Battery Parameters Help plz!!

Acho_303

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Nov 26, 2020
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220
Hello all,

I have decided to upgrade my battery bank and need a little help from the smart people on this forum. I previously built 4s2p 272ah Lishen cells (544ah) managed with JDB's bms.. The system is charged with an Orion 30amp dc to dc charger and 400watts of solar.... and when I want to run my generator, I can plug the victron inverter in and really get the AH in... My biggest issue is getting/keeping the cells charged up...

My electrical load includes a 4 camera security system/dvr, isotherm, S3, fans, induction cooktop, microwave, 24inch tv, ps5, pumps for engine heat/floor heat/shower and charging phones/laptops/gadgets... and well... if I could charge better I think it would work out okay..

When I am connected to my generator, I can charge at 50amp per pack, and it takes about 2 hours to load the cells up.... and that got me thinking and ultimately pulling the trigger on the nations 280amp dual alternator for my van… In that conversation I decided to upgrade my bms to a REC Active BMS system… They look legitimate; the hardware form factor reminds me of a cradle-point or pepwave router and looks pretty robust…

In the same effort to stop messing with my power during ski trips or when shaded by trees, cloudy days etc I also order 16 304 eve cells….. I hope 1200 AH of lifepo4 will stop any power insecurities I currently have as a full-time van dweller that works remotely.

I’m back at the start and need help with the form the REC people sent me, since the vernacular doesn’t match the xiaoxiang parameters, I’m stuck and hoped the nice people of the forum could help me.

This is what they sent me
 
Last edited:

Acho_303

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220

BMS Parameters Settings​

Please specify the system’s parameters settings for BMS.
Table 1: BMS parameters settings.
parameter
value
unit
end of charge voltage per cell
V​
end of charge hysteresis per cell
V​
balance start voltage(if charging)
V​
cell over voltage protection switch-off
V​
cell over voltage protection switch-off hysteresis
V​
cell under voltage protection switch-off
V​
cell under voltage protection switch-off hysteresis
V​
cells max difference voltage
V​
BMS under voltage sleep mode
V​
BMS under voltage sleep mode hysteresis
V​
BMS over temperature switch-off
°C​
BMS over temperature switch-off hysteresis
°C​
cell over temperature switch-off
°C​
under temperature charging disable
°C​
capacity of battery cells
Ah​
chemistry
number of cells

Note: In case of ordering BMS Control PC software, the table does not need to be filled-in.

Charger Communication Output​

BMS Master Module 9M has numerous outputs to control the charger. Please fill-in the Table 2 to determine output configuration for charger control. If options with enable or CAN control communication are chosen, please fill-in the charger type.

Table 2: BMS charger output settings.
Description
Option(underline or fill-in)
Compatible Charger type
Enable ON\OFF 5 V, 10 mA​
isolated / non-isolated​
PWM​
isolated / non-isolated
frequency: ______​
Piktronik KOP​
Analog 1-5 V​
isolated / non-isolated
max current: ______​
Elcon​
CAN control​
Non-isolated​

BMS CAN Communication​

CAN protocol communication frequency is microcontroller’s crystal selection dependent. CAN communication is galvanically isolated and it is powered from the Master module power supply (11-14 V).

Select the CAN protocol communication frequency:

125 kHz
250 kHz
500 kHz
1 MHz

CAN protocol can handle up to 8 bytes per 11-bit Identifier (ID). Please fill-in the table 3 to add additional CAN messages.
Table 3: CAN messages description.
11-bit ID
1. byte
2. byte
3. byte
4. byte
5. byte
6. byte
7. byte
8. byte
0x031​
SOC (0.5%)​
Voltage (mV)
HIGH BIT​
Voltage
(mV)
LOW
BIT​
Current
(x10mA)
HIGH BIT​
Current
(x10mA)
LOW
BIT​
MAX CELL TEMP
Unsigned char​
Error_data[2]​
Error_data[3]​

Current Sensor Selection​

Battery pack current is measured via voltage drop on precision shunt resistor (0.25 %). If option “Own shunt” is selected the resolution will be programmed as 200 A / 50 mV, if not filled-in. The resolution can be changed with BMS Control PC software.

Table 4: Shunt current sensor selection.
Selection
Shunt resistor
Resolution (LSB)
100 A/50 mV​
3.90 mA​
200 A/50 mV​
7.81 mA​
300 A/50 mV​
11.72 mA​
500 A/50 mV​
19.53 mA​
Own shunt:​

 

Acho_303

Solar Enthusiast
Joined
Nov 26, 2020
Messages
220

BMS Sensor Cable Data and Cable Lengths​

Shielded cable is used to connect the sensor to the BMS to cancel EMC. Please fill-in the sensor cable length.

Table 5: BMS Sensor cables data.
Sensor
Number of sensors
Cable length [m]
Temperature sensor
*​
Current sensor
n.a.​
*​

* max 2.5 m

** maximum 3 temp. sensors per BMS Slave unit

Master – Slave communication cable:
Cable
Cable length [m]
Master – 1st Slave
1st Slave – 2nd Slave
2nd Slave – 3rd Slave
3rd Slave – 4th Slave
etc...
*​

* if you require more than 4 Slave units, please write down the lengths of all cable connections.

Additional I/O Ports​

BMS Master Module 9M has 4 digital ports, that can be configured as inputs or outputs. They can be galvanically isolated with an internal optocoupler. Select required digital I/O task by selecting isolation option and describe its function in Table 6.

Table 6: Digital I/O specifications.
Digital I/O
Galvanic Isolation (underscore)​
Function
I/O 1​
Yes / No​
I/O 2​
Yes / No​
I/O 3​
Yes / No​
Buzzer alarm 4kHz 50% Duty cycle​
I/O 4​
Yes / No​

There are 4 relay outputs that can be individually programmed by your specifications and connected as Normally-closed (NC) or Normally-opened (NO). Relays can drive 3 A at 230 VAC or 3 A at 12 VDC (0.7 A at 60 VDC). Select the required relay port by selecting type of connection and describe its function in Table 7.

Table 7: Relay outputs specifications.
Relay port
NC / NO
(underscore)​
Function
1​
NC / NO​
2​
NC / NO​
3​
NC / NO​
4​
NC / NO​

Table 8: Analog inputs.
Input Port
Input Voltage Range
Function
1​
0-250 mV​
Shunt Current measurement​
2​
0-400 V DC​
3​
0-400 V DC​

Additional Requests​

In case of ordering the LCD touch display, please let us know the required cable length:
Cable length [m]
LCD touch display for REC BMS
*

* max 6 m

In case of custom-made software or additional algorithms shall be incorporated in the BMS 9M, please describe below your additional requests:

 
Last edited:

Acho_303

Solar Enthusiast
Joined
Nov 26, 2020
Messages
220
Currently I am using my Lishen packs until my Eves come in, since they are both lifepo4 I believe the parameter should be the same and only the AH will change.

Any help with the parameter configuration would be greatly appreciated
 

smoothJoey

Ding Ding!
Joined
Nov 30, 2019
Messages
11,802
Hello all,

I have decided to upgrade my battery bank and need a little help from the smart people on this forum. I previously built 2s4p 272ah Lishen cells managed with JDB's bms.. The system is charged with an Orion 30amp dc to dc charger and 400watts of solar.... and when I want to run my generator, I can plug the victron inverter in and really get the AH in... My biggest issue is getting/keeping the cells charged up...

My electrical load includes a 4 camera security system/dvr, isotherm, S3, fans, induction cooktop, microwave, 24inch tv, ps5, pumps for engine heat/floor heat/shower and charging phones/laptops/gadgets... and well... if I could charge better I think it would work out okay..

When I am connected to my generator, I can charge at 50amp per pack, and it takes about 2 hours to load the cells up.... and that got me thinking and ultimately pulling the trigger on the nations 280amp dual alternator for my van… In that conversation I decided to upgrade my bms to a REC Active BMS system… They look legitimate; the hardware form factor reminds me of a cradle-point or pepwave router and looks pretty robust…

In the same effort to stop messing with my power during ski trips or when shaded by trees, cloudy days etc I also order 16 304 eve cells…..

I’m back at the start and need help with the form the REC people sent me, since the vernacular doesn’t match the xiaoxiang parameters, I’m stuck and hoped the nice people of the forum could help me.

This is what they sent me
2s4p would be 4x 6.4 volt batteries.
I doubt that is what you meant.
Do you mean 4s2p which would be 2x 12.8 volt batteries?
 

Acho_303

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Joined
Nov 26, 2020
Messages
220
2s4p would be 4x 6.4 volt batteries.
I doubt that is what you meant.
Do you mean 4s2p which would be 2x 12.8 volt batteries?
Yes, sorry, I updated the text to curtail any additional confusion, sorry sorry
 

smoothJoey

Ding Ding!
Joined
Nov 30, 2019
Messages
11,802
Are we to understand that you will have a heterogeneous pack of 4s6p?

272 watt hours * 3.2 volts * 8 cells = 6963.2 watt hours
304 watt hours * 3.2 volts * 16 cells = 15564.8 watt hours
22528 watt hours total
 

Acho_303

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Joined
Nov 26, 2020
Messages
220
My current victron line up consist of
energy multiplus 3000
Lynx distributor
MPPT 100/50
Orion
BMV-712 with 500 A smart shunt
 

Acho_303

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Joined
Nov 26, 2020
Messages
220
Are we to understand that you will have a heterogeneous pack of 4s6p?

272 watt hours * 3.2 volts * 8 cells = 6963.2 watt hours
304 watt hours * 3.2 volts * 16 cells = 15564.8 watt hours
22528 watt hours total
I currently have two four packs of Lishen cells, two batteries at 272Ah each.... In 60days I will have 16 304AH cells of Eves that will be setup as four batteries at 304AH each or I might double the cells and create 2 608AH batteries... I only mention that because I wasnt sure if for some reason going from Lishen to Eves the charging profiles would change... but ultimately, I currently have 2 packs of Lishens at 272AH each... I guess i should mention I plan to sell the Lishens to partially finance the Eves that are coming, so I won't have both hooked up, going from Lishens to Eve cells, not a combination of both... I figure with name brands going for 1k for 100ah selling the Lishen packs at 1200 would be a great deal for someone else

Aren't the cells topped at 3.65 volts? I typically charge mine to 3.4 something when the BMS states they are full
 
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upnorthandpersonal

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Ok, let's go over a few things just to make sure I understand what we're trying to do.

Do you have a power audit. I know you listed a few things you're running, but it would be good to have the exact data of each item, it's consumption over 24 hours. 400W solar is not that much, but you're topping off with a generator - what is your daily consumption?
If I understand correctly, you have a 12V battery made out of 8 Lishen 272 Ah batteries, giving a total of 544Ah, or around 7kWh.

Some of your loads (induction cooktop, microwave, pumps) seem to be decent sized loads. The microwave is probably around 1kW, the cooktop between 1.5 and 3 kWh probably. So if you're running the microwave for 30 minutes a day and cook for an hour or two, you're possibly close to 50% of your state of charge. Add the pumps, etc.


As for the table you have in your second comment, they should be able to fill this in based on your cells info if you give them that. However I gave it a shot. Please note that I don't claim these values are the best or that this table is free of errors. Some values might be conservative, and some are the default ones for the REC LiFePO4 profile. I didn't fill in the capacity and number of cells since I wasn't sure which cells you would use this BMS for exactly.

parametervalueunit
end of charge voltage per cell3.5V
end of charge hysteresis per cell0.25V
balance start voltage(if charging)3.45V
cell over voltage protection switch-off3.65V
cell over voltage protection switch-off hysteresis0.25V
cell under voltage protection switch-off2.8V
cell under voltage protection switch-off hysteresis0.1V
cells max difference voltage0.25V
BMS under voltage sleep mode2.5V
BMS under voltage sleep mode hysteresis0.1V
BMS over temperature switch-off55°C
BMS over temperature switch-off hysteresis5°C
cell over temperature switch-off55°C
under temperature charging disable0°C
capacity of battery cellsAh
chemistryLiFePO4
number of cells
 

Acho_303

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Messages
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Ok, let's go over a few things just to make sure I understand what we're trying to do.

Do you have a power audit. I know you listed a few things you're running, but it would be good to have the exact data of each item, it's consumption over 24 hours. 400W solar is not that much, but you're topping off with a generator - what is your daily consumption?
No it changes so often... Like in the summer cooking in the van with the summer heat doesn't happen much so the induction cooktop doesn't get used much.... Last weekend I camped at the base of my ski hill and it got down to 7 or lower, so the espar was running pretty good to keep the van at 75.... I'm in Colorado so during the winter heating takes a good amount of power... when the espar is running its about 10amps, and that fires on and off... I also want to add a Mini split to my van for cooling during summer months.... but normally the security system, lights and random things charging I see 2 to 6amps coming out of a single pack.... My generator is at the storage lot with my school bus, so I have to drive there to charge which is anywhere from 30mins to a few hours away depending on where I park... so it gets old...especially in the winter... I normally go there on the weekend to get water, but driving there a few times a week and sitting for a few hours running my Generac is getting old... I also just got a PS5, and for example playing the spiderman game yesterday for 4 hours and cooking burgers I went from 213AH each to now like 130AH in each pack... That includes heat etc... so I think 150AH per day would cover my usage... and so I have 1200AH of Eve heading my way... I would rather have more battery than too little. I also would like to be able to sit in a dark forest for a week without needing to charge... or at the base of my ski hill.... so I am planning for a week of autonomy.
If I understand correctly, you have a 12V battery made out of 8 Lishen 272 Ah batteries, giving a total of 544Ah, or around 7kWh.
I have 12volts and have taken 8 Lishen 272ah cells and grouped them into 2 batteries for a total of 544ah at 12volts

Some of your loads (induction cooktop, microwave, pumps) seem to be decent sized loads. The microwave is probably around 1kW, the cooktop between 1.5 and 3 kWh probably. So if you're running the microwave for 30 minutes a day and cook for an hour or two, you're possibly close to 50% of your state of charge. Add the pumps, etc.
The espar is another pretty big hog... hot showers, heat etc... winter it runs all the time, or kicks on and off... when its shower time it runs contently but that's just for like 20mins or so

As for the table you have in your second comment, they should be able to fill this in based on your cells info if you give them that. However I gave it a shot. Please note that I don't claim these values are the best or that this table is free of errors. Some values might be conservative, and some are the default ones for the REC LiFePO4 profile. I didn't fill in the capacity and number of cells since I wasn't sure which cells you would use this BMS for exactly.
Thank you very much... You might not remember but you also helped me last yearish with my braided bus bars, you suggested the place overseas...
 

upnorthandpersonal

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You might not remember but you also helped me last yearish with my braided bus bars, you suggested the place overseas

I vaguely remember, but it's hard to keep track of everything.

From what you wrote, you should have enough power on the battery side of things for your load. Too bad you're limited with solar.
 

Acho_303

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Nov 26, 2020
Messages
220
I vaguely remember, but it's hard to keep track of everything.

From what you wrote, you should have enough power on the battery side of things for your load. Too bad you're limited with solar.
Yeah, but I like the dual altenator setup, and at 280amps... I should be able to charge everything up great... when/if starlink ever comes to mobile applications and Colorado I might need the roof for satellite space so the solar might need to go. My 400watts was great with 250ah agms, but now even with the Orion it is kind of a joke in the winter.
 
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HRTKD

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Somewhere South of Denver
I'm here in CO also and definitely do not have a four season RV trailer. I cook with a propane stovetop and oven, the water heater and furnace are also propane. There's just not enough room on the roof for enough PV, nor is there enough room inside the RV to store much more than about 560 Ah of LiFePO4. But I still get it done. I have 640 watts of PV on the roof and the same amount that I can deploy on the ground. Last year I camped at -8° F in the mountains. I froze one pipe for an hour, but otherwise managed OK. I have put in a lot of work to keep parts of the trailer from freezing.
 

Acho_303

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Messages
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I'm here in CO also and definitely do not have a four season RV trailer. I cook with a propane stovetop and oven, the water heater and furnace are also propane. There's just not enough room on the roof for enough PV, nor is there enough room inside the RV to store much more than about 560 Ah of LiFePO4. But I still get it done. I have 640 watts of PV on the roof and the same amount that I can deploy on the ground. Last year I camped at -8° F in the mountains. I froze one pipe for an hour, but otherwise managed OK. I have put in a lot of work to keep parts of the trailer from freezing.
I previously did propane with a propane heater... started with the mr buddy then went to a forced air unit.... the forced air was pretty good, Mr buddy sucked as far as condensation... with the forced air I had two BBQ tanks I'd carry.. and I cooked with propane... I just wanted to get away from it and filling the tanks at the feed store and the potential leak at night... I then went to the espar dw version which required a rebuild every 30days, that was hard in the winter. Rebuilding the sucker even if it was 10 degrees outside... now I have the s3 and it's amazing... haven't rebuilt it once after over a year of using it... its hooked into my gas tank so one fill up and the house and van is ready to go

For me the hardest thing about van life when I started in my e350 was showers and power... sure you can shower at the gym if you don't mind the looks.... now in my sprinter I build a small shower and just want to consume as much power as I want... I thought 544Ah would do it after moving from only 250ah of agms, and I think it would for a few days at fully charged... but I need a week, I have a week worth of showers, a week worth of food, and when my eves get here I'll have a week worth of batteries without moving my van from the forest or whatever ski parking lot I'm staying at. Heck when I install my dual altenator and can charge at let's say 250amp of the 280amps the altenator is rated for when I'm in town it should be perfect... but when I head to the hills I like to park for atleast a week.

As far as freezing, all my pipes are internal, and when I installed my floor over the sprinter flooring I ran pex pipe combined with the metal happy feet stuff from the front to back, I then pump the coolant the espar brings to 190 to keep everything warm, and have two air ducts like a school bus to heat the internal air... My sprinter has low-e reflective and the 3m insulate junk all over the walls and roof... 1 inch pink board in the floor and I cut the pex pipe grooves using my router... if I redid my insulation I would keep the floor system but would have more of a thermal break in the walls... I have quarter inch baltic birch attached using plus nuts and the bolts do get cold.... but I haven't been cold yet anywhere I've been. If I let the van get under 72 when it's really cold outside I can still get condensation leaking out, but I've started leaving it 72 inside when it is 40 or lower outside
 

HRTKD

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All my pipes are internal also. Unfortunately, the factory ran the pipes along the front wall which was one of the more poorly insulated walls. When I rebuilt that wall this summer I improved the insulation by a factor of almost 2 and added heat tape to the section of PEX that I thought was likely to freeze.
 

Acho_303

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Nov 26, 2020
Messages
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I'm excited my new eve cells are on the way, the nation's dual altenator is delayed for another 5 weeks and the REC master control is delayed as well.

Amy provided the testing sheets and the 304ah cells are pulling 320ah... super excited

r_1.gif
Code Details
r_2.gif
NoCodeCapacity(Ah)OCV1(V)Ri1(mohm)OCV2(V)Ri2(mohm)OCV3(V)Ri3(mohm)
1​
04QCB73719700JBB70006013​
322.7240​
2.786​
0.16​
2.774​
0.16​
3.298​
0.16​
2​
04QCB73719700JBB70006031​
322.2555​
2.784​
0.16​
2.773​
0.16​
3.298​
0.16​
3​
04QCB73719700JBB60005445​
322.1838​
2.788​
0.16​
2.777​
0.16​
3.298​
0.15​
4​
04QCB73719700JBB60002498​
322.9945​
2.796​
0.16​
2.781​
0.16​
3.298​
0.16​
5​
04QCB73719700JBB60004285​
321.1113​
2.790​
0.16​
2.774​
0.16​
3.298​
0.15​
6​
04QCB73719700JBB70006292​
321.9176​
2.794​
0.16​
2.780​
0.16​
3.298​
0.15​
7​
04QCB73719700JBB60005407​
322.1119​
2.790​
0.16​
2.777​
0.16​
3.298​
0.15​
8​
04QCB73719700JBB60002050​
322.7032​
2.790​
0.16​
2.774​
0.16​
3.298​
0.15​
9​
04QCB73719700JBB60004764​
321.8800​
2.795​
0.16​
2.782​
0.16​
3.298​
0.15​
10​
04QCB73719700JBB60004974​
322.2131​
2.788​
0.16​
2.773​
0.16​
3.298​
0.15​
11​
04QCB73719700JBB60005140​
323.2225​
2.795​
0.16​
2.783​
0.16​
3.298​
0.15​
12​
04QCB73719700JBB60004432​
321.7907​
2.790​
0.16​
2.773​
0.16​
3.298​
0.16​
13​
04QCB73719700JBB60004793​
321.7027​
2.795​
0.16​
2.783​
0.16​
3.298​
0.16​
14​
04QCB73719800JBB70000043​
322.0442​
2.791​
0.16​
2.778​
0.16​
3.298​
0.15​
15​
04QCB73719800JBB70000006​
323.1000​
2.794​
0.16​
2.781​
0.16​
3.298​
0.15​
16​
04QCB73719700JBB60003381​
322.5000​
2.789​
0.16​
2.774​
0.16​
3.298​
0.15​
 

Acho_303

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Joined
Nov 26, 2020
Messages
220
@HRTKD @upnorthandpersonal

Hey guys I have another question I hoped you could help me with... The REC Pro people are now saying I should do one big pack instead of the 2 battery packs I have now, and when I get my Eves instead of doing 4 battery packs just one... 4p4s system... Previously I worried about this because having 4 cells as 1 doesn't allow me to see the individual cells... what are you thoughts? The REC Pro teams feels 4p4s is more common now and it's safe...
 

upnorthandpersonal

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REC, just like Orion, have a particular view on this which is, let's just say, biased. There is no 'right' or 'wrong' way, it just depends on what you aim to do. Personally, I like the redundancy of two or more separate packs that can be added/removed on the fly for maintenance, etc. I also like the fact that each cell is monitored individually. Orion is known for a certain document where they argue against this set-up (with some dubious terminology and overall weak arguments). In the past this would be more relevant, but with the wide spread use of decent BMS's, this is no longer very valid. In fact, one of the proposed solutions in the Orion document is essentially what using a modern BMS does. My opinion is that REC and others are going by this Orion document, or that their BMS is more suitable for this kind of set-up and thus recommend it.
 
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