Melted battery terminal!!!!

Chat about all things battery in here.
Need to know what type to use or size or capacity then again place your thoughts here
User avatar
EV_dub
Posts: 93
Joined: Sun Jan 24, 2010 8:31 pm
Location: Dorset/Devon

Melted battery terminal!!!!

Postby EV_dub » Thu Jan 28, 2010 8:02 pm

Just before the MOT tomorrow, I thought I should take it for a test run.

OOOPPS! a big flash from the boot, I melted the battery terminal!

Was this because the resistance on the terminal was too much, or in the cables?

looks like the batteries threaded posts are a bolt moulded into the terminal.

The battery are trojan 1275 150ah

Image
1993 Veedub Golf, 156v, 1200A, 150ah's

User avatar
ChrisB
Posts: 4657
Joined: Fri Jul 14, 2006 11:33 am
Location: Hampshire on the Southcoast
Contact:

Re: Melted battery terminal!!!!

Postby ChrisB » Thu Jan 28, 2010 9:03 pm

oooops :(

I suspect what has happened is either some corrosion has got down between the bolt and the lead post causing the high resistance OR you when where tightening the bolt you may have over tightened it and fractured the bond slightly between the lead and the post, I've done that before :oops: :oops:

ChrisB
I reject reality and substitute my own !!!!!!

User avatar
EV_dub
Posts: 93
Joined: Sun Jan 24, 2010 8:31 pm
Location: Dorset/Devon

Re: Melted battery terminal!!!!

Postby EV_dub » Thu Jan 28, 2010 9:14 pm

Well yea perhaps I may have overtightened it. :?

I suspected resistance as it popped under higher current draw. Although i'm only using 35mm cable, thought that would have caught fire before the terminal would melt.
1993 Veedub Golf, 156v, 1200A, 150ah's

User avatar
EV_dub
Posts: 93
Joined: Sun Jan 24, 2010 8:31 pm
Location: Dorset/Devon

Re: Melted battery terminal!!!!

Postby EV_dub » Sat Jan 30, 2010 8:50 pm

Managed to repair it, pheww! The terminal is actualy quite deep. I drilled and tapped 20mm depth.

I think the propem was this battery may have moved causing the cable to twist slightly arching the terminal. Anyway will contact trojan and try and find out how much to torque the nuts up!

Does anyone coat their connectors with grease or anything to protect from corrosion?

Image
1993 Veedub Golf, 156v, 1200A, 150ah's

User avatar
ChrisB
Posts: 4657
Joined: Fri Jul 14, 2006 11:33 am
Location: Hampshire on the Southcoast
Contact:

Re: Melted battery terminal!!!!

Postby ChrisB » Sat Jan 30, 2010 10:07 pm

Nice one, just be careful tightening that one down :wink:

As for grease etc , I use to just put a this smear of vasaline over bare metal parts of the terminals, grease tends to be just too dirty and doesnt look very nice.
Dont use too much as its just a dirt magnet otherwise, keep an eye on them and clean and replace if you feel the need, thats what I did with the Fiesta and it was fine 8)

ChrisB
I reject reality and substitute my own !!!!!!

hardym
Posts: 6
Joined: Tue Jun 17, 2008 2:53 pm

Re: Melted battery terminal!!!!

Postby hardym » Tue Jun 29, 2010 4:07 pm

I had several of these blowouts on my Trojans T125 6v 240AH FLA batteries.

The good news about Trojans is that they can put out 1000A.
The bad news is that the terminals heat up pretty bad at 1000A even with good connections.
(My new Costco GC-2's dont put out nearly the current, so there's less of a problem :) )

Firstly, Suggest, use CONDUCTIVE grease, not vasoline. I have a tube of conductive graphite that is quite messy, but seems to work well. Others have used no-lox successfully.

Second, limit the controller to 500 or 600 amps output.

Third: suggest MESASURING the resistance between battery posts. This can be done during the initial charging stage, by putting a VOLT meter between connected battery posts, when charging at 20A. At 20 charging, any more than 1 mV per foot of 2/0 cable plus about .25 mV means you should check the battery post connecction. Sometimes the cable ends need to be soldered into the cable to reduce the resistance.

Another way to check for resistance at ther terminal is with your fingers. Go for a fast drive. Go home, then touch each battery post and when you find a hot one, clean and re-tighten it, or solder the connector.

Mark.

User avatar
EV_dub
Posts: 93
Joined: Sun Jan 24, 2010 8:31 pm
Location: Dorset/Devon

Re: Melted battery terminal!!!!

Postby EV_dub » Wed Jun 30, 2010 8:34 am

Thanks for the tips Mark.

The trojans have been ok since the repair. I think the problem came from the battery not being completely secure, resulting in it twisting the cable slightly. I check the security of terminal nuts every few weeks they haven't really moved though. :)

I think the most draw I have seen from the batteries is 450amps. But to be honest the batteries have such a voltage drop under high current discharge. I rarely draw over 200amps and if so, its only very briefly. Longer hills cost me <150amps for 40mph+ . The voltage drop is quite allot past 50% dod. I monitor the voltage to not allow the drop bellow 10volts per battery. I can cruise at 50mph for 65amps on the level and usually bellow 80amps for 60mph.

I am hoping to upgrade to a sealed battery soon. Those flooded batteries give of nasty corrosive gas under charging. The car is charged in a closed garage which affects the body work and my tools :(
1993 Veedub Golf, 156v, 1200A, 150ah's

User avatar
dillond666
Posts: 139
Joined: Mon May 26, 2008 7:52 pm
Location: Central Scotland

Re: Melted battery terminal!!!!

Postby dillond666 » Sat Jul 10, 2010 6:30 pm

Hi EV_dub

I agree with Chris that you may have fractured the terminal during tightening, but also notice the battery might be able to move about. If the battery can move about you could get the cable straining the terminal causing metal fatigue although a 35mm cable shouldn't be that stiff. Is the cable a welding cable or something stiffer? I would have thought 35mm a little too small anyway, I'm using 70mm welding cable on my pack (£5/M) and doubling it up on the motor side giving 140mm.

The good news about Trojans is that they can put out 1000A.

Err don't think so. Perhaps they will allow 1000 motor amps with the appropriate controller but 1000 battery amps would kill the Trojans.

What kind of sealed battery were you considering? (I'm nosey) :)

Derek

PS Neat repair, well done!

User avatar
EV_dub
Posts: 93
Joined: Sun Jan 24, 2010 8:31 pm
Location: Dorset/Devon

Re: Melted battery terminal!!!!

Postby EV_dub » Mon Jul 12, 2010 8:09 pm

Hi Derek

I'm thinking about the the hawker odyssey or the optimas.

There seems to be mixed opinions about these batteries.

Hopefully a nice new controller running 156volts. Slightly smaller capacity batteries but overall pack capacity should be about the same.

The zapi controller hasnt been liking the heat. I have raised the heat-sink, but still not enough colling. It happens when the car is traveling at lower speeds in a higher gear. Although the batteries aren't delivering many amps I think the controller is delivering alot of motor amps for high torque.

Anyway have solved the problem by attaching a 12v computer cooling fan, which seems to be doing the job nice.
1993 Veedub Golf, 156v, 1200A, 150ah's

User avatar
ChrisB
Posts: 4657
Joined: Fri Jul 14, 2006 11:33 am
Location: Hampshire on the Southcoast
Contact:

Re: Melted battery terminal!!!!

Postby ChrisB » Mon Jul 12, 2010 8:20 pm

EV_dub wrote:
Anyway have solved the problem by attaching a 12v computer cooling fan, which seems to be doing the job nice.


I was just about to recomend one of those, they are great little fans and can be robbed from old computer PSU's for zero cost, I have found though they dont like being over driven voltage wise so do be careful that they are only getting around 12-13volts, any more and the controlling pcb tends to go poof it seems.

ChrisB
I reject reality and substitute my own !!!!!!


Return to “All things battery related”

Who is online

Users browsing this forum: No registered users and 29 guests