Topic: Any wiring specialist ? electrical break down CB 750 K2

[aminemed]

Just to add a small precision, when fully charged battery is at 13v, not only after its full charge, but it remains at this voltage without any drop, that's why I'm wondering if anything is going on in the bike itself

[calj737]

13.0v is not fully charged for most lithium batteries. As said before, they don’t tolerate being over-discharged. If it drops to <10v when turning the key ON, you’re toast.

[Keith]

Yep....bad ground is my guess, a simple voltage drop test will find this in a few minutes. Everyone shoud learn this essential test.

[Spanner 1]

It's common to measure 12v in a circuit with no load and then to measure 0v when the load is applied = #$%*ty battery connections/ground / fuse box

Yes, if the circuit had both a POS and a NEG connection. But the statements were “bad fuse block” and “poor ground”. If these were the cause, then there wouldn’t be a reliable voltage measured the other side of the circuit. Capisci?!

What ?.... with the Black meter lead on the battery Neg. and the Red lead on the red to the ign. switch and you read 12v, then turn the ign. 'on' and voltage drops to 0, proof of #$%*ty battery connection or #$%*ty main ground ( as OP confirmed today ).

[aminemed]

13.0v is not fully charged for most lithium batteries. As said before, they don’t tolerate being over-discharged. If it drops to <10v when turning the key ON, you’re toast.

not when turning key on, it remains above 13v in this case. It drops to 9.8 volts when I hit the electric start. Engine cranks without firing up

Then I believe as well that if the battery is completely toasted it wouldn't go up to 13.7 volts when i charge it. Guess so..

[calj737]

What is the voltage with the key ON, no starter employed? What actual value does it read? Not whole numbers, but xx.x please.

[aminemed]

13.6 volts (that's the voltage of my battery). When key on, battery voltage does not drop.

[calj737]

13.6 volts (that's the voltage of my battery). When key on, battery voltage does not drop.

Thanks. That is not the impression I had from your prior posts.

[aminemed]

13.6 volts (that's the voltage of my battery). When key on, battery voltage does not drop.

Thanks. That is not the impression I had from your prior posts.

battery voltage drops when i press start button, engine cranks then battery is around 9.88 volts all of the sudden

[calj737]

Specs on the battery please? Cranking amps, model, etc...

[aminemed]

lithium lifepo4 battery, 12v 4.6ah. Was working greatly, one pressure on starter and bike fired up.

[calj737]

What are the “cranking amps” of the battery?

[aminemed]

240 A

[nuwonder]

Would be good to do a quick test with another (good) battery, if you can get a spare cheap. Perhaps the old battery is still ok after charging?

Also, is your engine grounding properly with the frame? I had all kinds of electrical trouble back in the day because I overlooked this.

[aminemed]

i'm going to jump start the bike with my car battery

[aminemed]

Ok sorry made a mistake and took a wrong value from my meter.

I took my meter again and this time measured correctly:

Voltage battery, bike off: 13.69 volt

Key on and kill switch OFF: battery voltage starts dropping, almost 0.1 volt / sec, i turned the key off and battery voltage remained at 12.7 (and did not revert back to 13.6 volt..)

With kill switch ON: worst..battery drops quickly at 12 volts and lower

I took off battery and connected it to my wall charger until voltage was around 13.6. This time, i disconnected my tail light wires (don't know why i did it, seemed to me that i was doing something as a pro). Anyways, same phenomenon, but this time i quickly pressed the elec start and bike started for a few seconds..(did not start for 3 weeks now).

Battery is now at 12.47