where to find cheap and good 36v 20ah battery pack???

[wesnewell]

awesome, thanks for the advice, i think i will start with 6 pack of 4s1p and run then 12s2p, and if i need more range, then I can just add 3 more pack to make is 12s3p. any recommend battery charger? and what is monitor voltage good to have? what do i need to check on the battery? or if the voltage on each battery are different how do i fix it?
-Derek

There are many ways to charge the batteries and keep them in balance. One method would be a 6s charger where you could parallel balance charge them. That will keep all cells in balance with every6 charge. 6s balance chargers start at $20 for a 50W charger and go up from there depending on how fast you want to charge them. With a 50W charger it'll take about 9 hours to fully charge from 100% dod. The faster you want to charge them this way the more the charger will cost. Your 12s2p pack will be 444Wh, but recommended charge rate is 1C, so a 6s 10A charger would charge at that rate. If you added another 3 packs for 15ah, then you could charge at 15A with a charger capable of that, and so forth.
Another way to charge would be with a 48V (adjusted to 50V) power supply with current limiting, and use something like battery medics to balance the individual packs while bulk charging at 50V.
And yet another way would be to get a charger capable of balance charging a 12s pack all at once, like the Hyperion 1420i. You could still use it to charge as paralleled 4s packs or mod the 3 4s balance plugs into 2 6s plugs and balance charge the whole pack in less than 1 hour. This is where using 2 6s packs instead of 3 4s packs in series comes in handy. I paid $179 for my 1420i 2 years ago, but I think you can find them now for ~$130. It will charge up to 20A for 14s pack. Hence 1420. You need 24V 600W to power it too for max output.
So what sounds like a simple question becomes real difficult to answer since there are so many different ways to do it.
On the bike, all you really need is a voltmeter to keep from over discharging the pack I wouldn't run it under 44V resting voltage to insure longer life.

 

[skaplan]

Did anyone mention that rc batteries can catch fire if you abuse them? I'm not trying to scare anyone off, just pointing out that they are not as plug and play as LiFePO4. If you don't mind the extra work, there's a reason so many people here use them.

SK

 

[wesnewell]

Pretty much any battery can catch fire or even explode if abused. lifepo4 can too.

 

[EdwardNY]

I went to order some of these from hobby king and they are sold out in the USA. Anyone know how long the wait is for new stock on these?

 

[wesnewell]

I went to order some of these from hobby king and they are sold out in the USA. Anyone know how long the wait is for new stock on these?

I waited a month or more for mine. Just bookmarked them and kept checking every day.

 

[RC Extreme Power]

I am new to E-Bikes but not new to using Lipo batteries.

I have been reading different opinions here for a few weeks about batteries.

From what I have read, people like the Ping and V power batteries and say they last a long time, I have lipo's here that are well over 4 years old that are used in RC planes and pushed hard and still going.

For the cost and just sports riding I decided to use lipo's for my E-bike, Cost is close to 1/2 of the other batteries and the voltage drop is just about zip.

If I understand things right a 48 volt 1000 watt motor only draws about 20.83 amps which is about 1C discharge on a 20c rated battery.

You can set up a 36 volt 20AH battery for about $320.00 but you do need to do some research on how to charge and keep them in balance.
Always charge them in a safe environment and use the right charger.

Even with the RC plane batteries I do not balance them on every charge but keep a eye on the balance and about every 10-15 cycles do a balance charge.

One thing I like about the Hobby King batteries is the bullet connectors they come with, You can hook them up in series for as many voltage as you want and make a parallel connector for your amp hours.

Milton
milton@rcextremepower.net

 

[redstone02]

I am new to electric bike, so if you can give me more detail it will be great appreciate. Thanks~
-Derek

If you are considering LiPo, you might want to read this thread: http://endless-sphere.com/forums/viewtopic.php?f=3&t=43332
I am still considering LiPo, just got to mitigate the hazard.

 

[RC Extreme Power]

I am new to electric bike, so if you can give me more detail it will be great appreciate. Thanks~
-Derek

If you are considering LiPo, you might want to read this thread: http://endless-sphere.com/forums/viewtopic.php?f=3&t=43332
I am still considering LiPo, just got to mitigate the hazard.

That thread is about Li-ion batteries which are suppose the be more stable than Lipo's

It looks to me like when the batteries were put together and there was some sort of direct short and if the battery had been tested before shipping this would never had happened.

That is one thing that has bothered me about the duck tape batteries and some of the others that are coming from China is how well they are made and put together, You can not tell without removing the cover and inspecting them.

I have been using Lipo's for over eight years and so far no mishap with them, As far back as to when you could only get a 2-5 C rated battery.

At least if you make you own packs from made made Lipo packs you have control over how the connections are done.

But as with any battery anything can happen at anytime, I have had car batteries to blow up in my face and was lucky not to get hurt.

Milton

 

[adli3381]

Looks like i got more study while i wait for hobbyking lipo battery to have stock. Thanks for all the tips, My kit it did come with a controller, not sure if that will prevent power use on the battery to make it on fire, but my old SLA battery can hit about 23mph, so i will make not not to ride anything faster than that in most of situation.

Hope i can get my battery pack soon, so i can test them out soon! =)

-Derek

 

[EdwardNY]

Can someone recommend an alternative Lipo battery that hobby king has in stock in USA?

Or is it worth waiting for them to get this particular battery back in stock? If it will cost $50-100 difference for another battery maybe it is not worth holding back your whole project because of this.

 

[dnmun]

the lowest prices i have seen were the sun-thing28 lifepo4 packs that jdo found. he had them on sale for $434 for a 48V20Ah delivered to the US. only a few have been purchased by sphere members so far. but that is the cheapest we know of.

 

[redstone02]

I am new to electric bike, so if you can give me more detail it will be great appreciate. Thanks~
-Derek

If you are considering LiPo, you might want to read this thread: http://endless-sphere.com/forums/viewtopic.php?f=3&t=43332
I am still considering LiPo, just got to mitigate the hazard.

That thread is about Li-ion batteries which are suppose the be more stable than Lipo's


At least if you make you own packs from made made Lipo packs you have control over how the connections are done.

But as with any battery anything can happen at anytime, I have had car batteries to blow up in my face and was lucky not to get hurt.

Milton

The thread I linked discussed fire control/extinguishing in general and could be applied to LiPo.
The probability of an event with LiPo is greater than with lead, simple as that.

 

[wesnewell]

Can someone recommend an alternative Lipo battery that hobby king has in stock in USA?

Or is it worth waiting for them to get this particular battery back in stock? If it will cost $50-100 difference for another battery maybe it is not worth holding back your whole project because of this.

http://www.hobbyking.com/hobbyking/store/__16207__Turnigy_5000mAh_6S_20C_Lipo_Pack_USA_Warehouse_.html
38.7 cents per Wh. Works for 12s, 18s, and 24s. About 25% higher than the 4s hardcase packs, but easier to manage.

 

[dogman dan]

1 Any chemistry can short, and that short can start anything flamable nearby burning.

2 But lico,( RC lipo from hobby king) IS more dangerous if abused than lifepo4. Lico has improved, and is actually fairly difficult to get to burst into flames. But with lifepo4 bursting into flames is truly rare.

3 So don't abuse your lico, and it's all good. It's not really that likely to burst into flames just stitting there. Follow the "lipo rules"

I still like lifepo4 for lower amps, routine commuting type uses. It's long lasting and convenient. But my race bike, my trail bike, they run lico.

 

[-dg]

There are so many battery to pick, a lot of people mention ping battery, but they doesn't look cheap and small, not sure if i can fit them in my battery bag. But thanks for the tip, i will keep learning and looking =)

I see you are very focused on the cost of the battery and RC lipo looks inexpensive compared to Ping. I'm considering the same set of issues to build an ebike for my wife. A few points to consider:

- The Ping battery comes with a charger and BMS. These have to be purchased separately for RC lipo. To get decent ones I think this adds between $100 and $300 to the battery cost unless you get very slow charging.

- There are lots of reports of HK RC lipo arriving defective. To be sure of getting enough good packs to not delay your project because you got a bad one you might want to order a couple extra packs.

- Ping is willing and able to make packs in different shapes. I have a 24v 20ah pack from him that had to go in a specific box that is longer and narrower than the usual build and he was able to make that shape. It did cost $10 extra for shipping because it had to be packed in a bigger box.

- I would not trust my wife to charge RC lipo correctly, she's a nice person, but not very technical. My plan if I go that way is to handle all the charging myself since she would always charge here at home. I think it can be done safely, but only with consistant attention to detail.

I might go with RC lipo anyway because I plan to build more than one bike and so the charger cost and extra dud battery risk gets spread out over multiple units and I think I'm OCD enough to do it safely. However for only one bike, especially one for a casual user, I think the included Ping charger washes out most of the cost advantage of RC lipo and the plug and play and safety issues make Ping a much stronger choice than you are giving it credit for.

 

[pff7]

Connected my 4 x 4s-5000mah once wrong way(shorted-it) ,melted prong on the connecter,saw smoke and was like crap! now I blown it,probably wrecked the controller too!!!! but no it was fine , batterie didn't blow-up,go on fire,ect,ect...the prong acted as a fuse, but you can tell lot of power there,definitely folks get a fuse though.

Seriously folks , at full throttle with my cheapo 48V,500 Watt I go like a bat out of h*ll,(I think the 20-30c rating has something to do with this) no speedometer,but seemed like 40mph(only have my gas-bike to compare with,and it would beat my 60/70cc 2-stroke) which really surprised me.

 

[redstone02]

Check out this for a charger.... no worries about balancing...
http://endless-sphere.com/forums/viewtopic.php?f=31&t=41107

 

[EdwardNY]

If I build a 24S lipo pack, or should I say Lico? Not sure the terminology here, but the 5000MAH Turnigy packs from Hobbyking.

Do I need a BMS? What will a BMS do?

 

[amberwolf]

That question is answered in many threads around the forums, particularly in the Battery Technology subforum. You will probably want to read up on such things before you begin making any kind of purchasing decisions.