Author Topic: battery drain on my cb 750 f1 (Read 1684 times)

fr33man · « **on:** March 05, 2013, 01:56:04 pm »

Hi,

i recently bought a 750 f1 that seems to be in good condition - but i have experienced some problems with the battery... it runs totally flat - bought a new one today but it was the same.

charged it good and it started with out hesitation - rode a few miles and it had no power - went on the highway for 10 km and while on the junktion coming off it had so little power left that it died and i couldnt start it again.

after a good friend picked us up and drove me home i took the other battery from charger and installed it - after starting i drove 5 min and it couldnt start again with the electric starter..
measured voltage while rev'ing it up and it went up to about 13V -

after another charge i tried to disconnect the battery while running and it kept going. so i think my charger is working - or am i all wrong ??

as a bonus info i might have overheated one of my ignition coils from trying to boost the starting process with a car battery ( yes stupid me - but school of life is a hard learner and i was desperate) it still starts but i cant figger out if it is damaged!!

HELP! =)

bruzer59 · « **Reply #1 on:** March 05, 2013, 02:11:12 pm »

YOU NEED TO TEST THE CHARGING SYSTEN ... ie THE FIELD COIL MUST BE MEASURED FOR RESIDENCE.

ALSO CHECK YOU VOLTAGE REGULATOR .. REMOVE THE COVER TO INSPECT.
inside the voltage regulator is a contactor this may need to be cleaned or re-gap

bruzer59 · « **Reply #2 on:** March 05, 2013, 02:21:48 pm »

If the field coil reads less than 7.2 ohms, there is a short somewhere in the winding needs to be replaced.. B.T.W., the stator needs to read 0.2ohms between any yellow to any other yellow to be good. .

Jerry Rxman Griffin aka MuthaF'er · « **Reply #3 on:** March 05, 2013, 02:40:26 pm »

ALSO:

This is easy and it will eliminate one of many possibilities - Check your rectifier. It converts/rectifies AC current into DC current. If it has some blown diodes from jumping with the car, etc then it will allow less current through into the system. 3 sets of diodes to check for continuity. 3 should allow current through and 3 should not, thus eliminating the "alternating" part of AC. If you have more than 3 without continuity it's time to replace. Aftermarket solid state units are available that replace both the regulator and rectifier but you can find used originals relatively cheap.

Check your ignition switch. The connector could be loose or the guts could be nasty/worn and in need of a good cleaning. If you are lucky it will have the later style switch base that can be purchased and replaced. My earlier 75 with serial number 1001954 has a base that is not available. See what amount of voltage loss there is going in and coming out.

Once you've checked these things it's time to roll up yer sleeves and dig into the wiring harness for dirty/loose/broken connectors/wires etc. If you find the problem first I'm still going to recommend an entire cleaning of all connectors.

Most times the hardware components are fine ie stator, field coil, regulator, rectifier but we find other issues. In the mean time you can pull the headlight fuse.

fr33man · « **Reply #4 on:** March 05, 2013, 03:12:29 pm »

great help - now i have something to deal with tomorrow - now i just need to find out where to find the stator, field coil, regulator and rectifier

Jerry Rxman Griffin aka MuthaF'er · « **Reply #5 on:** March 05, 2013, 03:39:13 pm »

Regulator and rectifier are behind the left side cover. Rectifier is mounted upside down. Regulator is mounted backwards. Stator is attached to the inside of the alternator cover as is the field coil. Stator has 3 yellow wires. Field coil is the center piece with 2 wires. You can test these without removing the alternator cover but you'll have to remove the shift lever then carefully, as to not break the gasket, remove that cover. Disconnect then test. You are testing the stator and field coil for continuity then resistance. You could test these at the larger plastic connector but there could be an issue between there and the original connections so go to the source.

scottly · « **Reply #6 on:** March 05, 2013, 06:00:18 pm »

Do some simple tests: with a fully charged battery, turn the ignition on and measure the voltage on the black terminal on the regulator; it should be close to the battery voltage. The white terminal on the regulator should be the same voltage as the black.

BeSeeingYou · « **Reply #7 on:** March 05, 2013, 07:05:51 pm »

13 volts will not charge the battery. At idle you may have been putting out even less. You need around 14.2-4 at 3000 rpm for effective charging. Could be as simple as an out of adjustment regulator(easy to spot it's the gold colored metal device). It's easy to check and adjust if needed. There are instructions in the service manual that you can download from the forum if you don't have a manual.

fr33man · « **Reply #8 on:** March 07, 2013, 02:27:57 am »

ive checked the voltage at 3000 rpm - it hit 14,2 so that one seems ok.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #9 on:** March 07, 2013, 01:00:40 pm »

Quote from: fr33man on March 07, 2013, 02:27:57 am

ive checked the voltage at 3000 rpm - it hit 14,2 so that one seems ok.

If you have 14.2V at the battery at 3000rpm then I don't know why it won't 'hold' a charge unless there is an unswitched drain on it or the battery is bad??

fr33man · « **Reply #10 on:** March 10, 2013, 10:02:45 am »

ive checked my regulator - black was a little bit under battery voltage - white was about 1 v under

ive checked the rectifier - all diodes seems good

ive checked the stator - all yellow showed below 2 ohms - wich i think should be ok

ive cleaned a lot of connectors here and there - also the one from - on the battery down to the frame wich was a little dirty -

replaced the broken ignition coil and got it running on all four - havent checked if i still have the battery drain - but at least i havent found anything that seemed wront ..

Jerry Rxman Griffin aka MuthaF'er · « **Reply #11 on:** March 10, 2013, 11:44:55 am »

What about your ignition switch?

fr33man · « **Reply #12 on:** March 10, 2013, 01:16:00 pm »

sorry for being dumb - but how do i test it? =))

Jerry Rxman Griffin aka MuthaF'er · « **Reply #13 on:** March 10, 2013, 05:50:22 pm »

I was afraid you were going to ask that

I went through my #$%*ty system but never did an actual test on the switch. I managed to find a new one/set for my restore and replaced so much in the system I wouldn't be able to say which actually caused what. Voltage in and voltage out in the different key positions is best I can advise. Let's get one of the other guys to chime in on this. Can you post up a picture of the base connector of your's? The base is the only 'electrical' part of the switch. The very early ones do not have replacement bases while the later ones do. If your's is the later variety I'd recommend getting a replacement base (cheap) and I can ID it for you. I need to see a picture from the side so I can see where the base connects to the aluminum body. I have both.

scottly · « **Reply #14 on:** March 10, 2013, 08:49:05 pm »

Quote from: fr33man on March 10, 2013, 10:02:45 am

ive checked my regulator - black was a little bit under battery voltage - white was about 1 v under

If the black regulator terminal was within .5V of the battery, it would rule out the ignition switch. The voltage drop from the black to white should be very little.

Put the black meter lead on the white, and the red meter lead on the black, turn the ignition switch on, motor not running, and measure the voltage.

fr33man · « **Reply #15 on:** March 16, 2013, 12:12:39 pm »

Update.. ü

Its running smoothly, it passed the check and I got my licenceplate.. haven't had any problems with drained battery and was running 190 km/h on the autoroute.. I'm happy and ready for a cafe conversion

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Jerry Rxman Griffin aka MuthaF'er · « **Reply #16 on:** March 16, 2013, 12:18:11 pm »

What has been the problem with it??

fr33man · « **Reply #17 on:** March 16, 2013, 01:17:39 pm »

It drained the battery while running but still giving good voltage while reving up but would die even after 15 km on highway and be so low on battery that the horn wouldn't make any noice

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Jerry Rxman Griffin aka MuthaF'er · « **Reply #18 on:** March 16, 2013, 04:21:44 pm »

Understood that but did you find the reason? Bad battery?

fr33man · « **Reply #19 on:** March 18, 2013, 11:06:49 pm »

Think it was the #$%*ty Ground connection

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74750k4 · « **Reply #20 on:** March 19, 2013, 10:09:18 am »

That would definitely do it. No matter if you have a resident field coil of 7.2 ohms resistance!

if it never hits ground, no current will flow through it.

fr33man · « **Reply #21 on:** March 19, 2013, 11:06:30 pm »

Was wondering IF i should give all connections some white lithium grease to prevent corrosion in the future or is it not normally an issue?

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Jerry Rxman Griffin aka MuthaF'er · « **Reply #22 on:** March 20, 2013, 11:16:44 am »

It is a good idea to clean, tighten and grease them. Each one is a potential voltage drop. Multiply that by 100

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Author Topic: battery drain on my cb 750 f1 (Read 1684 times)