Battery Needed

[dmccart4]

Hi, I'm thinking of buying a 5303 hub motor (cuz its the only one I can get my hands on; 5 series motors sell like hot cakes) and a 36/72 Volt controller brushless 35~40Amp controller. Now just looking for the right battery. I weight about 180lbs plus a steel frame mountain bike (not sure how about the weight). I'm in a area with short steep hills and need a little help up them, but won't be using the motor all the time. An average trip on my bike would be about 15km.

What voltage and ah would i need?
Would the 5303 drain a 72v 8ah battery nicad quicker that a NiMh battery?
Could I connect two 36V 8Ah NiCad to give me 72v 8ah?
Could I connect one NiCad and One NiMh battery together?
Could I connect two batteries with different ah? eg. 8ah and 10ah.

 

[Ted_Z]

Would the 5303 drain a 72v 8ah battery nicad quicker that a NiMh battery?

NiCad cells can typically handle higher discharge rates without suffering from reduced capacity.

Could I connect two 36V 8Ah NiCad to give me 72v 8ah?

Yes, you can do this.

Could I connect one NiCad and One NiMh battery together?

Yes, if they are the same voltage and only in parallel.

Could I connect two batteries with different ah? eg. 8ah and 10ah.

Same as above.

 

[Link]

Could I connect one NiCad and One NiMh battery together?

Yes, if they are the same voltage and only in parallel.

Could I connect two batteries with different ah? eg. 8ah and 10ah.

Same as above.

To elaborate, NiXX can be discharged in parallel, but not charged. They tend to get kind of 'splodie when you do that.

And connecting two different capacity packs in series isn't generally a good idea because you can accidentally over-discharge the lower-capacity pack and destroy it.

 

[John in CR]

Could I connect one NiCad and One NiMh battery together?

Yes, if they are the same voltage and only in parallel.

I don't understand. Please correct me if I'm wrong, but it would seem ok to combine different chemistry batteries in series, but NOT in parallel. In parallel the batteries would retain identical voltages, which to me would seem problematic due to different voltage curves during discharge. For parallel connection wouldn't you want identical batteries, not just same chemistry?

John

 

[gmouchawar]

Since they are both rechargable, then paralleling differnt chemistries would be fine even with different capacities. The stronger one will charge the weaker.
However they will not be fine in series specially if they have different capacities

 

[powermed]

You might want to consider Prius cells - your bike and distance is perfect for an 6 (44.4v) or 8 (59.2v) module pack. 6.5AH and will deliver every amp you need going up those hills. The really nice part is they can be recharged in an hour. You might want to see my post in Batteries "Prius cells - how to make them work"
z.

 

[Link]

Could I connect one NiCad and One NiMh battery together?

Yes, if they are the same voltage and only in parallel.

I don't understand. Please correct me if I'm wrong, but it would seem ok to combine different chemistry batteries in series, but NOT in parallel. In parallel the batteries would retain identical voltages, which to me would seem problematic due to different voltage curves during discharge. For parallel connection wouldn't you want identical batteries, not just same chemistry?

John

As long as their resting voltages are similar, then different chemistries can be put in parallel. It's really series where capacity difference can have serious effect.

 

[dogman dan]

Won't you be limited to the ah capacity of the smallest battery? After the small one drains the big one will be all that is left, and if still connected, the small one would get really discharged if you kept riding.

 

[dmccart4]

Once I had a dream of just buying any hub motor, controller and battery; attaching them to my bike and riding an eco-friendly green wave down the street. I really thought it was that easy

The current plan is to buy and connect two 36V 20AH LiFePO4 (from Ping Battery on ebay) in parallel to my 5303 rear motor with a 36/72 Volt controller 40Amp. Please somebody lie to me and tell me that its a good idea

 

[totals]

Don't dream too hard man ! It is possible, don't get too worried about all the tech talk that is out here. I bought my 5303 kit from electricrider.com and the battery from Diaw. The rest was simply assembly. I haven't had any major issues as of yet. But I guess it is kinda like shopping for a car .... you can get scared off from buying any brand if you read the reviews. Be a smart shopper ... go with your gut, and go with what you feel comfortable with. My final set up has been fantastic. If anything changes, believe me, I will be the first to complain !

 

[fechter]

The current plan is to buy and connect two 36V 20AH LiFePO4 (from Ping Battery on ebay) in parallel to my 5303 rear motor with a 36/72 Volt controller 40Amp. Please somebody lie to me and tell me that its a good idea

That sounds like a fairly proven combination. The only 'iffy' part is the controller. I'd steer away from the current Crystalyte controllers unless they've changed their design. I'd be more inclined to get an ecrazyman controller from Knuckles or Keywin. The downside of this would be a bit more messing around with connecting the wires, but it's not too bad to figure it out.