Charging Woes

[Sandgrounder]

First post, here goes, 2000 Blackbird Fi, I'm only getting 12.5 v at the battery, new alt, new battery, new reg/rec. All tested OK, when I unplug the RR (not the alt) and plug in cables to another battery on the garage floor I get 14.5v . When I connect those leads onto the bike battery I get 12.5v. I have re-sloderd (?) the earths. I can feel heat in the wires around the plug/socket when the R/R is conected to the bike battery. I can't understand what's going on where is the missing 2v going? I have a 2nd hand R/R and get the same readings. The alt is putting out the correct AC voltage, I don't understand why it works OK on a battery on the floor but not the bike one!! There is continuity along all the wires + & - and to earth PLEASE HELP!!

[jjdugen]

Hmmmm..

First check I would do would be to disconnect the positive lead at the battery and measure your volts, engine running, and verify that you are getting circa 14 volts.
If you are, then it is one of two things. Your new battery is faulty, (bad cell (s)), or you have a short in the loom.

As all seems to be well when running with the external battery, I would point the finger at the new one.
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[Sandgrounder]

Thanks for the reply, when I borrowed the second battery I fitted into the bike and put mine on the floor, no difference 14.5v (at idle) but same problem with the battery on the bike.
When disconnected the battery it shows 13v at idle, when rev'd then the green immobiliser light comes on as the engine stops. I've had the battery checked and is OK I can leave it a week (or longer) and it starts no trouble. I don't think the trouble lies with the 3 charging components i.e. battery, alt, R/R they have all been checked and swopped for known good ones, it's something I don't know about.

[Casper]

Chaf wire. Stick the meter back on and pull apart block connectors one at a time as you might be lucky to find a chaff not on the loom. How about the alarm taking power. Have you any other electrical items added like high watt bulbs in the main lamps? could be taking more power that the system can handle.

[Fizzer Thou]

On a Honda the regulated +12v is sent around the bike via the black wire.This is switched by the ignition switch via the red wire,which is direct from the battery.Disconnect the battery and connect a resistance meter between the red and black wires and switch the ignition switch on.You should read zero ohms.If there is anything higher than say 2 or 3 ohms this can cause heat buildup and cause a resulting voltage drop.
Once this has been checked reconnect the battery and measure the +12v at the red and the black wires with respect to earth/ground/chassis.
Another test to perform is to connect the resistance meter to the negative side of the battery and to a known good earth/ground/chassis point somewhere on the bike.This should read zero ohms.If even 2 or 3 ohms show then clean all of the earth points/green wire contacts.
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[unitynotsocri...]

sounds like somthings wrongly wired to the earth or a main live feed cable is worn and catching on the frame.,aslo,check there is good continuity between the engine and frame.
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[Bezzer]

Check the connectors at the reg/rec and wiring down to the stator, it's common on Blackbirds for bits of them to start melting, people end up hardwiring them.
.....and
the $64,000 question has the loom fix been done??it's the cause of many problems electrical on the FI 'bird but is an easy DIY hardwire fix. I bit the bullet years ago and was the first to try it, did a how to on it if you want a long read Even if it isn't the cause of your problem it should be done as a preventative measure.
https://www.bikersoracle.com/blackbird/forum/showthread.php?t=16438
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[Sandgrounder]

Thanks very much for the time and trouble in replying guys.

I've tried all the tests, and when I said I resolderd (?) the earths, that was the 'loom fix' I was refering to, I 'fixed' it two years ago. There's zero ohms where there should be, and continuity where there should be, although this bit bothers me, if there is a large wire to carry a large current and it has worn through reducing it to only a couple of strands it would show continuity, wouldn't if? but it couldn't carry the correct current (would it ?) if so could it produce my trouble? I know I'm asking more questions buy I'm still only getting 12v at the battery with the engine running and the sun's shining.

Thanks again.

[Nb]

[Robby]

My fix/test in this situation would be to run a number of additional earths.

Try running additional earth leads from the engine to frame, and from the back of the reg/reg to frame, and one from the frame to the battery negative lead.