Custom BMS vs. Off-the-Shelf BMS: A Comprehensive Comparison

Customers who use products or applications powered by lithium batteries are concerning safety. As a professional custom battery pack designer and manufacturer, CM Batteries is committed to providing the most reliable battery pack. However, the Battery Management System (BMS) is the brain of lithium battery packs. what is the best battery management system？

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We suggest each li-ion battery pack should be equipped with one battery management system. The BMS would monitor individual cells with overcharging, over-discharging, and overheating protection. Besides, the smart BMS provides cell balance and SOH function.

We’ll explore how to choose a custom BMS or off-the-shelf BMS.

Different Battery Management System Solutions Comparison

A comparison between off-the-shelf Battery Management Systems (standard BMS) and custom Battery Management Systems(custom BMS)

Advantages of Custom Battery Management Systems

• The custom battery management system is designed with a compact size which makes the dimension of the complete battery pack smaller.
• More functions to protect the battery pack and custom the functions according to your needs.

Advantages of Off-the-Shelf Battery Management Systems

• The standard battery management system with lower cost.
• The technology of off-the-shelf battery management systems is more mature and stable.

What is the best battery management system? If you want to make your battery pack solution more reliable, one professional battery pack manufacturer who has rich knowledge and experience on li-ion cells, BMS, and battery pack assembly will support your business success.

Off-the-Shelf BMS Cell Configurations Limitations

Most off-the-shelf BMS are tailored for specific applications of electric vehicles, or grid-tied and off-grid battery systems. These systems might be limited to working with certain battery chemistries. For example, some off-the-shelf BMS are designed exclusively for lithium-ion chemistries, while others can handle both lithium-ion and lead-acid battery packs. In addition, off-the-shelf models may only be suitable for specific lithium batteries, such as 3.2V LiFePO4 batteries or 3.6V LiNiMnCoO2 batteries.

Cell configurations play a crucial role in the compatibility and efficiency of the BMS. The format, size, and array of the batteries must align with the capabilities of the BMS. The common cell formats are as below:

• Large prismatic packs,made of 3.2V 50Ah,100Ah,280A LiFePO4 prismatic cells
• Small cylindrical packs, made of 3.2V , cylindrical lifepo4 cells
• Large cylindrical packs, made of lifepo4 cells
• Pouches

The number of batteries in a pack can vary significantly, and off-the-shelf BMS may support anywhere from 2 to 11,000 cells, and 1 to 60 banks in series or parallel configurations. They might also monitor battery arrays ranging from 2 to 60 batteries in series or parallel.

However, the standard solutions also have limitations. At CM Batteries, we offer custom BMS solutions that provide greater flexibility and control. We can design and manufacture a BMS that precisely fits your battery pack’s configuration and application needs.

Standard Battery Management Systems Feature Limitations  

As a dedicated custom battery pack designer and manufacturer, we have realized the challenges of off-the-shelf battery management systems. The BMS manufacturers strive to meet the diverse applications and industries and tailor to specific consumer needs. However, this approach inevitably leads to feature limitations without the desired functions.

For more Customized battery systemsinformation, please contact us. We will provide professional answers.

Tailored Solutions for Unique Needs

Both custom and off-the-shelf battery management systems prioritize essential features such as battery cell protection, and charge/discharge monitoring. The off-the-shelf systems typically provide these core functionalities. However custom battery management systems offer the advantages of additional tailored features that enhance performance and longevity. The extra functions are included:

• Cell balancing
• Charge control
• State of Health (SOH) readings
• State of Charge (SOC) readings
• Logbook function

Choosing a custom battery management system from CM Batteries allows you to go beyond standard offerings. We can design and incorporate features specific to your application’s requirements, ensuring seamless integration and optimal performance. Whether you need advanced monitoring capabilities or specific functionalities like detailed SOH and SOC readings, our team is committed to delivering solutions that meet your exact specifications.

Data Packages and BOM: Custom Solutions vs. Off-the-Shelf Options

At CM Batteries, we prioritize transparency and comprehensive technology support for our customers. One professional custom battery pack manufacturer and custom BMS designer offers integrated solutions that include both the battery pack and the BMS system. This comprehensive package includes a full data package, Gerber data, schematics, and a bill of materials (BOM). These detailed resources empower our customers to fully understand the functions, features, materials, and component layout within the BMS system when applied to their specific applications. Off-the-shelf battery management system manufacturers will not go into such information about their goods’ manufacturing processes.

The custom BMS designer will provide a technical instruction about how to set up, install, and test the battery management system with the battery pack, but will also supply basic and detailed specifications for the electrical and mechanical features of the components.

BMS Testing of Custom Solutions vs. Off-the-Shelf Options

Off-the-Shelf BMS Testing

Off-the-shelf battery management systems undergo design testing based on specific cell configurations, battery sizes, and formats advertised to customers. While manufacturers conduct initial testing, the end customer is responsible for ensuring proper functionality post-installation. This includes verifying that the BMS effectively controls charging and discharging and monitoring initial cycles to confirm optimal operation.

Not all off-the-shelf BMS feature programmed software, some utilize analog technologies with fault detection capabilities. However, advancements are introducing more digital systems with programmable software, featuring GUI interfaces, State of Charge (SOC) displays, dashboard gauges, and status indicators. Manufacturers may seek independent testing from organizations like Underwriters Laboratories (UL) to validate performance and safety.

Custom BMS Testing

Custom BMS should be verified with the battery management systems many times before mass production. The customer and manufacturer should make their needs very clear and work closely. A complete BMS development also includes PCB assembly and testing, which will take a lot of time.

Technical Support and Maintenance

Custom BMS solutions typically come with dedicated, specialized technical support. Manufacturers offer in-depth knowledge and tailored assistance. Off-the-shelf BMS systems provide standardized technical support, which may lack the depth of understanding needed for complex or unique applications.

Regular updates and maintenance will modify the reliability and performance. Off-the-shelf BMS systems may require more frequent maintenance and updates to address evolving standards or operational requirements.

 Choosing the Right Solution

The decision between off-the-shelf and custom BMS hinges on your project’s unique demands and long-term objectives. Off-the-shelf solutions offer quick development and standard quality but may struggle to adapt to future innovations. On the other hand, custom BMS solutions empower you with flexibility, scalability, and tailored support, ensuring optimal performance and alignment with evolving technologies.

Want more information on Battery Energy Storage Solution? Feel free to contact us.

I've been thinking of a set standard on battery packs and believe it's finally time to create a simple standard on what kind of battery packs work perfectly well for our DIY Electric Skateboards.

I'm been looking into moving into Lithium NCM cells and/or LiFePO4 cells with built in charging ports.

My Reasons For Choosing Completely Custom Battery Packs
- completely custom build battery packs -- under 1" (Ex 8/9ah) or 1.5" - 1.5" if you want more capacity/longer distance Ex. 11ah
- longer life cycles
- built in charging ports
- option for cheaper battery chargers (use of multiple packs) (ex. work/home)
- safer battery packs
- safer charging - ability to leave charger alone no need to watch or monitor your charger (aka lipo)
- battery led indicator *save additional cost built-in
- built in on/off switch *save additional cost built-in

A low profile metal enclosure is on my to do list as well.

I'll actually create a post on this as it's something I've been looking into lately.

COSTS!!!
Factor in the costs for a nice lipo battery pack other than 6S --> 8S/10S/12S are hefty in cost and lack the other great features. $100-$160.

A HobbyKing 350W Power Supply + iCharger 208B = $160-$180

Easily a $300 battery pack for LIPO!

We could very easily have a $300-$450 battery pack that would have 2-5 times the life cycle as a standard HK Lipo battery.

Replacing our batteries every year or every other year isn't ideal. It ends up making our boards cost way more then they should.

What are your suggestions and your ideas on a custom battery pack that is most ideal?

Enclosure Questions

Do you prefer an aluminum one piece enclosure that goes across the entire bottom deck?

Do you prefer two aluminum enclosures to keep the flex within the center of the deck?

Define your most ideal enclosure for your battery pack + electronics? 100% behind your battery idea! Definitely at least 8ah, especially bc from what I've read on here pneumatics get less range. My HK150a esc only takes up to 6s, so not having to get a new esc would be nice.

As for enclosures, definitely sold on aluminum, again from what I've read on here (help dissipate heat and serve as a safe box for batteries). 1" in height would be perfect. Currently, I've got 2x3ss, so the minimum width of my box has to be 7" to leave room for wires, which will run between the two (not at all an ideal width). I'd imagine your battery will be much narrower than 7" though.

I'm stuck at the same fork in the road, regarding the placement. On one hand, I love Boosted's setup, with the wires concealed under the grip tape. But I'm not sure if there's a significant advantage to a split setup that would merit the work to make it. My board is stiff, and I'm planning on future decks to be too, so that's not a factor for me. I've been looking into a 7S mah pack and a 13S mah pack. Still debating and looking into if I want LiNCM packs or LiFePO4. LiFePO4 has a much larger life cycle rating than LiNCM - Although, heavier and bigger.

I was planning on about 7" width and perhaps 12" or longer and 1" height is what I would prefer.

13S mah will actually get you much further than 7S mah because of the Watt Hours. However, I have yet to figure out the actual run time for both.

We aren't using Lipo batteries so they are much bigger in size or slightly bigger.

I also prefer stiffer decks as I go downhill and uphill more often. I do need them to flex a little as I tend to ride down slight curbs. Too stiff and it might put stress on components. I do like enertion's setup with the wires underneath as trying to put them over the board for a kit is a bit too much unless you know how and have the tools.

I'm thinking of going with an aluminum enclosure that can be easily removed. I'm also trying to think of how it can be easily opened as well even though with these packs it probably doesn't matter a whole lot. What do you guys think? For some reason, I still like the option of easily opening my enclosure regardless if I ever use it or not.

So far from the looks of it. 7S mah will cost about $200-$220 and a 13S perhaps about $300-$350 in LiNCM. Haven't fully checked on LiFePO4.

My pack ratings are about 40A Cont and 80-100A Peak. With a 13S pack we won't nearly hit those amp ratings and they would actually be way less. Perhaps on the 7S it may be around those ratings.

I choose LiNCM for lighter weight and cheaper cost. I'm still debating as the LiFePo4 life cycle seems to be much more. Just need to decide if the trade off is worth it aka bigger packs + heavier weight.

ESC + Receiver shouold be fine. Velcro adhesive from HobbyKing seems to work real well. They can take the vibration. I would wrap my battery around a thin piece of foam although my current lipo's aren't and it's fine.

drmacgyver said: Shadeeba: I've seen a video that showed how to assemble lifepo4 cells that had screw tops and connected to each other with either copper or steel brackets. If I can find that video I'll link it. I'd imagine soldering would be a more reliable method though.

I think 8 of those 3v blue lifepo4 cells would make for a nice size/power pack (2 rows of 4). And I think they're 10ah too, which is awesome.

I can't find the pic. One of the coolest boards I've seen. On wacky boards .com or sounded like that. It was an aluminum deck with 2 or 4 red batteries which looked like they simply bolted at the terminals. Like the visible-board. Probably protected enough and a safer chemisty than lipo and ok exposed to rocks flying. Ill be looking for those connectors and how they do. I've seen pressurized with foam or something non-solder connections but not for sale to build something as small as 8ah. Loose cells that screwed on w some electrolyte jell at the connection if need be.. Still sounds very convenient. And cool looking.



Translucent DIY batteries might be cooler @torque they say great minds think a like

I too have been thinking about higher voltage for some time now, even more lately since vedder came on the scene with his high voltage ESC.

I have also been spending more time reading about electric bikes, the DIY E-bike scene has a lot more minds and several years head start on the DIY eboard scene... I guarantee you won't find many people building e bikes with 6S batteries. In fact even 8s or 10s is too low for most.... & there is a good reason, higher voltage is more efficient.

Obviously you can build higher voltage batteries using LIPO... but it gets problematic... Lipo pouches are more difficult to arrange when you are dealing with the small area under a skateboard deck. I must also mention more volatile chemistry.

So whats the smallest high quality battery available... looks like is the winner! at only 18mm diameter its VERY SLIM... However it needs to be used in a system thats not going to suck it too hard...Or you need to build a very large pack so it can supply the appropriate power output... but we only have the size of a skateboard to work with.

Hummina Shadeeba said: The li-ion will hit 20c and i hear thats good enough.

What cells are you referring to? Are you talking type? I think the Sony VTC5 are 12C which equates to MAX 30A cont discharge.


So i have spent some time thinking really hard about how to design the best electric skateboard components housing possible to hold the large number of cells required to deliver the power we need.

I love aluminium, it is relatively low cost, low weight & also fairly easy to work with & i think it looks great >>>


The only problem with aluminium is it you need to use what is already available, or make your own design by extruding from a mold, so to make the perfect housing to hold cells you have some expensive setup costs before you get your final product.

Also aluminium can interfere with radio signals, so for you guys with Wii receivers that would have to be housed in something else because there is no antenna to mount externally....


I personally think separate box for battery & esc is better for several reasons, for example having them separate is better for people who want to use a slightly flexi board as the flexi bit is in the middle where you don't have stiff aluminium....

However when you start to size up your cells into a format that can offer ample Wh (enough for 1.5 to 2hrs ride time) you realise that the size of the battery is fairly large, especially when your primary objective is SUPER-SLIM... which is what i want.

If you don't care about component housing thickness you have many more options.....

So you get to a point, due to battery size, where there is no point having them separate, because the gap would be about 1 inch! so no benefit.

So for me i am focusing on one single components housing......

My reasoning is, that most people do not want really flexible decks... mostly because they are not great for handling when travelling at high speeds of 45km/h plus

So this is the concept i'm working on at the moment, its a constructed housing made from a composite of carbon fibre, GR10 plate & aluminium.... super lightweight, very strong, no radio interference, only 24mm thick, & looks frocking sexy!


[youtube]HdZmRjFfWuU[/youtube]

I have taken inspiration from multicopter chassis.

I am also developing a special anti-vibration flexible mounting system that will allow the, mostly rigid housing, to be fitted to boards that have a bit of flex... However if you have a really flexiboard you will need a smaller battery and a split housing design. @onloop -- Ebike's are awesome. I've been wanting to build one but no time/space and wouldn't use it as much. Another big rabbit hole to go down. Can't fit the bike as easily on a commuter train and/or at work either.

From what it looks like 33-36" boards would be a bit too small for a thinner and larger pack. 38" - 42" boards similar to boosted/evolve would need to be used to allow for the additional space for the battery packs.

are nice.. Question is supposedly LiNCM are about 800- life cycles and LiFePO4 is about - cycles. I could be wrong haven't done additional research on it just yet.

I'm opting for the LiFePO4. If your spending $300-400 on a pack. I'd rather have the longer cycle pack.

That's also a major issue if we want 8ah to 11ah and underneath 1" in height. We need to use all space available. Having a 2 part enclosure makes it a bit more difficult.

I also agree with the flexible decks. I climb hills and go down steep hills with potholes in the way. I'm not really interested in a flexible deck. Also flex decks are mainly used for people going around 20mph and pot holes aren't as existant. If I didn't have to deal with potholes. I probably would think otherwise but for commuters I would prefer a sturdy deck. I also want the added space.

@voodoojar.

Those are some pretty great prices. I think something around 8-10ah would be a bit better for longer rides. What do you expect those 6.8ah packs to achieve in miles? What are the cont amp and peak amp for the pack? @Silenthunter - For the 13S, I plan on using Vedder ESC once it's available.

@Drmacgyver - Some 's are the same voltage as lipos and are 4.2v max and 3.7v nominal. I plan on using similar cells with 3.7v nominal. Voltage should be equal if you are referring to LiFePO4 you might be right. I haven't done as much research with LiFePO4.

I plan on switching to LiFePO4 for the added benefit of increased life cycles as well. It only makes sense hopefully it doesn't affect the size and weight as much but it perhaps might.

I plan on using my new packs with either the 8S 120A Dual ESCs and/or Vedder's ESC once it's available.

The reason for the odd cells 7S/13S is what is readily available with my supplier which would keep costs considerably lower and quicker to produce. 7S should be fine for single or dual boards looking to go under 20mph. I've been using 6S and I think I've outgrown it and enjoy using my 8S packs but they are considerably much more expensive than my 6S packs as well as since the life span is not as long as I would like. I prefer to use a custom built pack if I'm spending the money anyhow. Not sure how many miles most people have traveled with their board just yet. 8S allows me to go up hills much faster. I think the minimum height we'd be able to get with lifepo4 is right under 2". The holders for the lifepo4 headways are 40mm x 80mm and the cells themselves are 138mm x 38mm. The 's are really small though. I guess the way I see it is my enclosure now is 2.5", so getting down to 2" is still an improvement. Add to that a better battery and it's a win-win. It's still not close to ideal, which I know will irk me.

As far as speed is concerned, we should factor in the increased speed from the pneumatics for those of us that will be using those. While having extra voltage would be nice too, I've been happy with 6s (1:3 on 83mms). I think the pneumatics will give me that extra speed without having to up the voltage. The only thing I'd like are more AH's, which the lifepo4's definitely offer.

There's other factors to consider, but basically it seems we're talking about:
A slimmer (prettier?) product for a shorter time -vs- a bulkier (uglier?) product for a longer time.

I'm not sure if we'll ever reach a definitive answer, but I'm interested to hear what more people think about "size vs life span". I think you'll still find that Lipo packs are the best option. I spend some time over on the ebike forum and most of them are still using Lipo packs or want to switch over. You just can't beat their pricing. You can get 12s mah packs for around $75. Compare that to $300 to $400 for other similar Li chemistry packs. The bikers use higher voltage because of a few reasons. Most ebike controllers are rated at 30amps max. You reduce amps by increasing voltage. Also most of them are trying to increase speeds or get over a certain speed. As you know higher volts equals higher rpm and thus higher speeds. Eboards might benefit from 8s, but not much from running 12s. I've never found that I need to go faster. I've gone the other way though. Lowered the gearing to climb hills faster and make it easier on starting.
Ease of use is another thing, but not worth the extra costs. If you want higher voltage use the Lipo in series. You can get two mah 4s hard case packs for $25 each - that's cheaper than one 6s pack. Plus you keep saying a charger is over $150. You don't need a 150w charger if you charge two packs in parallel. The cheapos will do just fine.
You also will be dealing with larger size and heavier weight with other chemistries. Seems like a step backwards. Again bikes can get away with this, but on a small board you don't have the room. C rating is another factor. Most of these other packs aren't able to drain very quickly. As soon as Rc goes to something else it'll be time to change. I do think the Multistar batteries look interesting and might be great for boards. I've seen a few bikes using them. They have some mah packs. Stinks to get a bad cell on something like that.
In regards to bad cells. It does stink to have to replace batteries every once in awhile, but I had a gas powered skateboard before, and I spent much more on gas. I have batteries that are over two years old still.
I do wish that there would be some more communication between the forums. You are right that they have a few years on us with this stuff. As a boarder turned biker I'm frustrated with ebike controllers. They are massive compared to what boards use. It would be awesome to have an RC controller on a bike, but there are issues that haven't been addressed by the manufacturers. The great thing about RC stuff is the companys make so much product it brings the costs down and they are obviously making things as small as possible.