Building first lipo pack - Drift Trike

[Bikegirl]

I'm looking at building a 20S 1P 5ah 12C lipo pack for a high power short runtime drift bike using 5 turnigy 4S packs to give 72v nominal to a 3000W motor and controller (50a) from aliexpress.

This build would be for a friend, so i'm looking to provide a safe and simple charging routine and probably a BMS (or other PCB's) to keep cells happy during use (auto cut out for undervoltage, out of balance etc.)

I have read a bit and watched west coast cycles video regarding lipo cell balancing, charging and testing of new packs, and wary of preventing a fire.

What would be the most compact and safe charging solution that would be simple and easy to follow?

Also, is there any rules of thumb with physical protection during use? and could wrapping the cells too much cause them to overheat? I am in a tropical area (20degC-35degC) if that helps.

I am an electrician so am experienced with soldering, connectors etc. just need some more experience with which charger, bms, would provide value for money with safety.

 

[pullin-gs]

Basic advice:
*)Just get one (or more) 4S RC chargers which will keep packs balanced....this is both safe and effective.
*)Use fuse(s).
*)Charge each of the 5 packs separately....keeps things simple.
*)Use cheap 4S battery monitors for when pack is being used.
*)Develop written process for connecting/charging/monitoring of packs when being used, charged, and stored.

 

[jonescg]

Protect the cells from physical trauma, and never stack pressure on them in the X or Y planes as the cells will delaminate. Z plane (the face of the cells) is fine - as much pressure as you can build into the pack. Heat will damage the cells long term. Bad packaging will damage them in the short term.

 

[DogDipstick]

50A should be nothing for the 5Ah 12C cells... to a point. Continuous use would stress the packs lifespan but you should be ok for a while. For example, I hit my 5Ah packs 3-=65C packs w 3000W all summer... Drain them in 4 min... each at a time... but only the ones that go down less than to 50% are the ones that make it to the next summer. If the cells were bigger they would not care so much about the 50 A.

As for BMS you are either choosing cheap chineese or some company product, batrium, orion, elithionn, ect. You want bluetooth, and a good charger, to see individual string voltages and so you dont have to wait around for a big pack to charge.

 

[motomech]

I'm looking at building a 20S 1P 5ah 12C lipo pack for a high power short runtime drift bike using 5 turnigy 4S packs to give 72v nominal to a 3000W motor and controller (50a) from aliexpress.

This build would be for a friend, so i'm looking to provide a safe and simple charging routine and probably a BMS (or other PCB's) to keep cells happy during use (auto cut out for undervoltage, out of balance etc.)

I have read a bit and watched west coast cycles video regarding lipo cell balancing, charging and testing of new packs, and wary of preventing a fire.

What would be the most compact and safe charging solution that would be simple and easy to follow?

Also, is there any rules of thumb with physical protection during use? and could wrapping the cells too much cause them to overheat? I am in a tropical area (20degC-35degC) if that helps.

I am an electrician so am experienced with soldering, connectors etc. just need some more experience with which charger, bms, would provide value for money with safety.

I'm looking at building a 20S 1P 5ah 12C lipo pack for a high power short runtime drift bike using 5 turnigy 4S packs to give 72v nominal to a 3000W motor and controller (50a) from aliexpress.

12C Turnigy is too low a rate for a 50 Amp continous dis-charge, 20C is not bad, but 25C would be best for what you want to do.
A member here, icecube57, has done much testing of sustained LiPoly dis-charge rates. He spent a lot of time testing the MultiStar 10C and 12C and his conclusion was that a MS 10C pack in the 15Ah to 20Ah range was good to 40 Amps max. Given that your proposed pack is only 5 Ah, 12C would b cutting it too close. I have run 2) 20 Amp controllers off a single MultiStar 15 Ah 10C pack and at full throttle I would see a 2 Volt drop, not good.
Always use the fewest bricks possible to get the Voltage you want, right now, the Turnigy 5S 5Ah 20C is $46 a brick from Hk. The 25C is only $4 more, so get the 5S 5Ah 25C, 4) for $200.
Cut off the XT 60 connectors and use Turnigy 6 MM bullets and connect the 4 bricks in series for 20S/5 Ah pack.

This build would be for a friend, so i'm looking to provide a safe and simple charging routine and probably a BMS (or other PCB's) to keep cells happy during use (auto cut out for undervoltage, out of balance etc.)

There are no practical BMS's for a LiPoly pack like this.
A LVC(Low Voltage Cut-off)in the controller would be best, but at 20S, this may not be practical. You will probably have to use an alarm. These can be tricky because around 3.75V/cell, one or two cells may start to drop further than the others, setting the alarm off.
Under no circumstances let the cells drop below 3.65V! To do so on a regular basis will ruin the bricks. The rider will have to experiment w/ the alarm value where he/she will know to stop before the pack over dis-charges. At the dis-charge rates mentioned, it won't take long as the 5Ah pack capacity is really too sm.
The best way to charge this pack is to bulk charge w/ a Mean Well HLG-320-48-A, which is a CC/CV adjustable Voltage power supply. The pack string will have to be broken into 2) 10S packs. Two Mean Wells could charge both halves at the same time if one was in a hurry. Ck'ing and balancing the cells would be done w/ Battery Medics, one for each brick. Or 2) for a 1) Mean Well/2 brick system or 4( for 2) systems.

Also, is there any rules of thumb with physical protection during use? and could wrapping the cells too much cause them to overheat? I am in a tropical area (20degC-35degC) if that helps.

A 20S/5Ah pack is not very large. so they should be able to be paced in a space not subject to crash damage, so other than wrapping each brick w/ Gorilla tape, they shouldn't need any more protection than that. But if a little more protection is desired, pieces of coroplast could be cut to size and taped to the sides of the bricks.

 

[SilverLine]

Do you have pics of this build What motor are you using ?

 

[Bikegirl]

I'm looking at building a 20S 1P 5ah 12C lipo pack for a high power short runtime drift bike using 5 turnigy 4S packs to give 72v nominal to a 3000W motor and controller (50a) from aliexpress.


12C Turnigy is too low a rate for a 50 Amp continous dis-charge, 20C is not bad, but 25C would be best for what you want to do.
A member here, icecube57, has done much testing of sustained LiPoly dis-charge rates. He spent a lot of time testing the MultiStar 10C and 12C and his conclusion was that a MS 10C pack in the 15Ah to 20Ah range was good to 40 Amps max. Given that your proposed pack is only 5 Ah, 12C would b cutting it too close. I have run 2) 20 Amp controllers off a single MultiStar 15 Ah 10C pack and at full throttle I would see a 2 Volt drop, not good.
Always use the fewest bricks possible to get the Voltage you want, right now, the Turnigy 5S 5Ah 20C is $46 a brick from Hk. The 25C is only $4 more, so get the 5S 5Ah 25C, 4) for $200.
Cut off the XT 60 connectors and use Turnigy 6 MM bullets and connect the 4 bricks in series for 20S/5 Ah pack.

Under no circumstances let the cells drop below 3.65V! To do so on a regular basis will ruin the bricks. The rider will have to experiment w/ the alarm value where he/she will know to stop before the pack over dis-charges. At the dis-charge rates mentioned, it won't take long as the 5Ah pack capacity is really too sm.
The best way to charge this pack is to bulk charge w/ a Mean Well HLG-320-48-A, which is a CC/CV adjustable Voltage power supply. The pack string will have to be broken into 2) 10S packs. Two Mean Wells could charge both halves at the same time if one was in a hurry. Ck'ing and balancing the cells would be done w/ Battery Medics, one for each brick. Or 2) for a 1) Mean Well/2 brick system or 4( for 2) systems.

Thanks for the C rating feedback. I thought that 12C for 5ah would be fine as its 12*5=110a continuous, but good to know what happens in reality. The 25C was my original choice but changed my mind because the other pack was lighter.

The trike will only be a toy so long running time isn't important but do you think I should go more than 5ah?

I think a bms is still a good idea to low for automatic LVC shut down so that the rider doesn't have to be constantly vigilant on battery voltage while riding.

A 20S/5Ah pack is not very large. so they should be able to be paced in a space not subject to crash damage, so other than wrapping each brick w/ Gorilla tape, they shouldn't need any more protection than that. But if a little more protection is desired, pieces of coroplast could be cut to size and taped to the sides of the bricks.

Thanks for the info on pack loading on different planes. Will be very useful in designing pack holder.

My friend will be doing an axle changeout to a go kart one and looking to put 3kw motor with chain drive to it. Can I reuse existing brakes? (hydraulic front and rear)

Sorry for post format. Posting quickly on my phone

 

[DogDipstick]

Thanks for the C rating feedback. I thought that 12C for 5ah would be fine as its 12*5=110a continuous, but good to know what happens in reality. The 25C was my original choice but changed my mind because the other pack was lighter.

The trike will only be a toy so long running time isn't important but do you think I should go more than 5ah?

I think a bms is still a good idea to low for automatic LVC shut down so that the rider doesn't have to be constantly vigilant on battery voltage while riding.

A 20S/5Ah pack is not very large. so they should be able to be paced in a space not subject to crash damage, so other than wrapping each brick w/ Gorilla tape, they shouldn't need any more protection than that. But if a little more protection is desired, pieces of coroplast could be cut to size and taped to the sides of the bricks.

Thanks for the info on pack loading on different planes. Will be very useful in designing pack holder.

My friend will be doing an axle changeout to a go kart one and looking to put 3kw motor with chain drive to it. Can I reuse existing brakes? (hydraulic front and rear)

Sorry for post format. Posting quickly on my phone

12C on a 5,ooomAh battery is not 110A continuous. It is (12C)(5Ah)= 60 amps.

This is why the larger cell is advantageous. a 15,000mAh cell will have a 12 C rating of (12C)(15Ah)= 180A... ----- or a 20,000mAh cell will do 240A... ---(12C)(20Ah) = 240A.... the bigger the cell the more punch. Think of it like that. You can parallel cells for more capacity, but remember to check cells often and don't let cells v. wander unbalanced in groups.



Recommend at least 10Ah for an hour of fun with peaks in the 3Kw range and normally pulling < 20A-30A. just riding gently around max.. ...

 

[Bikegirl]

Do you have pics of this build What motor are you using ?

https://m.aliexpress.com/item/32957102216.html?trace=storeDetail2msiteDetail&spm=2114.12010612.8148356.10.73e821acJKwV4x

Not ordered yet

 

[Bikegirl]

Lol. I meant to say that I was sizing my pack on 50a continuous draw.

With the motor and controller linked above what would you expect for peak amps?

 

[Bikegirl]

https://hobbyking.com/en_us/turnigy-battery-5000mah-4s-25c-lipo-pack-xt-90.html

Flash deal for Turnigy 5000mAh 4S 25C Lipo Pack w/XT-90

$42.45 aud

Say get 10 packs for 20s x 2p for 72v 10ah for 50a continuous?

 

[motomech]

I think a bms is still a good idea to low for automatic LVC shut down so that the rider doesn't have to be constantly vigilant on battery voltage while riding.

Then I think you will have to engineer and build it. Those cheap BMS boards are designed for Li-Ion or LiFePO4, NOT LiPoly and their LVC's of 2.9V are useless.
The way to use LiPoly is to carry enough capacity that one doesn't need to deep dis-charge. It's already 30% smaller and lighter than other chemistries, so adding capacity to your "toy" project is a non-issue.
DogDipstick's info is very good. By using a 10Ah pack you could keep w/ 12C stuff and not even have to worry about the LVC. Just keep an alarm on one brick as a fail-safe.
Do not start paralleling sm. bricks to get capacity when there are big capacity bricks available. You will end up w/ a rat's nest of wires and other complications. KISS w/ LiPoly!
Unfortunately, there are no 5S bricks in the 12C stuff, but you could use 5) of these in series to get 20S/10Ah pack;
https://hobbyking.com/en_us/turnigy-high-capacity-10000mah-4s-12c-multi-rotor-lipo-pack-w-xt90.html
There are no 12S RC balance chargers and you don't want to get started w/ those "toy" chargers anyway.
The 20S string would have to be broken;
8S and 12S, so that would mean two Mean Wells;
HLG-320-36A
HLG-320-48A
You wanta play, you got to pay.
What the airplane guys do and what we who use LiPoly w/. Ebikes are two different things. I have learned my ebike LiPoly lessions the hard way over the last 7 years.
In brief they are;
1)Keep things as simple as possible
2)Use largest bricks (capacity) as the mounting space allows. 1P is better than 2P and 3P should not even be considered.
3)Follow the 80% depth of discharge rule, 70% is better yet.
4)Bulk charge using Satiator or Mean Wells. RC toy chargers will not hold up.
5)Always store LiPoly @ 3.85V/cell or less. Only top charge right before use.
6)Use GENUINE Battery Medics to ck/balance bricks. If done right, balance will seldom be needed, but if fast balance is required, buy extra bricks and have another pack to swap in. LiPoly is cheap, especially if....
7)Buy LiPoly when on sale, it will store forever.

 

[Bikegirl]

I think a bms is still a good idea to low for automatic LVC shut down so that the rider doesn't have to be constantly vigilant on battery voltage while riding.

Then I think you will have to engineer and build it. Those cheap BMS boards are designed for Li-Ion or LiFePO4, NOT LiPoly and their LVC's of 2.9V are useless.
The way to use LiPoly is to carry enough capacity that one doesn't need to deep dis-charge. It's already 30% smaller and lighter than other chemistries, so adding capacity to your "toy" project is a non-issue.
DogDipstick's info is very good. By using a 10Ah pack you could keep w/ 12C stuff and not even have to worry about the LVC. Just keep an alarm on one brick as a fail-safe.
Do not start paralleling sm. bricks to get capacity when there are big capacity bricks available. You will end up w/ a rat's nest of wires and other complications. KISS w/ LiPoly!
Unfortunately, there are no 5S bricks in the 12C stuff, but you could use 5) of these in series to get 20S/10Ah pack;
https://hobbyking.com/en_us/turnigy-high-capacity-10000mah-4s-12c-multi-rotor-lipo-pack-w-xt90.html
There are no 12S RC balance chargers and you don't want to get started w/ those "toy" chargers anyway.
The 20S string would have to be broken;
8S and 12S, so that would mean two Mean Wells;
HLG-320-36A
HLG-320-48A
You wanta play, you got to pay.
What the airplane guys do and what we who use LiPoly w/. Ebikes are two different things. I have learned my ebike LiPoly lessions the hard way over the last 7 years.
In brief they are;
1)Keep things as simple as possible
2)Use largest bricks (capacity) as the mounting space allows. 1P is better than 2P and 3P should not even be considered.
3)Follow the 80% depth of discharge rule, 70% is better yet.
4)Bulk charge using Satiator or Mean Wells. RC toy chargers will not hold up.
5)Always store LiPoly @ 3.85V/cell or less. Only top charge right before use.
6)Use GENUINE Battery Medics to ck/balance bricks. If done right, balance will seldom be needed, but if fast balance is required, buy extra bricks and have another pack to swap in. LiPoly is cheap, especially if....
7)Buy LiPoly when on sale, it will store forever.

Thanks motomech, could do 10ah 4s cells was just looking a 2p 5ah cells for cost more than anything but in the long run having a simpler system to charge will be better like you said.

I haven't looked into what option s there are with LVC and other "monitors" whilst riding. I will have to do some more reading. I was just assuming I could put a bms on to do that work but may be more cost effective to go another way.

 

[motomech]

Search my posts using search-words; bulk charging, Mean Well, LiPoly and especially Battery Medic.

 

[Bikegirl]

just regarding lithium polymer charging; is it ok to bulk charge the majority of the time and then just balance each brick afterwards using battery medic. When would I need to balance charge?

 

[DogDipstick]

Depends on the manufacturer and the quality... and how low you go. Cells wander the lower you go, then when charged dont come back together easily without some serious taper current such as C/20 or C/50.... most balance chargers balance taper @ C/5. This accuracy in balancing is not nesccesary for some high quality cells.

The EV lipo NMC i build with are able to drain to 3V... and come back together without balancing @ 3.4... very advanced.... But a hK lipo, if you bring it down below 3.6 alot the cells will wander, chnage IR, and give you trouble on subsequent charges. So: To be safe...

Moniter the charge and discharge,

Balance the first time to get an idea of how long it takes

Then try to balance every third time, with a bulk charge to 4.1 or so, then check voltages for complete charge and like voltages

Then try every 5 times if all went well

Then every ten times... Work your way up. Know how the batteries respond before hooking them up to a PS and walking away expecting the charge to be automatic...

I have seen HobbyKing cells take hours to balance and never even get very balanced... Ive seen datalogs of self discharged 18650 packs that discharge to the point of wandering cells, then never come back because the taper current is to low and the cells never balance... I wouldn't even bulk charge them every other time... Balance every time if you want cells to last... It makes an even discharge.... Bulk charging is a convenience but not the best for longevity or range. Cells are happier when balanced. I know RC heli guy who will send a Brand new purchased pack back for warranty for a single cell that is .2v out ( considered ok by Hobbyking and low quality lipo manufacturers). My EV cells are balanced on discharge and charge but cells NEVER wander more than .002V. That is balanced. They bulk charge in unison because the IR is so good and similar.

The EV cells I use are very well behaved ( best Ive seen, ). Drained to 3v and they come back together easiy. I could show yo a datalog of a 18650 pack comming together ( voltages under balance current )... a HK lipo pack, and a homemade EV pack.... comparing the three, and the balance times and current tapers. The EV pack wins on both time to balance and charge. Also, the higher the C-rate to charge will beat up packs too... charge a 5Ah pack at 1C ( 5 amps) and it will last along time. Charge it at 5C ( like I do my hobby rc packs)( 25A) and plan for new batteries in a year or two.

 

[motomech]

just regarding lithium polymer charging; is it ok to bulk charge the majority of the time and then just balance each brick afterwards using battery medic. When would I need to balance charge?

My procedure is as follows;
After a ride, I charge to storage value of 3.85/cell. My bikes use 12S and 14S, so I do not have to break the pack, just simply plug my Mean Well into two leads left vacant for that purpose. Here is pic of HLG charging 12S off the bike;
https://endless-sphere.com/forums/download/file.php?id=191251
The HLG is silent(No fan) and unlike a balance charger, it does not cycle thru charge-stop-read cells-start again, so on avg., it will put back 5Ah to 10Ah in an hour or so.
Once it reaches top set storage value, it just sits there, gently clicking. I do not have to watch it, but I do not leave the general area.
Then I clip on a Battery Medic on ea. brick and ck. cell values. 95%of the time, they are in line and nothing else needs to be done. In the rare event some cells are off, I set the lowest common value on the BM's, so they bring all the cells down to the same value. Battery Medics are passive and somewhat slow and can be left unattended. They beep softly when they reach their set value.
Before I leave for next ride, I top charge to 4.1 V or so. If I try and go much above that, the cells might start to stray. But I carry plenty of capacity and don't need to cram as energy into them as possible.
There have been times when I top charged and for some reason, did not go out on a ride. Now I need to bring them back down to storage level and on a 10Ah or 15Ah pack, this can take a while w/ BM's. In this case, I have left the BM's on overnight.
Since I don't break my strings and never go below 3.65V/cell, balancing is very rare. The BM's are used more as a checker, than a balancer.
Charging on bike w/ Battery Medics attached;
https://endless-sphere.com/forums/download/file.php?id=192174
In this set-up, I have dis-connected the Headlight leads and am using them to charge the pack.

 

[motomech]

As shown above, the down-side to LiPoly is time. The two-stage process requires some extra attention when compared to a "plug and play" Li-Ion pack w/ a BMS.
But I am retired and actually enjoy "fusting" over "my babies".
On the other hand, no other chem. offers the the energy vs cost value, lighter weight and smaller form factor.
Best of all, I enjoy the "modular" nature of the bricks and the ability to quickly construct a pack sized to the range I need.
Another thing not yet mentioned here is the low volatility of the 10C and 12C LiPoly. Even if a pouch is punctured, a fire will not erupt.
I once punctured a Zippy (20C or 25C) cell and all that happened was some smoke came out and a red glow could be seen though the hole(Mini Mordor

 

[Bikegirl]

Thanks for the info guys

I have been looking at this BMS.

https://www.ebay.com/itm/8S-24S-Lifepo4-li-ion-Lipo-Battery-Protection-Board-Smart-BMS-Balance-Bluetooth/192713045620?hash=item2cde97b674:m:mmYGtW2LCsV0HOzua9mBVkw&var=492855192727

Is it true that the low voltage cutoff could be set at 3.5 or 3.6v per cell? it looks as though it would be able to which would cut my throttle input to the controller and ensure that I cannot overdischarge a 20S lipo pack?

Otherwise i'll probably just hook up a piezo alarm and smack my firend over the head if he drives through it

 

[motomech]

I give up

 

[Bikegirl]

I give up

Sorry motomech

Thanks for the detailed charging information.

I'm still in two minds about the most appropriate battery for this trike, balancing safety considerations giving battery maintenance to someone else and high discharge amps required.

I have much to learn in this area and will keep reading.

 

[Bikegirl]

I've been looking at the fiik drifter as inspiration.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://fiik.com/products/fiik-drifter&ved=2ahUKEwif5O7wxJTiAhXJeisKHdQYAw0QFjAAegQIAhAB&usg=AOvVaw0SkqbP0hNbPb3isNRcneqK

Dual 1000w motors belt driven to each rear wheel with most likely a lithium ion battery on the downtube with a modified stick controller and twist throttle.

I know this is the battery thread but any quick tips on the effects on the controller with say 2x QSmotor 1000w? Looking at running 48 or 52v.

Same voltage, more current required?