70lb AGM G31 with my new Lion Energy UT1300. My 4 AGM from 2018 cannot support my 1000 watt micro that pulls 130 amps DC.

[UFO]

When you top end balance individual 3.2 cells it takes for ever to get to 3.4V (13.6V) and then to 3.5V and 3.6V is a VERY short period of time - They are around 90% Charged at 3.4V (13.6V).



My BMS has a stated setting for LiFePo4 for top end balancing at 3.4V (13.6V) and once balanced at this level shuts down the charge sources.


I have set the maximum shut down for any individual cell at 3.6V, but as long as they stay in balance they will never hit that.


From my reading (marinehowto and Nordyk) there really is no need to take them to 100% and they will live a lot longer if you don't.


So in my system my chargers are set to switch to absorption at 13.7V with zero minutes in absorption. The batteries never make it to 13.7V though as the BMS balances them and then shuts down the charge source once balanced at 13.6V

[T1 Terry]

From over 10 yrs doing this as a full time business, I'll offer this advice.
Forget any charger regime that says it is for lithium batteries, "unless" that charger also is controlled by a BMS that monitors cell voltages and can shut the charger off if a cell goes over 3.6v.
The first thing you will notice is that no matter how perfectly balanced the 4 cell groups are, 4 x 3.6v = 14.4v and not 14.6v. This means the person writing the lithium charging regime didn't really understand LFPor LYP lithium chemistry.

Use the Üser configured"setting if the charger has these, if not, the Gel settings and use a quality BMS that stops the charging if a cell goes over 3.6v.

Set the bulk charging to 14v if there is a separate absorption voltage setting available. If not, then set the bulk to absorption voltage values.

Absorption voltage is 13.9v and a max of 30 mins if the charger will allow the time to be limited

Float for a working system is 13.8v, for a system in storage short term (6 weeks) 13.5v, for a system in storage longer than 6 weeks, discharge the battery to an average of 3.3v per cell and disconnect the terminals. It can remain in this state for yrs, but as fas as a drop in battery, who knows because you can't actually disconnect the cells, so about the best you can do is use the 13.5v storage and return to boost voltage every 14 days.

For the Victron BMV 712

Voltage at fully charged can be 13.9v or 14v, see which works better for you system. You will know if the SOC suddenly charges to 100% yet the battery is still charging at a rate greater than 2% of the advertised capacity ... just set the fully charged higher. Alternatively, if the BMV never seems to reset to 100% even though the charging has reduced to a few amps in good sun, drop the voltage down a bit.

The charge detection time is 1 min

Current is less than 2% of capacity, this varies depending on just how much capacity you have ....I.E 2% of 100Ah is only 2 amps, 2% of 1000Ah is 20 amps and a bit high for the purpose of judging when the battery is fully charged. % amps to 10 amps is probably a reasonable figure to judge when the 100% SOC is at least close.

Low voltage relay is for isolating the battery to save it from being damaged. 11.8v and 0 mins to 1 min delay.

Reset low voltage relay 12.2v

Low SOC 5% for a single battery built from multiple cells in parallel to build capacity and these groups linked in series to build voltage. Drop in batteries, probably 20% would be about as low as I'd be game to go because the genuine capacity at a C2 discharge rate is an unknown.
Reset SOC relay 6% for the all in one battery and 30% for the drop ins.

Half pack voltage for the all in one battery, 7 .4 high and 7v reset, 5.8v low and 6v reset and 5% differential.
Drop ins, set the aux to start battery voltage and connect the positive wire to the second battery in the string. 12v cut, 12.2v reset and 10% differential. If this alarm trips regularly you need to revisit how you have the batteries *linked together .
set the alarm votages to what ever you are happy with and be prepared to be woken in the middle of the night if you are too severe on the settings (wink)

As far as the alarm triggers and display, personally I'd disable the "time to go" function because each time you use a heavy load that number will drop to silly figures and cause undue panic. That number only means how long you can keep pulling that high load until the relay cuts the battery.

Hope all that helps

T1 Terry

[T1 Terry]

Forgot to put the bit in about the red *

Each negative lead from each drop in battery should be the same thickness and the same length and all joint at the BMV shunt battery side.
All the positive cables should be the same thickness and length and join at the mega fuse, or alternatively, a mega fuse in each cable and those join at the Gigavac used to isolate the battery. Do not attempt to drive the Gigavac directly from the BMV relay terminals, the current is to great, use a small 10 amp relay to drive the Gigavac and drive the relay negative with the BMV relay contact

Sounds complicated but it will give you the best end result. If you are industrious, you can try limiting the thickness of each cable to better force the load to be shared across all the batteries in parallel, but use a Mega fuse in each cable rated to the max current the cable can handle ... you don't want it melting and starting a fire eh ....

T1 Terry

[serpa4]

That was too much. Let me see if I understood all the details you provided. I’m new to this. I do have drop-in batteries, Lion Energy UT1300.
I don’t know what LForLYP is. I assume…it is the prismatic cells? Prismatic is the square cells vice round AA battery looking cells.
I have a custom setting in my inverter/charger, Xantrex Pro Freedom XC.
The Xantrex owner’s manual says, ”Bulk charge is the first stage in the charging process and provides
the batteries with a controlled, constant current. Once the battery voltage rises to the absorption voltage threshold, the charger switches to the absorption stage.”

So, I should use the “User setting” which it has and set the “absorption” voltage to 14.4 volts. Thus when bulk charge voltage rises to the absorption voltage threshold, the charger will switch to absorption and continue charging at 14.4 volts now in the absorption mode.
However, you said, “Set the bulk charging to 14v if there is a separate absorption voltage setting available. If not, then set the bulk to absorption voltage values.”
Should I set the absorption voltage to 14 or 14.4 since it is sort of related to the bulk charge voltage?
I assume…I should set the absorption to 14.4 volts which is I guess also the max bulk voltage???
I.e. the charger enters bulk mode at some amperage, say 50amps and say 13.5 volts. It maintains a constant 50 amps charging and the voltage slowly rises from 13.5 volts to whatever I set the absorption voltage at (14.4 volts). When the charger at a constant 50 amps hits 14.4 volts, the charger changes from bulk to absorption.


Then your statement contradicts this, “Absorption voltage is 13.9v and a max of 30 mins if the charger will allow the time to be limited.”
Should I set Absorption to 13.9 volts, 14 volts, or 14.4 volts? Thanks. I’m new and may be misunderstanding you.
I can set an absorption time limit. What should it be? 6 hours is default.

I can set the float voltage to 13.8 as you suggest. Thanks.
The Freedom XC PRO transitions to the float stage if either one of the following two conditions are met:

1. The charge current allowed by the batteries falls below the exit current threshold, which is equal to 10% (15 amps) of the programmed charge current (150amps) and a minimum of 2A.
2. The Freedom XC PRO has been in absorption for the programmed maximum absorption time limit. The default is 6 h.

I have the charger set for 150 amps as that is the max charging it can support. This is 37.5 amps max per battery (4 Lion UT1300, 105Ahr). So the charger should change from Absorption to Float when the charger’s amp output drops below, 15 amps total charge current.

When I put the boat in storage and shaded (no solar input/output to charger), I will discharge the batteries to 13.2 volts for sitting for maybe 4 months.
-------------
For the Victron BMV 712

Voltage at fully charged can be 13.9v or 14v, see which works better for you system. You will know if the SOC suddenly charges to 100% yet the battery is still charging at a rate greater than 2% of the advertised capacity.
So, If the BMV SOC says 100% and I see more than 8.4 amps going into the batteries, then I should change the “fully charged” setting to 14v otherwise leave it at 13.9 volts. (105Ah x 4 = 420Ahr x 2% = 8.4 amps output).
The charge detection time is 1 min

Low voltage relay is for isolating the battery to save it from being damaged. 11.8v and 0 mins to 1 min delay.
How much capacity is left at 11.8 volts? I thought that 10 volts was dead, but 10 volts is probably to late and I should be above 10 volts. Is that the 20% or 30% you mentioned? At 11.8 volts there is about 30% left in the batteries?
Thank you very much for taking your time to help. I’m learning from you input and I appreciate it.

[serpa4]

I hope to not start any fires.
The boat was built from the factory to support the 1000 watt micro (really about 1500 watts) pulling 130 amps DC. Even though I have replaced the 2000 watt inverter from the factory (55 amp, non-lithium) charger to a 3000 watt inverter (150 amp, lithium charger), my loads have not increased. I still only have the 1000 watt micro.

[MartinR]

Victron uses 14.2v Absorption, 2 hours absorption time, 13.5v float as standard. They make also batteries, so they should know.

If you are unsure, just use these and be happy.

I charge to 14V without absorption, works also.
Float at 13.5v

If I leave the boat for a longer period, I reduce the charging voltage, but there is really no reliable way to charge to for example 90%. as the voltage curve is very flat.

Every two weeks I charge fully to 14v to reset/calibrate the battery monitor. That drifts about 1.5% a day, so about 20% off after two weeks. Probably mostly due to very small currents used when the boat is not used, about 1A on average.

I am sure it is possible to optimize the cycle life of the batteries, but I think 5 years from now we have much better technology, so really no reason to think too much about that.

[T1 Terry]

Originally Posted by MartinR

Victron uses 14.2v Absorption, 2 hours absorption time, 13.5v float as standard. They make also batteries, so they should know.

If you are unsure, just use these and be happy.

I charge to 14V without absorption, works also.
Float at 13.5v

If I leave the boat for a longer period, I reduce the charging voltage, but there is really no reliable way to charge to for example 90%. as the voltage curve is very flat.

Every two weeks I charge fully to 14v to reset/calibrate the battery monitor. That drifts about 1.5% a day, so about 20% off after two weeks. Probably mostly due to very small currents used when the boat is not used, about 1A on average.

I am sure it is possible to optimize the cycle life of the batteries, but I think 5 years from now we have much better technology, so really no reason to think too much about that.

Victron make one of the better BMS controls that plug into their proprietary batteries, so they can actually control the charging if a cell goes high. If you don't have a BMS that can read the cell voltages and stop the charging before a cell is damaged, I'd avoid using excessively high bulk/absorption voltages and long absorption times .... but they are your batteries so I'm only trying to offer advice gained over the last 10yrs plus building lthium battery systems in RVs.

Sorry for the acronyms, LFP is the short version of Lithium Ferrous Phosphate, the cell chemistry used in safe from fire/explosion house batteries, LYP is just an upgraded version of the same chemistry where yttrium is added to the mix to extend the temperature range from 0*C to -32*C, increase the ability to fast charge without increasing the internal resistance and basically extending the cycle life.

As far as the bulk/absorption, 13.9v is safer and a 30 minute absorption time to allow the internal balancers to do there thing with a reduced risk of run away cell voltages.
Hope that helped clear up any confusion I've caused.
If you want to get a bit more background about lithium batteries as house batteries, my wife has written a website at t1lithium.com.au it might be useful or it might not, she asked me about different aspects until she understood it and then wrote it in her words in an attempt to share the info without causing the eyes to roll back like when I try to do a similar thing

T1 Terry

[UFO]

Originally Posted by T1 Terry

As far as the bulk/absorption, 13.9v is safer and a 30 minute absorption time to allow the internal balancers to do there thing with a reduced risk of run away cell voltages.


T1 Terry

I can watch my BMS balance the cells via the Bluetooth app - It takes around 5 minutes with my bank 4P4S 1120Ah. Balancing with my BMS is done at 3.4v per cell (13.6V) and once balanced it turns off the chargers. All my cells though stay very close to one another on discharge/charge - The app also shows cell voltages amongst other things.