Serengeti Panther: is COTS Battery an Option?

[KDKD]

Been lurking here for a while and I'm finally in a position to be able to ask for help...

My Serengeti Panther scooter ran fine initially, and slowly the battery was dying sooner and sooner until one day when I had to walk the scooter home as my poor little champ could not even get me where I was going. I took the battery apart just to see what it looked like inside. Then I moved, but I could not take the scooter because it would not run, and I could not lift it by myself into my SUV. So it sat in my old condo complex for about 6 months.

Yesterday I got a call from a scooter repair place. Someone tried to steal it, couldn't get it to run, and ended up scamming the scooter shop. The shop owner unlocked the seat and found my registration paperwork and called me.

So now I (finally) have my scooter back, but the thief removed a bunch of the panels and I cannot tell what wires he took apart. I have a feeling I will be able to figure it out if I knew I had a working battery pack.

So here I am to ask a simple battery question to start ... I want to know if it is possible to buy a COTS 48V 15Ah rechargeable battery with a built-in BMS off the shelf, replace connector with a C13 connector, use my existing charger ... and basically just plug and play? I have never built a battery pack from scratch and I am already overwhelmed after the mess the thief made. I always loved this scooter. It was in pristine condition before the guy stole it and I'm not ready to let it go

(The guy at the scooter shop was super nice, but I read reviews and he can be really unreliable and I was not impressed with his work habits when I came by to pick it up, so I would rather just figure this out myself.)

If I could just start with a known good battery, I think I can get the scooter running. I know it's not the cheapest option but would buying COTS work?

 

[amberwolf]

What battery did it have to start with?

Required information:
--chemistry (to know if existing charger could work)
--full voltage, empty voltage (average voltage plus chemistry will also tell us this) (48v noted so far)
--capacity (Ah and/or Wh) (15Ah noted so far)
--continous A (amps) it can produce
--peak A it can produce and for how long)
--exterior dimensions?

 

[KDKD]

Thank you so much for getting back to me! Wish I'd seen your response yesterday... sorry for delay. I have checked the "Notify me"

--chemistry (to know if existing charger could work): Lithium Ion
--full voltage, empty voltage (average voltage plus chemistry will also tell us this) (48v noted so far): All I know is that it has 15 flat cells stacked side by side, wired in series, and each battery is 3.2V
--capacity (Ah and/or Wh) (15Ah noted so far): 15Ah
--continous A (amps) it can produce: I am not sure, and also not sure how to figure out continuous vs peak. I believe the charger is 4A but I don't know what that tells us.
--peak A it can produce and for how long): see previous
--exterior dimensions?: the custom pack and BMS fit inside an oddly shaped plastic molded case with interior dimension 7" x 7.5" x 8" ... HOWEVER the case sits inside the seat which has much larger dimensions 7" x 7.5" x 15" (and maybe even taller/longer depending on orientation)


I dug through all the Serengeti Panther threads on this site but I don't see Amp info you asked for
https://endless-sphere.com/forums/viewtopic.php?f=14&t=45741
https://endless-sphere.com/forums/viewtopic.php?f=10&t=107972
https://endless-sphere.com/forums/viewtopic.php?f=10&t=71825
https://endless-sphere.com/forums/viewtopic.php?f=10&t=52634
https://endless-sphere.com/forums/viewtopic.php?f=7&t=53114
https://endless-sphere.com/forums/viewtopic.php?f=7&t=45244


I'm wondering if I were to find a battery that met the following specifications, would it work?
-48V, 15Ah
-with built-in BMS
-with 3A or 4A charger? (I would need to find a converter so I could plug in the charger and also plug in to the scooter's C13 connector)
-fits in the space available inside the seat
-does it have to be Lithium Ion or can I pick something else?

Thank you so much!

 

[amberwolf]

--chemistry (to know if existing charger could work): Lithium Ion

That's better than the common SLA (lead acid) stuff in many scooters/etc. Fairly easy to find decent ones.

--full voltage, empty voltage (average voltage plus chemistry will also tell us this) (48v noted so far): All I know is that it has 15 flat cells stacked side by side, wired in series, and each battery is 3.2V

The 3.2v means it is a LiFePO4 battery. (a type of lithium ion). 3.2v is an "average" voltage, meaning the voltage the cells are at for most of the discharge curve. These types generally charge to about 3.6v full, and empty to about 2.8v.

15s x 3.2v = 48v, so that's the average pack voltage. Meaning that generally any "lithium" 48v battery will operate the scooter, voltage-wise. Just have to find out how much current the scooter uses to be able to find a battery capable of driving the motor with the torque/etc it needs to have.

When it's full it would be at around 54v.

--capacity (Ah and/or Wh) (15Ah noted so far): 15Ah

So to get the same range, you'll need one that has at least that many Ah. More Ah means more range, generally, but it will also be larger and heavier.

--continous A (amps) it can produce: I am not sure, and also not sure how to figure out continuous vs peak. I believe the charger is 4A but I don't know what that tells us.
--peak A it can produce and for how long): see previous

The 4A charger just tells us that's how much current it can supply maximum during charging, and thus how much current the battery you have can handle for charging.

The reason it's important to know the peak and continuous A is to find a battery that can supply at least that much, so that your scooter will run like it used to without stressing the battery out.

Do you know how many watts your system is supposed to be? It might be marked on the manual, or other paperwork that came with it, if it's not marked on the scooter anywhere. That will give us a good guesstimate. Watts = Volts x Amps, so Amps = Watts / Volts. If it is a 500w scooter, then 500w / 48v = 11a. (round up for demands on a system for a bit of margin ).

--exterior dimensions?: the custom pack and BMS fit inside an oddly shaped plastic molded case with interior dimension 7" x 7.5" x 8" ... HOWEVER the case sits inside the seat which has much larger dimensions 7" x 7.5" x 15" (and maybe even taller/longer depending on orientation)

Then you can use the space inside the seat as your pack size limit, if you don't need the casing to secure the battery or waterproof it. Most generic packs are just shrinkwrapped, and don't have any waterproofing. If the seat compartment itself is waterproof, then that doesn't matter. Otherwise you'll want some form of waterproofing, unless you *NEVER* leave it outside, ride in any kind of damp or wet conditions, etc.

I'm wondering if I were to find a battery that met the following specifications, would it work?
-48V, 15Ah
-with built-in BMS
-with 3A or 4A charger? (I would need to find a converter so I could plug in the charger and also plug in to the scooter's C13 connector)
-fits in the space available inside the seat
-does it have to be Lithium Ion or can I pick something else?

I recommend lithium because it's the best of the options available. Lead (SLA, etc) will weigh a lot more for pretty much half the capacity/size/etc. Nickel (NiCd, NiMH) are similar, not practical as you'd need to build them yourself from cells, and they have special charging considerations that make them not very DIY friendly for the average user.

If you stick with LiFePO4 you can use the same charger you already have. You may also be able to use it with other Lithium packs, but only if their final voltage matches that on your charger. If it does not list a final voltage, we could assume that calculated previously, but it's best if you can measure it with a voltmeter, if it's not labelled. However, a new battery generally comes with it's own charger (though it might be only a 2A type, higher current faster chargers may cost extra), so you could use that instead of your existing one if necessary.

Non-LiFePO4 lithium packs that are 13s will be around 54v full, so may be able to use your existing charger.

All the lithium batteries will come with a BMS, but there are different types. I'd recommend making sure it states specifically that the BMS is a Balancing type; many cheap ones are not, and with the cheap cells also used in those, tend to lose usable capacity quickly from imbalances that grow over time. The higher quality cells make a better battery pack overall, but are more expensive (though higher price isn't a guarantee of better).

By C13 connector, do you mean one that looks like a computer-style AC plug? If so, it's fairly likely that a new battery charger wont' have that (but it might). That connector can be changed on hte scooter, if necessary, or move the one from the old charger to the new one, etc. If you prefer, you can make it a requirement that the new battery charger (if required) comes with that connector.

Does your existing battery also have that connector on it? Because a new battery that comes with that connector on it's charger will also have it on the battery.

 

[KDKD]

You are my absolute hero!! Those were AMAZING explanations. Thank you so so much <3
Let me read than 10 more times and do some research and will report back.
THANKYOUTHANKYOU!

 

[amberwolf]

If you have questions about any of it, just ask.

 

[KDKD]

I read through your post about 10 times ... so much great info in there. Thank you so so much (have I said that already?)

So I am looking for a 48V 15Ah 500W (found that spec online) LiFePO4 battery
- with balancing BMS
- 500W/48V = round up to 11 Amps (but it looks like I order by Watts)
- Good point about waterproofing, thank you!

Few questions:

1) I would order 48V knowing it will be at around 54V when full - meaning I do not order 54V, right?
2) I understand it is possible to go "up" on the 15Ah ... maybe 48V 20Ah 500W for better range (but heavier and more expensive). I would still want 500W because it is based on Voltage and current draw Amperage, and they do not change, right? (So I can only increase the 15Ah to 20Ah, but not the Voltage or Wattage, right?)
3) My existing battery does have a C13 (yes, the one that looks like computer), and as you have guessed so does the charger, and of course that's what the existing battery plugs into on the scooter as well so it would make everything easier if I could find a battery with a C13 as well, but in my initial searching I am not seeing that option sadly. I will continue to look but I think I might have to swap whatever connector the battery has for a C13. (Or, better yet, I am hoping a converter dongle exists for this purpose.) If I can't find a C13 or a dongle, I wanted to ask: how hard is it to swap the connector out?

THANKYOUTHANKYOU

 

[amberwolf]

So I am looking for a 48V 15Ah 500W (found that spec online) LiFePO4 battery
- with balancing BMS
- 500W/48V = round up to 11 Amps (but it looks like I order by Watts)

Not that I know of. The battery should be rated by how many amps (A) peak and continuous it can supply. The peak is only a few seconds and may be several times the continuous rating. If the BMS is not designed to shut it off if this is exceeded, then either the BMS or the cells could be damaged going too high for too long. The continuous is for as long as it takes to drain it to empty at that rate.

If it only states one A rating, it could be peak, or continuous. If it says "max" that's probably peak. If it doesn't say it's safer to assume that is a peak, because if it is but you use it continuously at that rate then it could result in damage, worst case, or shutdown while you really need that power best case.

If it only states watts, then you have to make assumptions about what voltage number and what amp number they used to calculate the watts from (just like we made assumptions on power the scooter actually takes, by using the 500w rather than an actual amp rating...which could be very different than the derived 11a). Stacking even more assumptions on top of each other can lead to trouble, so using specific, known data points is safer whenever that is possible.

Many batteries don't specify much info...especially cheaply-made ones, and some of them actualy lie, stating a peak rating as if it were continuous, exaggerating ratings in general, and so on. Hard to know which are accurate info, good sellers, etc. Sometimes you can just "tell" it's a bad idea to buy from a place, etc., sometimes you can't.

The more detailed and specific info they give, and the more clearly they state this stuff, the better. Put those on your "which one of these do I buy?" list.

The more conflicting info on a page there is, or the more "multiple models" are on the same sales page, the more likely it is that the information is unreliable. Put those on your " "well, I couldn't find anything better" list.

1) I would order 48V knowing it will be at around 54V when full - meaning I do not order 54V, right?

That depends on how detailed the specifications are for the battery you look at. The better ones will provide the charger voltage, which is the actual full voltage of the pack, while also usually calling it a "48v" or "52v", "60v", etc battery, which is the nominal or average pack voltage.

Some "52v" batteries are also called 48v, but they are 4v higher than the "actual" 48v batteries. It's pretty likely that your scooter will handle that fine, and may even have peppier performance (very slightly higher top speed at full charge, possibly higher startup torque from a stop due to higher voltage at the same current draw, etc). So you can probably use those, too--but if the controller is designed with an HVC (high voltage cutoff) above 54v for some reason, it may not operate when it's fully charged (or may operate differently); additionally any battery meter may not display correctly and it will seem full longer than it really is...and the controller's LVC (low voltage cutoff) will not shutdown until the battery is *really* low or possibly even the battery's BMS will have to do the shutdown instead, and this is harder on the battery to run it "deader" than usual.


So, sticking to a LiFePO4 battery that is 15s (s= cells in series) like what you have, whether they call it 54v or 48v, is "safer", more likely to work just like what you have.

If they don't specify this, put that battery on your "well, I couldn't find anything better" list.

2) I understand it is possible to go "up" on the 15Ah ... maybe 48V 20Ah 500W for better range (but heavier and more expensive). I would still want 500W because it is based on Voltage and current draw Amperage, and they do not change, right? (So I can only increase the 15Ah to 20Ah, but not the Voltage or Wattage, right?)

If all you want is more range, then you only change the Ah.

If you want to change other behaviors of the scooter, you'll need to state what you want it to do that it doesn't do now, under what conditions, and then we can figure out what you need to change (which could be battery, controller, motor, or all of them).

3) My existing battery does have a C13 (yes, the one that looks like computer), and as you have guessed so does the charger, and of course that's what the existing battery plugs into on the scooter as well so it would make everything easier if I could find a battery with a C13 as well, but in my initial searching I am not seeing that option sadly. I will continue to look but I think I might have to swap whatever connector the battery has for a C13. (Or, better yet, I am hoping a converter dongle exists for this purpose.) If I can't find a C13 or a dongle, I wanted to ask: how hard is it to swap the connector out?

Converter dongles...I don't know of any but have never specifically looked for one. It's very likely you'd need to make one. Simple way is to get one of the mating connectors to what's used on the battery, and an extension C13 cable with the thickest gauge wire you can get. Cut the C13 cable in half, and use one end for the one dongle, and the other if you need it for a charger dongle. If you won't need the other end, just get a C13 power cord that has the end you need for the battery, and cut the other off to put the battery connector on. Polarity is extremely important, so you have to test that before you do anything.

That depends on your DIY skills, and your electrical / wiring experience. For someone that has never done this stuff, then to do it well can be a challenge; doing it well is important for performance of the system and for safety. I remember some of the first wiring thigns I ever did (as a kid) and cringe at myself thinking of the fires I could have caused (but luckily didn't).

For someone with moderate experience, it's pretty easy.

There are plenty of tutorials about how to do voltmeter testing, wiring, crimping, soldering, etc. (even using the wrong tools for the job and still get an adequate result)...but it's still something you'd want to practice a few times on something you don't care about.

We can help with that part, too, once you get that far, but you may have to buy some tools (to be determined once you have the new stuff), to do whatever work is found necessary.

 

[KDKD]

Good grief, this is so frustrating.

I'm trying to find batteries online. I googled, ebay, amazon ... there are a bazillion no-name Chinese outfits with 1-2 reviews. The ones that have a lot of reviews meet the "well, I couldn't find anything better" list and most don't explain what kind of BMS they have (balancing).

Is there a brand you trust for your scooters/ebikes? Or a seller you trust?

Thank you so much again...

 

[Chalo]

15S lithium ferrophosphate is an unusual cell count these days. 16S is more common, and in some cases more convenient because it can use chargers and state-of-charge indicators rated for 48V lead-acid batteries.

If your charger's open circuit voltage doesn't exceed 54.6V, you could substitute a 13S (nominally 48V) lithium ion pack, which will be much easier to find.

 

[KDKD]

Yes, I was looking for 48V LiFePo4 but I think I also looked at 48V Lithium Ion as well. Where do you buy your batteries from?

 

[Chalo]

Mostly I get batteries from Battery Hookup these days, but their selection is pretty random, and often I have to remove some OEM components and install my own BMS. Last I checked, they didn't have too much high energy density stuff to offer. But that could change at any time.

 

[nicobie]

While Amberwolf and Chalo are 100% correct you might try calling Grin tech and asking their advice. They are probably the most trusted ebike outlet in the world right now.

Here is a link to their battery page, but if you called them and tell them what you told us would be your best bet.

https://ebikes.ca/shop/electric-bicycle-parts/batteries.html

 

[john61ct]

If you can fit 15 of these, incredible deal, get a few spares

https://batteryhookup.com/products/calb-ca100-3-2v-100ah-lifepo4-prismatic-cell

These are much smaller, new but not as great quality
https://batteryhookup.com/products/new-3-2v-25ah-lifepo4-topband-navitas-prismatic

Need to check if these are LFP pretty sure yes
crazy good deal
would 4+ of these fit?

https://batteryhookup.com/collections/all/products/boston-power-5300-pack-10-95v-26-5ah-290-175wh-3s5p

 

[Chalo]

If you can fit 15 of these, incredible deal, get a few spares

https://batteryhookup.com/products/calb-ca100-3-2v-100ah-lifepo4-prismatic-cell

That's over a cubic foot and more than 112 pounds of cells. This is a pretty dinky scooter we're talking about, with a 30A controller. 15 of those big CALB cells would be a better match for a golf cart or a full sized motorcycle.

https://www.endless-sphere.com/forums/viewtopic.php?t=71825

 

[john61ct]

OK then, I did say "if"

in this case a Big If

 

[KDKD]

I found this 48V 15Ah 500W battery online and I think they might even be willing to swap the connector to a C13:
https://amzn.to/3tnQlIn [Edit: I am referring to this one as OPTION A]

Lithium Ion
48V, 15Ah, compatible with 200-1000W
BMS: 20A
Max Constant Discharge Current: 20A
Peak Discharge Current: 40A

If it is a 500w scooter, then 500w / 48v = 11a.

Amberwolf, I'm not 100% sure what the 11A is ... is that an average current?

I'm attaching a pic of the controller which I found in another thread on this forum as I think it is relevant to battery selection.

Would OPTION A battery work?

 

[amberwolf]

If it is a 500w scooter, then 500w / 48v = 11a.

Amberwolf, I'm not 100% sure what the 11A is ... is that an average current?

It is the current that would be drawn at 48v to create 500w of power. Because it's just a calculated static number, and not based on "real" numbers from equipment or testing data, it doesn't represent what the system actually does, it's a guesstimate of the minimum amount of current your battery would have to be able to supply, probably continuously. It might need to supply more than that peak, depends on the controller specifics.

A real system changes voltage over time as the battery charges and discharges. It also drops (voltage sag) as the load increases (startup from a stop, going up a hill, faster speeds), because the current increases and the internal resistance of the battery (lower for better ones) drops some of the voltage inside the battery, wasting power as heat.

I'm attaching a pic of the controller which I found in another thread on this forum as I think it is relevant to battery selection.

Very relevant; the Max Current listing on there means you need a battery that can supply at least 30A (almost 3x what we calculated based on the "guess" numbers). Since it doesn't specify if Max means max continuous or max peak, you're safer to assume continuous, and make sure you get a battery that could supply that much constantly.

However, 30A x 48v = 1440W, which is about three times what the system is rated for, if the "500w" is correct--meaning if it is a "500w" motor, and is rated like some small ones are, it can probably handle that 1440w for a short while before overheating (few minutes?), but not all day.

Depends on the speeds you go for how much power will actually be drawn; most "truly only 500w" scooters wont' be able to much past 20mph, depends on conditions and aerodynamics, etc. (see the motor and trip simulators on the ebikes.ca site for how this all interacts).

Assuming other factors are also correct, you might get 30mph out of a "1500w" version. (not necessarily up a hill or in a headwind).


The Low Battery Protection is important, at 42v, because that's the point it will shut off to protect your battery. If you're using a non-lifepo4 13s li-ion pack, that's the normal shutdown for those (the bms in the pack will shutdown at a lower voltage, but it is only there to protect the pack from damage, not as an everyday cutoff).

If you're using a 16s lifepo4 pack, or a 14s li-ion pack, that LVC is too low, and would (if the bms didn't stop it first) discharge the 16s lifepo4 pack to 2.63v/cell (2.8 is better), and the 14s to 3v/cell (3.3v is better).

A 15s lifepo4 or 13s li-ion pack is better suited to this controller's LVC.

The battery spec on Amazon says:
- BMS: 20A
- Max Constant Discharge Current: 20A
- Peak Discharge Current: 40A

Would this battery work?

They specify the 48v version is 13s, so it should work with the 42v lvc of the controller. The charger it uses is 54.6v; if your charger is not as high, it may not fully balance the pack, and you may need to periodically use the charger it comes with to balance it at least overnight (for instance, if you start to lose range or have performance issues).

However, they do not specify anywhere I can find what the BMS specifics are (such as if it is a balancing type, and which of the different balancing types it is, if so). So before buying you should ask them exactly what BMS is in it, preferably with a link to the "manual" or "datasheet" for the BMS so you can find out if it will balance the cells for you, or if you will have to cut open the pack to check them and balance them manually after performance / range problems appear.

THey also don't specify which cells they use, which usually means they're using the cheapest generic stuff they can possibly get hold of. That might be fine, but it may not have as long a lifespan as "brand name" cells.

Keep in mind that the $259 price *includes 2-week shipping from China* (it says it ships from the company in question, which lists their address in Beijing, China), which is probably not all that cheap, so doesn't leave a lot of money for them to spend building the battery itself.

Since it comes from China, any warranty it might have would mean shiping it back there, which will probably cost you more than the entire battery did, so if something goes wrong with it, it'd be up to you to deal with that. I don't know how applicable the amazon protection plan they offer is (meaning, whether you'd get service or replacement/etc from it); I've never used their plans.

 

[KDKD]

Thank you Amberwolf!

Sounds like OPTION A battery won't work for me because the controller needs 30A constant discharge current (assumption because we don't know for sure) and this one only goes to 20A. I'm guessing the 30A max current is peak (for hills) because it is a fairly light scooter otherwise, but no point taking a chance. The third photo is about the BMS and it said "Balanced power" so I assumed that meant balancing. Didn't know there were different kinds of balancing ... silly me, of course it wouldn't be simple

Ok! I think I found another candidate. It is more expensive but also better performance:
https://amzn.to/36CLVEU [I am referring to this one as OPTION B]

LiFePO4
48V 20Ah fits 350W-1500W motor
Max continuous 50A
Max peak 100A
Fits in the space
Even comes with a C13 as an option! (I think I will have to solder but I can do that.)

Now the question is the BMS ... it doesn't say "balancing." Would you take a look at the third pic please Amberwolf? Is one of those possibly a synonym for balancing? Like maybe "equilibrium function"?

I await your approval before purchase

 

[amberwolf]

The third photo is about the BMS and it said "Balanced power" so I assumed that meant balancing.

I didn't look at the pictures (mostly because amazon's messed up servers mix up pictures from various products relatively frequently, so you get totally wrong images that have nothing to do with anything else on the product page), just read/searched the text of the page.

"Balanced power" *could* mean the BMS does cell-group balancing...but you need to *ask the seller* and get absolute clarification about that to know for sure. The seller may not know, as all their info could be copied from a manufacturer site, or the mid-level seller *they* bought their stock from...but it's your only option, unless you know who made the BMS, and then you could ask that manufacturer (if it's not on their website, if they have one), assuming they answer questions from anyone but big dealers/sellers/etc.

Didn't know there were different kinds of balancing ... silly me, of course it wouldn't be simple

There are different kinds of balancing, but they dont usually matter to the end-user (their failure modes are different, so troubleshooting problems means knowing how each one works); the only part that matters is that they either do balance, or they don't, and that the cheaper the pack the less likely it will have a balancing BMS, as well as more likely to have cells that will *need* balancing, and thus the higher likelihood that problems will arise sooner with imbalance decreasing pack capacity and capability.


Capacitive balancers redistribute charge from high cells to low cells. They could do this at any time, not just during charging; whether they do or not depends on the specific BMS.

Resistive shunt balancers normally only work during charging. They just bleed off "overcharge" on high cells after stopping the charge current, down to some preset level, then restart charging until the high cells exceed some limit, and repeat the process until all the cells are about the same voltage.

NEither type is very fast; they're only intended to handle the minor imbalances that happen from nearly matched cells, so when you have a real problem they can take quite a while (hours to days to weeks) to fix it. But a "good" pack would be made from well-matched cells of high quality, and used well within it's capabilities so ti is never overstressed...and a pack like that doesn't even need a BMS to balance it until it begins to age enough. HOwever, most ebike/etc packs are simply not built of well-matched cells, and rarely of high quality cells (remember, marketing is lies), and usually used right up to their limits and beyond....




But the real problem with terminology is that just about everything you see on products like this is a translation of a technical term from Chinese to English, by non-technical people, so there are all sorts of "wierd" ways of saying things that often dont' even make sense in relation to what they are actually for.

One example is the "Door Lock" wire on ebike/scooter controllers--there aren't any doors, so there can't be any locks for them. What this wire actually does is provide battery power to the low voltage power supply to turn on the brain of the controller and power things like throttles and motor hall sensors, PAS, etc. It's usually called a Keyswitch line in English, because it's often switched with a key for security (or just a button or switch when that's not needed or used). Some call it "ignition", which even though electric stuff doesnt' have an ignition, at least makes some sort of sense in that it's like the ignition key on a gas vehicle that starts the engine...but "door lock" (and some of the other terms used for it) doesn't make any sense at all, of any kind, period. Yet it is one of the most common translations of whatever the actual Chinese term for this wire/function is.

Plenty of other stuff out there like that, and even worse, some terms are used for several completely different things, so you can't know which one they mean except occasionally by context, and more often by testing it out (perhaps to unintended destruction).

Is one of those possibly a synonym for balancing? Like maybe "equilibrium function"?

Could be...but again, you need to ask the seller to get absolute clarification about that to know for sure.

 

[KDKD]

Thank you Amberwolf!

I posed the following question to the seller about OPTION B battery:

Can you share more about the BMS? Does it do cell-group balancing? Do you have a spec sheet about the BMS or a part number I can look up?

This was the seller's response:

The 48v 20ah lifepo4 battery comes with 40A BMS which can do cell-group balancing, protect battery from over current, over voltage, short circuit, over load. it can make battery safer

(Bit annoying, the page says 50A BMS, and now they are saying 40A. However, if the controller says 30A maybe it is ok...)

Please tell me if you think I am making a big mistake...

 

[KDKD]

Amberwolf,

I put in an order for "OPTION B" on Amazon. It should arrive in about a week. I will report back...

Tara

 

[KDKD]

Update!

Battery came ... there are four wires ... two thin and two thick. I am supposed to solder connectors to it this way:

Instructions say: Solder two thin wires to regular C14 connector (used for charging)
- red thin wire --> solder to positive side of C14 connector
- black thin wire --> solder to negative side of C14 connector

Instructions say: Solder two thick wires to Anderson plug (used for discharging)
- red thick wire --> solder to positive side of Anderson connector
- black thick wires --> solder to negative side of Anderson connector

I'm assuming Anderson plugs are standard on scooters and that is why the connectors are included. In my case, the original battery only had one C14 connector that was used for both charging and discharging. I am curious whether I could set up the new battery with only one C14 connector that can also be used for both charging and discharging, the way my scooter worked originally. I am proposing I would solder it in this way:

Proposed: Solder all wires to regular C14 connector (used for both charging and discharging)
- red thin + red thick wires combined --> solder to positive side of C14 connector
- black thin + black thick wires combined --> solder to negative side of C14 connector

It would be much cleaner and I would be able to put the new battery in the original custom (non-standard) case which fits the scooter perfectly. The original case only has an opening for one connector.

Here is a pic of the new battery:


Anderson connector (male and female)


C13/14 (male and female)

 

[amberwolf]

Battery came ... there are four wires ... two thin and two thick.

This usually means that it has separate charge and discharge ports on the BMS.

Some of them are designed in a way that means you could tie them together and use just one connector for both.

But some of them will not have any protection against overcharge or overdischarge if you do this. Meaning, when the pack is discharging and turns off the output to protect from a low-voltage cell (etc), the charge port is still a path for current flow, and two problems result from that:

The charge port isn't typically capable of anything like what the discharge port is, current-wise, so the FETs will heat up and may overheat and fail (which usually means stuck on, unable to shut off, and that's a "silent" failure so you won't even know it has happened until it causes a further problem with the pack, like a fire).

The pack will continue to discharge even though it's in a state that shouldn't be allowed for safety and/or cell health. You won't get any "official" warning or notification of a problem because a BMS like this won't even know it is happening, and eventually (usually pretty quickly) cells will be drained below their safe-recharge levels, and the pack is toast. There will be the behavior of the system (slower, much less power than normal, possibly "zeroed" battery gauge, etc) to warn you if you're paying attention to it, but many people don't. If there's a severe enough imbalance between cell groups, it's possible to actually reverse the lowest-voltage groups, and that's unhealthy permanent damage you shouldn't try to recover them from.


If you have BMS documentation that tells you what specifically the BMS is designed to do in each eventuality of shutdown conditions, for each port, then you can make an easy judgement call for whether it's safe to parallel the ports or not.

Otherwise, you can do testing to see if a discharge port shutdown still allows current flow backwards out of the charge port or not. If it does, then paralleling them could be a problem in the future.

Same thing for whether a charge port shutdown still allows current flow backwards into the discharge port (whcih could lead to cell overcharging).


If it's possible, it would be safer to use them separately, if they are already separate ports.

 

[amberwolf]

I'm assuming Anderson plugs are standard on scooters

Not really; there isn't a standard for anything, really, regarding ebikes, escooters, or emotorcycles. Every company does whatever they feel like, usually the cheapest thing they can get away with. If they are aiming for compatibility with some other company's stuff because they know it will make them more money, they may use the same stuff they did, and sometimes you get a little corner of the market that all uses the same stuff for that reason.


Andersons, especially the SB-50 series pictured there, are a MUCH better plug for this than the IEC type connector your scooter has, which is NOT designed for DC, or generally for currents above 15A AC (some of them are marked for even less).

The Anderson plugs are also genderless, meaning there isn't a male or female end, so you only have to buy one kind. They are still polarized, and marked on the shells with that, so you can't plug them in wrong. You can even buy them in several keyed shell variations (color coded!) so you could use a different one for charging vs discharging, or for different voltage systems, etc.

I use the SB-50 for all of the high current connections on my stuff, and they work just fine. But they cost more *and* they are much larger, vs the IEC stuff, so they don't get used in these cheap e-motor stuff very often.

I have several AC-powered devices that use the standard IEC connectors you have there (C13, 14) to plug into the wall, that have intermittent connections, and nearly had a fire from one of them years ago. PIcs of the charred arcing area are in one of my bike threads (probalby CrazyBike2) someplace. It was just a bad power cord, with the female contacts spread out too much so they didn't mate with the prongs in the device's AC socket...but that kind of problem happens ALL THE TIME with these connectors.


Obviously, they do work for AC plugs relatively well, as they are on MILLIONS of devices (pretty much every computer system out there since at least the 1980s, and many many other devices). But like many things, the cheaper they are made the worse they perform, even in their intended use...and stuff on e-motor-stuff is often the cheapest of the cheap.

They'll probably work fine for you...but since you ahve the Anderson stuff there already, and yo'ure already going to have to splice connectors on *something*, I'd personally replace the scooter one(s) with the Anderson rather than vice-versa.