Noob battery questions

[Stone Meadow]

I'm still at the "overwhelmed" stage of learning about batteries, so I hope you'll bear with me for a few questions.

1. I am so shocked at the price of lithium batteries that I wonder why someone couldn't string together 6 of these Zippy packs for 8.4ah of 36v (or 8 for a 48v)? I'd spend well under half of the cost of a pre-made pack.

2. Can one run a 48v hubbie on 36v without damaging it?

I'm sure I'll think of more questions, so thanks in advance!

[amberwolf]

1. I am so shocked at the price of lithium batteries that I wonder why someone couldn't string together 6 of these Zippy packs for 8.4ah of 36v (or 8 for a 48v)? I'd spend well under half of the cost of a pre-made pack.

If I understand what you're asking, many many people are already doing this...but with the Zippy RC LiPo (LiCo) rather than the so-far-dissappointing-results Zippy LiFePO4. (I am using a pack built from 2s and 6s packs here:
http://endless-sphere.com/forums/viewto ... =4&t=39877
viewtopic.php?p=536242#p536242

2. Can one run a 48v hubbie on 36v without damaging it?

You can always run the motor on a lower voltage, but you won't get the same power level out of it, and it will not spin as fast. The speed and power difference will be proportional to the difference in the input.

Your *controller* however might not run on a lower voltage, becuase it may have an LVC below which it shuts off.

[dogman]

Those that tried the HK lifepo4 were not impressed with it. Not as good a c rate as the rating. Best deal on a battery I ever bought when looked at in cost per mile has been a 36v 20 ah or 48v 15 ah pingbattery. You need a big one to run a 20 amp controller though.

So if you don't need 20 mile range, ping can be the expensive way. So lots of us use an RC lipo pack from hobby king. 12s lipo is very popular. At 44v nominal, it's not too low for the low voltage cutoff on a 48v controller, and nearly all 36v controllers won't cook off on 44v. The popular size is 5000 mha, which is 5 ah. Two 5ah 6s packs makes a 44v 5 ah pack that is super small, super light, and takees you about 6-7 miles full speed.

But if you do need range, I still think the best battery for a 20-25 mph commuter bike is the 48v 15 ah pingbattery. 20-35 miles range, depending on the speed you ride. Yet not so large and heavy the bike can't carry it.

[Drunkskunk]

Lithium is Cheap now. Very cheap. When I first started using Lipo back in 2003 for my RC planes, I paid $100 for 11.1volt, 2 amp packs that could manage 10c at best. that worked out to $4.50 a watthour. Now its down to around $0.45 a watthour with zippy Flightmax Lipo than can pull 20C. Thats 1/10th the cost!


I would recomend LiFePO4 lithium over LiCo for someone just starting out. And for that, Hobbyking lithium is not the way to go. Try a vendor like Ping, or Cell_man. Or build your own out of headway cells.

[dnmun]

look in the BMS battery lifepo4 section too. i saw a 48V16Ah headway pack with bigger BMS rating for $434.

[Stone Meadow]

Good info, gents...thanks!

This is for my wife's commuter bike. It's only 15km/9+m each way with no significant hills, and even though we're both in decent shape we are nearly 60 and the heat of summer is coming. It just needs to be an "assist" more than anything else.

We've just spent a few hours looking at different options and are down to a premade 48v pack, either SLA or LiFePo4 for simplicity, safety and plug-n-play. I'll leave experimentation for a later build. Definitely no storing the batteries in the oven to preclude burning the house down...

dnmun, can you give me a direct link to that headway pack? I can't seem to find it on HK...thanks!

[dogman]

48v 15 ah pingbattery then. Or from Cellman at emissions free, you can get a smaller pack. Ping if you need more range for the best price.

[amberwolf]

dnmun, can you give me a direct link to that headway pack? I can't seem to find it on HK...thanks!

That's because it's not on HK, it's on BMS battery's site.

[docnjoj]

dnmun, can you give me a direct link to that headway pack? I can't seem to find it on HK...thanks!

[/quote]

I'm sure he wiill be back but here is a similar 36 volt battery from the same company.

http://www.bmsbattery.com/packs/431-36v ... -pack.html

You really don't wanna use lead, I hope. Check out the weight and the fact that you really only get half the amp.hrs stated! Bad choice generally. Sorry,
otherDoc

[dnmun]

yep this is the one, and you click on the current required over on the right side, and the 30-60A is $434:


http://www.bmsbattery.com/packs/430-48v ... -pack.html

also, you don't have to worry about the lifepo4 chemistry. it does not ignite if overcharged but it will not overcharge if it has a BMS.

that only happens with the lipo because they don't use a BMS and if one cell overcharges then it can ignite.

so you are safe with lifepo4, that is the entire argument for using them because they weigh twice as much as lipo and last 4 times as long.

[Stone Meadow]

That's because it's not on HK, it's on BMS battery's site.

Oops...my bad! Hey, I told ya I was a newbie!

Lots of choices over at BMS, so I'll keep looking. Heck, I may even buy a 36v controller (<$25) and drop down to a lower power setup. My brother-in-law commutes to work about the same distance (slightly longer and more hills) using a 36v15ah system and says he is very happy with it. Thanks again, everyone.