74v 20ah Li-Ion battery build

[jakequicksilver9]

this is what I have so far could someone with experience look over this so I don't get KFF
I also have a few questions
would the negative terminal have to be on top left and the positive on bottom right?
can I use the cheap alibaba batteries?
how long it would take a noob to build this?
possibly a link to how to prep the cells before building?
care needed after build, careful watch when charging like lipo, or plug and play like prebuilt?
which cell type is safest 18650's or samsung 25R?
can I charge it with a icharger and power supply?
are balange leads needed, balance charging?
any help is appreciated, Thanks

 

[dogman dan]

Diagram looks fine to me. 20s, charge it to 4.2v per cell and you have 72v nominal pack.

Re the charging, I don't know of an RC charger that does 20s. 6s, 8s, 12s, and 14s are the choices I know of.

Best approach would be to hunt down a 20s bms, and 72v bulk charger.

Meanwhile, you'd have to charge in blocks of whatever your charger can do. If your charger is the 14s one, then you could split the pack into two 10s sections to charge it. Ideally, with two chargers so you can do it all at the same time without a lot of plugging and unplugging shit. The more plugs you do every day, the sooner you will KFF. We all eventually get one.

Balance wires yes. It's how you can ever balance them. Or even use cell monitors, or any of the stuff you need to do if you have no bms.

How long would it take a noob to do this? Me, it would take the rest of my life. If I was you, I'd buy a decent ready made pack, or pair of 36v packs. Life is short, spend it riding.

Safety, it should be safer than Hobby king RC pouches for sure. But though it may be less likely to burn your house down, take common sense precautions. Don't set it on the carpet, or next to the curtains and charge it. Charge and store it in a fire resistant place. You can get a chunk of something less flammable to set it on.

But in any case, you still have to take the same precautions to avoid over discharging or over charging cells. Screwing up still ruins cells and costs a lot of $$. That's why naked packs are a bad idea. GET A BMS.

 

[BVH]

The Cycle Satiator does up to 63 Volts but the next future released version will do 103 Volts, IIRC. Limited to a total of 360 Watts. Full programmable, profile based.

 

[jakequicksilver9]

ok, I thought about what you said and maybe building a pack is a little more than I can handle . The pre-built packs are much too expensive for me though so my next option is lipos. I was looking at the turnigy 5s 5ah and decided on a 20s2p pack and a wiring harness from icecube57. from what I can tell these should be able to handle a max of 100a. does that mean with a 18fet infineon and a Mxus 4T it should be a cake walk? I also saw some threads on bms for lipos but they were all for 6s, will it make a difference if I fallow their instructions?
http://www.hobbyking.com/hobbyking/store/__9174__Turnigy_5000mAh_5S_20C_Lipo_Pack.html
http://em3ev.com/store/index.php?route=product/product&product_id=83

 

[BVH]

In my humble opinion, if you are not VERY familiar with the care, use and handling of Lipo's, then do not consider going this route. Lipos are not forgiving of errors and having them on your bike is not much different than having them on your person. If one "goes off", you are in serious trouble. You will have to be constantly plugging and unplugging many different battery connectors to run in 20S2P mode and then disconnect all of them and re-connect all of them for one-at-a-time charging or parallel charging and then reconnecting them for 20S operation again. You will inevitably make a mistake and possibly cause personal injury and property damage. Then there's the issue of not using a BMS and having to manually monitor each cell of each pack so as not to over discharge any one cell/pack. A single Voltmeter display will not be enough to correctly monitor your packs state of charge. You will need to purchase a balancing hobby charger and appropriately sized DC power supply in order to properly charge the packs. Most likely, a high power,high priced charger and power supply if you don't want to spend all day charging. It will be a cumbersome task to say the least. Wait until you have more knowledge with the use and handling of batteries in general before using Lipos.

Spend a little more money up front and you'll gain a higher level of safety and spend less valuable time screwing around with the batteries.

 

[jakequicksilver9]

the wiring harness will make it so I don't have to connect and disconnect every time i want to charge and I have been reading a lot on lipos to educate myself before I buy these. Safety is my first priority so I am going to use one of the Chinese enduro frames in case there is a unfortunate accident. As for the charger I don't know much about it yet but I have heard good things about the Icharger with a power supply and a few battery medics.

 

[jakequicksilver9]

http://e4bike.ru/collection/batarei/product/akkumulyatornaya-batareya-linmc-77v-16ah
any opinions on this, is this a trusted seller?

 

[DAND214]

http://e4bike.ru/collection/batarei/product/akkumulyatornaya-batareya-linmc-77v-16ah
any opinions on this, is this a trusted seller?

Don't know but this one is http://lunacycle.com/36v/
Reasonable and is in the states.

Dan

 

[jakequicksilver9]

would it be easy to put 2 of these into series? seems like a good deal

 

[jakequicksilver9]

I just found these on the forum and I could put together a 74v 10ah pack with only 5 of them! any reason why not to buy these?
http://www.hobbyking.com/hobbyking/store/__64438__Multistar_High_Capacity_4S_10000mAh_Multi_Rotor_Lipo_Pack_US_Warehouse_.html

 

[Ykick]

I just found these on the forum and I could put together a 74v 10ah pack with only 5 of them! any reason why not to buy these?
http://www.hobbyking.com/hobbyking/store/__64438__Multistar_High_Capacity_4S_10000mAh_Multi_Rotor_Lipo_Pack_US_Warehouse_.html

RC Lipo can work but there’s more chance of fireball than with decent can cell battery packs.

MultiStar packs use XT connectors so you’ll need something like 4mm bullets or anderson power pole to series string them up to your desired cell count.

If you go this route I’d buy an extra brick and stock up on some alarms, monitoring, measurement instruments/tools, balance charger, connectors, wire, etc.

Read and learn care & feeding of RC Lipo. It can work okay with some effort to learn and some luck.

 

[999zip999]

When buying lipo get a piece of paper and start writing down everything you will need just to get started. Power supply(s) charger(s) wires, connectors, monitors and or bms. Just try and get a clear money picture of your lipo expenses before you choose. About 600.00usd.
As your first battery luna cycle had a 60v pack with bms and a plug and play charger system. Plus make a cardboard box of the batteries to see if they fit.
Em3ev controller is 60amp stock and the.muxus 4t will be fast enough for a bike.

 

[jakequicksilver9]

Does anyone know if the luna cycle 32v 20ah batteries suggested earlier could be put in series and charged seperatly to reduce the risk? If the lipo charger and power supply and harness add up to <600$ then the lunacycle or e4bike.ru batteries could be better price per risk

 

[Ykick]

I dunno about $600? Even if you did spend that much it’s primarily one time purchases for super cool gadgets (chargers, power meters, celllogs) that’ll come in handy for all types of needs and projects.

And if you don’t screw up too bad, you’ll end up knowing so much more about battery pack construction and technology. Low cost of tuition, IMO.

But, there’s a lot to be said for not “managing” RC Lipo too. Just kinda depends on the person…

 

[dogman dan]

In general, paralleling batteries with a bms is not a problem. Series can be, but I honestly don't know enough to say which is ok, and which is not.

Speaking of alibaba. Sure, it's a risk, but 72v 20 ah is out there. http://www.alibaba.com/product-detail/triangle-battery-customized-size-battery-72v_669313784.html?spm=a2700.7724838.30.220.fz2Dc6

I wouldn't expect it to last with a 40 amps controller though. It's of course made from cheaper cells. If you are heading for 3000 watts, you may be best off to learn all about RC packs, invest in the chargers, create a fire proof place to store em, etc. Or, figure on big money for really good safe cells.

Nice thing about RC shit, you can start out with just 72v 5 ah. Bad thing, burn your house down if you screw up.

 

[jakequicksilver9]

could I use one of those fireproof bags when charging? also what would I need to get started(charger, balancing, power supply)? If I started with 5ah and upgraded later, 20C should be plenty right? 5000 mAh x 20C = 50000/1000 = 100A max continuous
so 5 of these and a wiring harness from icecube57
http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_Hardcase_Pack.html

 

[Ykick]

Used in 5Ah configuration you don’t need any special harness. i series mine up using the stock bullets and then convert to whatever connector ecosystem I need. Mostly Anderson Power Pole (APP) but that’s a whole “thing” too.

I use an iCharger 106B+ for general balance charging individual bricks/packs. Hobby King (HK) sells cheaper balance chargers which are probably good enough but I’ve never regretted buying the iCharger.

I also use CellLog 8S (8M if you don’t need or care about logging function which the iCharger can do, btw). G.T. or Turnigy Power Meter is another very useful item.

Eventually, I install BMS on my packs and bulk charge everything rarely using the balance charger and/or CellLogs, power meter, etc.

Here’s one of my 16S1P packs I assemble using those hardcase bricks in your link. I added some 4S extension cables for easier monitoring and measurement of individual cells.

Nice little 5lb battery pack with enough energy for short distances yet capable of delivering high power.

Just remember almost all battery specs are inflated with regard to C rate. 20C is really more like 10C when new and will only degrade over time and use.

If you can get everything from USA Hobby King warehouse they should have pretty good prices. BuddyRC or EPBuddy is also a pretty good vendor with USA location too.

 

[jakequicksilver9]

bmsbattery.com has some awesome deals so I think I will go with one of their 72v 10ah batteries for 500$ and their 250w charger for $30
in case anyone wants to see the rest of my build
mxus 3t in a 17in moto rim
infineon 18fet
cycle analyst v2.2
evelbike frame
fork, 24in front wheel, rear shock, handlebars, and others from donor full suspention MTB
total price: $1775

 

[Ykick]

bmsbattery.com has some awesome deals so I think I will go with one of their 72v 10ah batteries for 500$ and their 250w charger for $30
in case anyone wants to see the rest of my build
mxus 3t in a 17in moto rim
infineon 18fet
cycle analyst v2.2
evelbike frame
fork, 24in front wheel, rear shock, handlebars, and others from donor full suspention MTB
total price: $1775

BMSBattery Shipped?

 

[jakequicksilver9]

not sure about shipping

 

[stefan010]

Being using HK lipo for more then 3 years now ! with very different experiences .

I had build 2 packs first was a 6s 6*5ah and the moment i have a 6s 3*10ah.

Oke first the pro's
1: The price , i think their is no better price then aviable for a 72V 10ah that hobbyking offers. especially in the early days when eur/usd when the dollar was cheap.
2: weight and size , the pack is very small and light.
3: Dicharge rate , lipo can deliver very much power. ( however if you wanne really use 3kWon your motor you battery will drain really fast .


The Cons
1: Life time . the life of battery is i think kinde poor for the following reasons :
Lipo can have a life time of about 300 -400 charges but before reaching that the change is quite big one of the battery cells has already died
So i think the change of dead cells is really an issue on Lipo's some times you already have dead cell after 5 months !

2: Danger of getting fire my first package went on a tiny flame when the lipo has dead cell the package tried to compensate the dead cell by creating an overvoltage on the other cells.

My conclusion i recommend to spend some more money on a good life po4 package from a well reputated seller. The investment will be quite bigger but i think it will eventually safe money because the lifetime will be much better.
And i also think about safety and the fact that lipos are unforgiveable .( discharge you batt to low and your cells could be dead)