basic care of lithium polymer batteries for dummies

[ZeeZee]

Hey Hi!

I'm not sure if I should be putting this in the technical discussion on batteries or here in the general discussion. As my questions are not at all technical and just the very basics, I am choosing here and hope thats OK.

I recently bought an ebike. I live in rural area about 3 miles through the bush to the nearest town or 5 miles of hilly roadway. I haven't owned a car in decades, and don't want one. I got the ebike because I am getting too old to pack all my groceries home through the bush.

My problem is, I am not technically inclined and I want to learn what I need to know to maintain my bike and battery. To give you an idea of how ignorant I am, I haven't even figured out where the controller might be located ... All I know is this is something important and not something that should be allowed to get wet ...

The bike I got is a fold up bike and I am told it has a 360 watt brushless hub motor and a lithium polymer 36 volt 10 amp hour battery.

I picked this bike because it seems to have enough power to make most hills relatively easy to peddle up . It is light weight so I can lift it onto a bus rack without aggravating my back trouble. I also like that it folds so if I have a mechanical problem it will be easier to transport somewhere for help, and if the weather unexpectedly gets wet, I have the option of folding it up and hitchhiking with it. I live in the Pacific Northwest and rain that wasn't in the weather forecast is a very common occurrence.

As I haven't figured out what or where the controller is, of course I haven't even got close to figuring out how to water proof it, and from what I read it sounds like there is no way to completely do this. So I guess for the time being I will have to try and get to town and back when I am sure it will be dry.

The people I bought this bike from seem like nice people who want to be helpful, but they are just learning about ebikes themselves and they said all the instructions they got were in Chinese. They didn't seem to know much about lithium batteries and when I pointed out the battery said to avoid getting caught in the rain the sales person I talked to was a bit surprised. So I'm not sure about relying on them for all the information I may need.

The two other bike shops I know of also don't know much about ebikes ...

I still haven't figured out who manufactured this bike. The hub motor has Chinese writing on it. The battery has a key to turn the bike on and three green lights which show how depleted the battery is. There is instructions in English and Chinese. It says to avoid getting caught in the rain and to avoid heat or flame and store in a cool shady place, to only use the charger that comes with the battery. It also says if the battery not used a long time charge 2 hours every 2 months. Whoever wrote the instructions on the battery didn't speak English very well,and it is a bit unclear what they were trying to say.

The charger that came with the bike says it is for lithium ion but it seems to have a plug that is an exact fit for the lithium polymer battery I have, so I am assuming I have the right charger. I hope my assumption is correct. How the charger works is it has a red light when it is charging and the light turns green in about 1- 3 hours meaning it is charged. There doesn't seem to be anything else involved, or any way to measure what sort of charge the individual cells have.

I found a similar looking battery which is also 36 volt and 10 amp hour but I don't know if the battery I have has all the same safety features .

http://www.comcycle-usa.com/Enlarge.aspx?id=4856591

Although there is nothing on the battery warning me that it might be dangerous to charge it in my house, reading all the warnings I see on line I will be charging the battery outside away from flammables, but I am a bit surprised that it is even legal to sell lithium polymer batteries to technically ignorant people like me, if they are as unpredictable and dangerous as many people seem to suggest.

Are the extreme safety concerns really for all lithium polymer batteries, or is this instability just a problem if the batteries are home made or abused ?

My next question is about how to care for my battery.

I read that lithium polymer can become unstable if they get discharged too much. If I ride my bike the last bit home when the three battery lights have only one left on, but I still seem to have lots of power, am I in danger of destabilizing my battery ?

I am also unsure about what sort of charging practices are best for the battery. I read somewhere that lithium polymer batteries don't like to be topped up. Is this true and does that mean if I ride my bike and use 1/2 or 1/4 of the batteries energy, I shouldn't recharge it until it is getting low ( but on the other hand it sounds like I am not supposed to let it get too deeply discharged either)

Uh huh, I am a bit confused ...

I also wonder if I only ride my ebike to town once a week if I should keep the battery at 1/2 a charge for the week it is just sitting there and only charge it fully just before I go to town ? I usually fully charge it after the 10 mile trip and then it sits like that for a week till I go again. Is that going to be bad for the battery ?

It may be the store I bought the bike from could give me more information, but I got the impression they are just learning and don't know much more than I do. Before I try asking them, I'd like to have enough of a clue I will be able to know if they seem like they know what they are talking about.

 

[TylerDurden]

Welcome,

I suggest you post pictures of the pack and its guts and its charger; perhaps it can be identified.

Without knowing the exact chemistry of your lithium pack, you run the risk of burning down your house. It is not just the DIY packs, it is any pack that has LiCo.

LiCo/LiPoly packs are not really for dummies. This is not a cell-phone or a laptop.

There are RC enthusiasts who run LiCo on their ebikes, but they are experienced and understand the risks.

If it cannot be determined, or if it is verified to be LiCo/LiPoly, you can sell the pack and get safe chemistry.

 

[ZeeZee]

Thanks for the reply. I'd already gathered that LiPo batteries aren't for dummies. And I am one.

I guess the bigger issue is why are so many being sold to people like me, if they are so extremely unsafe ?

I don't have a digital camera but my friend does, and she knows how to upload pictures too so when I have a chance I will get her to photograph my bike and the battery and charger. It may be a week or so before I can do this.

I won't be opening it to photograph the guts though. On the case of the battery it says not to do that without proper instructions, and I don't have those. At least I'm smart enough to know I haven't got a clue what I am doing.

And assuming my battery doesn't explode, I would still like to know how lithium polymer batteries like to be treated to have a long life.

As I live in a fairly remote area it may be difficult to arrange to sell the battery I have or to find another one that is safer. Charging it outside, far from anything that could catch fire, is easy for me to do, and I don't store the battery where it is a fire hazard, so this is not my most serious concern.

 

[fechter]

With proper care, Lipo batteries can be used safely. I've seen some videos of what happens when they are abused. They can 'vent with flame', which resembles a large fireball that is short lived.

The battery manangement system (BMS) that is built into the battery is supposed to prevent any unsafe operating conditions. It also slowly drains the battery which is why they recommend charging every 2 months if unused.

It would be a good idea to charge it in a place where a sudden fireball can't start anything else on fire. Also inspect the battery frequently and look for signs of swelling or heat.

If you follow the wires from the motor, they will lead to the controller. In some rare cases, the controller is built into the motor.

 

[gmouchawar]

One advise I know for sure is charge the battery after each use provided it is not warm to touch.
If it is warm wait till it cools and charge it immediately after.
What kill Li batteries is if they every go below 2V, and how much time they spend in the discharged state.
When you are discharging a whole bunch in series there is a danger than one of them is near 2V. That is why
it is not good to discharge the pack all the way down till the bike stops.
So by all means top off and do it often.
There is a lot of battery chemistries out there, SLA, NICD, NiMH and multiple Li. What you hear for one doesn't apply to the others.
From this groups the only one I wouldn't top off is NiCDs.

 

[recumpence]

OK, if (and that is only IF) you do have a lithium polymer pack, there are some specific care instructions you should adhere to religeously.

#1 DO NOT overdischarge the pack! That is the MOST important thing. A lipo pack needs to have at least 20% of its charge remaining to prevent cell degradation and possible flamout.

#2 Do not overcharge it.

Now, that being said, your battery should have the "Ideal" charger already included with the bike, kind of like a cell phone or laptop. If the manufacturer includes a charger and/or BMS, that should be the ideal system for your particular pack.

A 36 volt, 10ah pack should be good for a minimum of 10 miles, probably more like 15. Knowing that, I would say recharge it after each run, never exceeding 10 miles and you should be fine.

If you were buying a separate charger and battery adn wanted some specifics on battery care, I would go into far greater detail. However, I think knowing those things I mentioned should be good to keep you running.

Matt

 

[TylerDurden]

ES member stew007 has a good example of an outside charging setup (mostly metal construction):

http://endless-sphere.com/forums/viewtopic.php?f=6&t=4805&p=71255&#p71255

 

[Drunkskunk]

I'm one of those who use Lipo batteries. LiCo is dangerous, and should be treated with respect. treat it like you were carrying the same weight of black powder and you should be fine. I.E. Don't let it get wet, or overly hot. don't let it get crushed or punctured, and keep it away from people who don't know how to handle it.

The real danger is during charging. Most problem happen when the battery is being charged, so the best practice is to charge it out side, away from anything that can burn. I use a standard of 2 feet per pound. That is, I make sure there isn't anything with in 2 feet of the battery for every pound it weighs. a 36 volt, 10 amp Lipo battery weighs 4 to 5 pounds, so keep it 10 feet from anything.

a good Lipo won't have a problem, and will work better than most other battery types. there is nothing else as small and light as Lipo. but it does need lots of attention to detail.


Lipo like to stay at 1/2 charge. they will last a long time if kept at 1/2 charge. keeping them fully charged shortens there life, but not by too much.
If the BMS is an active type, it will drain the battery over time, which may be why it needs to be charged every 2 months by the instructions.

 

[ZeeZee]

Thanks for all the additional information.

And now I will show how dumb I really am ...

On one of the bikes I looked at, it said it was a lithium polymer battery, and I assumed the tiny tiny words "Phylion high energy battery" was an abbreviation for lithium polymer. I needed to get a magnifying glass so I could see it was all one word, and a bit more searching on the web and I discovered this is the company that makes the battery. It is without doubt the same company because the company logo of a distorted square inside a square is on my battery.

Here is a page from the company on safety.

http://www.xingheng.com.cn/en/knowledge.html

I can't see a battery on the website with the exact same letters and numbers as are on my battery.

I haven't got a clue what they mean, but on my battery they are

XH370.07

and

DC37.0V

It sounds like this might be a safer type of lithium battery with Manganese, and it may have a battery management system built in, but I'm not sure if that is just some of the batteries this company produces or all of them.

I'm sorry if my earlier question wasted anyones time.

Is this battery safer than lithium polymer?

 

[recumpence]

Trust me, no question is too dumb for us here. :wink:

I am not familiar with that battery. The one set of numbers is voltage 37.0V is 37.0 volts. I am not sure about the other number.

Oh, welcome to the forum, by the way!

Matt

 

[TylerDurden]

Tricky bizness... don't trust company lit.

LiMn is quite safe, but:

A 37V pack could be 10 LiCo cells
A 37V pack could be 9 LiMn cells

The best way to know is to test individual cells for voltage.

 

[stew007]

If what you have is LIco/lipo then charging outdoors is my advice see the above pic 8) its not worth risking your house over. Saying that if used properly Lipo can be safe but it does require knowledge on the correct usage, esp charging/safe mounting (to avoid puncture) and risks. Lipos are at there most dangerous while charging, the reason for this is charging under the wrong settings or charger malfunction can cause the pack to over charge. Also packs should ALWAYS be balance charged by a high quality modern lipo charger. While using them they are about the same danger level as gas/petrol, if you have a bad crash and one gets punctured it might vent, same as if you crash a motorcycle and the fuel leaks out and catches fire. Also they should not be discharged below 3.3v per cell, 3.3v gives a healthy safety margin which will also prolong the life of your cells. Lipos are by far the lightest, most compact and powerful batteries available, perfect for a high performance ebike

 

[Lessss]

See http://endless-sphere.com/forums/viewtopic.php?f=14&t=6421&p=97222#p97222

 

[mickk]

What a crack up! batteries so dangerous someones charges em in a safe!