Crazy Noobie Idea

[ksw9915]

Hi 'Yall'

Been wanting an ebike for awhile now...have a 2smoke (stroke) gasser. But don't care for the noise or dirty air and decided I'd pay the premium for a clean and quiet ride.

I bought a well used and abused trek Fx 7.5 with a (i think) C-lyte 36v conversion for $375 with "dead batteries".

I opened up the pack and had no idea what I was looking at. Finally figured out its 30s of nimh.
I'm pretty sure the charger has gone dumb, it says pack is fully charged by its idiot light. It isn't, and the charger never says different.

Lets say 10cells are bad. I'd rather buy ten cells than a full lifepo4pavk

So here's my idea
get a Imaxb6 or Tenergy TB6AC 50W/5A AC/DC Dual Power Balancing Charger for NiMH/NiCD/Li-PO/Li-Fe/SLA
to test nimh cells, and hopefully only a few will be bad
string the pack back together in two 15s strands (not sure if I'm using the right terminology)with the option to join the two together in
one 30s
I can buy a "Multi-Current Universal Smart Charger for 9.6V - 18V NiMH Battery Packs (Tamiya Plug) , UL Listed" (or equivalent)
and charge them both as two different series. Always alternating the two 15s between the balancer and charger. I will not be charging them in parallel.

If too many nimh are fried, I'll do the same but with lifepo4. Charge one 6s with the balancer and the other 6s with a Tenergy 19.2V (6-Cell) Intelligent 2.2A LiFePO4 Battery Pack Charger (or equivalent . and join the two 12s for the 36v motor



The reason is because I don't want to waste decent batteries and spend more money than I need too.

my assumption is that I need the balancer to test the nimh cells and even if I went the lifepo4 route i would need the balancer anyway
and
19.2v (6cell) lifepo4 charger is considerably cheaper than the 36v


What am I missing???
Any input would be well appreciated
Because just a few days ago I thought I was sophisticated know that a watt is Volts times Amps

Kevin
Ps obviously charge time isn't a big concern

 

[Drunkskunk]

Honestly, a C-lyte on 36 volts is yawn inducing. I wouldn't waste money on a 36volt anything for it. But at 48 volts Clytes begin to wake up. Since it's Nicad, and a light weight bike, I'm betting its an older Clyte like a 406, 407, 408. Those motors aren't really happy untill you're feeding them atleast 72 volts. 48 volts is a good place to get started, though.

The only caveat to that is the possibility that it's a brushed Clyte. Does it have more than 2 wires running into the motor? Anything more than 2 is good. 2 wires is brushed, stick to 36v.

 

[Ypedal]

What he said above..

Check cell voltages and report back.

 

[ksw9915]

Er...it has seven wires. I know the difference between brushed and brushless motors, but not with ebikes. Time to read up.

I'm not looking for anything fast. I have a couple of motorcycles for that.
But I'm curious by it being a yawn, you mean in speed and power. Right.
How fast? I'm really fine with 13to 20mph.


Thanks
Kev

 

[amberwolf]

Regarding the cells and charger, it may well be only a broken battery or thermistor wire on the charger-to-battery connection causing the problem, or even a blown fuse. Check those connections first (using multimeter set to continuity or Ohms), on the charger's battery-side cable, from the connector pins back to the internal board connections. They are the most likely to break.

Next most likely is from the battery's charger connector to inside the battery itself.

 

[ksw9915]

Regarding the cells and charger, it may well be only a broken battery or thermistor wire on the charger-to-battery connection causing the problem, or even a blown fuse. Check those connections first (using multimeter set to continuity or Ohms), on the charger's battery-side cable, from the connector pins back to the internal board connections. They are the most likely to break.

Next most likely is from the battery's charger connector to inside the battery itself.

The voltage out is 41.1 I don't believe its the original charger, the pack has a thermistor wire but it doesn't look like the charger ever had one connected. The charger says output is 2amp and the packs voltage is going ever so slightly up.... And I'm hesitant to let it stay hooked up overnight to see if I can at least get a trickle out of it.
I opened the charger but couldn't see anything obvious.

Can you recommend the best value on a balancer.
I'm trying to stick to these nimh batteries if I can

Kev

 

[Ypedal]

nimh / nicad will ballance by tickle charge ( slow, controlled over-charge ) .

If the pack has been sitting for a while, it will take a few gentle cycles to get it going, first and foremost..

- what is the pack voltage now ?
- if you connect it to the bike and lift the wheel off the ground, will it spin ?

- It is perfectly normal for a Ni pack to get pretty hot at the end of a proper charge...

If the pack has sat too long, the voltage may be too low for the charger to start, the pack may need to be " boosted " to get things going but start by reporting back on the pack's voltage..

if possible.. report back on each cell's voltage if accessible.

see :
http://ypedal.com/Chaos2.htm

the crystalyte 4 series brushless motors are awsome, it's what i currently run on my daily driver ( a clyte 409 ) but i run mine in a 20" rim at 100v and it goes 60 kph and gets there in short order..

if 15mph is ok for your needs.. 36v will do that in a 26" rim... but know that the motor is capable of much much more with a proper controller and battery..

 

[ksw9915]

Thank You Amberwolf!!

I first thought the charger was beyond me...
After you posted I figure wth I'll at least try.

I bypassed the thermistor thing a ma gig when I tested its ohms and found it lead to the charger ground.
Green light turned red its a charging.

Sweet

 

[amberwolf]

You don't want to bypass the thermistor, as it is what tells the charger to stop charging when the pack gets too hot.

You can have a fire or bursting cells if it gets hot enough!


At best, if it gets too hot, it really *will* toast the pack, damaging the cells and (greatly) reducing both their capacity and their ability to deliver current. Been there, done that.


Normally the thermistor shoudl read some several k-ohms from the thermistor pin on the connector, to battery ground.

 

[ksw9915]

nimh / nicad will ballance by tickle charge ( slow, controlled over-charge ) .

If the pack has been sitting for a while, it will take a few gentle cycles to get it going, first and foremost..

- what is the pack voltage now ?
- if you connect it to the bike and lift the wheel off the ground, will it spin ?

- It is perfectly normal for a Ni pack to get pretty hot at the end of a proper charge...

If the pack has sat too long, the voltage may be too low for the charger to start, the pack may need to be " boosted " to get things going but start by reporting back on the pack's voltage..

if possible.. report back on each cell's voltage if accessible.

see :
http://ypedal.com/Chaos2.htm

the crystalyte 4 series brushless motors are awsome, it's what i currently run on my daily driver ( a clyte 409 ) but i run mine in a 20" rim at 100v and it goes 60 kph and gets there in short order..

if 15mph is ok for your needs.. 36v will do that in a 26" rim... but know that the motor is capable of much much more with a proper controller and battery..

I'm going to wait till I "run hog wild" with the ebikes
60kph on a 20"...that can't be legal

Dig your bike. I don't think you could have pulled off the mismatch wheels with out the long travel suspension.

I'm breathing some life back into this battery pack. Charger seems to be giving it a go. Pack voltage reads 41v but thats probably just a surface charge (if nimh do that)
I'm going to give it a full charge tomorrow when I can watch it better, I do not trust this charger at all.
I'll be able to read 12pairs voltages and 6 single cells without breaking up the pack. I'm thinking that should give me a general gist of what I'm working with..
assuming no operator error