help building ebike battery packs!

jatgm1

10 W
Joined
Mar 7, 2014
Messages
78
Location
mahopac, new york, united states of america
i currently have a brushless electric bike hub motor kit. the kit is rated for 48 volts 1000 watts (i believe 20ah) i currently have 4 12v 10ah sla battery packs on it. its heavy as hell and dosnt go far before needing to charge. i am thinking of switching to li-ion and wanted to know if 12 or 13 of these

http://www.ebay.com/itm/A-Grade-R-C-Remote-Radio-Control-Helicopter-Parts-3-7V-Li-ion-Battery-300mah-x4-/111286120709?_trksid=p2054897.l4275

would work to power my e-bike wired in series and how would i charge them? what chargers would you recomend (can i use a charger for sla batteries?) and how would you recomend wiring them? what plugs would i need to plug it into the charger? p.s. currently i am using standard 110 volt ac plugs (the ones from any household electric device) to plug my charger to my batteries and my batteries to my controller.
any help woud be greatly appreciated.
 
what are some cheap batteries i can string together to make a 48v 40ah battery pack? i am looking for somthing cheap, but not sla because their heavy as f***. i considered lipo but heard they are know to burst into flames. thats why i switched my vision to li-ion.
 
im just confused. in li-ion there are 3.7v cells. and 1ah is 1000 mah, so a 40ah is the same as 40000mah, so if i got 12 3.7v cells with 3500mah that would work right? like 12 of these?
http://www.ebay.com/itm/like/171203415324?lpid=82
and i just wire them serial, positive to negitive, and then plug it into a battery charger. and charge it as a pack, like i do with my sla's. and i have 4 sla's now that are huge its like 100lbs or someshit. li-ion couldnt be bigger than that.
 
Not bigger or as heavy, but.

12x3.7=44.4v but still only 3500mah. So here we go again. 12x12=144 to get to your or near 40AH. Cheap, only $2300.00+

And the C rate isn't enough to run it correctly.

You either add cells in series to get your voltage and do it again till you add up to your AH desired. or add cell in parallel to desired AH and then in series to get the voltage. It's a lot of cells and very complcated for the beginner.

So 12x3.7=44.4v at 3500mah x 12 = 144 cells aprox.
V x Ah = watthrour and you are looking for 2072 watthrs.

Then you will need a BMS and a special battery charger to do it correctly. Yes you could use your sla charger with a BMS but do not try it without. Buy one, it's a lot cheaper and easier. All numbers are not exact to what you asked for.

Dan
 
i see. i currently have 4 12v 10ah batteries. i assumed i was getting 48v 40ah however im actually only getting 10ah according to your calculations. i think. that would explain why my bike has such a small distance it can cover on one charge.. this is so confusing! if i were to purchase another 4 batteries and add it to the bike(lead acid) what would that do to the distance do you think? im sorry im not the most experianced at this.
 
Hey jatgm1!


OK, about your questions....

jatgm1 said:
i currently have a brushless electric bike hub motor kit. the kit is rated for 48 volts 1000 watts (i believe 20ah)

What do you mean (i believe 20ah)? Do you mean you have a 20 amp controller? If you could tell us what kit you have (a link would help) then we could help you get your need sorted out.
i currently have 4 12v 10ah sla battery packs on it. its heavy as hell and dosnt go far before needing to charge. i am thinking of switching to li-ion and wanted to know if 12 or 13 of these http://www.ebay.com/itm/A-Grade-R-C-Remote-Radio-Control-Helicopter-Parts-3-7V-Li-ion-Battery-300mah-x4-/111286120709?_trksid=p2054897.l4275

Those are the wrong batteries for your application. If you are a nube then LiFePO4 is probably the best chemistry to start with. It is more stable then RC Lipo. LiFePO4 batteries are a bit larger then RC Lipo batterys but from the reports on this forum, safer. This is not to say that you couldn't learn to handle RC Lipo, but if you are totaly unsure of what to do then LiFePO4 is probably the best lithium to start with.

But first you need to figure out a few things.
Budget
How far you want your bike to go on a single charge
How fast you want to go
local e-bike laws
What a "C" rating means
How many amps your controller is

Check out these links:
http://endless-sphere.com/w/index.php/Choosing_a_battery
http://endless-sphere.com/w/index.php/Rechargeable_battery_basics

As for your SLA questions, you can wire them up to either multiply the voltage or the amp hours but not both at the same time:
With 4 12v 10ah SLA's in series you will get 48v at 10ah. Or.... With 4 12v 10ah SLA's in paralle you will get 12v at 40ah.

If you add 4 more SLA's you can get more amp hours or voltage depending on how you wire them but you will also get more lead weight.

Lithium is a better option. About 150% times the distance of SLA's at about 1/2 the weight. There are several trusted battery dealers around this forum, but first we need to know where you are from.

:D
 
hey, i greatly appreciate your input, i dont even think you understand, i thought, im good with computers and thats all electronics electric bikes will be easy, and of course i did not do enough research. i should have realized that ah stayed the same when i wired it in series. i just thought if i put batteries together i'd add all the voltages and aperages. ugh im an idiot. i have this bike hub ,
http://www.aosom.com/d-4742/Aosom-48V-1000W-26%E2%80%9D-Rear-Wheel-Brushless-Hub-Powerful-Electric-Bike-Bicycle-Motor-Conversion-Kit.html?gclid=CIPUpIWDgr0CFafm7AodSyUAlA
it was cheap and 48volt so i got it. and i have 4 sla batteries to go with it, 12v 10ah each. after realizing how much money it would cost for a li-ion battery i thought, screw it, ill get 4 more sla's and use them until they die since i already have 4 sla's. but i didnt order any batteries yet because i wanted to know exactly how far i can go on a single charge with 8 sla batteries that are 12v and 10ah. (basicly 2 battery packs of 48v 10ah wired in serial, that are wired paralell) also i live in mahopac new york of the united states. but for legal purposes lets assume im only using this on private property. idk what the laws are and im pretty sure that a cop isnt going to pull someone over on a bicycle. if i hypothetically were to ride on the road right now i get very little distance on these batteries. if i were to add another set how would it affect the distance? i understand the pros of having li-ion or lipo but since i already have the 4 sla's exactly what am i going to get with another 4? because if its little to nothing i'll just wait until these die and get somthing better. but if i get significantly more distance then i'll go for another pack. like i said, any input i can get would be greatly appreciated, thank you.
 
You came back with where you live but didn't answer E-beach's questions.
Which should be in your profile. that makes it easier to help your questions as to where to buy and what is the laws.
I know "WE DON"T NEED NO STINKIN LAWS"

Speed, distance needed, weight, all are important to know.

How far does the lead get you now, 8 miles?
.
Are you running full throttle and how fast is that. To get distance you will need to back off the throttle and pedal on the starts and try to assist while riding.

You really don't want another load of lead. Are you charging after each use? Don't leave sla's discharged, they need to be charged right after use and should not be run stone dead.
I think a fair amount here started with lead and moved onto Lith in a short time.

I would say a 48v 20AH LiFePo4 pack can give you a minimum of 20 miles if not more. I have gone 42 miles on 16AH LiFePo and 55 on 20AH of LiPo. All was not at full speed and had a fair amount of assist from me.

Here is a great vendor on ES, just one of a few. http://em3ev.com/store/index.php?route=product/category&path=35 His battery doesn't come with a charger, but his products are great Another is http://www.pingbattery.com/servlet/the-48V-LiFePO4-Battery-Packs/Categoriesthis one has a charger with them. Also a great guy.

Dan
 
Budget - aprox 200-400$ im trying to replace my use of a 12mpg car. i gots no moneys to buy a good mpg car, and in 15 years when the word is poluted to the point where we need gas masks i want to be able to look my six year old sister in the eye and say i did somthing.
How far you want your bike to go on a single charge - the more the merrier, however 20 miles is preferable if not more. right now im getting tops 4.4 miles. mind you their was one huge ass hill. i tested the distance by biking to and from the same place twice. it is 1.1 miles to go there. also i was looking for places with a 110v plug so incase, worst case scenario it gone out and died i could chill for an hour or two while it charged.
How fast you want to go - it now goes, from what i experience, around 25 fully charged, and i find that sufficient.
local e-bike laws - lets assume that it is only ridden on private property.
What a "C" rating means - somthing to do with the rate at which a battery has the ability to safely discharge. need go google the s*** out of that i suppose.
How many amps your controller is - the site specifies that it is 48v 1000watts so mathematically i think thats 20ah. the people i talked to on the phone didnt seem to know anything at all. its just some german brand electric motor hub kit. "homcom"
and weight, im under 180lb and the bike is a "giant, boulder" and a mountian bike so its a tad bit heavy, but i figured a little extra weight was worth a good sturdy frame.
 
FWIW, that original link to the tiny batteries? That's LIPO, aka lico, the RC batteries that can be made to catch fire if you screw up. All lithium battery chemistries are li ion of some kind.

If you are willing to take the precautions, then go read up on them ( Lipo/ lico) in the battery section, then likely Hobby King is the place to get them. For short distances, this high C rate battery could be run in as low as 5000 mha size. 12s and 10 ah is ideal for many. The 20c hardpacks in 4s are the best price per ah in general.

Your best bet for a cheap battery that is safer, and will run a 20-25 amps controller, would be an Ebay vendor called Sunthing. Get a 48v 15 AH, or 48v 20 ah pack from him.

Much better stuff is out there in LIMN chemistry types, but more likely to cost a bit more than $500. EM3ev is a good place to look at what the latest cells are like.

If you can learn the skills, have the time, and can find a good source, people make real cheap bike batteries out of large numbers of recycled laptop battery cells. Generally takes a huge pack, but it gets er done.
 
i saw a 20ah sunthing battery pack for 589$, my question is can i use 50 of these
http://www.alibaba.com/product-detail/1270240-20ah-rechargeable-lithium-polymer-battery_1405357437.html
they are 20ah each so i just need to wire 12 serial for each battery pack and they run them parallel and find a charger for it right?
 
jatgm1 said:
.........my question is can i use 50 of these
http://www.alibaba.com/product-detail/1270240-20ah-rechargeable-lithium-polymer-battery_1405357437.html
they are 20ah each so i just need to wire 12 serial for each battery pack and they run them parallel and find a charger for it right?

Those are 1C batteries, your controller would be pushing the limit of what these batteries can do, providing you controller is 20 amp and not 30 amp. IMHO if you used these batteries on your hill with frequency, then you would kill these batteries in a few months.....unless they catch on fire first from the high discharge stresses.

Me thinks that you need to understand C rating "s*#!%" you were talking about...

http://www.endless-sphere.com/w/index.php/Rechargeable_battery_basics#Charging_C-rate

C-rate
Discharge C-rate

To avoid overloading your battery, you need to know the maximum current the battery can supply. The discharge C-rate is used to determine this: Amps = C-rate * Ah [13] [/quote

If you want to save some money and get batteries that on rare occasions catch on fire and burn people's house's down, go with RC Lipo from Hobby King, the USA warehouse. Also you will need to budget a good balance charger and get a power supply as the balance chargers sometimes aren't self powered. You have to learn how to handle the RC Lipo and be present when charging them. Also, don't store or charge them in a place where in the event they do catch on fire the fire and thick black smoke will damage anything. 15ah of RC Lipo should meet you needs.

If want to be safer go with LiFePo4. The sun thing battery kit is as inexpensive a battery you are going to get...if it has a BMS and charger.

:D
 
ugh :? so much stuffs. ok but currently i have 4 lead acid batteries that are 10ah's and 12 volts. if i were to get an identical set and hook them up paralell would the fact it was so heavy make the fact there is more power irrelevent or will i get more miles? i get tops 4.4 miles now.

sidenote - if i just run the 4 slas that i have now parelell (12v40ah) what would the results be? and could runnng a controller intended for 20ah on 10 damage the controller or batteries, and if can running a 48v controller on 12 v damage the controller? or batteries?
 
jatgm1 said:
ugh :? so much stuffs. ok but currently i have 4 lead acid batteries that are 10ah's and 12 volts. if i were to get an identical set and hook them up paralell would the fact it was so heavy make the fact there is more power irrelevent or will i get more miles? i get tops 4.4 miles now.

The fact that you only get 4.4 miles makes me wonder about your batteries. When I built my first e-bike I went with 3 12ah SLA's (36v at 12ah) and got 12 miles when they were new. They lasted about 8 months before they started to loose much distance. So I replaced them with 15ah LiFePo4 Headway batteries. Now I get 18-20 miles on a charge and have over 4000 miles on them.

To answer your question, you should about double your range with 48v 20ah worth of SLA's but the weight, and the fact the lead batteries only give up about 50% of rated AH before they need charging makes most of us move on to lithium.

A good LiFePO4 pack will give you 80% of rated AH for years, not months like SLA's.

This is what I think. Before you spend more money on batteries we should find out why you only get 4 miles from your sla's.

Do you have a watt meter? If not get one and hook in inline so you can see just how many watts you are pulling. They can be had inexpensively flea-bay. It will also help you extrapolate how many amps your controller is. Once that info is established then knowing which battery to upgrade to will make more since.

Check this one out. http://www.ebay.com/itm/130-Amps-G-...Control_Parts_Accessories&hash=item461b4c5d14

:D
 
could it be possible that the charger is not charging them correctly? i find it strange it only takes 1-2 hours to charge them.. and i may be able to get 3 sla's for the price of one, long story, so thats why i ask if its worth the money/weight. :? as to the meter, i really am only in the position to get one more battery so the meter may defeat the purpose. is their a good charger that has a meter built in for the same price?
 
jatgm1 said:
could it be possible that the charger is not charging them correctly? i find it strange it only takes 1-2 hours to charge them.. and i may be able to get 3 sla's for the price of one, long story, so thats why i ask if its worth the money/weight. :? as to the meter, i really am only in the position to get one more battery so the meter may defeat the purpose. is their a good charger that has a meter built in for the same price?

One to two hours does seem a bit short for fully discharged SLA's.......depends on the amps of your charger I guess....

Ok, I understand the tight money thing, been going through that for too long myself. So before we spend any of your money, lets take a step backwards.

What type of battery charger do you have? Can you give us a name and model number? Posting pictures is also a good way for us to look at what you have. It may be that your SLA's are not getting a full charge. It may be that they are now past their prime and need to be replaced.

But lets start with the free stuff first. What kind of charger do you have and if you can, post a picture of two of it.

Also, how many times have you recharged those SLA's? That will help us determine the life span left on them.

:D
 
since you know nothing about batteries or how to build them, why don't you just buy a 48V 15Ah pouch pack from sun-thing guy?

it is cheapest out there since he ships surface freight and it is the lightest for the capacity since it is a pouch type pack.

it should last for years if you just keep from over discharging it but that should be no problem since he uses a fairly effective BMS on it too.

it even has a switch to turn off the battery so you don't get the spark at the controller and if you turn it off in the winter when not riding then the battery does not drain down the first 4 cells driving the circuit current for the BMS.

ping costs a little more and is someone we all know and trust because he is the guy who started the pouch pack revolution 5 years ago. i am building a big battery now out of pouches from batteries he made back then. they are still totally functional after all this time.
 
i did come to the conclusion that i should just ride these dirty s*** batteries to the ground and save up while doing it, then go with a 40ah or 20ah battery. but can anyone tell me if any of these devices can be identified and if so is the charger or battery just bad all around? it was the cheapest one i could find that fit the specifications. (of what i thought was going to be a 48v 40ah battery pack but i was wrong) and also how to upload a picture because the "upload attachment" thing says the file is too big... first time actively participating in a forum.
edit*
http://s328.photobucket.com/user/Thomas_George_Margotta/slideshow/ alright here are some pictures from photobucket.
 
jatgm1 said:
i did come to the conclusion that i should just ride these dirty s*** batteries to the ground and save up while doing it, then go with a 40ah or 20ah battery. but can anyone tell me if any of these devices can be identified and if so is the charger or battery just bad all around? it was the cheapest one i could find that fit the specifications. (of what i thought was going to be a 48v 40ah battery pack but i was wrong) and also how to upload a picture because the "upload attachment" thing says the file is too big... first time actively participating in a forum.
edit*
http://s328.photobucket.com/user/Thomas_George_Margotta/slideshow/ alright here are some pictures from photobucket.

To post pics here you need to reduce the file size to under 500k I believe. But, only post them if they are really clear so we can see the labels clearly.

BTW, 40ah is a huge battery for a bike. 48v at 20ah will take where you need to go most of the time.
 
OK, so here is your charger lable......hummm.....I am beginning to think that your batteries are already toast...Can you give us a discription of where you are in your ride when the batterys stop working? On the flats, the hills, how many miles you have traveled? If the batteries stop working and then you let your bike sit for a little while will it work again for a little while? Give as much detail as you can.

Charger lable.JPG
 
Here are the Batteries Dogman was referring to. (They are the least expensive way to power your ebike. And also the most dangerous to use.)

http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack.html

If you wire 3 of them in series it will give you 12S (44.4V) and 5 AH of battery.

These cost About $25 + shipping each. That's probably about $120 shipped.

But as Dogman also mentioned, they are inherently dangerous.

Here is how I charge mine.

2014-03-08190118_zpse1594f5b.jpg
 
Why do people even bother buying garbage batteries on eBay? Seriously haven't enough people got burned?
 
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