Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesSRM EngineeringLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Welcome to BritBike Forum!
Britbike forum logo
Member Spotlight
Richard Phillips
Richard Phillips
San Luis Obispo, CA
Posts: 773
Joined: August 2001
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Previous Thread
Next Thread
Print Thread
Joined: Oct 2007
Posts: 153
G
Britbike forum member
OP Offline
Britbike forum member
G
Joined: Oct 2007
Posts: 153
In the 15 years I've owned my 71 Lightning I have never managed to do this. My bike has a custom wiring harness. The battery is also not a stock style. Instead of the posts like stock it has male connections that accept female wire connectors. The colors of the harness do not match the factory ones.
This is the way the bike was purchased. It has a Boyer ignition, Sparx regulator, and a Sparx alternator. I somehow reversed the battery connections. The bike ran OK for 10 miles then quit. It would start after a short rest, then stop after a couple of minutes. After my son-in-law brought his trailer and we got the bike home, I found what I did. I reconnected the battery correctly and checked everything. It starts OK, the lights and horn work as normal. The only thing I noticed was the battery has a little leakage at the top. Only 1 small drop. When running it appears the battery is charging. I checked with a volt meter. Before I take it out again, I want to be assured it will get me home. At 71 years old the thought of pushing it any distance is not good. Any suggestions ?

Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Joined: Jan 2014
Posts: 1,497
Likes: 137
N
Britbike forum member
Offline
Britbike forum member
N
Joined: Jan 2014
Posts: 1,497
Likes: 137
The battery is probably a little cooked but they are tough old things.
I'd put it on a charger for a night then do a simple load test, like
connecting a lamp to it for an hour or so and see how it fairs.
If it takes a charge and stays there around 12v after testing then it'll be ok.
Just my 2c.

Joined: Nov 2012
Posts: 2,117
Likes: 67
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 2,117
Likes: 67
NickL +1

When the battery was connected the wrong way round, I would have expected there to have been a short through the reg/rec and either the fuse to blow (if correct and fitted) or wires to suffer overheating.
Have you found a blown fuse? Or damaged wires between the battery and reg/rec?

I find it difficult to imagine how the Boyer worked under reverse polarity. I can only hope that the fuse blew, isolating the battery, and that the engine started and ran on alternator power alone.
Though this doesn’t explain why it wouldn’t run long term, unless you tried to use lights as well.

Whatever happened, it appears that you may have got away with it, though I’d suggest checking for compromised wires, ensure a correct fuse is fitted in a single wire battery connection (ideally the ground), and clearly label the battery wires!

1 member likes this: Allan G
Joined: Jan 2006
Posts: 7,800
Likes: 135
Britbike forum member
Offline
Britbike forum member
Joined: Jan 2006
Posts: 7,800
Likes: 135
Can't understand how it managed to run with the battery connected backwards...


GrandPaul (does not use emoticons)
Author of the book "Old Bikes"
Too many bikes to list, mostly Triumph & Norton, a BSA, & some Japanese
"The Iron in your blood should be Vintage"
Joined: May 2013
Posts: 8,015
Likes: 148
A
Britbike forum member
Offline
Britbike forum member
A
Joined: May 2013
Posts: 8,015
Likes: 148
Originally Posted by GrandPaul
Can't understand how it managed to run with the battery connected backwards...

The one time I connected a battery the wrong way around (I think both wires were brown from memory) the bike ran ok, but soon as the revs increased the fuse popped and stopped the bike.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Nov 2012
Posts: 2,117
Likes: 67
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 2,117
Likes: 67
"The one time I connected a battery the wrong way around (I think both wires were brown from memory) the bike ran ok, but soon as the revs increased the fuse popped and stopped the bike."

Was that with EI or points Allan?

If you have any electronic components it is hard to understand. I'd love an explanation as to how it would work!

Joined: Oct 2007
Posts: 1,877
Likes: 39
I
Britbike forum member
Offline
Britbike forum member
I
Joined: Oct 2007
Posts: 1,877
Likes: 39
what i would do is some simple maths
charge the battery up to max and give it a few extra hours just to be sur e

somewhere on the battey it wil tell you how many amp/hours it has fully charged
get a headlight bulb with know wattage and hook it up to battery and time how long it takes to go flat

eg a 50 watt lamp running on 12 volts of about 4 amps ( W/V = Amps)
so divide the amps of the bulb into the amphours of the battery

eg a 6 amphour battery should drive a 4 amp bulb 1.5 hours as i said not exact but its a pretty good test

this is a bit of a guess method because when the voltage drops it wont be the same amps

but if it goes flat in 5 minutes it will tell you

as for damage to all the EI stuff that is beyond my pay grade


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Joined: Nov 2012
Posts: 2,117
Likes: 67
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 2,117
Likes: 67
Simple maths would suggest with the battery the wrong way round the current through the rectifier (regulator) would be enormous and should blow the fuse (if fitted).
Failing that, it will blow the reg/rec and damage associated wiring, possibly causing a fire.

By the time you’ve done the simple math, the system is toast. I’d suggest it is better to anticipate such situations.

Joined: Sep 2013
Posts: 3,114
Likes: 101
Q
Britbike forum member
Offline
Britbike forum member
Q
Joined: Sep 2013
Posts: 3,114
Likes: 101
Originally Posted by Ignoramus
what i would do is some simple maths
charge the battery up to max and give it a few extra hours just to be sur e

somewhere on the battey it wil tell you how many amp/hours it has fully charged
get a headlight bulb with know wattage and hook it up to battery and time how long it takes to go flat

eg a 50 watt lamp running on 12 volts of about 4 amps ( W/V = Amps)
so divide the amps of the bulb into the amphours of the battery

eg a 6 amphour battery should drive a 4 amp bulb 1.5 hours as i said not exact but its a pretty good test

this is a bit of a guess method because when the voltage drops it wont be the same amps

but if it goes flat in 5 minutes it will tell you

as for damage to all the EI stuff that is beyond my pay grade

Calculating battery discharge is not that simple .
a faster discharge ... results in less return.
it you try are draw 4 amps out of a 12 amp battery it will release
about 9 amps in 2.75 hours and be dead .
... 3 amps are lost to heat in the battery , the heat lost is caused by the speed of the chemical reaction .
battery companies use slower discharge rates to boost the label rating .
( the label rating is real , but only if slowly discharged over 20 hours )

image is for a typical 12 amp battery ... 0.6 amps x 20hrs = 12amps
The amp rating on the side of the battery is based on a 20-hour discharge .
label amps / 20
[Linked Image from i.stack.imgur.com]

i would use a 2 amp draw to test a motorcycle battery ... drawn down to 12 volts
... 2 amps is the brake light filament side of a dual filament bulb , typically about 27 Watts .
2 amps is about what the Boyer /Pazon analog ignition uses .
So using a 2 Amp draw to 12 volts will tell you about 1/2 as long the battery will feed the ignition
... you can drop down to 10 volts to get an exact time ... been a full drawdown test is harder on the battery .
In either case the battery should be recharged immediately .

a britbike doesn't need that much of a battery ... it's more of a limp home feature should the
Alternator/V.regulator fail .
its kind of nice to know just how far your bike will run on the battery and not guess .
or carry a cell phone.

Joined: Feb 2008
Posts: 5,627
Likes: 243
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2008
Posts: 5,627
Likes: 243
Suggest that you buy a battery load tester.
They give you a firm indication of whether the battery has been well and truly b******d.
I bought mine several years ago for about $30 and it has proved to be a very worthwhile investment.
HTH

Joined: Aug 2001
Posts: 5,613
Likes: 71
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Aug 2001
Posts: 5,613
Likes: 71
Originally Posted by Tridentman
Suggest that you buy a battery load tester.
They give you a firm indication of whether the battery has been well and truly b******d.
I bought mine several years ago for about $30 and it has proved to be a very worthwhile investment.
HTH

I agree. For those who don't know, a load tester is a voltmeter and a low-ohm resistor. The resistor puts a big load on the battery, and the voltmeter shows to what extent the battery is drawn down. A load test can be accomplished with a light bulb, but a load tester will tell you in 10-15 seconds what takes many minutes to determine with a light bulb. And the load tester meter is marked with red, yellow, and green bands as well as volts (green = good, yellow = weak, red = replace).


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Joined: May 2013
Posts: 8,015
Likes: 148
A
Britbike forum member
Offline
Britbike forum member
A
Joined: May 2013
Posts: 8,015
Likes: 148
Originally Posted by koan58
"The one time I connected a battery the wrong way around (I think both wires were brown from memory) the bike ran ok, but soon as the revs increased the fuse popped and stopped the bike."

Was that with EI or points Allan?

If you have any electronic components it is hard to understand. I'd love an explanation as to how it would work!

Good point/question. It was on points at that time.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Oct 2007
Posts: 153
G
Britbike forum member
OP Offline
Britbike forum member
G
Joined: Oct 2007
Posts: 153
I do have a load tester and will try it today. I checked the harness and found nothing melted or charred. What's the best way to check to see if the regulator is toast ? I charged the battery with the battery Tender and it held voltage overnight. The battery is not very expensive so I might just replace it.

Joined: Oct 2007
Posts: 153
G
Britbike forum member
OP Offline
Britbike forum member
G
Joined: Oct 2007
Posts: 153
Checked the battery today with the load tester. Checked out fine. Checked the charging, seems to be OK. All wiring intact. Thanks to all who offered help. Great forum.

Joined: Mar 2011
Posts: 400
Likes: 20
L
Britbike forum member
Offline
Britbike forum member
L
Joined: Mar 2011
Posts: 400
Likes: 20
Suggestion: Buy your son in law dinner and in return, have him follow you with his trailer on your first ride. Real world advice.

Last edited by linker48x; 06/11/21 11:27 pm.
Joined: Oct 2007
Posts: 153
G
Britbike forum member
OP Offline
Britbike forum member
G
Joined: Oct 2007
Posts: 153
Originally Posted by linker48x
Suggestion: Buy your son in law dinner and in return, have him follow you with his trailer on your first ride. Real world advice.
Great idea. I live by a large parking lot. Will try test rides there. Only a couple hundred feet to push home if necessary. Thanks again.

Last edited by Gary in MI; 06/12/21 10:58 pm. Reason: spelling

Moderated by  Allan G, Jon W. Whitley 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5