# How to preceed with my EV car



## 59 Austin Healey (Jan 1, 2021)

I've posted a few times on this forum and received very valuable feed back but now it's time for the rubber to meet the road as it were.

I purchased a 1959 Austin Healey Sprite a few weeks ago, which was converted to EV in 2005. It has a MES-DEA TIM600, matched to a MES-DEA 200-175 motor. I have finally acquired the TIM software (thanks to [email protected]!) so am already further than I thought I'd be. 

The problem is that I know _nothing_ about how the car was built, no schematics, nothing. The original lead acid batteries are dead, and only provided a 25 mile range when new so that's gotta change. I'm sort of flying blind here. To further complicate things, I'm brand new to EV... I wasn't really looking for an electric Sprite, just a Sprite. So I don't have much background knowledge in this field. I'm a DIY techno-geek so am pretty sure I can come up to speed but don't want to reinvent the wheel.

I've heard that MES-DEA can be hard to work with which has me worried. For example, even with the manual, I don't know exactly how to power up the TIM to even see if it's functional!

I'm prepared to throw some money at this project because the idea of an electric Sprite excites me. So my question to the community: Should just rip out everything and go with newer hardware which is easier to work with, or stick with the MES-DEA setup and see what happens?

Thanks for your thoughts,
Mark


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## brian_ (Feb 7, 2017)

I can't see any sense in starting from scratch if you only need a new battery pack. If you were to start from scratch, you might be better off with a stock vehicle than with someone else's undocumented conversion.

Even though nothing may be working due to dead batteries, you can still understand what you have. For instance, just look at what voltage each battery has (if they have fill caps there's a cap per cell and each cell is two volts) and follow the wiring to see how many are connected in series to determine the nominal battery voltage.


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## 59 Austin Healey (Jan 1, 2021)

Thanks Brian, 

I appreciate the input!

I have the original battery configuration of 29 6V motorcycle batteries which I believe were in series. But I'm not looking to replace the existing config as it only had a ~25 mile range. I'd really like to update to newer tech to improve the range. 

If I'm reading the documentation correctly, I _think_ I just have to input the minimum and maximum voltage of the new battery pack(s) even if it's a different chemical mix. 

But the car itself is a mess! The engine bay is very well laid out but under the dash is a rats nest of wires and there are multiple unlabeled switches on the dash that do... something?

I think the cheapest and quickest option is to hire an EE to map out all of the wiring so I know what the heck is going on. 

But the real question remains: Is the current hardware/motor sufficient to provide proper power and range to make it worth keeping. Is the motor capable of _reasonable_ accelleration? I'm not looking for Tesla's ludicrous speed mode, but I would like to drive around town like a regular car, not like a moped.  I'm also not looking for a 300 mile range. I think 50 miles would be perfect for my needs.


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## hallkbrdz (Jan 2, 2018)

If in series, you are looking probably at an 180v controller. It won't care what type of battery is powering it. That's a reasonable voltage to hit with li-ion cell packs from other EVs. You will need a new charger and BMS to control those packs though. 50 miles should be quite reasonable for this upgrade.


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## 59 Austin Healey (Jan 1, 2021)

Awesome, thanks hallkbrdz!

I'm not sure what the charger and BMS are on this car though. There are a couple of grey boxes with loooots of electronics in them. They appear to be custom made so where do I start with replacing them.

I have some photos in my google drive for this project which have pics of these two boxes:





Austin Healey - Google Drive







drive.google.com





Please keep in mind that I'm a noob at this so not exactly sure where all of the parts fit in. If there is a EV 101 track that will help avoid dumb questions like this I'm all ears. 

Thanks!
Mark


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## MattsAwesomeStuff (Aug 10, 2017)

I'll throw my hat in with "Replace the batteries with lithiums and find out if it works".

You can probably get a cheap Prius battery pack. They're worthless for use (NiMH, bulky, and awful energy density), but a single pack is high enough voltage and small, they'll provide enough to test with (a minute or two) and you can get them cheap or free. Use that rather than buying new lead acids just to test. 

You don't need to hire an EE to map it out. You can follow wires and make a diagram of what goes where. It's probably not complicated, probably obvious what everything is for. Pay someone to run the last mile for you if need be, but do the gruntwork for them.

It's highly unlikely anything is wrong with the motor or controller. Lead acids die and aren't worth replacing, and then the car sits. That's probably what happened in your case.


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## reiderM (Dec 30, 2020)

59 Austin Healey said:


> Awesome, thanks hallkbrdz!
> 
> I'm not sure what the charger and BMS are on this car though. There are a couple of grey boxes with loooots of electronics in them. They appear to be custom made so where do I start with replacing them.
> 
> ...


I'm going to echo what everyone else is saying and get a lithium battery pack. The old lead-acid batteries probably don't have a BMS as they aren't needed with lead-acids. Lithium batteries definitely need a BMS for both safety and longevity. Your options really depend on budget.


High end - 7 Tesla modules in series ($10K)
Mid end - Nissan leaf batteries ($5k)
Low end - batteries from a hybrid (cheap)
I wouldn't recommend tinkering with the gray boxes yet. They're likely boxes for contactors, fuses, etc. and are more likely than not in good working condition.


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## 59 Austin Healey (Jan 1, 2021)

Thanks all, this is exactly the kind of advice I'm looking for!

So, I'm guessing that depending on what battery type/brand I buy will determine the charger and BMS I need?

Replacing the lead-acid batteries was never really on the table unless they've gotten exponentially better in the past 15 years. The original setup only had a range of 25 miles and I believe that was a generous estimate. I think the only reason I would toy with replacing them is that it would require the least amount of retrofitting, but I don't think it's worth it.

If I try to find a cheap/free Prius pack for testing, I would then have to buy a charger for it I'm sure, but since I won't be driving it using this pack, will I need a BMS?

Thanks again,
Mark


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## reiderM (Dec 30, 2020)

59 Austin Healey said:


> Thanks all, this is exactly the kind of advice I'm looking for!
> 
> So, I'm guessing that depending on what battery type/brand I buy will determine the charger and BMS I need?
> 
> ...


You will need a charger, but that same charger can be used with any battery. Chargers just convert AC power from the wall to the right DC voltage. 

A BMS isn't necessary if you're strictly testing, just be careful and don't let them charge to above the designed voltage. 

Sent from my GM1917 using Tapatalk


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> I think the cheapest and quickest option is to hire an EE to map out all of the wiring so I know what the heck is going on.


I don't think you're going to want to pay an electrical engineer to do that. Almost anyone is likely to tell you that it would be cheaper and safer to rip it all out and pay for a new design instead... and I doubt that you want to pay for that, either. If you can find another amateur in your area who is willing to help you because the project is interesting, you could work with them and learn about the system as he/she figures it out.


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> But the car itself is a mess! The engine bay is very well laid out but under the dash is a rats nest of wires and there are multiple unlabeled switches on the dash that do... something?


Unfortunately, that's roughly how Austin built them.  After years of working on more modern vehicles, I was interested to note how much our Triumph Spitfire's wiring looks like a homebuilt project... done by someone who only had spools of wire available in four colours. But there is likely an original factory wiring diagram available, and you might find that most of the wires are in the original Austin diagram.


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> But the real question remains: Is the current hardware/motor sufficient to provide proper power and range to make it worth keeping. Is the motor capable of _reasonable_ accelleration? I'm not looking for Tesla's ludicrous speed mode, but I would like to drive around town like a regular car, not like a moped.  I'm also not looking for a 300 mile range. I think 50 miles would be perfect for my needs.


I don't really know anything about the MES-DEA products, but for others I'll note that there is some detail in the earlier thread on this car, and in a product line datasheet.

21 kW is not much, even for a Sprite, but the motor and controller are likely efficient enough that they are not a concern for range - that's a battery issue.


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## 59 Austin Healey (Jan 1, 2021)

Thanks guys!

reiderM, I'm guessing there are better and worse chargers and BMSs out there. Is there one that DIY EV'ers lean toward? I'm also guessing it has to have the correct connection for whichever battery pack you have? 

brian_, Heh, yep, I've had an MGB and a TR6 and recall no end to electrical problems. My British auto mechanic buddy said that Lucas Electronics was commonly referred to as 'the prince of darkness'.

I managed to get the hood off today thanks to a couple buddies, thing weighs close to 100 pounds! Now have much better access to the engine bay so am feeling more confident about figuring this mess out. Kinda hard to strike up new friendships right now with C-19 and all but will look around for a local group. I'm outside of Denver so shouldn't be too hard. 

Looks lik the MES-DEA motors topped out at 30 kW, In an ideal world, what motor would suite that car? Doesn't need to race... but that would be fun too.


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## 59 Austin Healey (Jan 1, 2021)

reiderM said:


> You will need a charger, but that same charger can be used with any battery. Chargers just convert AC power from the wall to the right DC voltage.
> 
> A BMS isn't necessary if you're strictly testing, just be careful and don't let them charge to above the designed voltage.
> 
> Sent from my GM1917 using Tapatalk


I replied to two people at once, but I think I need to respond to you individually so you'll get notification of my response so I'll break it out:

I'm guessing there are better and worse chargers and BMSs out there. Is there one that DIY EV'ers lean toward? I'm also guessing it has to have the correct connection for whichever battery pack you have?


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## 59 Austin Healey (Jan 1, 2021)

brian_ said:


> I don't really know anything about the MES-DEA products, but for others I'll note that there is some detail in the earlier thread on this car, and in a product line datasheet.
> 
> 21 kW is not much, even for a Sprite, but the motor and controller are likely efficient enough that they are not a concern for range - that's a battery issue.


I replied to two people at once, but I think I need to respond to you individually so you'll get notification of my response so I'll break it out:

Heh, yep, I've had an MGB and a TR6 and recall no end to electrical problems. My British auto mechanic buddy said that Lucas Electronics was commonly referred to as 'the prince of darkness'.

I managed to get the hood off today thanks to a couple buddies, thing weighs close to 100 pounds! Now have much better access to the engine bay so am feeling more confident about figuring this mess out. Kinda hard to strike up new friendships right now with C-19 and all but will look around for a local group. I'm outside of Denver so shouldn't be too hard. 

Looks lik the MES-DEA motors topped out at 30 kW, In an ideal world, what motor would suite that car? Doesn't need to race... but that would be fun too.


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## 59 Austin Healey (Jan 1, 2021)

MattsAwesomeStuff said:


> I'll throw my hat in with "Replace the batteries with lithiums and find out if it works".
> 
> You can probably get a cheap Prius battery pack. They're worthless for use (NiMH, bulky, and awful energy density), but a single pack is high enough voltage and small, they'll provide enough to test with (a minute or two) and you can get them cheap or free. Use that rather than buying new lead acids just to test.
> 
> ...


Hey Mat, so I find a lot of cheap Prius NIMH batteries on Ebay, which range between 7 & 8 volts, how many of these bad boys do I need to get something that'll work?

Thanks!
Mark


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## OR-Carl (Oct 6, 2018)

59 Austin Healey said:


> Hey Mat, so I find a lot of cheap Prius NIMH batteries on Ebay, which range between 7 & 8 volts, how many of these bad boys do I need to get something that'll work?
> 
> Thanks!
> Mark


Hey, unless you can get a complete prius battery pack for free (Matt will tell you this is easy, but he would tell you the same thing about building your own rocketship ) then a prius NiMH pack is a dead end suggestion.

Basically, the car does not care what is producing the voltage, you just need to get to the right voltage. You said it originally had 29x 6v lead acid batteries - so you need 29x6 = 174ish volts. It does not have to be exact. So to get back up to 174v with 7.2v NiMH modules, you would need 24 of them. The problem is that those modules only have 6.5Ah, i.e. they can only put out 6.5 Amps for 1 hour. So your battery will be way too small to do anything but the most basic testing. You would have a little over 1 kwh of energy, so you might move a tiny little car 4 miles with that battery. The top speed would be miserably, probably a jogging pace, or you would blow out the cells by pulling too much juice out of them.

In short, spending 400-800 bucks on that would be silly. If you found a free one, sure. But if you can sell it on E-bay for 700 bucks, who would give it away for free? 

I suggest you hop on Wikipedia and read up on batteries. All sorts of batteries. Follow up on all the terms you have never heard of. Get a basic grasp of the science, and you will figure out what questions you really need to be asking. There are a lot of very smart and very informative people on this forum that can help you, but you will need to know which questions to ask. Anyway, hope I have not come off as a complete curmudgeon, I hope you will have success (and that you will post some pictures of batteries).


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## 59 Austin Healey (Jan 1, 2021)

OR-Carl said:


> Hey, unless you can get a complete prius battery pack for free (Matt will tell you this is easy, but he would tell you the same thing about building your own rocketship ) then a prius NiMH pack is a dead end suggestion.
> 
> Basically, the car does not care what is producing the voltage, you just need to get to the right voltage. You said it originally had 29x 6v lead acid batteries - so you need 29x6 = 174ish volts. It does not have to be exact. So to get back up to 174v with 7.2v NiMH modules, you would need 24 of them. The problem is that those modules only have 6.5Ah, i.e. they can only put out 6.5 Amps for 1 hour. So your battery will be way too small to do anything but the most basic testing. You would have a little over 1 kwh of energy, so you might move a tiny little car 4 miles with that battery. The top speed would be miserably, probably a jogging pace, or you would blow out the cells by pulling too much juice out of them.
> 
> ...


NO! This is exactly what I'm looking for, thanks to you and everyone who has chimed in! I have _no_ idea what I'm doing and really hate asking stupid questions. This is EV 101! However, one more stupid question if you don't mind. Can you give me a clue as to what to search for on Wikipedia so I don't go down the wrong rabbit hole? Getting up to speed is a lot quicker is there are no off-ramps. 

Thanks,
Mark


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## OR-Carl (Oct 6, 2018)

Electric vehicle battery - Wikipedia







en.wikipedia.org




You can start with this. It will be full of links, so if you are a little fuzzy on what an Ampere-hour is, follow the link and get a refresher. When you finish with that, you will probably have more questions than you started with. Google those, and search wikipedia some more. Then google your motor. You probably dont have a BMS, but you will need to learn about that. Watch videos on youtube. Go to websites selling EV conversion parts and download the product manuals. Read those, they are full of useful info. Starting from zero, you should probably plan on doing a hundred hours of reading or so. If it is not fun, then you have picked the wrong hobby, and you should maybe start over with something else


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> Getting up to speed is a lot quicker is there are no off-ramps.


True, but just as on a real highway, taking the wrong off-ramp is how everything interesting is found.


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## 59 Austin Healey (Jan 1, 2021)

OR-Carl said:


> Electric vehicle battery - Wikipedia
> 
> 
> 
> ...


Well, tinkering, reading manuals, youtube vids, and google searches are my hobbies, so I think I'm in the right place. 
I've dabbled in microcontroller electronics but nothing of this scale, it'll be fun to play with the big boys.

Thanks again, it was the "where to start" problem that was daunting. Your information what I needed to get moving!


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## reiderM (Dec 30, 2020)

59 Austin Healey said:


> I replied to two people at once, but I think I need to respond to you individually so you'll get notification of my response so I'll break it out:
> 
> I'm guessing there are better and worse chargers and BMSs out there. Is there one that DIY EV'ers lean toward? I'm also guessing it has to have the correct connection for whichever battery pack you have?


There's a company called ElCon that sells chargers. They're pricey but I've heard good things about them and am planning to use this one in my conversion.


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## 59 Austin Healey (Jan 1, 2021)

reiderM said:


> There's a company called ElCon that sells chargers. They're pricey but I've heard good things about them and am planning to use this one in my conversion.


Cool, thanks! I've been doing a lot of reading and realize I still need to do a lot more. 
There is a local car dealer that only sells electric cars. I'm going to stop in see if I can pick their brains.


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## MattsAwesomeStuff (Aug 10, 2017)

OR-Carl said:


> Hey, unless you can get a complete prius battery pack for free (Matt will tell you this is easy, but he would tell you the same thing about building your own rocketship ) then a prius NiMH pack is a dead end suggestion.


Indeed, for free, or for the half hour it might take them to yank it.

Plan B would just be a variac with an FWB and a smoothing cap.

I'm all about low barriers to curiosity.

And, you can find lots of stuff for free/cheap if you take your time. But it's like shopping for dishes at a thrift store. You can probably find something good enough 2/3 of the time, but you have to be okay with not finding it, or it taking a few tries.



> You would have a little over 1 kwh of energy, so you might move a tiny little car 4 miles with that battery. The top speed would be miserably, probably a jogging pace, or you would blow out the cells by pulling too much juice out of them.


I don't know if you'd blow out the cells, they will tell you they're not able to do it, by being not able to do it 

I meant more bench/roll testing. Not drive testing. Maybe around the block.

Mostly you want to determine if it works, if it's worth exploring more.



> In short, spending 400-800 bucks on that would be silly.


Indeed, for a lower price, buy a power supply and use that instead.

I was thinking, maybe $50, $100 tops to get a used Prius battery pack.

Not ebay, not individual cells. Call up a wrecker who's more than likely going to just dispose of the damned thing. Local guy here says he's got a dozen of them for literal free, but I don't have that same deal.


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## reiderM (Dec 30, 2020)

59 Austin Healey said:


> Cool, thanks! I've been doing a lot of reading and realize I still need to do a lot more.
> There is a local car dealer that only sells electric cars. I'm going to stop in see if I can pick their brains.


No problem! I've been learning about conversions for nearly 6 months now, and I still have a lot to learn.


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## 59 Austin Healey (Jan 1, 2021)

brian_ said:


> True, but just as on a real highway, taking the wrong off-ramp is how everything interesting is found.


LOL! It's also how lots of horror movies start.


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## scottherrington (Jul 3, 2020)

Same as the rest of the suggestions, even if you replace the lead acid with the same kWh of li ion you will end up with more usable kWh than before.

I suspect that with battery technology moving on you could get a lot more range in the same space as before.

If it ain't broke, don't fix it 

Sent from my moto g(8) power lite using Tapatalk


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## 59 Austin Healey (Jan 1, 2021)

scottherrington said:


> Same as the rest of the suggestions, even if you replace the lead acid with the same kWh of li ion you will end up with more usable kWh than before.
> 
> I suspect that with battery technology moving on you could get a lot more range in the same space as before.
> 
> ...


Thanks! 
That's the plan for now. Been doing a lot of reading on all of the tech involved but still not ready to buy anything yet.


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## Tremelune (Dec 8, 2009)

More or less echoing the good sentiments here...Ditch the lead-acid and charger, grab the cheapest lithium batteries you can for the voltage range you want, and just throw 'em in there at ~60% charge. Get the wheels turning, drive around the block, and go from there. Chargers will work with any lithium batteries, but some have voltage ranges, so it might help to understand what your final battery specs will need to be, even if it's a while before you decide on which ones to buy.

You definitely want a BMS when you start charging unattended. Otherwise...fires. For getting the car to drive it's not necessary if you're careful not to charge any cells close to max, and depending on what batteries you ultimately settle on, the BMS concerns might be different. I like Thunderstruck's stuff, and Orion gets used a lot.

Start googling serial numbers and what not to figure out what the specs of the components you find are. Maybe your motor can do 144-172V. Maybe it can do 72-240V. Maybe your contactors can handle 1000A. Maybe 200A. Knowing this stuff gives you options. Check to see if you have giant fuses for the high voltage wires.

A Sprite is on my list...The more photos the better!


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## 59 Austin Healey (Jan 1, 2021)

Tremelune said:


> More or less echoing the good sentiments here...Ditch the lead-acid and charger, grab the cheapest lithium batteries you can for the voltage range you want, and just throw 'em in there at ~60% charge. Get the wheels turning, drive around the block, and go from there. Chargers will work with any lithium batteries, but some have voltage ranges, so it might help to understand what your final battery specs will need to be, even if it's a while before you decide on which ones to buy.
> 
> You definitely want a BMS when you start charging unattended. Otherwise...fires. For getting the car to drive it's not necessary if you're careful not to charge any cells close to max, and depending on what batteries you ultimately settle on, the BMS concerns might be different. I like Thunderstruck's stuff, and Orion gets used a lot.
> 
> ...


Wow! That's pretty cool sounding!

Keep in mind, I have literally zero experience in this field and would prefer not to die, or burn my house down.... Wife would be super pissed, and if the German Shepherds got out it would cause chaos in the neighborhood. 

So, does the charger _tell_ you the percentage of charge in the batteries so, if you are paying attention, you can unplug it at the right time? It seems hard to get information on actual components. There's lots of theory out there but not much "here's what I did" stuff. I truly want to understand this technology, but at the same time, I want to see this thing move!


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## OR-Carl (Oct 6, 2018)

Its not as bad as it sounds. Basically, what you dont want to do is overcharge a lithium cell (undercharging is bad too, but you will get to that later). The whole point of the BMS is to monitor every cell in the battery, and alert you (or the charger) that something is going wrong. The charger itself will likely be completely devoid of any output. There are all sorts of displays available, and you can plug BMSes into a laptop and see all the info that way. I used the same BMS as Tremelune - and it is easy to set up. It communicates over CAN-bus - which you will need a broad-strokes understanding of - but dont worry, you wont need to be able to read hex to use it. There is a very simple command-line interface, which is well documented.

The battery charger then will communicate with the BMS about every half a second - so if anything is wrong the charging will stop. Check out Tremelunes mini build thread, it has a lot of good info in it. I am halfway through my s-10 project, but it might contain some useful info. If you click on a users name, you can see all the discussions they created. 

It may seem daunting at first, but plenty of people have started out at zero and gotten up to speed with this hobby. I am one of them


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## 59 Austin Healey (Jan 1, 2021)

OR-Carl said:


> Its not as bad as it sounds. Basically, what you dont want to do is overcharge a lithium cell (undercharging is bad too, but you will get to that later). The whole point of the BMS is to monitor every cell in the battery, and alert you (or the charger) that something is going wrong. The charger itself will likely be completely devoid of any output. There are all sorts of displays available, and you can plug BMSes into a laptop and see all the info that way. I used the same BMS as Tremelune - and it is easy to set up. It communicates over CAN-bus - which you will need a broad-strokes understanding of - but dont worry, you wont need to be able to read hex to use it. There is a very simple command-line interface, which is well documented.
> 
> The battery charger then will communicate with the BMS about every half a second - so if anything is wrong the charging will stop. Check out Tremelunes mini build thread, it has a lot of good info in it. I am halfway through my s-10 project, but it might contain some useful info. If you click on a users name, you can see all the discussions they created.
> 
> It may seem daunting at first, but plenty of people have started out at zero and gotten up to speed with this hobby. I am one of them


Thanks for the encouragement Carl!

Full disclosure, I'm really bad at math, had to retake it in college because I just didn't care in HS. 

I'm looking at a used a used battery on Ebay from a 2019 Nissan Leaf. The specs are 5826Wh 176Ah, so 5.8kWh. The connections are different from what I currently have but I think I can make it work. Given the power output, can I expect it to at least power my 21kW motor so I can see if things are working, and if so, for how long? Is it simple division or is load also a factor? Also, the Leaf from which it was pulled had a total of 62kWh of battery so how many of these suckers am I gonna need to get 50-100 miles? Or is that another "depends on the load, weight, etc.?

I've been reading all I can on Wikipedia but it's all high level, I don't see how to convert these numbers in to real world performance. If you you or anyone else has a website on this I'd love to see it.

Kinda just want to see the wheels spin to keep the fire burning. LOL!

Mark


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## 59 Austin Healey (Jan 1, 2021)

59 Austin Healey said:


> Thanks for the encouragement Carl!
> 
> Full disclosure, I'm really bad at math, had to retake it in college because I just didn't care in HS.
> 
> ...


Actually I also found the smaller version (little less than 1/2) from the same sell with lower specs for less than 1/2 the cost which is good if I'm just testing. I think I can stack 'em later so the money won't be wasted: 2019 Nissan Leaf 2589Wh 176Ah. It's $500 where the 5.8kWh was $1100. If this will work to move forward and start tuning the TIM that would be preferable.


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## OR-Carl (Oct 6, 2018)

Lithium batteries do not suffer the same drop in output as lead acid batteries (peukert effect), so you can basically ignore that. What you do need to keep in mind when running off a smaller than ideal pack is what is called the C-rate. Basically, it is a measure of how fast you are discharging a battery. If a battery has a capacity (C) of 100ah, then drawing a load of 100a would give you a 1C discharge rate. If you pulled 200amps, you are asking the batteries for 2C, and 1000amps would be 10C. Each battery chemistry has its own limits, but higher C-rates will lead to less longevity. Aiming for a 1C discharge is probably ideal. 

Since your motor is small (21kw), and your voltage is fairly high (174v) at rated power on a fully charged pack you would be pulling (21000/174=) 120amps. So ideally, you would want a pack that was 174v and 120ah, which is 21kwh. So yeah, if you got a pack that was only 5.8kwh, you would be using a 3.6C rate to get max power, and at half that size (2.6kwh), the C-rate would be 7.2C. That is likely not a good idea. But, the car should move with a lot less than the full rated power. You could test it at low speed, but you would want to keep your power draw down to not exceed whatever the max C-rate is on the batteries. 

Honestly, though, it is going to be a lot of work to install a new battery bank. Do you really want to have to redo it? If money is tight and time is not, then that plan might work out for you.


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> I'm looking at a used a used battery on Ebay from a 2019 Nissan Leaf. The specs are 5826Wh 176Ah, so 5.8kWh. The connections are different from what I currently have but I think I can make it work. Given the power output, can I expect it to at least power my 21kW motor so I can see if things are working, and if so, for how long? Is it simple division or is load also a factor? Also, the Leaf from which it was pulled had a total of 62kWh of battery so how many of these suckers am I gonna need to get 50-100 miles? Or is that another "depends on the load, weight, etc.?
> 
> I've been reading all I can on Wikipedia but it's all high level, I don't see how to convert these numbers in to real world performance. If you you or anyone else has a website on this I'd love to see it.
> 
> ...


This appears to be one 9S3P module from the 62 kW pack. 
2019 Nissan Leaf 5826Wh 176Ah 3P9S Lithium Ion Battery Module from 62kWh Pack 
That's 9 x 3.75 = 33.75 V nominal. That is very low compared to the original pack, so presumably very low compared to what the motor needs for peak power and for high speed; the motor's placard says it is rated for 21 kW at 140 V and 115 A. As long as the controller works with the low input voltage it would run, with limited performance, and allow you to "see the wheels spin" and decide if you want to proceed with adding more modules in series.

The 62 kWh Leaf pack can deliver at least 150 kW, so this module - 9.4% of the whole pack - can safely deliver at least 14 kW. A motor controller trades voltage for current, so it matches the high-voltage battery to the lower voltage (and higher current) needed by a motor at low speed; however, it generally can't make the trade the other way - it can't increase voltage so as you speed up or push the accelerator pedal more at some point the battery doesn't provide enough voltage to get the requested power from the motor. With only 34 V and that motor, that will occur at a low speed. For full motor performance, four of those modules might be suitable, but the modules in that Leaf pack come in 9S, 7S, and 4S sizes, and combination of which can be connected in series. They're all the same in two dimensions, just with different stack lengths (heights, in the orientation they are installed in the Leaf pack).

Yes, endurance and range are basically just simple math: power multiplied by time is energy. Energy needed per unit distance multiplied by the distance you travel is the energy used (needed). With any battery the energy available is less if it is taken out at higher power, and as Carl mentioned this (the Peukert effect) is a major issue with lead-acid, but it's not a big issue with lithium-ion.

If you need (for instance) 200 Wh for each kilometre or 300 Wh for each mile, 50 to 100 miles will require 10 to 20 kWh... one-sixth to one-third of the 62 kWh Leaf pack.


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> Actually I also found the smaller version (little less than 1/2) from the same sell with lower specs for less than 1/2 the cost which is good if I'm just testing. I think I can stack 'em later so the money won't be wasted: 2019 Nissan Leaf 2589Wh 176Ah.


That would be the 4S3P module of the 62 kWh Leaf pack. 
2019 Nissan Leaf 2589Wh 176Ah 3P4S Lithium Ion Battery Module from 62kWh Pack

If you stacked two of them that would be about the same height - with more mounting and wiring complication - as one 7S3P or 9S3P module. Even for testing, 15 volts is very low; I don't know if the controller would even work at that input voltage.


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## 59 Austin Healey (Jan 1, 2021)

OR-Carl said:


> Lithium batteries do not suffer the same drop in output as lead acid batteries (peukert effect), so you can basically ignore that. What you do need to keep in mind when running off a smaller than ideal pack is what is called the C-rate. Basically, it is a measure of how fast you are discharging a battery. If a battery has a capacity (C) of 100ah, then drawing a load of 100a would give you a 1C discharge rate. If you pulled 200amps, you are asking the batteries for 2C, and 1000amps would be 10C. Each battery chemistry has its own limits, but higher C-rates will lead to less longevity. Aiming for a 1C discharge is probably ideal.
> 
> Since your motor is small (21kw), and your voltage is fairly high (174v) at rated power on a fully charged pack you would be pulling (21000/174=) 120amps. So ideally, you would want a pack that was 174v and 120ah, which is 21kwh. So yeah, if you got a pack that was only 5.8kwh, you would be using a 3.6C rate to get max power, and at half that size (2.6kwh), the C-rate would be 7.2C. That is likely not a good idea. But, the car should move with a lot less than the full rated power. You could test it at low speed, but you would want to keep your power draw down to not exceed whatever the max C-rate is on the batteries.
> 
> Honestly, though, it is going to be a lot of work to install a new battery bank. Do you really want to have to redo it? If money is tight and time is not, then that plan might work out for you.


Perfect, thanks!

Money could be a bit more loose but since I'm working from home I certainly have the time.  The 5.8kWh is actually pretty small and modular and there is a lot of room under the hood so I don't think creating the whole bank will be difficult. The idea is to buy one to make sure the electronics work, then buy the rest (identical to first) when I have the money. So not really 'redoing' it.


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## 59 Austin Healey (Jan 1, 2021)

brian_ said:


> That would be the 4S3P module of the 62 kWh Leaf pack.
> 2019 Nissan Leaf 2589Wh 176Ah 3P4S Lithium Ion Battery Module from 62kWh Pack
> 
> If you stacked two of them that would be about the same height - with more mounting and wiring complication - as one 7S3P or 9S3P module. Even for testing, 15 volts is very low; I don't know if the controller would even work at that input voltage.


Thanks Brian,

The math help from peeps on this forum is much appreciated! I'm starting to tie things together.

I think I can afford one of the 9S3P packs right now, which, at 33v is enough for testing and keeping the flame alive.  Probably shouldn't have used all of my spare cash to buy the car. heh.

I'll start researching BMUs and chargers now. The car has a bunch of electronics in the rear but since it has no trunk it's hard to access that space. Taking the seats out will help with that. There's probably a charger back there since that's where the plug is.


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## reiderM (Dec 30, 2020)

59 Austin Healey said:


> So, does the charger _tell_ you the percentage of charge in the batteries so, if you are paying attention, you can unplug it at the right time? It seems hard to get information on actual components. There's lots of theory out there but not much "here's what I did" stuff. I truly want to understand this technology, but at the same time, I want to see this thing move!


The charger (assuming you get a CAN bus enabled one, which I highly recommend) receives commands from the BMS regarding when to charge and when to stop charging. The BMS will detect SoC (state of charge) and determine what to have the charger do. The charger is just a dumb brick that converts AC power to the right DC voltage. A CAN-enabled charger can be turned on and off over CAN bus.

CAN bus is the universal communication language of just about everything car-related.


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## 59 Austin Healey (Jan 1, 2021)

Thanks!

I've been reading up on CAN bus and will most likely go that route if I can afford it.

What I don't quite understand is, if each battery pack has it's own sensor cable, how does the BMS know what pack it's charging so it doesn't overcharge a cell? Is the TIM considered a BMS, or is it just the inverter?


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## scottherrington (Jul 3, 2020)

59 Austin Healey said:


> Thanks!
> 
> I've been reading up on CAN bus and will most likely go that route if I can afford it.
> 
> What I don't quite understand is, if each battery pack has it's own sensor cable, how does the BMS know what pack it's charging so it doesn't overcharge a cell? Is the TIM considered a BMS, or is it just the inverter?


Check out South West EV UK on YouTube, he has lots of info about BMS etc.
Others can feel free to correct me if I'm wrong but when wiring a BMS it is important that the correct module is wired to the BMS in order, the BMS will then know which module is which.
If that makes sense?

Sent from my moto g(8) power lite using Tapatalk


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## OR-Carl (Oct 6, 2018)

59 Austin Healey said:


> What I don't quite understand is, if each battery pack has it's own sensor cable, how does the BMS know what pack it's charging so it doesn't overcharge a cell?


So, a battery is made of of cells, and the BMSes job is to monitor every cell. If you can combine cells together in parallel with very large conductors, then you can treat such a cell-group as a cell, and that will need only 1 BMS tap. Different BMS systems handle different numbers of cells. If you are going to try and get back up to 174volts, you would need 47 cells in series. (47x3.7 = 173.9) So your BMS would need to be able to handle at least 47 cells. 

Your car should not have separate battery banks, even if you plan on adding more batteries after doing some initial testing. You will likely want to just add more in series with the original pack. Bear in mind that the charger that came with the car might not be adjustable, so that might be worth looking into. The CAN enabled chargers can be programmed, so they are pretty flexible. 

Keep researching, and post some pics of the stuff that is in the car already.


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> What I don't quite understand is, if each battery pack has it's own sensor cable, how does the BMS know what pack it's charging so it doesn't overcharge a cell?


Just to add to Carl's excellent explanation, the battery pack is charged by a single charger (not the BMS), so all cells are charging at the same time. The BMS just monitors the charging and tells the charger to stop charging the entire pack as soon as _any_ cell voltage gets too high. It balances the cells by discharging (or bypassing some of the charging current) individual cells to bring them down to match the other cells. For these purposes, it doesn't matter what order the cells are in.


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## 59 Austin Healey (Jan 1, 2021)

scottherrington said:


> Check out South West EV UK on YouTube, he has lots of info about BMS etc.
> Others can feel free to correct me if I'm wrong but when wiring a BMS it is important that the correct module is wired to the BMS in order, the BMS will then know which module is which.
> If that makes sense?
> 
> Sent from my moto g(8) power lite using Tapatalk


Wow, this guy is great! ...a bit long winded but I guess at this point more info is better than less. I watched a 20 min vid of him meticulously wiring up the BMS and now understand a lot more about how that works.! 

Thanks again!


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## 59 Austin Healey (Jan 1, 2021)

OR-Carl said:


> So, a battery is made of of cells, and the BMSes job is to monitor every cell. If you can combine cells together in parallel with very large conductors, then you can treat such a cell-group as a cell, and that will need only 1 BMS tap. Different BMS systems handle different numbers of cells. If you are going to try and get back up to 174volts, you would need 47 cells in series. (47x3.7 = 173.9) So your BMS would need to be able to handle at least 47 cells.
> 
> Your car should not have separate battery banks, even if you plan on adding more batteries after doing some initial testing. You will likely want to just add more in series with the original pack. Bear in mind that the charger that came with the car might not be adjustable, so that might be worth looking into. The CAN enabled chargers can be programmed, so they are pretty flexible.
> 
> Keep researching, and post some pics of the stuff that is in the car already.


Excellent! This info along with the youtube channel that Scott sent are really helping a lot! The video showed me exactly how the BMS connects which makes sense now.

So if the Leaf packs I'm looking at are 9 cells, 5 packs would get me to 45 cells which would be 166.5v which I guess is close enough right? I think I can get four of those packs into the engine compartment without a problem, the 5th might be tricky. Is there a way to stack them in three dimensions so one or more could go above the other? Whenever I see people connecting their packs they always use a short thick copper bar.


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## 59 Austin Healey (Jan 1, 2021)

brian_ said:


> Just to add to Carl's excellent explanation, the battery pack is charged by a single charger (not the BMS), so all cells are charging at the same time. The BMS just monitors the charging and tells the charger to stop charging the entire pack as soon as _any_ cell voltage gets too high. It balances the cells by discharging (or bypassing some of the charging current) individual cells to bring them down to match the other cells. For these purposes, it doesn't matter what order the cells are in.


Thanks, that's some good detail! I'll post some pics in a bit.


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## 59 Austin Healey (Jan 1, 2021)

I jacked up the rear of the car today and was able to access some more components, including another MES-DEA box that looks like a DC/DC converter, though I'm not sure what it's used for. It's watercooled just like the other MES stuff.

Not the greatest pics but it's not jacked up very high. I may go buy some better jack stands.


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## 59 Austin Healey (Jan 1, 2021)

Oops, looks like they were duplicated. ')


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## 59 Austin Healey (Jan 1, 2021)

As I've mentioned in the past the car has no trunk, just a large open space behind the seats where I believe the soft is stored when not in use.

I've taken progressively closer pics of the rear 'trunk' electronics so you get the proper perspective. I think the box underneath the car is how they were able to get all of this stuff installed as I can't imagine anyone laying flat and doing all of this. The white plug on the far right is the external L6-30 connector for 220v charging. There is also a 110v plug behind the license plate. The blue plastic thing on the left is a spring loaded cord retractor for the 110v plug. The pic of the rear of the car is so you can see the silver charge port which looks like a gas cap.


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## scottherrington (Jul 3, 2020)

59 Austin Healey said:


> Wow, this guy is great! ...a bit long winded but I guess at this point more info is better than less. I watched a 20 min vid of him meticulously wiring up the BMS and now understand a lot more about how that works.!
> 
> Thanks again!


Was that his first attempt or second?
He had to re do the whole thing 
You're right, you can never have too much info at this stage

Sent from my moto g(8) power lite using Tapatalk


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## 59 Austin Healey (Jan 1, 2021)

Here's pretty good pics of engine bay with measuring tape. The rear area is 24" across, the front is 12" across, the two sections are about 14" deep. I think I can only go up about about 8" in the rear section because of the steering shaft and other metal protrusions. The front area can go up to about 16".


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## 59 Austin Healey (Jan 1, 2021)

scottherrington said:


> Was that his first attempt or second?
> He had to re do the whole thing
> You're right, you can never have too much info at this stage
> 
> Sent from my moto g(8) power lite using Tapatalk


It was the 2nd try where he used better wire. Great info because Cat-5 would have been something I considered as well!


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## 59 Austin Healey (Jan 1, 2021)

Now that I'm looking at the dimensions of the existing battery box, and dimensions of my example battery seen here:








2019 Nissan Leaf 5826Wh 176Ah 3P9S Lithium Ion Battery Module from 62kWh Pack | eBay


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The numbers don't really match up with what I need.
Length: 12.25 inches(319mm)
Width: 8.75 inches (222mm)
Height: 9.625 inches (244mm)

So I think I'll brush up on my novice MIG welding skills and make something more suitable. 

But, this comes back to my earlier question of how do you connect batteries if they are not on the same plane and right next to each other? Thick copper cable?


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## brian_ (Feb 7, 2017)

59 Austin Healey said:


> But, this comes back to my earlier question of how do you connect batteries if they are not on the same plane and right next to each other? Thick copper cable?


Yes, while bars work well and are routinely used in OEM packs, cables with crimped-on terminals work fine, too.


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