Help building a battery

Joined
Apr 10, 2017
Messages
276
Location
Duluth, MN
I want to build a lipo battery for.my electric bike. My bike is a 48v bike. I want to have a 15ah battery. How many cells do I need in series and parallel? How many "s" equals a 48v battery? What bms should I use. And so on. I have lots of questions. I want to do it right the first time. Thank you.
 
The usual for 48v is 12s . I recommend you to buy 4 6s bricks of 8000 mah
so you will have 48v 16ah. Since the full voltage you can get is 4.2vx6= 25.2vx2=50.4v most of the time you will be under 48v Therefore some people prefers going for 7s instead. 7s is not so common not so cheap and most probably not 8000 mah available. Also you will need special chargers able to run above 6s. Not worth it.
4 of these
https://hobbyking.com/es_es/turnigy-nano-tech-8000mah-6s-25-50c-lipo-pack.html or zippy will do.
do you know how to make a harness?
 
rojitor said:
The usual for 48v is 12s . I recommend you to buy 4 6s bricks of 8000 mah
so you will have 48v 16ah. Since the full voltage you can get is 4.2vx6= 25.2vx2=50.4v most of the time you will be under 48v Therefore some people prefers going for 7s instead. 7s is not so common not so cheap and most probably not 8000 mah available. Also you will need special chargers able to run above 6s. Not worth it.
4 of these
https://hobbyking.com/es_es/turnigy-nano-tech-8000mah-6s-25-50c-lipo-pack.html or zippy will do.
do you know how to make a harness?
No I do not know how to make a harness. I know nothing about building a battery. Just thought I would give it a shot.
 
You can do the harness with bullets. I prefer andersons. The risk is lower.
You can tape all the bricks together and gather the connectors.
w70c5s.jpg

now you have 6s4p
4vhedf.jpg

This is the view from another angle.
Now you make the series section cable
161jpmh.jpg

if you plug it now you have 12s2p use it for discharge.
for charge again you need to make not her parallel section as the one you have in the lipo pack.
And get an end-user harness for the balance.

2mxfnyw.jpg

and you are done. You only have to plug/unplug the series cable to use it. If you get a bulk charger you use the series cable to charge as well.
bulk charge has some risks so you better don't Rush it to 4.2v 4.15 or 4.10 is enough. Balance the pack at least once every 10 charges. It is better if you do it often though. I do it once every two charges.
 
maybe i didn't explain myself correctly. now that i see my post i think you will not understand.
fp5f1h.jpg

this is a 18s2p i did time ago.
f44sj6.jpg

these are the parallel charge and series discharge cables
if you have 4 lipos you need to parallel them so you should make a cable to convert 4 sets of connectors into 2 so you can do as i said
2ngyaky.jpg

two cables like this one. in one side bullets and the other side andersons. so now you have 2 red and 2 black and can do as i said.
maybe it is a little confusing but is very easy when you see it.

Wait for a second opinion. Maybe someone can tell you about multistar and graphene. I have no exp with those lipos. two of those will do and you skip making the harness
https://hobbyking.com/en_us/multistar-high-capacity-6s-16000mah-multi-rotor-lipo-pack.html
+https://hobbyking.com/en_us/xt90-battery-harness-10awg-for-2-packs-in-series.html
https://hobbyking.com/en_us/turnigy-graphene-16000mah-6s-15c-w-5-5mm-bullet-connector.html
+https://hobbyking.com/en_us/hxt4mm-battery-harness-14awg-for-2-packs-in-series.html(actually you need 5.5 bullets)
 
2s? I don't think you want to make a battery pack with Those. Try to make it 2-4 bricks.
Take in consideration 18650 li-ion packs too. The risk is lower and the prices have improved a lot lately. Most people is quitting lipo for that reason.
 
Those turnigy hard case used to be very popular here. High density, cheap price and hard case... but as I said you better do very few bricks. Balancing big packs is annoying. The fewer the better unless they have low c.
 
I like the turnigy multistar 22.2v 16ah packs you linked. I will buy two of those for 44.4v at 16Ah. They will do. I really like the 2c charge rate. Half an hour is Awsome. My current li-ion takes 5hours to charge. At $240 I can't complain. I bought my 48v 15ah li-ion for $317
 
You don't need to make the harness if you get Those. That series cable they sell will work. I never used multistar nor the graphene. Dunno which is better. I'd ask for a second opinion before buying.
 
rojitor said:
You don't need to make the harness if you get Those. That series cable they sell will work. I never used multistar nor the graphene. Dunno which is better. I'd ask for a second opinion before buying.
rojitor said:
You don't need to make the harness if you get Those. That series cable they sell will work. I never used multistar nor the graphene. Dunno which is better. I'd ask for a second opinion before buying.
Ok sure will
 
The sheet specs look cool and all but it's always better when someone talks about real life experience. Use the search engine as well. Probably many members discussed about their performance. Good luck with your build ronnie.
 
Thanks. They say that the batteries last at least 16,000 miles with proper care. I will have to get a voltage alarm or some kind of programmable LVC. Thanks for your help rojitor. :D
 
Also, I have a li-ion battery. I want Lipo because of faster charging and Lipo batteries cost a little less. But mainly for faster charging. Lighter weight is also a plus as well.
 
If your controller is not programmable those buzzers are a good solution. Inexpensive and efficient.
http://www.ebay.com/itm/RC-Lipo-Bat...er-Indicator-Checker-Tester-LED-/271746517929

I have a cycle analyst. I see the voltage and the amps spent so I always know the juice I have left.
Be extra careful charging and Balancing. They are not meant to leave unattended.
A smoke detector and lipo charge bag is a convenient investment too.
https://es.aliexpress.com/category/204005845/smoke-detector.html

https://www.aliexpress.com/cheap/cheap-lipo-battery-bag.html
take care pal 8)
 
Mr. Browen posts so many questions, it hard to know which to respond to;

https://endless-sphere.com/forums/viewtopic.php?f=14&t=88382
 
motomech said:
Mr. Browen posts so many questions, it hard to know which to respond to;

https://endless-sphere.com/forums/viewtopic.php?f=14&t=88382
I love to ask lots of quetions. Better to ask poeple who are experienced in these matters. I want to do everything right the first time
 
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