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WHICH BMS for my LiFepo4

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Which combination to use  with 48 V , 200 AH Lifepo4 cells  ( keep in mind battery was less than 3000 Euro)

Following options 

Option 1 - Costliest most reliable  Victron Multi 5KVA /48 - with  REC BMS ( cost with Contactor, software etc almost 900 Euro)

Option 2 - Axpert  5KVA - Coulomb's firmware patched - Which BMS ??? have not found any third party which will work with Axpert yet  via serial port 

Option 3 - use a generic BMS to switch off the battery on extreme  low/high voltage with the contractor  and use additional  BMV 702  relay to switch off Axpert  load  through a power contactor on low SOC say 20 %  ( my loads are backed by the generator in office so the soc rarely drops below 70 %)

The BMS I have in mind  ( also works with victron with two wire assistant)- https://www.ev-power.eu/Battery-Management/BMS123-Smart/123-Smart-BMS-Complete-Set-4-cells-with-Bluetooth-4-0.html 

http://gwl-power.tumblr.com/tagged/BMS123Smart

 

========================

I recently got hold of a cheap Chinese Lifepo4  battery with BMS  - The BMS has allowed to charge and allowed to discharge contacts 

I found out  that the BMS has no equalization !! ( active or passive) and  reported Current and voltages my flukes did not agree to at all

closer inspection  Revealed why it was cheap - The BMS looks to be fried although batteries report almost similar voltages 

20180526_133231.jpg

20180526_180054_HDR.jpg

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Interesting question, I was thinking about this the other day and a way of doing it on the dirt cheap.

Say for example you have a [16s??p] bank;

  • rely on the Axpert/ICC upper charge limits at 3.6x16 = 57.6V (I know Axpert overshoots but these anomalies are of very short duration and very unlikely to cause damage),
  • use ICC switch to grid at your chosen SOC (say 30% for example),
  • use relay contact on Victron BMV to disconnect battery at a lower level than above for safety margin (say 20% SOC for example),
  • set Axpert Menu29 (low DC cutoff) to the absolute cutoff voltage as per battery spec (it should never get there),
  • use 4x HA-02 for battery balancing of the series sets (maybe a 5th one to balance the 4x HA's).

Any reason why the above cant be done? The HA-02 will start working at 2.4V and 4 of them will set you back around EUR200. I have used them on a number of AGM banks and had no problems to date (except that I DONT recommend using them on 2V cells).

 

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REC and Orion remains the best options in my opinion.

In my experience with LFP the last 6 months -- which has been somewhat of a crash course combined with being thrown in at the deep end -- I've seen issues with cells rising in voltage really quickly. All the main makers (BYD, Pylontech, Sony, LG, Victron, MG) use cut-off voltages that are far below dangerous, usually the protection contactor opens at around 3.65V per cell. Danger only arrives somewhere above 4V.

Even at around 3.5V,  a couple hundred milliamps is enough to spike the voltage.

The question now is if the HA-02 will react fast enough and pass enough current in a sufficiently interleaved way. I don't know. I can easily see the voltage rise with the HA02 unable to squelch it. Maybe, maybe not. I would not feel safe without a physical switch opening in case something goes wrong.

The BMS has to handle 1) overcharge, 2) over-discharge, 3) over-current, 4) short-circuit, 5) temperature monitoring. The HA02 might handle 1. The BMV is not going to handle 2 if there is an imbalance. There is nothing handling 3. 4 You could handle with a fuse. There is nothing for 5, and LFP does not want to be charged below freezing. You'd probably not start fires though, which is the important bit :-)

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Thanks, Guys,.

 

I contacted REC and they Confirmed the 16Q model is fully compatible with Victron over CABUS out of the BOX . The BMS on spec sheet looks wonderful but is rather expensive 400 Euro plus for basic ( software, cables, contactor, adding temp probe etc) take you well north of 900 Euro 

 

Maybe I will get one of those cheap Chinese versions, USE the ATC/ATD contacts   and  keep the battery isolated with sandbags :)

https://www.dhgate.com/product/high-accuracy-battery-management-system-bms/409065600.html#s1-2-7b;searl|3968060313

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Have a cheap passive Daly 2p16s 48V BMS. EasySolar + BMV on the way. Not comfortable with that BMS, at all. Active management seems much saner given LiFePO4 bank cost. Voltage and current are main concerns in the southern hemisphere.

Could a BMV-712 Smart talk to an EasySolar-II to tell it when to shut off charge?

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The BMV will talk to the EasySolar, but it will only have some battery info available. The BMS will manage your battery cell by cell. The BMV does not have that info. It will look at the battery as a complete unit and report that. 
So if your BMS does a good job the BVM should work well. 
If one of your cells are off though the BVM will not know about that.

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@Nick the Daly bms works OK. What Size lifepo4s is it? The trick with this stuff is, don't push all the charging volts in to it. Take it from me. We already tested it and know. The victron is going to give you errors and mppt spikes. Someone off forum is running a full victron setup with a Daly BMS and lifepo4s and he started getting ripple warning and errors because of charging at 56v over. He adjustes his victron to my settings and so far everything running stable now. 

Run bulk charge at 54.6v and float at 53.6v. The BMV will help the mppt and inverter when to stop. Just remember to adjust the Peukert Factor to 1.05. The BMV is design for lead acid so you need to adjust that part. 

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Posted (edited)

Other option is to get a Smart Ant BMS. I'm using them in my setup and they work really good, you get info via the screens and you can connect to it via your phone and adjust all the settings on the BMS. There is n Python script that you can use to connect the BMS via pi to get data and stuff. 

FB_IMG_1594214148609.jpg

Edited by Gerlach

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33 minutes ago, Gerlach said:

Smart Ant BMS

Is the Smart Ant BMS the one you need to start the BMS with a 12V charge to get it started\booted?

I also build my LiFePO4 battery with a smart BMS, but used this one with 15 cells 
https://www.lithiumbatterypcb.com/product/14s-bluetooth-lithium-e-bike-battery-pcb-board-with-30a-constant-charge-and-discharge-current-2/

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56 minutes ago, Louisvdw said:

Is the Smart Ant BMS the one you need to start the BMS with a 12V charge to get it started\booted?

I also build my LiFePO4 battery with a smart BMS, but used this one with 15 cells 
https://www.lithiumbatterypcb.com/product/14s-bluetooth-lithium-e-bike-battery-pcb-board-with-30a-constant-charge-and-discharge-current-2/

If you take it with the screen option, then you don't have to start it that way. The screen connects to the 51.5v output part of the battery "well from 3.5v to 96v " and the screen switches the bms on when the screen gets power. You can switch the screen off and the bms stays on, till you unplug the ballancing leads, then it switches the bms off. 

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Posted (edited)

Thanks folks. I'd be interested in any locally supplied lithium cell monitoring system, but to my knowledge there is currently nothing (affordable) - stock is all overseas.

What irks me the most is the lack of visible cell monitoring. This has to be easy to put on a cheap display from even a passive BMS, since it is monitoring cell values anyway, but they just don't provide a few pins to output the data for monitoring. Let's hope the cheap ones like Daly will improve in the coming months. You can go with the little LCD cell balancers, but that is a separate device supporting only 8 cells / channels - I have 32 that I need to see together, on a PC or 'Droid screen, all at once.

What is the cost of the AntBMS, as a matter of interest? The cheapest REC apparently comes in at $400 (reputedly, though some say there are additional overheads), and the Smart123 Gen3 @ $400. Of course these exclude shipping etc. to S.A.

@Gerlach, appreciate your remarks on getting Daly to work with a Victron setup - this gives me confidence to order the Victron stuff. I'm not really comfortable being in a smallish space with an Axpert / RCT / Mecer that might crash and burn due to poorly spec'ed components.
 

Edited by Nick

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Brian has local Daly stock https://lithiumbatteriessa.co.za/

But you are looking for a Smart BMS. Those tend to have bluetooth and you can see the cells on the app/screen. 
There are some links to the BMS I have and also the ANT in this thread 

I have a 100A 15s with Bluetooth and UART that came to R2100 (Aramex shipping included). The ANT will be similar in price (with 16s).

I guess your sells are 2 in parallel to get to the 32? If you want to see each sell you will have to look at something bigger or settle to pair 2 sells and see their stats as a unit.

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The smart123 bms is nice. BLUENOVA strated to use them rite in the beginning with there units, and then they started to build inhouse. 

Hidden info in the smart123 bms, you need to buy the extra units. They only sell 4 sell controllers with the controller.  You need extra 12 of them. 

Batrium bms the same storie. Orion bms the same storie. They all over R7500 plus if you import your self. 

The Smart ANT bms is cheap. My first one cost me R1450 with courier shipping that took a bit longer. Thats a 20s bms 300amp.  My second one was R1150, still waiting for after close to 4 months. Thats a 16s 320amp. Just as they shipped that one we went in to lock down. It's on it's way and tracking showing it's at JHB hub. 3de bms i order with a friend where we placed 4 in order with local Scottshipping and cost me R2050 and it was here in 3 weeks in the lock down time. Thats a 16s 320amp to. 

I'm just waiting for the lockdown to clam down, then I'm pulling a programmer closer to help with python script on a Pi to run all the data and stuff via pi to Grafana.  Got all the stuff for this. 

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Posted (edited)

@Gerlach  Sounds great. I'm a simulations / graphcis programmer so might write some code at some point for monitoring - Pi sounds good, Arduino better, they say, for low-level signal monitoring... bit of C code for low power consumption. Frankly though, I'd rather someone else did the work.

@Louisvdw Yes that's where I got the Daly I don't really want. Should just have bought cells from Bain. Thanks for the Smart ANT link!

I am very keen to get 2x Smart ANT or Smart 123 BMS. If you know of ANY local sources with stock, please shout! I don't want to wait months for arrival!

I do not agree with using 1x BMS and paralleling cells beneath this. Suppose even cells top-balanced and in parallel can still go out of balance over time - and the BMS will be none the wiser. Better to do 2x BMS and have that redundancy of 2 batteries / packs; if you need to take one down for maintenance, you can still rely on the other.

Edited by Wick

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33 minutes ago, Wick said:

I don't want to wait months for arrival!

I have not found any local supplies. But if you use AliExpress and take the Aramex/DHL/FedEx shipping options it will be at your door in about 2 weeks. (even in lockdown L3)

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@Wick i already got the python script. It just needs to be loaded on a pi and run via Node-red to Grafana.  Let me know if you need it. I need someone toe help me with it to get it up and running on a pi. 

Shipping you can do via Scotts shipping. This order we did in Level 4 lockdown.

Worked out about R2100 per bms with customs and everthing and was hand delivered in our hands. 

Screenshot_20200714-222147.thumb.jpg.60a5e857af3a90a5a54278962c01914d.jpg

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11 hours ago, Luminous said:

@Gerlach which site did you order from on Aliexpress? 

I have used scott's shipping before. Maybe i must chat to him to bring one in for me as well.

@Luminous You can check here. https://www.aliexpress.com/item/33014476298.html?spm=a2g0s.9042311.0.0.408e4c4dVnBege If you planning to order, let the guys know on the forum and do a bulk order then via Scott's. There some guys on the 4x4 forum. 

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Posted (edited)

One belated question for you @Gerlach, have you ever connected Smart ANT BMS to Victron MultiPlus / MultiGrid / EasySolar? I'm wondering if they can chat.

Edited by Wick

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1 minute ago, Wick said:

One question for you @Gerlach, have you ever connected Smart ANT BMS to Victron MultiPlus / MultiGrid / EasySolar? I'm wondering if they can chat.

The bms uses rs485 to communicate to the screen. There is some forums that that gives info. To get it connect to Victron, you need to find out from Plonkster if there is a way.

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3 hours ago, Wick said:

Grandmaster @plonkster , what sayest thou of ANT + Victron connection via RS485? Hast thou arcane knowledge hereof?

 

Haha. No. I know nothing about the ANT BMS. But I can tell you that Venus supports only CAN-bus BMSes, so RS485-styles won't work unless someone makes a driver for them. Which is not impossible, it's open enough that anyone with a bit of Linux+python experience could do it probably in about a weekend... 🙂

 

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I ordered the one from Bain for now, would have liked something more than 100A but this one is the same price as aliexpress for the 100A and then you don't have to worry about getting it here.

 

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