Topic: A battery just blew up in my face: A few Questions

[Scrubs]

my bike has had difficulty starting in the past few days, traced it down to a dodgy kill switch (i think) today
after swapping the coils. cranked her with the button - nothing - so pulled out a spark lead to see if power
was getting to the coils - it wasent, so I fiddled with the kill switch on and off and got a few sparks.
theres the problem I thought, so I took finger off the starter button, but it was still cranking...hmmm
strange... switched it off by the keys..still going... pulled keys out.. still going strong... ...
up with the seat latch to dissconnect the battery...#$%*.... where's the screw driver...
found it started to undo the terminal been cranking for around 50 seconds now,
nearly get the terminal off when there is a loud bang a pressure cap flies off hits me in the face
splits my top lip, bit of blood trickles down my face and a small plume of smoke billows out
while I stand there with screw driver in hand shaking.

thank #$%* it was a sealed battery otherwise it would have been a very nasty accident indeed
My face was within a foot of the battery.

Ok.. first question .. any idea what cause the ignition to continue cranking like that?
secondly and I know this sounds like a daft question...do I need a new battery?
I've just put the charger on it and it appears to be charging..

If so, will any 12v battery that will fit do, or do I have to get an OEM one,
no idea where I can pick one up - quickly, if so.

[okie]

It sounds like the starter solenoid stuck in the closed position.  It could possibly be repaired, but with the questions you are asking, you will probably want to get a new solenoid.

If it takes(and holds)  a charge, and isn't leaking, your old battery might be fine.  Basically any battery that will fit and has the correct polarity will work.  A sealed battery may have saved you from possible blindness or other injuries.  I've known a couple of guys who weren't as lucky as you.  The eye patch is kinda' cool when he wants to dress up like a pirate tho'. 

[turboguzzi]

geee.... that sounds scary!

never happened to me in 30 years of wrenching.....

The only culprit could be a faulty starter relay that got stuck. get rid of it immediately!

Wouldnt recharge that battery either, would attach a stick of TNT to it and blow it in an emtpy field. Just dont stand near.

TG

[Scrubs]

I may have found the culprit...

I just opened the handle bar switch -- the actual cut off switch felt knackered since i bought it, it wouldent 'click'
and hold into position - like the ball bearing had gone. when I opened it up I found a ball bearing rattling around .
when I opened up further to see the cut out switch itself, there was another bearing still in place but but absolutley
shagged all chewed up, so it wasent doing the job. the 'other' bearing I had found rattling about was too big to
fit in the switch housing on top of the spring, so it seems the old owner did some kind of bodge job by fitting a new
oversized bearing over the old one - don't know what he was thinking as it clearly wouldent work looking at it.
I think this loose bearing may have dropped down and shorted the starter button. I am gonna hotwire it for now.


Just incase. how do I check the starter solenoid/relay? Is it attatched to the starter motor?

[goon 1492]

I may have found the culprit...

I just opened the handle bar switch -- the actual cut off switch felt knackered since i bought it, it wouldent 'click'
and hold into position - like the ball bearing had gone. when I opened it up I found a ball bearing rattling around .
when I opened up further to see the cut out switch itself, there was another bearing still in place but but absolutley
shagged all chewed up, so it wasent doing the job. the 'other' bearing I had found rattling about was too big to
fit in the switch housing on top of the spring, so it seems the old owner did some kind of bodge job by fitting a new
oversized bearing over the old one - don't know what he was thinking as it clearly wouldent work looking at it.
I think this loose bearing may have dropped down and shorted the starter button. I am gonna hotwire it for now.


Just incase. how do I check the starter solenoid/relay? Is it attatched to the starter motor?

I still think its the soleniod,I'm pretty sure the starter button only has power when the key is on; if i am wrong i will be corrected surely.  The solenoid also is located behind the left side cover by the fuses and such, when my starter switch went south on me i got a 12v push button starter switch from the local autoparts store and installed it on the back side of my headlight bucket, along with a toggle switch for the head light and it was installed onto the side of my head light bucket, and both are well hidden + the toggle switch has a blue LED on it when til up.  I say this about the head light switch because the power for it also goes through the starter switch, and with the starter switch gone bad you also won't have any headlight power now

[markjenn]

I still think its the soleniod,I'm pretty sure the starter button only has power when the key is on; if i am wrong i will be corrected surely.

No correction from me - if the starter continues to crank with the ignition key off, has to be the solenoid (or I suppose some weirdo failure in the ignition circuit).

The battery explosion was from the ignition of hydrogen gas.  The continual cranking was really taxing the battery and it was giving off gas - disconnecting the terminals provided the ignition spark.

Unless gel-type, modern maintenance-free batteries (typically AGMs) are not completely sealed so they will gas off and possibly blow off vents in an explosion.  Nasty.  That's why procedures to jump start vehicles have the last connection not made at the battery - instead you make it at a ground connection away from the battery.

I'd replace solenoid and battery (obviously).

- Mark

[Scrubs]

Thanks

With the 12v starter switch installed - I assume you don't need the Solenoid anymore?

If it does turn out to be this, can I bypass the solenoid, An I run without it temporarlily
in the meantime by running a screwdrive acrross the two solenoid terminals to hot wire it?

Ive seen a cb750 coil for sale model number 714999  It's listed as for models 1970 - 1972..
it should work on a 74 shouldent it?

[okie]

You are still going to need a solenoid.  The starter switch simply activates the starter solenoid/starter relay/whatever you want to call it.  I really don't like your idea of using the screwdriver across the solenoid terminals.  Your problem started with the solenoid being stuck in the CLOSED position. Shorting with a screwdriver won't solve that problem.  I suspect that when you reconnect a battery the starter will immediately engage because the solenoid is still stuck closed.  I believe the solenoid was the primary problem and will continue to be a problem until it is replaced.  Mickey Mouse repairs tend to cause other problems that might be bigger (more expensive) than simply fixing the original problem correctly. 

[Scrubs]

You are still going to need a solenoid.  The starter switch simply activates the starter solenoid/starter relay/whatever you want to call it.  I really don't like your idea of using the screwdriver across the solenoid terminals.  Your problem started with the solenoid being stuck in the CLOSED position. Shorting with a screwdriver won't solve that problem.  I suspect that when you reconnect a battery the starter will immediately engage because the solenoid is still stuck closed.  I believe the solenoid was the primary problem and will continue to be a problem until it is replaced.  Mickey Mouse repairs tend to cause other problems that might be bigger (more expensive) than simply fixing the original problem correctly. 

Good advice, I got off lightly today..I'll order one now. I don't wanna push my luck 
Infact, I don't think I will use anything other than sealed batterys after today.

[goon 1492]

I still think its the soleniod,I'm pretty sure the starter button only has power when the key is on; if i am wrong i will be corrected surely.

No correction from me - if the starter continues to crank with the ignition key off, has to be the solenoid (or I suppose some weirdo failure in the ignition circuit).

The battery explosion was from the ignition of hydrogen gas.  The continual cranking was really taxing the battery and it was giving off gas - disconnecting the terminals provided the ignition spark.

Unless gel-type, modern maintenance-free batteries (typically AGMs) are not completely sealed so they will gas off and possibly blow off vents in an explosion.  Nasty.  That's why procedures to jump start vehicles have the last connection not made at the battery - instead you make it at a ground connection away from the battery.

I'd replace solenoid and battery (obviously).

- Mark

Yeah when i get taxed i get gassy too , wait I am gassy all the time it just gets stinkier when i get taxed.

[jmckinne]

Scrubs

I've used that screw driver across the terminals trick on old cars with seperate solenoids a thousand times

It does work but on a bike, and I wouldn't want to cruise around with my side voer open to the elements so I could get to the solenoid.

I'd ebay-order one and get that right handle bar switch assembly too. You're lucky it's the right, those are easy to find. My left could use replacement and those are tough to find at reasonable prices.

[markjenn]

Infact, I don't think I will use anything other than sealed batterys after today.

As I said earlier, I don't think the commonly available AGM batteries you buy today are completely sealed - they can still gas off and you have to be careful with sparks around them.

- Mark