Bike went up in smoke last night..

Well hopefully I grabbed your attention.. The bike did indeed go up in smoke, luckily it wasn't a fire. I do need tons of help trying to figure this out though. So stick with my and share in my misery.. You all probably hate i cut up the xj and get a bit of joy when i fail anyways. So here's my story..

Was out on the bike, probably about 20 miles into my ride last night and suddenly all power dimmed, then cut off, i coasted about 10 feet before i realized smoke was pouring up from under me. I jump off the bike and thankfully no flames, just TONS of smoke from the battery cooking itself. Bye bye $150 battery.. The battery cooked like that for about 5 minutes. It was late, and dark and by the time my wife towed me home I only had time to disconnect the battery and do a quick once over.




So now that daylights here i went for my first suspicion... The rectifier went and i over volted the battery via a bad diode or something. (Not horribly familiar with the rectifier diodes and wiring) I get no further than taking off the rectifier than noticing that the brown pin had worked its way out of the connection. I can't imagine it was making any contact to complete its path at the point when this happened.




First off, I would like to test the rectifier's diode but i can't find the link to the procedure. Second I wanna be sure as hell I figure out what this is before I put a $150 battery in here again. So I'm calling on all the experts here to really help me get through this. The bike has been running find and I probably have about 75 miles on since I rebuilt it. So I'm not sure why tonight this happened, and not sooner. So please throw all the knowledge, criticism, and ideas my way please and thank you!

 

That switched voltage on the brown wire is an input to the regulator to sense battery voltage. As the voltage rises to indicate battery full charge the current applied to the field coil (rotor) is reduced to limit the output of the AC Generator, and consequently the charging current to the battery. With no connection at the brown wire you were at full charge, which will seriously overheat the battery.

Here is a correct drawing to test the diodes and the rest of the charging system:

 

"yamaha pocket tester" .. I'm assuming this is a multimeter on the continuity setting? Obviously can't test the charging system until a new battery comes in but the second half of that procedure seems like a bench test.

 

Yes it is a multimeter, but the old less expensive variety. If you check the diode with a more modern multimeter in the "diode" mode you will notice that the polarity of the leads is opposite of what is depicted in the FSM literature. It was common for older meters to reverse the polarity of the leads, which resulted in the polarities noted in the chart. As long as the diodes read approximately 500 ohms in one direction (diode mode), and open in the other they should be OK.

 

Bummer, lucky though it wasn't a Tesla............

Good info from Rooster.

 

So assuming the rectifier tests fine, this brown wire seems like the smoking gun to this problem? I ran over the harness and didn't see any other visual problems and all grounds appeared good. Just want to make sure I go over everything before putting another $150 battery in.

 

May not hurt to run through all the charging system tests since they're fairly simple to do just to make sure. I agree that likely the lack of connection on the brown wire is your smoking gun. No pun intended haha

 

For sure will once the battery is back in. Can't test it until then, want to make sure to cross everything off my list. (Or everyone else's list because my list is apparently inadequate)

 

here are my findings according to the chart using my 'yamaha pocket tester' (multimeter) :

D1 - 545
D2 - 527
D3 - 532
D4 - 543
D5 - 547
D6 - 544


Not sure if theirs anything else to bench test but this was my results. The only tested one way.. if i had the black and red leads flipped on my multimeter i wasnt getting any reading. took me a minute to figure that one out.

 

should be good by the numbers you posted . didn't you drag the rectifier on a test run? could be what pulled out your wire

 

Possible. But when I rewired it,it did not appear to be that way. The pin retainer on the brown wire needed to be bent out, but it now snapped it and is fully seated.

 

Got my new battery in, tested everything in the charging system. although I didn't get up in the revs tooo much (very loud bike). Anyways, v2 was .84V with main switch on. V2 than rose gradually.. the highest I got it was about 4.9 volts but it seemed like it wanted to climb if i would pin it. I'd say throttle half way was about 4. As for V1, it was in the high 13's upon start but stablalized at 14.4V when reving and then in idle it hovered about there.

Everything sound okay according to the tests or should i dig deeper?

 

Seems to me like you were just waaay overcharging the battery. Get that wire back in where it belong, get a new battery from Walmart, and go ride.

 

Good read, and be very happy the battery didn't bust on you...WOW so lucky...glad that worked out for you and you were able to trouble shoot it down to the "Brown" wire.

 

don't some of those batteries have protection circuits built in?

 

Yeah--- see how well they work ?

 

his didn't have a protection circuit, obviously. that whole line is discontinued, i wonder why http://www.batterytender.com/new-batteries
think the new ones will?

 

I'm thankful whatever it was happened in the battery and the battery only.. seems I cooked it for sure, brown wire was the culprit based on my findings. I'm not exactly pleased with the battery but it offers the CCA in a size i can hide where I NEED(want) to hide it. Maybe the new one has it maybe not, Wish i could go with one that did for sure? At any rate, Some miles in the saddle to get the battery up and charged will tell.

Speaking of circuits, Not sure of the best type to maybe monitor this situation? a temp sensor seems maybe it could be rigged up... I dunno just kinda thinking of a way to maybe monitor it, temp, voltage, whether its charging, simple LED yes no style. I'd imagine if i get past 10 miles this time I SHOULD be good.

Someone had mentioned silicone on the back of the connector so the plugs can't rattle loose out the back side.. I think it would server its purpose but might make it hard to work on in the future? Any insight?

 

Check to see if the little barb broke off. That really shouldn't have slipped out the back that easily.

 

ebay "voltmeter motorcycle" bunches of them. that's what you want to monitor

 

it was def flat... Thats how i fixed it by moving the tang so it 'clicked' in when seated.

 

So, check the others then---- my bet is that you already did... lol

 

That little tab needs to be checked as hogfiddles said, they tend to get bent and pull away with the movement and vibration of the bike. Sometimes that plastic is just old and brittle or has been warmed up and melted a few times and will not hold like it did from factory. Might even want to pull the brown wire out of the plug and make a new connection that you know will not come apart.

 

Yes, indeed I checked them all, in all honesty it looks like I should depin them all and replace the actual connector, its for sure seen better days.. At this point I'm just waiting to find the time to give her a test ride. Pretty sure its problem solved, and with a full charge on the battery I'm hoping anything after 10 miles and I'm home free!

 

This is what I use to monitor my voltage on the fly. Seems to work ok for a very inexpensive unit.

 

Can you share where you got this? The ones I see don't have a handle bar strap.

 

MonkeyJack DC 12V 24V Car Motorbike... https://www.amazon.com/dp/B06Y3XWRDF?ref=yo_pop_ma_swf

If I did this right, there should be an Amazon link to it above this text. Like o said, it's a cheap unit and I don't expect it to last forever but it does serve it's intended purpose well enough.

 

so how accurate is it? What would indicate over charging? seeing anything above 14 volts? anything under 14 is general running? Would hooking it up to v1 on the test diagram be the best?

 

It seems to be fairly accurate. It read 17v when my bike was severely overcharging. I tapped into the ignition feed. Comes on with key. You can also easily watch the voltage as you're pushing the start button too. My only real complaint about it is that when the sun hits it just right it's hard to read what it says.

 

something like this would come in handy
http://www.batteryspace.com/pcbprot...4cells128vlifepo4batterypackat30alimited.aspx
their protection starts at 15.6 volts, 3.9 X 4
i think you could make that board work but right now i'm in no condition to figure it out

 

bummer deal hope you get it all worded out

 

This one looks nice too, especially if using cell phone for navigation or tunes (bluetooth). https://www.amazon.com/BlueFire-Wat...2RSD8ZYZ8VV&psc=1&refRID=C19XXGBRJ2RSD8ZYZ8VV

 

^^ I like that one thanks for linking that. I think that will go on the brat BMW. Good find.