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BMS china vs Batrium
#1
Hi All another newbie question  Smile

I see Batrium seems to be the choice of many for balancing their packs, but that does come at a price, and appears the Rolls Royce of BMS's 

I have recently seen a video by  "DIY Solar Power with Will Prowse"

 https://www.youtube.com/watch?v=im4ggvon...gQ&index=2

This is a BMS offering from HK/China seems from the Video very cheap, has also low and upper temp control and looks like it can match the job of a Batrium at a fraction of the cost, (I would love a Batrium but at the moment cost prohibitive for me).

Has anyone any experience of this device? I was looking at building the BMSDIYv4 but Will's solution looks like it could save me loads of build time. 

I've taken a punt and order one, its not going to arrive until mid January, if anyone else is interested here's the link.

https://www.ebay.co.uk/itm/Smart-Lifepo4...2749.l2649

When it arrives I'll try it out and post my findings in the mean time if anyone has any experience of this device I would love to hear.

I understand that the main battery leads will probably need to be upgrading

Cheers

Paul
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#2
No it cannot match Batrium

Its like with everything else that for most gear the price defines what you get in the end. A cheaper BMS will work to some extent as said. And you choose the Gear based on your goal and what you can afford compare to what you need.

Its cheap for a reason and if you start to look at what Batrium can do and how accurate it can do you you quickly see whats going on between them.

I have tested many BMS systems during the year but for my main powerbank Batrium just works and I have not touched my main battery bank for 2 years now...
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The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#3
Agree with @Daromer 100%.    

One example (but by no means the only example) of what Batrium does for me is 'ongoing info'...  which I record.  This is critical for my strategy to detect/repair failing packs and to provide clear insight into what's happening.   

I think that one aspect of this cheap vs expensive discussion is short-term vs long-term.  For the short-term, sure a cheaper BMS may be completely adequate protection.   For the long term... and/or larger power production... the decision becomes clearer over time.
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#4
Thanks offthegrid and daromer, appreciate your reply's, its obvious this journey is not necessarily going to be cheap.

I fully understand the risks of using such high density storage devices so its key to air on the safe side especially dealing with Balancers. Did you folk start off with a Batrium or did you start of with something more basic first?
I've quickly discovered by the time you've purchased your batteries, solar panels, inverter and BMS the money soon mounts up.
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#5
Yeap its not cheap. If you think Batrium is expensive i can say that batrium was 3% of my battery cost and just 1% of my total cost Big Grin


For a small 1kwh battery bank i would agree that Batrium is way over the top expensive comparing and for such a system a cheaper BMS might just be the best choice.

It is what makes "you" feel secure over the installation that you basically pay for. But at same time just getting the gear does not make it safe unless its set up correctly and you know how to work with it.

Many people havent even tested critical fault and have no idea how it works. Then they come back weeks later complaining "The BMS didnt work"..... In most cases user-errors.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#6
As you know the board members here are heavy with batrium. But there are a few of us that do use chinese bms and have achieved a level of success. The most important thing for a bms is to be able to report and trigger a cutoff when necessary. The other aspect is to balance the packs. I managed to take the output from my active balancer and log the output into the influxdb database. At this point I am still fascinated and watch this data over grafana daily. So I do know just as much as a batrium system would report and I would not even think a batrium system would do any better. Some members here think a batrium is the only answer and that it is money worth spent, but I disagree, since it's still a diy effort and if you're willing to work on it, then its worth it. Otherwise why bother building a DIY powerwall at all? Just buy a Tesla powerwall and you have all of the above, all supported, with warranties, etc.

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#7
(12-19-2019, 10:52 PM)not2bme Wrote: As you know the board members here are heavy with batrium. But there are a few of us that do use chinese bms and have achieved a level of success. The most important thing for a bms is to be able to report and trigger a cutoff when necessary. The other aspect is to balance the packs. I managed to take the output from my active balancer and log the output into the influxdb database. At this point I am still fascinated and watch this data over grafana daily. So I do know just as much as a batrium system would report and I would not even think a batrium system would do any better. Some members here think a batrium is the only answer and that it is money worth spent, but I disagree, since it's still a diy effort and if you're willing to work on it, then its worth it. Otherwise why bother building a DIY powerwall at all? Just buy a Tesla powerwall and you have all of the above, all supported, with warranties, etc.


Not sure if I missed a build thread. If I did please link it! I'd love to see a thread on how you got that all to work. Which hardware and whatnot. That would be awesome to setup.
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#8
For balancing a pack, especially if the pack has balance issues, active balancers work best. The bms in your link only balances at 100ma, if you plan to fast charge your pack at high amps, the 100ma might not keep up with that.

If you plan to charge your lithium with solar, a bms that uses external contactors to stop the charge is recommended. If the bms uses mosfets to stop the charge you will get power surges from the charge controller.

I been using the chargery bms8 as my bms on my 4s 220ah lifepo4 which is charged by a 240 watt panel/20 amp mppt. The chargery cost me 86 dollars and uses external contactors ( I use 4 dollar 30 amp automotive relays) . This bms also balances at 1.2 amps per cell. It has a nice bright lcd where it shows each cells voltage.

I used almost a year and has been perfect, it just works. All the other bms I use gave me voltage surges when they triggered. No more voltage surges. If you will be charging with solar and your new bms gives you voltage surges, get a bms with contactors.
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#9
(12-19-2019, 10:52 PM)not2bme Wrote: As you know the board members here are heavy with batrium. But there are a few of us that do use chinese bms and have achieved a level of success. The most important thing for a bms is to be able to report and trigger a cutoff when necessary. The other aspect is to balance the packs. I managed to take the output from my active balancer and log the output into the influxdb database. At this point I am still fascinated and watch this data over grafana daily. So I do know just as much as a batrium system would report and I would not even think a batrium system would do any better. Some members here think a batrium is the only answer and that it is money worth spent, but I disagree, since it's still a diy effort and if you're willing to work on it, then its worth it. Otherwise why bother building a DIY powerwall at all? Just buy a Tesla powerwall and you have all of the above, all supported, with warranties, etc.

Can't agree more, including being addicted to watching the Grafana stats ;-)
Those Chinese BMSs are more aimed towards ebikes and such, so they only provide Bluetooth (ie short range) Apps for viewing stats.  Requires some programming knowledge to make the data available via WiFi/LAN/Internet.
Also the balancing current may be inadequate for larger powerwall batteries.  It'll depend on the quality of your cells, but I'd say 10kWh is about the max, at which point you should consider using 2 batteries with one BMS each.
Have a look at my powerwall.  I currently use 4x similar BMSs in parallel.
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Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#10
(12-20-2019, 03:55 AM)gpn Wrote: Not sure if I missed a build thread. If I did please link it! I'd love to see a thread on how you got that all to work. Which hardware and whatnot. That would be awesome to setup.

Here is the link
https://secondlifestorage.com/showthread...3#pid35023

I have to say the balancer I'm using right now isn't the best. It balances but with no adjustable parameters. So I can't trigger it to activate at certain voltages, etc. It just balances to 40mv. Other than that it functions. What it had was it uses a TTL serial output to a LCD screen to display the current voltages. I knew I could take that serial output and bring it into the raspberry. From there that's where the magic happens, using python, it takes the output from the LCD, then I parse the output through it and input it into influxdb. Don't need to have any real programming skills but I've learned enough through the years and it's really the basic stuff, taking a string of characters like 'Temp: 10.0c' and extract just the 10.0 part of it. Grafana is currently alerting me when voltages and temp are reaching critical values, while when reaching critical values I can fire off relays to cut the battery.

The bms from the original poster is what I believe ajw22 is using and there's quite a few posts on communicating through bluetooth on that unit already. I would check his setup out.

I'm working on another active balancer that has programmability and bluetooth communication. I think this one is worth exploring and if I do get it to work I will post up a build thread just on it. My goal is to have an under $100 bms that is good enough, combined with a raspberry pi, able to fire off a few relays and sense a few temp using a 1-wire sensors.  
This is the balancer.
https://www.aliexpress.com/item/32945565819.html
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