48V 16Ah

General Discussion about electric bicycles.
Post Reply
User avatar
29a   100 W

100 W
Posts: 144
Joined: Nov 26 2006 10:28pm
Location: Inside your mind

48V 16Ah

Post by 29a » Apr 21 2007 11:52am

I went with Nicd because they last longer (get to cycle them more times), or do you :?:

what causes this :?:
Attachments
D  melt 3.JPG
D melt 3.JPG (61.39 KiB) Viewed 2434 times
C  melt 2.JPG
C melt 2.JPG (53.95 KiB) Viewed 2420 times
B  melt.JPG
B melt.JPG (53.14 KiB) Viewed 2419 times
Not everything that can be counted counts, and not everything that counts can be counted.
- Albert Einstein

User avatar
TylerDurden   100 GW

100 GW
Posts: 7177
Joined: Jan 04 2007 5:50pm
Location: Wear the fox hat.
Contact:

Post by TylerDurden » Apr 21 2007 12:24pm

Looks like the leads shorted together right where they enter the pack. Most the heat damage is on the leads and surrounding area.

When did the event occur?

Were they flexing at that area?

:?:
Have a Nice Day,

TD

Image
___________________________________________________________

FYI: Adding pictures?

Bored?... take a crack at the unanswered posts

Please post your Watts-at-speed in the survey.



Image

User avatar
TylerDurden   100 GW

100 GW
Posts: 7177
Joined: Jan 04 2007 5:50pm
Location: Wear the fox hat.
Contact:

Post by TylerDurden » Apr 21 2007 12:29pm

Looks like all the battery bars got hot. A short in mid-pack might spare some cells, but they all look fried... full pack damage would support main leads being shorted.

:(
Have a Nice Day,

TD

Image
___________________________________________________________

FYI: Adding pictures?

Bored?... take a crack at the unanswered posts

Please post your Watts-at-speed in the survey.



Image

User avatar
Ypedal   100 GW

100 GW
Posts: 12519
Joined: Dec 27 2006 12:55pm
Location: Moncton NB, Canada
Contact:

Post by Ypedal » Apr 21 2007 1:07pm

Wowzers.. :shock: .. i can almost smell it from here !! ( gotta add that to the " damaged components " thread for sure !

I'd take the time to check the individual cells.. might be a few good one's left. maybe..

So.. yeah.. what's the story behind it ?
ES site status page:
http://www.ypedal.com/ES/ES.htm
----------------
http://www.ypedal.com

knightmb   100 kW

100 kW
Posts: 1070
Joined: May 08 2006 12:32am
Location: Franklin, TN

Post by knightmb » Apr 21 2007 1:18pm

I'm surprised to see them in the upside down configuration rather than all of them with the positive at the top. It's really hard to tell exactly what happened short of someone connecting the positive to the negative and leaving it to sit on a table to see what happens :evil:

That kind of thermal runaway would take some serious current, so it must have happened at a full charge and something touched somewhere that it shouldn't have. I take it the pack didn't have a thermal fuse?

User avatar
TylerDurden   100 GW

100 GW
Posts: 7177
Joined: Jan 04 2007 5:50pm
Location: Wear the fox hat.
Contact:

Post by TylerDurden » Apr 21 2007 2:05pm

Looks like the current never made it out of the pack. The 30A fuse is intact.

I've only seen thermal cutoffs in series with early NiCd trickle-charge relays and LiPo BMS circuits.

:?:
Have a Nice Day,

TD

Image
___________________________________________________________

FYI: Adding pictures?

Bored?... take a crack at the unanswered posts

Please post your Watts-at-speed in the survey.



Image

User avatar
29a   100 W

100 W
Posts: 144
Joined: Nov 26 2006 10:28pm
Location: Inside your mind

Post by 29a » Apr 21 2007 2:16pm

It happened this morning (Sat 21st Aprill)
This was one of 4 24v 8AH packs (to give 48V 16AH) none of the others wher damaged except for a little heat transfer to a touching pack and melted through my batt bag.I was only doing about 25-30Km/h on road with a 406 at 48V using 72V 35A controller. I had allready travelled 11km the bike was still working when i stopped at a light i noticed smoke.
I think i stopped just in time as ive since heard of a guy whose 5Ah Nicd pack had exploded on him sending hot cadnium scrapnell into his legs the blast was heard two blocks away. :!: If you look in Cmelt 2.jpg you can see the thermal 55C cut out thermister (small,oblong,white undamaged)
Last edited by 29a on Apr 21 2007 4:15pm, edited 1 time in total.
Not everything that can be counted counts, and not everything that counts can be counted.
- Albert Einstein

Matt Gruber   100 kW

100 kW
Posts: 1465
Joined: Feb 08 2007 11:02am
Location: New Smyrna Beach FL

Post by Matt Gruber » Apr 21 2007 2:29pm

be sure to check the parallel pack for shorted cells!
.
extra fuses needed.
ASE CERTIFIED IN ELECTRICAL SYSTEMS 1984
2006- added fail-safe controller bypass circuit with power boost to Razor MX500 using 2 80amp relays.
Now testing JB Weld cell fuses. No more soldering to a bare cell for a repair. Connect it safely with JB Weld cured with slight clamping pressure for both a good connection and thermal fuse protection.
Why build a pack from scratch? I buy tool packs instead.

User avatar
Ypedal   100 GW

100 GW
Posts: 12519
Joined: Dec 27 2006 12:55pm
Location: Moncton NB, Canada
Contact:

Post by Ypedal » Apr 21 2007 2:53pm

It looks like the short happened between the positive and negative power leads before the fuse.. hense the fuse did not burn..

The temp fuse is only on the charging wires.. the power leads to the motor do not have this temp safety device.

Not fun.. at all.. that's a lesson for all of us, aka: regularly check all wires and conections. :oops:

Can you imagine if that was a Lithium pack !!!
ES site status page:
http://www.ypedal.com/ES/ES.htm
----------------
http://www.ypedal.com

User avatar
29a   100 W

100 W
Posts: 144
Joined: Nov 26 2006 10:28pm
Location: Inside your mind

Post by 29a » Apr 21 2007 4:13pm

Now the pack has cooled down I took a closer look .
It looks like the most damage is top row left cell below
with most leakage damage in the center of the pack.
Not everything that can be counted counts, and not everything that counts can be counted.
- Albert Einstein

Matt Gruber   100 kW

100 kW
Posts: 1465
Joined: Feb 08 2007 11:02am
Location: New Smyrna Beach FL

Post by Matt Gruber » Apr 21 2007 4:23pm

WOW! Great pics!
what does DVM say?
any show life?(volts)
ASE CERTIFIED IN ELECTRICAL SYSTEMS 1984
2006- added fail-safe controller bypass circuit with power boost to Razor MX500 using 2 80amp relays.
Now testing JB Weld cell fuses. No more soldering to a bare cell for a repair. Connect it safely with JB Weld cured with slight clamping pressure for both a good connection and thermal fuse protection.
Why build a pack from scratch? I buy tool packs instead.

NickF23   100 W

100 W
Posts: 272
Joined: Nov 23 2006 3:41pm

Post by NickF23 » Apr 21 2007 4:34pm

Ypedal wrote:It looks like the short happened between the positive and negative power leads before the fuse.. hense the fuse did not burn..
If that's true then in its totally preventable. The fuse should be always be in the middle of the pack, right? My nimh packs I got from china are like, isn't that always the best place?

29A,

Can you confirm where the fuse was? where did you get the packs from?

Nimbuzz   100 W

100 W
Posts: 299
Joined: Jan 05 2007 10:57pm
Location: Stinson Beach, CA

Post by Nimbuzz » Apr 21 2007 5:46pm

Well 'C melt 2.jpg' only shows part of the pack and the other pics don't quite get the essential part. It looks to me like the leads did not exit the pack straight to the fuse as they definitely should but instead wrap around to the other side across the cell tops then exit the pack. It looks like the red lead was on top of the cell and perhaps rubbed through its insulation causing the short.

Leads should be soldered so they aim straight out of the pack and should never be running across a cell top -- unless you like fireworks.

Please take a pic that clearly shows the route of the red lead from its origion to its exit to see if I'm correct.
Al
Tidalforce M750X
C-Lyte 5304, 36V, Montague
Optibike 800Li
Optibike 1100R

D-Man   1 MW

1 MW
Posts: 1543
Joined: Nov 28 2006 8:43pm

Post by D-Man » Apr 21 2007 5:54pm

Where did you buy this nicad pack at?

Mathurin   100 kW

100 kW
Posts: 1166
Joined: May 24 2006 2:49pm
Location: Quebec
Contact:

Post by Mathurin » Apr 21 2007 6:45pm

Beautiful!
You have to know, not fear, that someday you are going to die. Until you know that and embrace that, you are useless. - Tyler Durden, Fight club. Ditch the fake identity you've created for yourself, walk your own way in a society of mindless drones to become real, you are not your social status.

User avatar
fechter   100 GW

100 GW
Posts: 12766
Joined: Dec 31 2006 3:23pm
Location: California Bay Area, USA

Post by fechter » Apr 22 2007 12:10am

Oh yeah. I can almost smell those from here.
Post a coulple of those pics over in the "failed component pics" thread.

I'm surprised the damage was so complete. usually the sort just burns away and only frys a small area. I guess your cells were well balanced.

Some of the cells might still be good.
"One test is worth a thousand opinions"

User avatar
TylerDurden   100 GW

100 GW
Posts: 7177
Joined: Jan 04 2007 5:50pm
Location: Wear the fox hat.
Contact:

Post by TylerDurden » Apr 22 2007 8:38am

Nimbuzz wrote: It looks like the red lead was on top of the cell and perhaps rubbed through its insulation causing the short.
I agree w/ Nimbuzz (except methinks the black lead). I'd be lookin real close at the other packs to see if the same thing is starting to occur.

If it is faulty construction, you may be entitled to a replacement. At the very least you may save your other packs and help others do the same.

(Shucks, you might save somebody's life...)

:?
Have a Nice Day,

TD

Image
___________________________________________________________

FYI: Adding pictures?

Bored?... take a crack at the unanswered posts

Please post your Watts-at-speed in the survey.



Image

Nimbuzz   100 W

100 W
Posts: 299
Joined: Jan 05 2007 10:57pm
Location: Stinson Beach, CA

Post by Nimbuzz » Apr 22 2007 8:46am

Yep -- could be the black lead but the pics don't quite show it for certain. It looks to me like both leads might come up the side of the pack then over the top of the cells then out.

If so, I would also call it "faulty construction" and I would advise us all to peek under our shrink wrap for such 'entanglements' An application like ours, with a pack bumping along in a bag can definitely wear through insulation that is bending over metal, sharp edged tabs.
Al
Tidalforce M750X
C-Lyte 5304, 36V, Montague
Optibike 800Li
Optibike 1100R

User avatar
29a   100 W

100 W
Posts: 144
Joined: Nov 26 2006 10:28pm
Location: Inside your mind

Post by 29a » Apr 23 2007 7:19am

Hi guy's
These are the standard 24V 8Ah Nicd packs manufactured by Sanforce which recently have been reported to have cells explode.
The damage is so extensive i can't tell if the cell blew causing the black to short or the insulation on the black melted causing the short,
Your dead right the output wires wrap round the pack over the top of cells to the output cells,seems a real stupid design. I'm thinkink of putting output tabs direct from the output cells so no output wireing inside pack on the remaining 3 good packs any thoughts :!:
I would allso like to put some sort of thermal protection in pack any thoughts ideas :?:
Any other suggestions to stop this happening again :?:
Not everything that can be counted counts, and not everything that counts can be counted.
- Albert Einstein

User avatar
TylerDurden   100 GW

100 GW
Posts: 7177
Joined: Jan 04 2007 5:50pm
Location: Wear the fox hat.
Contact:

Post by TylerDurden » Apr 23 2007 8:57am

You might want to determine which happpened first: the heat or the short.

You could take the shrink-wrap off the other packs and look for abrasions on the leads.

Then you could also do a test under load, and use a thermometer to read those battery-bars. The bars look kinda thin and the tack-welds can be high resistance.

:?
Have a Nice Day,

TD

Image
___________________________________________________________

FYI: Adding pictures?

Bored?... take a crack at the unanswered posts

Please post your Watts-at-speed in the survey.



Image

Nimbuzz   100 W

100 W
Posts: 299
Joined: Jan 05 2007 10:57pm
Location: Stinson Beach, CA

Post by Nimbuzz » Apr 23 2007 9:02am

I've used hundreds of Nicad packs over the years in RC racing. I agree with your original post that they are very robust. Of course in RC we use the very best Sanyo cells -- they pick the cream of the crop for us. I've seen a few melt down about 1/4 as bad as yours from overcharging now and then. Some racers would even solder the pack into a dead short to totally drain it after each race to eliminate any memory. But then these were nearly dead packs, top quality cells and sponsored racers that got free packs.

I'd just make the leads out of the heaviest, best quality = most expensive 12 (or 10) ga, fine strand wire and simply solder the wire to go straight out of the pack to the fuse -- that's easy to do and the way it is done 99.9% of the time.

Do your other packs have the 'wrap around bomb-fuse' method? What brand are they -- so others can check?
Al
Tidalforce M750X
C-Lyte 5304, 36V, Montague
Optibike 800Li
Optibike 1100R

User avatar
fechter   100 GW

100 GW
Posts: 12766
Joined: Dec 31 2006 3:23pm
Location: California Bay Area, USA

Post by fechter » Apr 23 2007 9:23am

It seems like it would be good if there was a strong, thin, non-flammable insulating sheet to cover the ends of the cells. The wires could go over the insulator. I've seen this sort of hard cardboard stuff they use for that. 1/16" polycarbonate sheet might work OK, you can cut it with tin snips.

A mid-pack fuse of some sort might be a good backup safety.
"One test is worth a thousand opinions"

User avatar
29a   100 W

100 W
Posts: 144
Joined: Nov 26 2006 10:28pm
Location: Inside your mind

Post by 29a » Apr 23 2007 9:36am

All the packs are the same wireing
I opened one and there is no abrasion marks/damage anywhere, The wires are glued to the plastic covering on the cells, I guess to prevent any movement abrasion.
Could any of u guys give me a basic buzzer 24V schematic i could put in pack for over heat warning :?:
It would be greatly appreciated.

Any sugestions on packing these for return, so they dont short out on mail trip.
Not everything that can be counted counts, and not everything that counts can be counted.
- Albert Einstein

User avatar
RatoN   100 W

100 W
Posts: 104
Joined: Jan 19 2007 12:18pm
Location: Montréal, Qc
Contact:

Post by RatoN » Apr 23 2007 11:46am

Geewiz. Didn't know that nicads could burn like that or explode! Maybe the batts you added were not exactly the same?

Anyway get her back on the road 29a.

Be gone April

User avatar
Ypedal   100 GW

100 GW
Posts: 12519
Joined: Dec 27 2006 12:55pm
Location: Moncton NB, Canada
Contact:

Post by Ypedal » Apr 23 2007 12:20pm

For a temp monitor, i have a few Radio-Shack digital Indoor/Outdoor thermometers, they have a thin wire-probe you slip under your window jam to record outdoor temps.. this could be placed under the shrink wrap and the display mounted to the bars... Not very convenient for 4 packs tho.

I have 4 of these packs as well.. i'm going over them tonight checking every inch of wire !!!
ES site status page:
http://www.ypedal.com/ES/ES.htm
----------------
http://www.ypedal.com

Post Reply