Please help me design my LiPo backpack. I dont like fires.

Hi, I am looking into purchasing the 2500 watt LightningRod mid drive kit found here: http://endless-sphere.com/forums/viewtopic.php?f=28&t=57720
I will be pairing it with a Lyen 12 FET 4110 MOSFET MK2 found here: http://endless-sphere.com/forums/viewtopic.php?f=31&t=17683

I plan on running a 16s3p LiPo battery setup using batteries from Hobbyking. My initial idea was to use six Zippy 8s 5800mah batteries and carry them in a small camel pack style backpack. 1000 watts of power and 14 pounds is quite reasonable I think.

This is my first foray into building batteries and there seems to be a hell of a lot of information. I know that it must be done right and handled and stored with care so I dont burn my apartment down! I plan to store and charge my batteries in a metal container on my balcony to mitigate fires. That being said, I would like recommendations on which Hobbyking batteries you would use, what wiring harnesses I should use and where I should get them. I assume there must be some prebuilt harnesses out there for hobby batteries. I also need to know what battery charger I should buy to charge up my 16s3p battery.
Any other relevant information would be fantastic.

Thanks again!

These HK LiPo are your best bang for your dollar.

http://www.hobbyking.com/hobbyking/...P_14_8v_20C_hardcase_pack_USA_Warehouse_.html

Unfortunately, they are out of stock at both US and Global warehouses.

If you are looking for a wiring harness, you want ES member icecube57 to build it for you.

http://www.lipoconnectionsolutions.com/Lipo-Harnesses-0quote.htm

Or you can build it yourself with parts and silicone wire from Hobbyking. They are not that hard to build, actually.

FWIW, it could be a long time till stock levels are very good at HK. There seems to be a pattern of stock vanishing with the better weather of spring and summer.

Better find something in stock, and jump on it.

The most likely to be safe setup would be a 16s bms, many would agree. Very wise to plan on charging outside. If you don't have plans to use a bms, then the safe setup resides between your ears. It won't matter that much what your hardware is, if you don't run a discharge pattern that keeps the pack more balanced, and make sure you don't allow overdischarges or overcharges. If you are the bms, I'm saying you have to pay attention in addition to having a battery that is big enough for your typical trip.

Then there is not poking holes in the packs. Breaking that rule is easy to do, unless you do things to help prevent that.

But since you do live in an apartment, is it possible for you to afford a safer chemistry? Like an EM3ev pack? You are risking a lot more lives than just your own, to save a buck.

I have to totally agree with dogman, it's not worth the risk messing with LiPo unless you are 100% confident that you know what you are doing.
EM3ev has some excellent packs, and if you get one with the Samsung INR18650-20R cells, then you've got plenty of power to play with.
Yes, they will be heavier than LiPo, but you could get Paul to build a pack that has a low profile. You won't notice it once in a pack close to your back.

jdevo2004 said:

Hi, I am looking into purchasing the 2500 watt LightningRod mid drive kit found here: http://endless-sphere.com/forums/viewtopic.php?f=28&t=57720
I will be pairing it with a Lyen 12 FET 4110 MOSFET MK2 found here: http://endless-sphere.com/forums/viewtopic.php?f=31&t=17683

I plan on running a 16s3p LiPo battery setup using batteries from Hobbyking. My initial idea was to use six Zippy 8s 5800mah batteries and carry them in a small camel pack style backpack. 1000 watts of power and 14 pounds is quite reasonable I think.

This is my first foray into building batteries and there seems to be a hell of a lot of information. I know that it must be done right and handled and stored with care so I dont burn my apartment down! I plan to store and charge my batteries in a metal container on my balcony to mitigate fires. That being said, I would like recommendations on which Hobbyking batteries you would use, what wiring harnesses I should use and where I should get them. I assume there must be some prebuilt harnesses out there for hobby batteries. I also need to know what battery charger I should buy to charge up my 16s3p battery.
Any other relevant information would be fantastic.

Thanks again!

Click to expand...

will your controller handle 16S lipo? why do you plan to carry the lipo in a backpack? will it not fit on your bike? the risk of fire is overblown but your risk of damaging the lipo pack carrying it around in a backpack is high. is theft the concern? fire is a risk from overcharging and from shorting the output wires so you can manage that by charging with either lipo BMS and lifepo4 bulk charger or using a balancing charger, power supply and fuses to protect against shorted output. you should use some sorta LVC protection for the battery too, but if you carry it inside and leave the bike outside the risk of leaving the controller on is low.

Do you know what a bms is JD?

Briefly, there is a big divide on pack building. RC modelers just carry cells, while everyone else builds packs with a protection board incorporated.

When I say everyone, I mean professionals

Putting a bms on an rc lipo pack is like putting a governor on a muscle car. If you want ease of charging then a BMS works pretty good. If you want the full potential of your lipo pack, it doesn't, unless you bypass the output of the bms. That would work fine for easy charging and not limit the amp draw from the battery. None the lipo BMS's I've seen are designed for rc lipo, which is not the same as 18650 type which has a lower lvc rating than rc lipo. A f*cking professional should know that.

wesnewell said:

Putting a bms on an rc lipo pack is like putting a governor on a muscle car. If you want ease of charging then a BMS works pretty good. If you want the full potential of your lipo pack, it doesn't, unless you bypass the output of the bms. That would work fine for easy charging and not limit the amp draw from the battery. None the lipo BMS's I've seen are designed for rc lipo, which is not the same as 18650 type which has a lower lvc rating than rc lipo. A f*cking professional should know that.

Click to expand...

so you have never seen a lipo BMS. you have never seen a lifepo4 BMS either so how does that qualify you to pretend you know anything about a BMS?

I've seen hundreds of bms's for both lipo and lifepo4. I've also seen the specs on them. And how they work has been talked about here and other places for years. The technology is at least 50 years old and used for many things, not just EV's. All telco CO's had bms's on their huge 48V battery backup systems. That system took up a room about 20' x 10'and used 200AH single cell LA batteries that were huge and very heavy. I've never designed a BMS, but I have designed a lot of computer stuff which is far more complicated then a simple bms. So yeah, I know wtf it is and wtf it does. But keep saying I don't. There's a lot of stupid people in the world (I quote 90%) and some of them may believe you.

I'm getting tired of the same arguments in every thread. He did not ask for information on bms's yet.

There I said it again and set off another flame thread. BMS BMS BMS, now beetlejuice will come makes us miserable.

The guy has a fairly safe place to charge apparently, but I did not see him say where he would store cheap lico cells safely, in an apartment.

It's quite possible to build a box strong enough to protect the lico cells in a backpack. But I am concerned about possible damage to cells, then they get stored inside the building. Once damaged bashing around in the pack, they can light up in storage.

So, if that happens, the pack could burn down the apartments regardless of whether he uses a bms or not.

In general, a less volatile chemistry is advisable for apartments, or even a house with kids in it. Unless you have a good place to keep it.

There's no reason for you to use RC lipo now that other options are available. For 1000 watts you have no need for the power density of RC lipo. While it's fine for you to make your own risk decisions, since you live in a multi-family dwelling it's really not appropriate for you to make that decision for others without their knowledge.

The part you miss about RC lipo is that almost all the guys using them on their ebikes have a time consuming hobby they downplay, which I call Fiddling with Batteries.

I agree with John. Using LiPo's is complicated enough, that I would trust no one else in my household to touch them, nor would I want to steer a customer or friend towards them. If you want something user friendly, choose a battery with a BMS, and a simple charge cable connection.

dogman said:

I'm getting tired of the same arguments in every thread. He did not ask for information on bms's yet.
There I said it again and set off another flame thread. BMS BMS BMS, now beetlejuice will come makes us miserable.

Click to expand...

didn't you expect that? i think EVERY thread which is about lipo ends in a flame thread about bms or no bms. and it's always the same argument. i stopped stating my thoughts about it. i also think that we should start concentrating on the questions asked ...
so the thread starter WANTS to build a LIPO BACKPACK. we should help him doing so. i do have a lipo backpack. but only as backup battery for long tours. it's 4x 6s 5000mah zippys. they don't have any bms and they are charged seperately after ride to 3.85v. they are just connected in parallel on a cell base as well. but even this is not needed. if the backpack is connected i know i have around 8Ah to play with and i'm on the save side. i ride with reduced power (around 500-1000w). so this is a good way to do it for me. the main battery 20Ah is secured by a bms.

There's lots of reasons to use rc lipo. Especially if you don't need more than a 10 mile range. A 3.5 lb. 5ah 12s 20C pack that you can buy for $75 will support controllers up to 50A comfortably, If you can name one other battery chemistry that can do that for the same price, size, and weight I'll buy it. None of the other current lithium chemistries can come close to it.

No not surprised.

Lets concentrate on the OP's question. That said, and reading back, I see I missed that he plans to both charge and store his lipo on the balcony in a metal box of some kind. That's covering safety pretty good IMO, provided the backpack rig is not causing dings and hole in the packs. Building a hard shell around the pack generally takes care of that pretty good. Masonite, Coroplast, PVC sheets, etc make good tight fitting protective boxes.

It seems that he plans to pull 2500w, so he may want to chose lico from the RC stuff.

Now we need to hear back from him, Does he want a bms? If no, then there are lots of threads on how to connect series and parallel. My preferred method is to connect packs in parallel first, using big crimp sleeves. Then one original connector remains for the series connections. So it's a Y connection ending in the original bullet connector from one of the packs. ( that's for 2 packs in parallel) I like this way because you cannot have one half of a pair of packs disconnect by accident.

From pack to bike, 12g wire minimum. Maybe much thicker for 2500w continuous. Some kind of quick disconnect plug, either at the pack, or near the seat. Andersons in 45 amps pull off real easy, but most 4mm bullets would pull loose easy enough in a crash.

I don't get how we are going to build a safe backpack when were meant to avoid talking about how packs are made.

Having a bms doesn't mean your stuck with a particular lvc or that your power will be limited to less than you need. Totally invalid arguments. That just means you bought the wrong one.

Try and buy a pack that doesn't have a bms. You can't because only a fool would try and sell such a thing. So why would you try and build it.


Radio control users are the only ones who don't use a bms, because they won't carry the extra 20-30grams. They also have lots of cells they reconfigure for different toys, making bms use a little harder. They also have to charge there cells in fire proof bags at most events because the organisers recognise how many charging mistakes their constant wires swapping causes.

RC users often move over to boards and bikes and bring their tech with them. This doesn't make it right though. The ev industry uses battery management systems because they are cheaper and offer better protection, while being easier to use and tidier. Look on any EV suppliers site, You will find all packs contain the safety board and non of these suppliers sell RC like chargers.


So why wouldn't the OP want a bms?
This is indeed getting ridiculous, and it is always Wes spouting the nonsense.



My question to the OP was very simple. Does he know about this, or does he need telling. If we are not going to let him know, we should shut the forum down because it is not working. All the fires belong to the Radio Control users. I'm not going to sit here keeping the truth to myself while people advise others to take the road that leads to fires. Not a hope.




dnmun...pm'd you.

dogman said:

No not surprised.

Lets concentrate on the OP's question. That said, and reading back, I see I missed that he plans to both charge and store his lipo on the balcony in a metal box of some kind. That's covering safety pretty good IMO, provided the backpack rig is not causing dings and hole in the packs. Building a hard shell around the pack generally takes care of that pretty good. Masonite, Coroplast, PVC sheets, etc make good tight fitting protective boxes.

It seems that he plans to pull 2500w, so he may want to chose lico from the RC stuff.

Now we need to hear back from him, Does he want a bms? If no, then there are lots of threads on how to connect series and parallel. My preferred method is to connect packs in parallel first, using big crimp sleeves. Then one original connector remains for the series connections. So it's a Y connection ending in the original bullet connector from one of the packs. ( that's for 2 packs in parallel) I like this way because you cannot have one half of a pair of packs disconnect by accident.

From pack to bike, 12g wire minimum. Maybe much thicker for 2500w continuous. Some kind of quick disconnect plug, either at the pack, or near the seat. Andersons in 45 amps pull off real easy, but most 4mm bullets would pull loose easy enough in a crash.

Click to expand...

LIPO IS OUT! I have decided that it is not worth using lipo.

I am thinking of using two of these in series and setting the speed controller for 25 amps. http://em3ev.com/store/index.php?route=product/product&path=35&product_id=128
I will be using the 20R version of the battery pack which is capable of pulling up to 50amps in case I want to ramp things up later. I am confused as to the description of this pack whether it contains a bms or not.
I have been informed that the motor is capable of 100 volts so no worries there.
There does not seem to be much out there for prebuilt lion battery packs that can handle higher amp outputs. Maybe one of you guys can visit em3ev and tell me what equipment you think would work well for me.

I was thinking about purchasing this charger to go with it: http://em3ev.com/store/index.php?route=product/product&path=37&product_id=120
Once again, I am not sure if this charger can also balance the pack?

Other things I am thinking about purchasing include:
18 Fet Infinion Controller: http://em3ev.com/store/index.php?route=product/product&path=38&product_id=84
Cycle Analyste V3: http://em3ev.com/store/index.php?route=product/product&path=41&product_id=126
Ebrakes: http://em3ev.com/store/index.php?route=product/product&path=41&product_id=102
Throttle Full twist: http://em3ev.com/store/index.php?route=product/product&path=41&product_id=94

If you guys can think of better options for me than what I have chosen, or more importantly tell me if I am missing anything vital, please feel free to teach me! This is a big money purchase and I would rather spend a little extra to get things right the first time than regret it later on.



Thanks for the help guys.

Good decision. Yes the pack has a BMS.

there have been three lipo fires reported here on the sphere.

one was caused by a short on the balancing wires of a BC168 balancing charger. smoke damage and loss of battery and some garage items, bike eventually rebuilt with much work.

the second was caused by a Hyperion 1403 and resulted in the loss of house and garage. this was reported on the RC group and made it to this blogspot.

the third reported from charging here was the result it appears of overcharging using meanwell chargers in series to build up to 135V as bulk charging with no BMS to supervise the charging. this also resulted in loss of the house and garage.

i had a lipo fire here from one of my tenants charging his sony laptop and he left it smothered in a comforter on his bed so the cells overheated and went into thermal runaway. small fire resulted in smoke damage and carpet was damaged when the laptop cell fell out of the plastic laptop case as it was being carried outside on the still smoldering bed. the can burned a hole through the carpet but did not catch the carpet on fire even though it was still discharging and heating internally from the shorted electrodes inside.

there have been no fires reported from charging using a BMS to supervise charging.

lipo goes into thermal runaway when it is overcharged well above the 4.3V limit or if the battery output is shorted causing the cells to overheat from the huge current flow through the short. the short on the balancing leads of the first fire is how the first fire was started. the assumption is that the second fire started in a similar fashion but was not investigated here. the third fire from bulk charging with no supervision was from interpretation of previous communications with the guy who used the meanwells to bulk charge.

lipo does not catch fire from being discharged to low voltage. it does not catch fire from punctures or dents in the foil packages. it results from overcharging beyond full charge that leads to the breakdown of the SEI layer on the surface of the anode that allows the electrolyte chemicals to react with the freshly exposed carbon surface as the SEI layer spalls off from the heat generated by the exothermic reaction of the electrolytes with the carbon of the anode. it is called thermal runaway because as more and more of the carbon surface is exposed, there is more heat generated which causes more and more of the anode carbon surface to break off larger areas of the SEI.

You seem to of missed a fair few fires dnmun. One was a pack that got squashed and went up, and he had a bms. Not that a bms can save you from physical damage.

dnmun,

RC lipo can go thermal and flameout just sitting there unused.

Also, the whole attended/unattended thing would make little difference in many, if not most, cases, other than to give occupants enough time to get out. Once a cell goes into thermal runaway everything happens pretty quickly, and with an ebike size pack the event will be large enough that you're unlike to get it out of the house. I saw a video of someone supervising a single 18650 LiCo cell charge, and he reacted pretty quickly, but the few feet to the door and maybe 15ft more of balcony were too much to avoid him burning himself before tossing it to the ground. Imagine 10kg of fireball instead of a 45g 18650.

No company puts RC lipo in any ebike, emoto, or electric car sold for very good reasons. We really should be more responsible around here and stop promoting their use by downplaying the danger when there are now safer more convenient options available now. The anecdotal evidence of "I've used RC lipo on my ebikes for years without issue" simply doesn't fly.

your shorted pack did not result in a fire though. i was talking about fires caused during charging.

i think in general it can be said that all these fires are the result of shorts in the conductors or in the sense wires. both the balancing chargers, the BC168 and the hyperion, would never have overcharged an individual cell because they have electronic controls, but it was the sense wire shorts that led to thermal runaway imo.

we do not have any info about floont's fire but i know he was using a series of meanwells before that with no BMS because that was even before we had found the guys at Bestechpower and started testing the lipo BMSs. but his fire may well have been caused by shorts also.

i think bikefanatic may be the only one who had a pack start smoking because it was overcharged but in that case it was a simple mistake of miswiring the lipo packs together so the bigger one overvolted the smaller one and that led to the thermal event. i did not consider that a charging fire.

so rather than focusing on how risky it is to use lipo, there should be some responsibility in proper wiring layout and fusing of susceptible wires imo. i consider the BMS to provide adequate short circuit protection so i feel totally comfortable with a battery where there is a BMS to protect the battery from these problems of overcharging and shorts on the output. if you use a balancing charger then you need to identify where fuses will protect the battery and the bike or house if and when the conductors are shorted out.

dnmun said:

lipo does not catch fire from being discharged to low voltage. it does not catch fire from punctures or dents in the foil packages. it results from overcharging beyond full charge that leads to the breakdown of the SEI layer on the surface of the anode that allows the electrolyte chemicals to react with the freshly exposed carbon surface as the SEI layer spalls off from the heat generated by the exothermic reaction of the electrolytes with the carbon of the anode. it is called thermal runaway because as more and more of the carbon surface is exposed, there is more heat generated which causes more and more of the anode carbon surface to break off larger areas of the SEI.

Click to expand...

friendly1uk said:

You seem to of missed a fair few fires dnmun. One was a pack that got squashed and went up, and he had a bms. Not that a bms can save you from physical damage.

Click to expand...

dnmun said:

your shorted pack did not result in a fire though. i was talking about fires caused during charging.

Click to expand...

There are 2 major types of faults in RC LiPo ebike packs: those created by the poor QC on RC LiPo packs and those created by poor pack building practices.

Fires while charging fall under the first group and fires while from physical damage fall into the second.

i don't see how you can draw that conclusion when there is no data to support your presumption.

everybody talks about what causes fires and how using a tin cooking pot will save them and how balancing chargers are safe but there have two fires where balancing chargers were used. there have been no fires where a BMS was used. in spite of his claims that BMSs cause fires.

This is getting fricking ridiculous. A balance charger for lipo is a bms. It just has the charger built into it. Mine cost a lot more than what a simple bms would cost. That's because it's fricking designed to charge and balance lipo, lion, life and many other types of batteries. A pack being charged by a BMS is just as likely to catch fire as one being charged with a balance charger, since they are basically the same thing. And this BS about being no fires where a bms was used is just that. BS. There are many reported EV fires where a BMS was used. The most famous was probably the ones on the Boeing dreamliners, but here's been many in electric cars that all had bms's. And there's been reports of the bms itself starting a fire here too. I think it was faulty wiring on the bms, but so what. That wiring wouldn't have been there if he didn't have a bms to begin with. I'm sick of the BS being spread on this forum by people that are either ignorant, or have other agendas. If offends anyone I don't care.