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diy solar

Help us design a rack-mounted system for the UK

B

Ben@Fogstar

Solar Enthusiast
Joined
Aug 25, 2022
Messages
45
Hello,

It's my first time posting here, we run a small business in the UK - but have offices and warehousing in China (www.fogstar.co.uk). We have several customers on this forum and thank you if you have purchased prismatic cells from us in the past.

We're looking to design a rack-mounted 48v 100Ah battery - however, we've come to a point where there are design specifications that we'd like feedback on. We'd like to ask all you knowledgeable folk what you'd like to see as a consumer. We're extremely honest, and like to tell our customers everything about what's inside of each rack - something we believe is missing from most retailer websites.

Cells

Some of these cells have been selected due to the size of the rack we are trying to create (3U) - most Chinese racks are using Gotion grade B cells - and quoting something like 7000+cycles. This is simply not true, however, they are extremely cheap.

EVE 100LA Grade A
  • 100Ah
  • Will fit in a 3U system
  • Good cycle life
  • Good relationship with Eve
  • Expensive
Gotion 100 Grade A
  • 100Ah
  • Will fit in a 3U system
  • Average cycle life
  • No pre-existing relationship
  • Cheaper
Gotion 100 Grade B
  • Most racks using this cell
  • 100Ah
  • Will fit in a 3U system
  • Bad cycle life
  • No pre-existing relationship
  • Cheapest
BMS (JBD vs Pace vs ?)

Pace
The general consensus in China is that PACE makes the best BMS for storage batteries (found in Jakiper Batteries). They've been established longer than JBD, however, they don't have much of a following. 5 inverter protocols can be programmed into each Pace BMS - however a new version of the pace BMS will soon be able to handle 10 inverter protocols.
  • Expensive
  • 5 Inverter Protocols (10 soon)
  • Lack of APP. but we could make one
  • Windows Software
  • Less of a following and community projects
  • More Reliable (?)
JBD
  • Inexpensive
  • 5 Inverter Protocols
  • App
  • Windows Software
  • Popular, with community projects
  • Less reliable (?)

Any other BMS suggestions? Seplos? (although I think pace make this) JK?

I think the EVE LA with a JBD BMS is the best solution. Cells we really believe in, with a BMS that seems to be tried and tested.


Let me know your thoughts, happy to upload spec sheets of each cell if it helps

Thanks,

Ben
Fogstar
 
Hi Ben

I've had 16 x LF280Ks from you recently and have another 16 on backorder for October, i've been looking at the prospect of using an empty Seplos Mason box with the JK-BMS (active balancing). We will be bolting it to a Victron Multiplus II 10kw 48v to do ESS - canbus to JKBMS.

Given the speed that your batteries flew out the door, I wasn't surprised that when I went to place my 2nd order after QA'ing the 1st 16, that the 700 left a week before had all gone, so there is definately a market for boxes for the 280/305Ah cells in the UK to put those in, as shipping from China is probably putting must folk off.

Theres also these - https://www.alibaba.com/product-det...00593903876.html?spm=a2700.9114905.0.0.efraa7

Regards

Simon.
 
Last edited:
I don't think that JBD has a bms that is designed for server rack casing. Which one you had in mind?
 
I think cycle life is king, and I suspect most people would do the cycles vs cost comparison pretty instantly - So I'd go for the EVE cells. It is also less hassle as you won't be replacing it too often.

Also for ease - whatever BMS it should be Pylontech compatible -people want ease of use - and everything supports Plylontech.

A display would be nice to quickly check the pack - Bluetooth etc is great, but sometimes you just want to quickly check without digging out the phone. If you want to stand out against the name brands something like a decent nextion display adds more perceived value than it costs - Pretty graphics with SOC, battery temps and balance info. I say nextion as adding one is very low on development costs, but you could save money on production but spend more on development using something else

Of course Bluetooth is great for checking in depth, but that probably would be less important to the average buyer.

Then again, here is not necessarily where you will find the average buyer and so the answers might be a bit skewed..

Oh - make sure they are stackable!

and a DC breaker - they are a bore to find and then get a case and glands for.

Easily sourced DC connectors too.
 
Last edited:
Ben@Fogstar said:
... I think the EVE LA with a JBD BMS is the best solution. Cells we really believe in, with a BMS that seems to be tried and tested.
Click to expand...

I'd agree with the above. I am using grade A 280Ah cells purchased from yourselves, with an Overkill BMS, which is based on the JBD and have been very happy with the result.

From making a rack-mount server point of view, it would be, IMHO, great for the UK and European market. I looked into lots of possible pre-made solutions and none were ideal or readily available, or shipping costs from USA were too expensive, so went down the DIY route.

I guess because of weight and cost, rack systems usually come in 100Ah, rather than 280Ah solutions - which means that you will need to engineer a way of interconnecting multiple racks together and providing the necessary data to an inverter. As mentioned above, most inverters support Pylontech protocol, but as they are based on 15cells rather than 16, maybe not always compatible with all inverters.

So, in answer to your question as to what I'd like to see as a consumer...
- Grade A cells for sure and a "known and specified" BMS,
- Support for range of inverters,
- LCD / similar type display on the battery rack to see what's happening at a glance (as mentioned above too),
- MQTT output for integrating with emonPi or similar monitoring systems,
- The ability for advanced users to "configure" their system - e.g. the ability to set DoD to their own settings, rather than all have to use the same settings. Or the ability to restrict charge rates at high and low SOC or temperatures - as some people will care more about DoD than longevity and others the opposite,
- Low temp cut-off is a must (JBD does this anyway),
- A heater, or at least a heater option - e.g. like Trophy offer - for those in UK and Northern Europe who may want their racks to be in unheated garages / outbuildings etc. would be a huge bonus,
- Finally I _don't_ see any need for an IP54/65 type rating (as, for example PureDrive have). Just my opinion, but I don't think many in UK would want such expensive equipment to be outside in the wet and cold weather we have, let alone the risk of it being stolen.

Hope that helps.
 
Richard_C said:
I think cycle life is king, and I suspect most people would do the cycles vs cost comparison pretty instantly - So I'd go for the EVE cells. It is also less hassle as you won't be replacing it too often.

Also for ease - whatever BMS it should be Pylontech compatible -people want ease of use - and everything supports Plylontech.

A display would be nice to quickly check the pack - Bluetooth etc is great, but sometimes you just want to quickly check without digging out the phone. If you want to stand out against the name brands something like a decent nextion display adds more perceived value than it costs - Pretty graphics with SOC, battery temps and balance info. I say nextion as adding one is very low on development costs, but you could save money on production but spend more on development using something else

Of course Bluetooth is great for checking in depth, but that probably would be less important to the average buyer.

Then again, here is not necessarily where you will find the average buyer and so the answers might be a bit skewed..

Oh - make sure they are stackable!

and a DC breaker - they are a bore to find and then get a case and glands for.

Easily sourced DC connectors too.
Click to expand...

Thanks! We've found a full colour LCD we want to use. So have incorporated this. It was actually cheaper to add the LCD than I first thought!

We've added a DC breaker, but we've had to increase the case size to 3.5U as we were just running out of space for features.

Thanks for the help and comments
!
 
SeaGal said:
I'd agree with the above. I am using grade A 280Ah cells purchased from yourselves, with an Overkill BMS, which is based on the JBD and have been very happy with the result.

From making a rack-mount server point of view, it would be, IMHO, great for the UK and European market. I looked into lots of possible pre-made solutions and none were ideal or readily available, or shipping costs from USA were too expensive, so went down the DIY route.

I guess because of weight and cost, rack systems usually come in 100Ah, rather than 280Ah solutions - which means that you will need to engineer a way of interconnecting multiple racks together and providing the necessary data to an inverter. As mentioned above, most inverters support Pylontech protocol, but as they are based on 15cells rather than 16, maybe not always compatible with all inverters.

So, in answer to your question as to what I'd like to see as a consumer...
- Grade A cells for sure and a "known and specified" BMS,
- Support for range of inverters,
- LCD / similar type display on the battery rack to see what's happening at a glance (as mentioned above too),
- MQTT output for integrating with emonPi or similar monitoring systems,
- The ability for advanced users to "configure" their system - e.g. the ability to set DoD to their own settings, rather than all have to use the same settings. Or the ability to restrict charge rates at high and low SOC or temperatures - as some people will care more about DoD than longevity and others the opposite,
- Low temp cut-off is a must (JBD does this anyway),
- A heater, or at least a heater option - e.g. like Trophy offer - for those in UK and Northern Europe who may want their racks to be in unheated garages / outbuildings etc. would be a huge bonus,
- Finally I _don't_ see any need for an IP54/65 type rating (as, for example PureDrive have). Just my opinion, but I don't think many in UK would want such expensive equipment to be outside in the wet and cold weather we have, let alone the risk of it being stolen.

Hope that helps.
Click to expand...

Thank you. I agree with the IP rating - not many people will want an outside system. We've added a heating function so battery can be charged down to -20C. So storing in garages etc won't be an issue.

A premade 48V system using Eve 280Ah/Eve 304 is the next project. We're also looking at stocking a seplos system for those who like DIY. It's finding a UK carrier that will pallet ship for a reasonable price.

Thanks for comments, all taken on-board.
 
hello and good luck with project. seeking feedback in earnest in forum is admirable and thank you for spurring discussion.

thermal regulation is a rare feature, heating type, even more rare is cooling and heating type. due to engineering burden, heating type quickest roi maybe.

active balancing is a feature desired by some. with matching cells it is less important of course. passive balancing at least is expected.

thank you for posting.
 
Ben@Fogstar said:
Thanks Simat. I am speaking to them now, either way I think we should offer this BMS.
Click to expand...
If you are speaking to them - they do have a canbus option - it just needs programming to make it usable . So I would suggest asking them to add a pylontech compatible mode. I think it would be worth the investment. It seems a good BMS - apart from the few cases reported of it dying after a few months - Hopefully they will resolve this.
 
+1 for JK BMS - I'm using this integration which has a few additions that enable the JKBMS to "talk" in Pylontech's CANBUS protocol, and so far it's been brilliant ( ? the fact that the JKBMS has 2.0A active balancing, which is why I'm glad I went for it over the Seplos BMS):

diysolarforum.com

DIY Battery via Smart shunt to inverter integration (Solis etc)

Hi All, I've taken some code that handles Victron's VE.Direct protocol (Smart Shunt) and added in CAN Bus / PylonTech protocol connections, this allows the State of Charge, Voltage, Amps etc all be sent to the inverter - any one that supports the PylonTech protocol. I have it connected to a...
diysolarforum.com diysolarforum.com

(decided to go this route rather than using the JK BMS CAN/RS485 port/adapter, as I really like the fact that @sijones2010 's integration means you can use any BMS with the battery, which future-proofs the DIY build hugely! Plus, I really like the Victron Smart Shunt, despite its price-tag).
 
Ben@Fogstar said:
Project underway, screen development took an insane amount of time. However, I think it'll be worth it in the long run!
Click to expand...

100Ah cells & Seplos BMS? (I know, I probably shouldn't be asking as still in development).

Know how it feels re the insane amount of time - always more challenging when there's already too many other things going on!!
 
Looking good - does it have the heating function discussed above for when it's ☃️ out there?
 
Ben@Fogstar said:
A premade 48V system using Eve 280Ah/Eve 304 is the next project. We're also looking at stocking a seplos system for those who like DIY. It's finding a UK carrier that will pallet ship for a reasonable price.
Click to expand...
Ben, i think the issue wont just be with the shipping, when they get to their destination, how will someone be able to pick them up and move them? However if you also designed a self build pack of four boxes of cells and one box containing the rack mount (or wall mount?) then it becomes more viable
 
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