Valence u27 12 xp lithium batterys

jimbob01 · December 2017

Hi guys/gals.....Ive just purchased 12 of these
To replace an agm bank at 24v
i currently have:
2.5kw of pv
A back up generator 12kw
ms mppt 45 amp x 2 of
xanterex 60 amp pwm 1 of
outback 3.5kw inverter / charger

Q: re charging/bulk /float settings for these batteries ?
Balancing?
They are 130ah each at 12v so i guess i may run 2 strings of 4 to make520ah at 24v

Then maybe keep 4 aside for my e outboard project

Raj174 · December 2017

@jimbob01
The batteries need to be fully charged before connecting them in series/parallel. That will take care of the initial balancing. Since they have a BMS it is recommended that you fully charge the bank about once a week to keep the cells balanced. Bulk/absorb voltage setting for a 24 volt bank is 29.2 volts according to the spec sheet below. Float at 26.8, that's about 90% SOC. The link below is a spec sheet on the Valence battery line.

https://www.valence.com/wp-content/uploads/2017/02/Valence-Module-Range-071717.pdf

Rick

jimbob01 · December 2017

Thanks for that link raj... just what i was looking for ☺jim

jimbob01 · December 2017

Ok is anyone out there charging valence u27 12xp lithium cells with mstar charge controllers? Im a little confused on bulk charging times/ current and weather variable solar current is acceptable or do i need to guarantee a fixed time period at a fixed current to keep the batterys happy

Raj174 · December 2017

@jimbob01
The Valence batteries will take the variable output that is solar charging. In many respects your lithium batteries, just like mine, although mine are prismatic LFP cells, are just like any other battery and should be treated so. The bulk charge can take 2 hours or 5 hours, just depends on how much power the panels are producing. With a 520 amp hour lithium battery bank, you don't have to worry about too little or too much current. Nor bad weather other than the fact that you will get little charging done.

Rick

karrak · December 2017

Have you purchased the Valance BMS that goes with these batteries?

Simon

myocardia · December 2017

jimbob01 said:

They are 130ah each at 12v so i guess i may run 2 strings of 4 to make520ah at 24v

Hi, Jim. That is not how batteries and their Ahr amounts work. When you series any two batteries, the voltage doubles, but the Ahr amount stays identical, and when you parallel any two batteries or banks of batteries, the voltage stays the same, and the Ahr amount doubles. 130 Ahr @ 12V series with 130 Ahr @ 12V= 130 Ahr @ 24V, not 260 Ahr @ 24V. Your batteries are a total of 260 Ahr @ 24V.

jimbob01 · December 2017

I was looking at the bms.... im using 8 cells @12v 130ah... i need 24v
I thought the best way may be to put them in 4 x pairs... so 4 pairsof 130ah batts @24v ?520?
I was wandering maybe is the external bms a must?
Maybe could i switch each pair somehow for better balancing/charging ?
I need to cycle the cells for some 600w heat mats i would like to run for about 6 hrs inno charge conditions each day...

karrak · December 2017

From what I can work out looking at the Valence website your batteries have the balancing circuitry inbuilt but unless you have their external BMS you will have no way of knowing if the battery is balanced or if there is a problem that could damage the battery unless it is attended to. Their BMS can also be used to disconnect any loads if the battery is over discharged or charging sources if the battery is overcharged.

The web page I linked to above gives details on how to wire up the batteries in parallel and series with their BMS.

I would recommend getting a battery SOC meter which uses a current shunt to measure the current going into and out of the battery. Because LFP (lithium iron phosphate) batteries have a coulomb/current efficiency of greater than 99% you can very accurately keep track of how much energy you have left in the battery.

If you put them in four pairs you would have 520Ah of storage which would be ~20kWh.

I agree with Rick to float at 26.8V. The bulk/absorb voltage is a little more complicated. You need to have a high enough voltage to operate the balancing circuitry but only need 3.45V/cell (27.6V) at a termination current of C/50 to fully charge the battery. Charging above 3.45V/cell might decrease the lifespan of the battery. One way around this is on a daily basis to charge to 3.45V/cell and only do a balance charge at the higher voltage when the battery goes out of balance or on a regular basis. You might be able to use the equilise function on your charge controller if your charge controller allows you to set the correct voltage.

Simon

jimbob01 · December 2017

Thanks simon... ive spent a day yesterday connecting 8 of these cells in 4 strings of 2 to get the 24v bank i need ... i got these cells at a reasonable price .... which is why i havent made 1 battery out up of say 2v cells.. would you have any suggestions as to a quality soc meter?
Sounds good... its getting the bulk charging times right that im a little concerned about
☺james

karrak · December 2017

Have you fully charged and balanced the individual batteries up separately before you put them together as Rick suggested? This step is very important and damage to the battery may result if it is not done correctly before you commission the battery. Did you get any information with the batteries on how to do the initial commissioning balance and how to wire the individual batteries up.

Have you read this thread http://forum.solar-electric.com/discussion/352673/victron-smart-12-8v-smart-lithium-battery
This discusses how to do the first balancing charge with Victron LFP batteries and other things that may be relevant to you.

With LFP batteries it is the charging voltage that is important not the time.

I haven't managed to get a user manual for your batteries from their website, do you have one?

Sorry if I sound a little alarmist, but it is really important that you get all this right before you put the battery into service.

Simon

jimbob01 · December 2017

Hi...they were all given to me fully charged...
These are not new cells...they have been used 20 to 80 cycles...
They were all at 13.40 v when tested. ...
I bulk charged them.... after 5 min they went to float on my outback inverter taking 2400w then taimi g off to 200w.
Shoud i still disconnect and charge each one?

BB. · December 2017

As I understand, at this point, measure the voltage of each "group" of paralleled cells, and make sure they are "balanced" voltages across the entire string of cells.

You can either charge the parallel group (bring up to average group voltages), or even place a (filament) lamp across the "high group" and bring paralleled group down to others.

Is this matching to 0.1 volts or 0.0x volts--That I am not sure of.

And part of your maintenance would be to check (monthly?) that the cells remain balanced.

If you have active battery balancing, then the electronics should take care of this as you go through (a couple?) discharge/charge cycles.

The initial warning was about miss-matching parallel cells (one discharge + one charged) creating high current flow between paralleled cells (I think).

Also, if you have a group of cells where (for example) one parallel group is near depleted (or even fully charge) with respect to the rest in the string... You run the risk of over discharging or over charging a series string of cells (both bad for most battery chemistries, but can ruin a Li Ion cell (or worst for some Li-Ion chemistries).

-Bill "as I understand" B.

jimbob01 · December 2017

Ok thanks ... all my cells were identical to.00
with a voltage test....can anyone reccommend a good meter to measure the in and out going current quantity to the batteries as that would be nice...
All of a sudden i can run the washing machine...with no sun☺

BB. · December 2017

Sears has an AC/DC clamp on DMM that is "good enough" for our needs at ~$60 or so. It does take a bit of understanding to use the ZERO DC Current button (does not work the same as many other "push to zero" buttons on other meters).

DC current clamp meters do drift over time--So you have to rezero them every few minutes or so (depending...) for "accurate/repeatable" DC current measurements.

A poster suggested teh Klein CL800 as working well for them:

http://forum.solar-electric.com/discussion/351961/klein-cl800

Note, that when you use a DC or AC current clamp meter, you mush separate the wires to measure the current in each wire. If you measure a pair of wire (such as +/- or L1+L2 for AC) to a circuit, you will read zero current flow (the current clamp measures the "sun of the currents"--If you both + and - leads in the clamp, the sum of the current is Zero.

Also, there are current clamp meters with a Peak Hold function--That can be very handy to measure starting loads (a question we get quite frequently). There are are also True RMS (root mean square) meters that are more accurate when measuring "arbitrary" wave forms--Not usually needed for debugging our systems.

Lastly, even if you buy a very good quality Fluke meter--Any battery powered meter can give "strange" results. Typically it is when the battery(ies) get weak. The meter will "sort of work" but gives strange results.

Just a few weeks ago, a friend was using his Fluke meter to measure 120/280 VAC (3 phase) voltage. He was measuring ~90/180 VAC readings--Which should not have been possible with standard utility power (everything in the shop+lighting was working fine).. Used his "cheap" Sears meter and got ~120/208 VAC as he should have.

-Bill

karrak · December 2017

jimbob01 said:

Hi...they were all given to me fully charged...
These are not new cells...they have been used 20 to 80 cycles...
They were all at 13.40 v when tested. ...
I bulk charged them.... after 5 min they went to float on my outback inverter taking 2400w then taimi g off to 200w.
Shoud i still disconnect and charge each one?

Hi Jim,
If they have all been used before and they were all at 13.4V and you had no problem when you charged them I would not disconnect and charge each one.

What voltage did you charge them to? How was the charge controller programmed to end the bulk/absorb charge cycle, was it with a timed absorb, or when the charge current decreased to a certain current or something else?

I am still concerned that we do not know how balanced the individual cells in the batteries are or if the internal balancing circuitry will work without the batteries being connected together and/or connected to the Valence BMS.

Depending on your level of electrical knowledge there maybe a way to see if the batteries are balanced without needing the Valence BMS by removing the panels on the sides of the battery and measuring the voltages of the individual cells directly with a multimeter.

I have found the Uni-T UT1210E DC/AC clamp multimeter good for low DC currents down to milliamp level. Highest current range is 100A

Simon

jimbob01 · December 2017

My cells are at 13.45each when fully charged ...
Each string of 2. @ 26.90 all thesame.
As its winter here they probably wont get much pv input..max 3kwhours on a sunny day..
So as im planning to work them hard for 2-3 months should i bulk them up and then float every week or could i leave it 2? For best battery health?
whats the best practice?
Ive heard lithium cells dont like sitting at high voltages for 2 long?
If im not cycling them is it better to knock down the bulk/absorb levels a bit?James

Im totally new to the lithium life po4 mg batts
Many thanks for all the replies James

Raj174 · December 2017

@jimbob01
Are the batteries for emergency backup? You are correct. LFP does not like to sit above float (90%) very long. If you are not cycling them, then they really do not need routine charging. If you want them on line and available to deliver power, then just float charge them during the day.

Rick

karrak · December 2017

jimbob01 said:

My cells are at 13.45each when fully charged ...
Each string of 2. @ 26.90 all thesame.
As its winter here they probably wont get much pv input..max 3kwhours on a sunny day..
So as im planning to work them hard for 2-3 months should i bulk them up and then float every week or could i leave it 2? For best battery health?
whats the best practice?
Ive heard lithium cells dont like sitting at high voltages for 2 long?
If im not cycling them is it better to knock down the bulk/absorb levels a bit?James

Im totally new to the lithium life po4 mg batts
Many thanks for all the replies James

To fully charge an LFP battery you need to charge it to 3.45V/cell (13.8v) and let the charge current taper off to C/50 (1/50 of the rated battery capacity). When the charge has finished the battery will drop down to around 3.35V/cell (13.4). If you float the battery at 13.4V after charging to 13.8V it will stay at around 99%SOC. If you charge to and float the battery at 13.4V you will get an SOC of around 92%-93%.

If you are not using the battery discharge it to around 50%SOC and leave it with nothing connected to it. If you are using it intermittently I would try to float charge it at around 50%SOC which is around 13.2-13.3V. You will have to play around with the voltage.

I don't know much about commercial SOC meters but from what I hear the Victron BV700 or BV712 if you wanted Bluetooth connectivity which may allow you to log the battery SOC seem OK.

Simon

jimbob01 · December 2017

Interesting information...thanks raj and simon for your input i shall be adjusting some settings and working out whats best all round ☺

Philly911 · August 2019

Hello! I purchased two u27 RT from An older generation for an RV off grid application that I intend to put in parallel and didn’t realize that their continuous discharge rate is only 30 amps. (The newer version of the same battery is 150A) Would that only give me 360w continuous ? What happens if I draw 2800w with a MagnaSine 2812 inverter charger? Will the BMS prevent it from happening ? Is it safe? Thank you all for your help! Cheers,

BB. · August 2019

Looks like the original link went dead... You have to go to the new website and get permission to see their support data:

https://lithiumwerks.com/support-download

Without knowing more about the BMS system--IT is difficult to say what will happen. But, in general, BMS limiting systems are more for "last results" than primary current control. I would worry about "stressing" the BMS FETs (or whatever they use, if they have any), or even the cells themselves if you regularly tripped the protection.

The MS 2812 takes about 30 Watts "Tare" (power just turned on, no loads). A smaller inverter (like the MorningStar 300 Watts TSW 12 volt inverter) will only take 6 Watts Tare.

https://www.solar-electric.com/lib/wind-sun/Magnum-MS-Inverters.pdf

I would get a smaller inverter (and/or new batteries)... 2,800 Watts is a lot from a 12 volt battery bank (I would humbly suggest a maximum of 1,200 to possibly 1,800 Watts as the practical upper limit for a "happy" 12 volt AC inverter installation (estimated):

2,800 Watts * 1/0.85 AC inverter eff * 1/10.5 battery cut off voltage = 314 Amps max continuous
3,900 Watts (max surge) * 1/0.85 AC inverter eff * 1/10.5 volts cut off = 437 Amp max surge

I really like to suggested a "balanced system" design. Required loads drives Battery bank type/size/capacity. The chargering systems are there to keep the battery bank "happy". The inverter is large enough to support your loads (and small enough to not damage the battery bank and high Tare current greatly reducing "useful" energy storage for your loads).

-Bill

Dave Angelini · August 2019

The biggest cause of lithium battery failure is overcurrent. You would have to know the failure mode of the design. Or trust the company to have done this.
Will the BMS fail, will the battery, or both. Maybe they will help you?

Markz · December 2019

Does anyone know if these batteries can be used on their side? Do they have to be upright?

I just got a few of these batteries and looking install them and to set up a BMS of sorts. I have a solar charger with a low voltage cut off and voltage limiter. I believe this serves the similar function of the factory BMS.

I am also looking to connect the batteries to a laptop.
Does anyone here know where we can find a custom USB connector for these and do we need a communications cable terminator? I understand the factory terminator is 120 holms.

Thank you
Mark

travissand · March 2021

Markz said:

Does anyone know if these batteries can be used on their side? Do they have to be upright?

I just got a few of these batteries and looking install them and to set up a BMS of sorts. I have a solar charger with a low voltage cut off and voltage limiter. I believe this serves the similar function of the factory BMS.

I am also looking to connect the batteries to a laptop.
Does anyone here know where we can find a custom USB connector for these and do we need a communications cable terminator? I understand the factory terminator is 120 holms.

Thank you
Mark

If you have 16 or less you won't need The Terminator.
There's a position on its side that you would want to avoid because Heat rises and the location of the temperature sensors. This would not really be a problem in low demand setups.

The Built-in BMS board needs to be activated by communicating to an external source. Anything that tries to communicate will cause this. You can tell when the board is successfully balancing because the green light will Flash every 5 seconds instead of 20 seconds.

Before put into service and especially before putting batteries in Ceres They need to be connected in parallel and fully top balanced Until the internal state of charge metre shows 100% as shown using the rs485 cable and the valence software On your laptop.

Your high voltage and low voltage cutoff will not protect the battery Because it's not communicating & it does not know the cell voltage.

I sell custom programmed actual valance branded BMS.
Do a Google search for (DIY valence super thread) for more information. Or call me 557-9058 I left out my Hawaii a rea code so the bots don't harvest my number.

travissand · March 2021

And yes I also sell the custom cable Wired correctly for these batteries. It's very difficult to get the software to work & it's nice to have a cable That isn't suspect for being the reason it's not working.

Valence u27 12 xp lithium batterys

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