80a bms with 200a controller

[Chris A]

Hi guys. I’m new here and have had a 72v enduro e bike for over a year now. I recently blew the 100a controller that came with the bike and have upgraded to a 200a. However my battery bms is only 80a I believe, is there a way to upgrade the bms to 200a to get the full power potential? And are there any other upgrades I should consider? I’m looking to get more power from the bike. It’s currently got a 8kw hub motor with a 21” rear wheel and struggles on hills and off road

 

[lnanek]

A BMS doesn't gradually decrease your current up to the max, it cuts the current off completely when any limit is reached. So doesn't sound like you are actually hitting the BMS limits yet.

 

[fechter]

The BMS should be rated a little higher than the controller maximum so it doesn't trip during normal operation. Make sure the battery can handle it.
Do you know what the battery configuration is?

 

[amberwolf]

Hi guys. I’m new here and have had a 72v enduro e bike for over a year now. I recently blew the 100a controller that came with the bike and have upgraded to a 200a. However my battery bms is only 80a I believe, is there a way to upgrade the bms to 200a to get the full power potential? And are there any other upgrades I should consider? I’m looking to get more power from the bike. It’s currently got a 8kw hub motor with a 21” rear wheel and struggles on hills and off road

If the bike is operating normally even under the worst case load, with the new controller, but the original BMS, then either the controller is not ever drawing more than the BMS can supply (80A, if that's it's max rating), because the load on the motor is never higher than that, or else the BMS has failed and is unable to turn off it's output when overloaded or any other problem happens (the FETs are stuck on, so that the BMS can no longer protect the pack).

Regarding changing the BMS to 200A from 80A:

Can the cells in the battery handle the more-than-doubled current? I expect they probably can't. The BMS for a pack should be chosen to limit current to whatever the cells can handle (and so should already be the right one for the cells), so if you change the BMS to a higher-current one to try to use the cells at more than twice their original current you could damage them (which could lead to a fire, in the worst case).

Best case if they can't is they'll sag in voltage a lot under the higher current demand, reducing actual power output at the motor to much less than if they were capable without such sag, and the cells will heat up faster than normal, and have less capacity (range) than normal, and the BMS will shutdown output sooner than normal when under enough load to cause sag below LVC. The cells will also probably unbalance easier and worse, and require much longer time on the charger to rebalance them after the main part of charging is complete.

If you have specs from the battery (not bike) manufacturer on the cells themselves (not the battery as a whole, since that is determined by the BMS's limitations), or the specify which brand and model cells are in it so we can try to locate the cell specs, we can then guesstimate

If you aren't sure what they are capable of and no specs were available from the battery (not bike) manufacturer, but can open the battery carefully, you could see if they are marked with a brand name and model number so the specs might be located (assuming they aren't rewrapped / counterfeit cells, or old used cells salvaged and reused in a new pack, both of which are not that uncommon).

I think that realistically you will probably have to replace the entire battery with a new one that can handle the more-than-double current your new controller will be asking of it, to get the performance you need if not for safety.

Note that for the same capacity of battery, drawing more current means you will get less range, so if there is space you may want to upgrade capacity at the same time, if you need the range. (a higher capacity pack that can put out higher current will generally be proportionally larger than the one you have).

 

[Chris A]

The BMS should be rated a little higher than the controller maximum so it doesn't trip during normal operation. Make sure the battery can handle it.
Do you know what the battery configuration is?

I Belice it’s a 72v 20ah with 80a bms. Is there a way to upgrade the bms to 200+a so that when I install the new 200a controller everything will match and be an ideal setup?

 

[Chris A]

If the bike is operating normally even under the worst case load, with the new controller, but the original BMS, then either the controller is not ever drawing more than the BMS can supply (80A, if that's it's max rating), because the load on the motor is never higher than that, or else the BMS has failed and is unable to turn off it's output when overloaded or any other problem happens (the FETs are stuck on, so that the BMS can no longer protect the pack).

Regarding changing the BMS to 200A from 80A:

Can the cells in the battery handle the more-than-doubled current? I expect they probably can't. The BMS for a pack should be chosen to limit current to whatever the cells can handle (and so should already be the right one for the cells), so if you change the BMS to a higher-current one to try to use the cells at more than twice their original current you could damage them (which could lead to a fire, in the worst case).

Best case if they can't is they'll sag in voltage a lot under the higher current demand, reducing actual power output at the motor to much less than if they were capable without such sag, and the cells will heat up faster than normal, and have less capacity (range) than normal, and the BMS will shutdown output sooner than normal when under enough load to cause sag below LVC. The cells will also probably unbalance easier and worse, and require much longer time on the charger to rebalance them after the main part of charging is complete.

If you have specs from the battery (not bike) manufacturer on the cells themselves (not the battery as a whole, since that is determined by the BMS's limitations), or the specify which brand and model cells are in it so we can try to locate the cell specs, we can then guesstimate

If you aren't sure what they are capable of and no specs were available from the battery (not bike) manufacturer, but can open the battery carefully, you could see if they are marked with a brand name and model number so the specs might be located (assuming they aren't rewrapped / counterfeit cells, or old used cells salvaged and reused in a new pack, both of which are not that uncommon).

I think that realistically you will probably have to replace the entire battery with a new one that can handle the more-than-double current your new controller will be asking of it, to get the performance you need if not for safety.

Note that for the same capacity of battery, drawing more current means you will get less range, so if there is space you may want to upgrade capacity at the same time, if you need the range. (a higher capacity pack that can put out higher current will generally be proportionally larger than the one you have).

Wow, thank you for the in depth reply. That was exactly what I was looking for. I already bought the 200a controller so I’ll be looking into a battery upgrade next. I don’t have any information on the battery because I bought the bike used, but it looks to be a 72v 20ah and it’s a few years old now so I suspect the cells have seen better days. Is there a way to adjust the controller settings so it will work with the smaller bms until I can upgrade the battery?

Also, I use the bike off road on mtb trails primarily and trip the bms almost every ride on steep hills or if the rear tire loses traction momentarily it will trip and the display says “controller protect” and must be powered off and then back on to resume riding. Because of this I am on the fence about just selling the bike and buying a Sur-Ron type bike that may be a better fit for my riding style. I’m on my 3rd controller and my second 8kw hub motor with this bike and It’s become a bit of a money pit. What are your thoughts on that? Am I expecting too much from this enduro e bike or do I just not have it setup properly? Pic of my bike attached for reference of what I’m working with

 

[amberwolf]

Wow, thank you for the in depth reply. That was exactly what I was looking for. I already bought the 200a controller so I’ll be looking into a battery upgrade next. I don’t have any information on the battery because I bought the bike used, but it looks to be a 72v 20ah and it’s a few years old now so I suspect the cells have seen better days. Is there a way to adjust the controller settings so it will work with the smaller bms until I can upgrade the battery?

You'd have to look at the controller manual to see if it is programmable, and if so what software and hardware is used to do this, and acquire those (software from the manufacturer, hardware usually a USB-serial cable, sometimes a Bluetooth board for inside it, or BT dongle to plug into it, etc, and then an app for your phone/tablet/etc).

There are often multiple current settings, such as overcurrent for shutdown or lowering current as battery voltage drops, etc, so you may need to change more than one setting.

Also, I use the bike off road on mtb trails primarily and trip the bms almost every ride on steep hills

That means your battery can't provide the power the system needs to do it's job, so you will need a new battery that can do this. I recommend using the motor simulator at ebikes.ca to input your worst-case riding conditions and then play with the various hardware listed, or use custom settings (per the instructions below the simulator) to determine the amount of power actually required to do the job you need it to do.

Once you know that, then you can decide if your existing motor and controlelr can do it, and if not replace those, and then get a good-quallyt well-made battery (made of well-matched cells, which is rather hard to find) that can easily handle this power, preferably with a margin of at least 50% (so that it will also do what you ask of it in the next upgrade, since batteries are the most expensive and most important part of the system).

or if the rear tire loses traction momentarily it will trip and the display says “controller protect” and must be powered off and then back on to resume riding.

That could be a controlelr setting (which you can experiment with to find a solution), or just a badly written firmware in it (which you can't fix), or a hardware design problem with the controller (which you can't fix).

Because of this I am on the fence about just selling the bike and buying a Sur-Ron type bike that may be a better fit for my riding style. I’m on my 3rd controller and my second 8kw hub motor with this bike and It’s become a bit of a money pit. What are your thoughts on that? Am I expecting too much from this enduro e bike or do I just not have it setup properly? Pic of my bike attached for reference of what I’m working with

You'll need to find out what it takes to do the job you want it to do before you can know what parts can do that. That simulator can help you guesstimate this. There is a thread about it here with some info on using it, and there are numerous motorcycle and high-power bike conversions also with info on it and examples, that should hlep you figure that out.

If you don't know the power, etc., that it takes to do the job, you will just have to replace parts (or whole bikes) until it does what you want, or find someone else that does exactly what you do (or even harder usage) under exactly the same conditions (or worse), and get what they got.

 

[Chris A]

You'd have to look at the controller manual to see if it is programmable, and if so what software and hardware is used to do this, and acquire those (software from the manufacturer, hardware usually a USB-serial cable, sometimes a Bluetooth board for inside it, or BT dongle to plug into it, etc, and then an app for your phone/tablet/etc).

There are often multiple current settings, such as overcurrent for shutdown or lowering current as battery voltage drops, etc, so you may need to change more than one setting.




That means your battery can't provide the power the system needs to do it's job, so you will need a new battery that can do this. I recommend using the motor simulator at ebikes.ca to input your worst-case riding conditions and then play with the various hardware listed, or use custom settings (per the instructions below the simulator) to determine the amount of power actually required to do the job you need it to do.

Once you know that, then you can decide if your existing motor and controlelr can do it, and if not replace those, and then get a good-quallyt well-made battery (made of well-matched cells, which is rather hard to find) that can easily handle this power, preferably with a margin of at least 50% (so that it will also do what you ask of it in the next upgrade, since batteries are the most expensive and most important part of the system).



That could be a controlelr setting (which you can experiment with to find a solution), or just a badly written firmware in it (which you can't fix), or a hardware design problem with the controller (which you can't fix).




You'll need to find out what it takes to do the job you want it to do before you can know what parts can do that. That simulator can help you guesstimate this. There is a thread about it here with some info on using it, and there are numerous motorcycle and high-power bike conversions also with info on it and examples, that should hlep you figure that out.

If you don't know the power, etc., that it takes to do the job, you will just have to replace parts (or whole bikes) until it does what you want, or find someone else that does exactly what you do (or even harder usage) under exactly the same conditions (or worse), and get what they got.

Again thank you for the very informative reply. I messaged the seller of the sabvaton 200a controller I just bought to see if I can adjust it to work with my 80a bms until I figure out what to do about a battery…. They are also quoting me for a new battery but they are in China so the communication is tough and I have no way to verify quality. Do you know where I should look to get a good battery? Would a used one high quality one be better than a cheaper brand new one?

 

[999zip999]

Most 72v20ah would have a 80a bms or maybe 100ah with good cells. It would need hobby lipo 40C for a 200 amp BMS. Like for big helicopters

 

[Chris A]

I got a quote for a 72v 40ah custom battery with 200a bms for the Amazon seller I bought the controller from. They said the battery would be $1700 shipped. Is that a good price? And how do I know if the cells are high enough quality? Is there any other information I should be asking for from the battery manufacturer?

 

[E-HP]

I got a quote for a 72v 40ah custom battery with 200a bms for the Amazon seller I bought the controller from. They said the battery would be $1700 shipped. Is that a good price? And how do I know if the cells are high enough quality? Is there any other information I should be asking for from the battery manufacturer?

Knowing the brand and model of the cells being used is the most important question. Knowing the same for the BMS would be nice, but for a 200A pack, knowing about how it's constructed (if it uses nickel or copper strips and the specs, etc.) to make sure it can provide that current continuously. Those are areas where they can cut corners, and will determine if it's a fair deal or not.

 

[amberwolf]

Before you go buying a new battery, you should first find out how much power you need to do the job you're after, especially on the hills that shut the system down now.

Otherwise you may be buying a battery that still can't do the job.

 

[Chris A]

Knowing the brand and model of the cells being used is the most important question. Knowing the same for the BMS would be nice, but for a 200A pack, knowing about how it's constructed (if it uses nickel or copper strips and the specs, etc.) to make sure it can provide that current continuously. Those are areas where they can cut corners, and will determine if it's a fair deal or not.

That’s a great point, I messaged the seller to ask about this information hopefully they can provide it for me. If not, do you know of a good source to get a 200a 72v battery that uses suitable construction materials?

 

[Chris A]

Before you go buying a new battery, you should first find out how much power you need to do the job you're after, especially on the hills that shut the system down now.

Otherwise you may be buying a battery that still can't do the job.

How would I go about doing that? If I did so and found that I need more than 200a of power would there be sufficient options that are reasonably affordable (less than 3k) Or would I be better off ditching the enduro e bike platform and move to something like a sur ron that uses a mid drive instead of a hub motor?

 

[amberwolf]

The motor simulator at ebikes.ca in the Tools section can be used to guesstimate this, based on your specific riding conditions, terrain (hill slope and type of surface), winds, weight of you and bike and anything else carried on it, speed you need to maintain under those conditions, etc.

You don't specify the hill slope, so we'll just stick 10% into the simulator, and guess 500lbs for you and the bike and anything else you might carry, and assume 20mph up that slope would be enough, and left the wheel size at 26" (it's in bicycle size so not the same as the motorcycle size you have of 21"; not sure if it's a little bigger or a little smaller but is similar) to get a guesstimate of power. If your conditions are different, you can change those in the simulation to get a guesstimate. You may need to change other things too. I used a fake controller/motor/battery that don't limit the system (within reason) so you can just see guesstimated power requirements.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

This gives the following results, which aren't enough to be doing what you see, so I increased the slope to 20% and tried again, after the below chart. Thenumbers don't really mean much in themselves because they are from guessed data, but the important number for the battery are bolded, and the important numbers for the motor / controller are italicized.

Graph	Syst A
Wheel Torq	88.5Nm
Mtr Power	2389W
Load	2395W
Efficiency	62.1%
RPM	257.6 rpm

Electrical	Syst A
Mtr Amps	97.6A
Batt Power	3845W
Batt Amps	54.2A
Batt Volts	71.0V

This brings power requirements up to the following:

Graph	Syst A
Wheel Torq	159.5Nm
Mtr Power	4301W
Load	4309W
Efficiency	49.5%
RPM	257.6 rpm

Electrical	Syst A
Mtr Amps	174.7A
Batt Power	8682W
Batt Amps	122.3A
Batt Volts	71.0V

which would at least cause the problem you see of battery tripping off.

a bigger wheel size, or a steeper slope, or a higher speed up that slope, or a higher total weight, etc., will take more power.


A middrive system will still take the same power to do the same job, the difference is the motor itself doesn't have to be as physically large to do that job, as it can spin faster and be geared down. If there is a shiftable-gear drivetrain between the motor and the ground, then motor RPM can be optimized for power usage vs speed/terrain by shifting gears (just like a bicycle or motorcycle, car, truck, etc).

A hubmotor can't shift gears, so it is only optimized for a specific speed and terrain; if it's setup for toodling up steep hills, it won't give fast speed for riding on the flats unless it is very large and heavy to handle the worst-case power requirements.

 

[Chris A]

The motor simulator at ebikes.ca in the Tools section can be used to guesstimate this, based on your specific riding conditions, terrain (hill slope and type of surface), winds, weight of you and bike and anything else carried on it, speed you need to maintain under those conditions, etc.

You don't specify the hill slope, so we'll just stick 10% into the simulator, and guess 500lbs for you and the bike and anything else you might carry, and assume 20mph up that slope would be enough, and left the wheel size at 26" (it's in bicycle size so not the same as the motorcycle size you have of 21"; not sure if it's a little bigger or a little smaller but is similar) to get a guesstimate of power. If your conditions are different, you can change those in the simulation to get a guesstimate. You may need to change other things too. I used a fake controller/motor/battery that don't limit the system (within reason) so you can just see guesstimated power requirements.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

This gives the following results, which aren't enough to be doing what you see, so I increased the slope to 20% and tried again, after the below chart. Thenumbers don't really mean much in themselves because they are from guessed data, but the important number for the battery are bolded, and the important numbers for the motor / controller are italicized.

Graph	Syst A
Wheel Torq	88.5Nm
Mtr Power	2389W
Load	2395W
Efficiency	62.1%
RPM	257.6 rpm

Electrical	Syst A
Mtr Amps	97.6A
Batt Power	3845W
Batt Amps	54.2A
Batt Volts	71.0V

This brings power requirements up to the following:

Graph	Syst A
Wheel Torq	159.5Nm
Mtr Power	4301W
Load	4309W
Efficiency	49.5%
RPM	257.6 rpm

Electrical	Syst A
Mtr Amps	174.7A
Batt Power	8682W
Batt Amps	122.3A
Batt Volts	71.0V

which would at least cause the problem you see of battery tripping off.

a bigger wheel size, or a steeper slope, or a higher speed up that slope, or a higher total weight, etc., will take more power.


A middrive system will still take the same power to do the same job, the difference is the motor itself doesn't have to be as physically large to do that job, as it can spin faster and be geared down. If there is a shiftable-gear drivetrain between the motor and the ground, then motor RPM can be optimized for power usage vs speed/terrain by shifting gears (just like a bicycle or motorcycle, car, truck, etc).

A hubmotor can't shift gears, so it is only optimized for a specific speed and terrain; if it's setup for toodling up steep hills, it won't give fast speed for riding on the flats unless it is very large and heavy to handle the worst-case power requirements.

Ok great. It looks like I should be in pretty good shape with the 200a controller/bms, thanks for running the info through the simulation for me

 

[Chris A]

I asked about the battery cell info with the battery manufacturer and they sent me this pic of the cells they will use. Can anyone tell me if these are good quality cells and will work well for my intended purpose?

 

[amberwolf]

Well, there's no way for us to know their quality, since we don't know their condition, or how well matched they are.

The image shows three different kinds of cell, possibly three different brands. If they are building packs by mixing them like that, then the packs are unlikely to perform as well as they would if built from well-matched sets of the same model and brand of cell.

If you can get cell-manufacturer spec sheets from them on the actual cell brand and model that they will use to build your pack, then you can use the data on the spec sheet to figure out how many cells in parallel and series will be required at minimum to build the pack you need.

If they offer multiple options of cells, you need the spec sheets for each of the options.

Even then, you still wont' know if they are good quality until you actually have the pack and can test it to see how it performs under heavy loads over time.

 

[amberwolf]

Ok great. It looks like I should be in pretty good shape with the 200a controller/bms, thanks for running the info through the simulation for me

Keep in mind the simulation I ran does not use your actual conditions, since we don't know what those are. It is only a guess based on other guesses.

You still need to run the simulation yourself with the actual conditions you have there since we don't have that data. Without doing that, you won't know how much power is really needed, and anything you buy may be a waste of money as it may still be unable to handle the job.

 

[Chris A]

Well, there's no way for us to know their quality, since we don't know their condition, or how well matched they are.

The image shows three different kinds of cell, possibly three different brands. If they are building packs by mixing them like that, then the packs are unlikely to perform as well as they would if built from well-matched sets of the same model and brand of cell.

If you can get cell-manufacturer spec sheets from them on the actual cell brand and model that they will use to build your pack, then you can use the data on the spec sheet to figure out how many cells in parallel and series will be required at minimum to build the pack you need.

If they offer multiple options of cells, you need the spec sheets for each of the options.

Even then, you still wont' know if they are good quality until you actually have the pack and can test it to see how it performs under heavy loads over time.

Ok, what would you do? Risk it with a the custom built 200a bms China battery or try to find a higher quicker battery? From what I gather, worst case senario would be the cells aren’t up to par and catch fire

 

[amberwolf]

Ok, what would you do? Risk it with a the custom built 200a bms China battery or try to find a higher quicker battery? From what I gather, worst case senario would be the cells aren’t up to par and catch fire

That's a pretty bad worst case, don't you think?

What does "higher quicker battery" mean? I don't understand those terms in relation to batteries (haven't seen them used that way before).

If those are the only two possible options, I would definitely not risk a battery that I don't know anything about, so I would have to pick the completely unknown option of "higher quicker battery" and hope that it means a well-researched quality battery that will do the job required.


If I were to do this myself for my own usage, and not be limited to the two options above:

I would first try to determine the power requirements to do the job.

I would then look for EV-grade batteries (even used ones) that could do that job, or if a whole battery wasn't available that could do this, I would look for EV-grade cells (even used ones) that could do the job, and build or have them built into a pack by a builder with a known-good reputation. The only such pack builder I actually know / have experience of is EM3EV, but I don't know that they would build using cells I would send them or have sent to them. I'm sure there are others that people here (or elsewhere) have reliable repeated good experiences with and that have no bad experiences with, but I don't know any of them by name. I don't trust any of the oft-mentioned pack builders like UPP, etc., though there are other people that do.

If EV-grade cells / batteries are not an option, and I had to use whatever the pack builder happens to provide, then I would require that the pack builder provide me the spec sheets for the cells, so I can decide how many cells to use, and require that they test and document all cells to be well-matched with each other, but I don't know any of them that do this (or even understand what it means, even when explained to them). I'd require the documentation before they built the pack, so I could see that each cell had actually been tested and all were really matched to each other).

Then I would use a contactor-based BMS (rather than one that uses FETs to control charge/discharge switching), preferably one that allowed me to customize settings and log data or at least see realtime cell (group) voltages. I don't know what model or brand, as I don't presently use a BMS so I'd have to research those to find a reliable one.

There's other things too, but those are the major ones.

 

[Chris A]

That's a pretty bad worst case, don't you think?

What does "higher quicker battery" mean? I don't understand those terms in relation to batteries (haven't seen them used that way before).

If those are the only two possible options, I would definitely not risk a battery that I don't know anything about, so I would have to pick the completely unknown option of "higher quicker battery" and hope that it means a well-researched quality battery that will do the job required.


If I were to do this myself for my own usage, and not be limited to the two options above:

I would first try to determine the power requirements to do the job.

I would then look for EV-grade batteries (even used ones) that could do that job, or if a whole battery wasn't available that could do this, I would look for EV-grade cells (even used ones) that could do the job, and build or have them built into a pack by a builder with a known-good reputation. The only such pack builder I actually know / have experience of is EM3EV, but I don't know that they would build using cells I would send them or have sent to them. I'm sure there are others that people here (or elsewhere) have reliable repeated good experiences with and that have no bad experiences with, but I don't know any of them by name. I don't trust any of the oft-mentioned pack builders like UPP, etc., though there are other people that do.

If EV-grade cells / batteries are not an option, and I had to use whatever the pack builder happens to provide, then I would require that the pack builder provide me the spec sheets for the cells, so I can decide how many cells to use, and require that they test and document all cells to be well-matched with each other, but I don't know any of them that do this (or even understand what it means, even when explained to them). I'd require the documentation before they built the pack, so I could see that each cell had actually been tested and all were really matched to each other).

Then I would use a contactor-based BMS (rather than one that uses FETs to control charge/discharge switching), preferably one that allowed me to customize settings and log data or at least see realtime cell (group) voltages. I don't know what model or brand, as I don't presently use a BMS so I'd have to research those to find a reliable one.

There's other things too, but those are the major ones.

sorry about the typo, I was supposed to say “higher quality battery”

Thanks again for all the great information. I would like to get a quote for a high quality battery with EV grade cells but I don’t even know where to look for something like that, or what I should expect to pay. Is building my own battery a viable option or is that something best left to the pros?

 

[amberwolf]

you could ask em3ev.com what they use these days and if they can use ev-type large-format cells. some time bakc they used a123 pouch cells, they've used 18650s for at least some stuff since then but i don't know which ones or if they match them.

there are probably builders here in the states, but i don't know any particular ones. there have been threads about finding builders, if you poke around the forums, that might have that info.

you can always build your own, keeping in mind that it's a fair bit of research into learning what the various methods are, and deciding which one to go with, then learning the details of that method and buying the tools to do it and then doing it and testing it. it will probably cost more than having a big place build you one, and is certainly more work, but you then know whats in it and how it's built, and have the knowledge and tools to repair it if it ever needs it. there are lots of battery building and repair threads that will give you some idea of what you might be getting into before the deep dive.

building a battery is probably the hardest thing you can diy for an ebike, other than perhaps rewinding a motor which is probably about equal in time-consuming pita-ness but has less dire consequences if it's done wrong.

if you do decide to build your own, it would be better if you can post everything as a thread here on es, so that the real experts in pack building can help if you run into trouble, but if you're in the phoenix area (your profile says arizona but not where), then if you really needed in-person help, we might be able to meet up depending on time and place and scheduling and whether or not i'm sick again (like right now; i keep catching long-lasting colds over and over again the last several months). i'm not a true battery building expert, but i have learned quite a lot about them and can recognize good vs bad when i'm looking at it for construction, etc. and am very good at diy of many things though not at the level of manufactured goods. the only batteries i have truly built are using premade oem hardware and user-made busbars or interconnects, all bolted together, with the eig cells i have now. i have repaired a poorly-built 18650 pack to bypass dead and damaged cells, but never got to rebuilding it.

sources for ev cells new, i don't know, but batteryhookup and the like often have used ev modules that can be repurposed, often with some rearrangement or rebuilding, directly into ebike packs, depending on the space/etc you have available. these are often a really good deal, making it well worth using used cells.. but this method isn't for everyone, even if they like building their own packs.. it's almost certainly what i will do when i need to replace my eig packs.

 

[Chris A]

you could ask em3ev.com what they use these days and if they can use ev-type large-format cells. some time bakc they used a123 pouch cells, they've used 18650s for at least some stuff since then but i don't know which ones or if they match them.

there are probably builders here in the states, but i don't know any particular ones. there have been threads about finding builders, if you poke around the forums, that might have that info.

you can always build your own, keeping in mind that it's a fair bit of research into learning what the various methods are, and deciding which one to go with, then learning the details of that method and buying the tools to do it and then doing it and testing it. it will probably cost more than having a big place build you one, and is certainly more work, but you then know whats in it and how it's built, and have the knowledge and tools to repair it if it ever needs it. there are lots of battery building and repair threads that will give you some idea of what you might be getting into before the deep dive.

building a battery is probably the hardest thing you can diy for an ebike, other than perhaps rewinding a motor which is probably about equal in time-consuming pita-ness but has less dire consequences if it's done wrong.

if you do decide to build your own, it would be better if you can post everything as a thread here on es, so that the real experts in pack building can help if you run into trouble, but if you're in the phoenix area (your profile says arizona but not where), then if you really needed in-person help, we might be able to meet up depending on time and place and scheduling and whether or not i'm sick again (like right now; i keep catching long-lasting colds over and over again the last several months). i'm not a true battery building expert, but i have learned quite a lot about them and can recognize good vs bad when i'm looking at it for construction, etc. and am very good at diy of many things though not at the level of manufactured goods. the only batteries i have truly built are using premade oem hardware and user-made busbars or interconnects, all bolted together, with the eig cells i have now. i have repaired a poorly-built 18650 pack to bypass dead and damaged cells, but never got to rebuilding it.

sources for ev cells new, i don't know, but batteryhookup and the like often have used ev modules that can be repurposed, often with some rearrangement or rebuilding, directly into ebike packs, depending on the space/etc you have available. these are often a really good deal, making it well worth using used cells.. but this method isn't for everyone, even if they like building their own packs.. it's almost certainly what i will do when i need to replace my eig packs.

Im located up in Prescott Valley, so about an hour from Phoenix. I actually have a second enduro e bike that I’m stumped on what’s wrong with it and could use some help getting it goin again, you seem quite knowledgeable about this stuff and I’ve had zero luck finding anyone in my local area that can help. I would be more than happy to pay you to take a look at it if you’re willing to do so? I can bring it to you aswell

Back to the original topic, my new sabvaton 200a controller came in yesterday and I installed it really quick with my old 72v 20ah battery to test and see if the 80a bms limits the power and I was shocked at the power increase right off the bat with no tuning in the app or anything. I was expecting the power output to be about the same as the 100a controller I had before due to the small battery and BMS being the limiting factor. I’m planning to take the bike out this wknd and put it to the test on the trail to see how it holds up

This being the 3rd controller the bike has had in a year I figured there’s got to be a reason they arnt lasting, first issue that comes to mind is heat soak being an issue because the controller is mounted inside the frame of the bike and gets hot enough that I can feel it on the outside of the bike. My plan is to add a couple small air scoops up front and a 5” computer fan under the seat to function as an exhaust fan to keep fresh air flowing over the control so the heat sink fins can do their job more efficiently. Have you seen anyone do this mod before? Or anything similar that had good results?

 

[amberwolf]

For the bike you're stumped on, I'd first recommend making a thread here with everything you already know about it, and anything that's been tried and results of that. Then we can work out what hasn't been tried, and what might be tested to figure out what's wrong.

For the hot controller issue, if the controller gets that hot, how hot does the motor get? If the motor doesn't get hot when the controller does, it's probably just that the controller gets no airflow. Best way to fix that is to move the controller where it can get air, or force airflow over it. Scoops aren't needed, since you'd have to go pretty fast for anything reasonably sized to scoop up much air, just intake holes at the appropriate point to cause airflow over or thru the controller then to the fan pulling the air. If you can take the end caps off the controller (depending on it's design) you'll get a lot better cooling than just airflow over the outside, especially since most controllers have at least two heat-transfer junctions between the FETs and cooling airflow (and those are not always made well enough for very good transfers).

If the motor gets hot too, does it get that hot even with minimal load, or only when used hard? If it gets hot even with minimal load, it probably has the wrong phase/hall combination, and that's easy to fix. If it only gets hot when used hard, it's probably just not enough controller and motor for the job; increasing cooling can help with that in some cases.


With the new controller, it's probably setup for high motor phase amps, which will give it a lot more pull (but will work the battery harder in doing so, making it more likely to trip the BMS either more often or sooner, assuming the BMS is tripping from overcurrent).

If you want you can order a cheap wattmeter, something like this one:

https://www.amazon.com/gp/product/B013PKYILS

(there are better ones that do more stuff, like the Cycle Analyst, but cost is far greater if you don't need the extra stuff)
and measure the actual power / current used in various situations, and see how much voltage sag your battery has under that kind of load. See this thread

SOLVED: Blown Fuse on New Stealth Bomber Clone

I just received my Stealth Bomber Clone from an outfit in China called Coolfly Bikes. 8000W QSMotor SVMC72V100(M) Sabvoton sinewave controller 72V 41.6AH(China Battery) On the trial run, going about 35MPH / 56 KPH, after riding for about 20 minutes.. all power died to the bike, display went...

endless-sphere.com

for an example of a similar situation; in his case it was a fuse blowing rather than BMS shutdown, because his bike was built with a too-small battery pack as well that couldn't handle the controller used, so they used the fuse to protect the battery from overload by the controller. In his case limiting the controller via programming is a first-line option, then probably getting a new battery that can handle the power required by the controller's full capabilities (as measured by the wattmeter), or some similar end-result, if it doesn't do the necessary job as-is.


For coming down here to directly work on anything, my first real free time will be coming up near the end of April, which with luck will mostly be used to do some major stuff to my SB Cruiser trike, but if plans go as they should I could work on something else like looking at your stuff. Don't know if I can fix anything, but possibly find out what a problem might be. But it would have to be something where you bring it down, we look at it, and you take it back with you, rather than leaving it here to work on.

I am typically off Sundays (which I usually have to spend recovering from the rest of the week) and Mondays, and sometimes have enough energy recovered by Monday to do something for a short time, if you are free to come down here about the middle of a Monday.