Topic: Some urgent electrical help needed!

[The Lone Builder]

I need some urgent advice, as I’m stuck about 350km from Addis Ababa with a flat battery and a charging system that has me stumped.

Changes to the stock electrics are: Hondaman ignition unit; electronic replacements for regulator and rectifier (from Horst on the German SOHC site); relays to save switches as per Hondaman; and an LED running light that is on all the time.

About 3 weeks ago bike wouldn’t start on electric starter; it worked OK on kick. I noticed that the headlight was switched on and had been all day while I tootled around in Kampala traffic at 0 kph which I reckoned could have run down the battery. I got the battery charged and all seemed well.

Until yesterday that is. It started Ok in the morning and ran well for about 60km. Then it started dying if the revs fell below 3000 rpm. Horn and flashers stopped working and then it died. Jump started it and it ran for about 1-2km and then died. Repeated this several times, trying to get to next town, before giving up. Battery removed and recharged.

It kept it’s charge till this morning and started fine on kick start. Ran fine for 40kms and then died. I put it on a truck and took it to the next town and set about checking the electrics thoroughly.

The battery voltage was 11.5 when I started. So why did the bike die? When I started teh bike with kick start, it ran well, but battery voltage dropped to +/- 7V and didn’t rise with revs; in fact it started to fall.

Checking components, these are the readings I got:

Alternator
Yellow to yellow - 0.6 Ohms - same for all 3 tests
Yellow to earth - no connection
Green to white - 7.2 Ohms
Green on the harness side is grounded.

Rectifier
All checked out with continuity in one direction and not in the other.

Regulator
Black wire shows battery voltage when ignition on and nil when off
Green to earth resistance 0.7 Ohms
White wire shows no voltage at all.
Voltage drop from battery +ve to black - 0
Voltage drop from battery -ve to green - 0

I connected white wire to regulator to battery +ve, leaving the green and black in place. Battery voltage didn’t change with rpm. Does this indicate alternator failure?

So it seems that each component is OK, but the battery is not charging! Why? Is the battery dead?

I know that I should be starting with a known good, fully charged battery, but getting a temporary replacement to test is difficult - they want you to buy one rather than lend one – and getting a new battery, with right spec even more so.

The battery is now being charged overnight, so any suggestions as to where I go form here will be a great help. Provided I can access them of course; govt keeps blocking the internet!

[69cb750]

Get a new battery, start engine, rev from 1000 rpm to 3500 rmp, use volt meter, battery voltage should go from 12.5 volt to 13.5 volts as engine revs.
No increase means bad alternator, regulator, rectifier.

[Honda3]

Its the reg/rec or Stator. You will need to determine which....

Sounds to me like your Reg/Rec.

[BenelliSEI]

Try a “low tech” load test. After charging the battery, use the starter motor. If the battery voltage drops quickly? Get a new one.

[PeWe]

No headlight on in city at daylight. 4000 rpm and more needed to keep voltage OK with headlight on

[Don R]

What he said, ^ sounds like a heat induced battery failure. 

[Patrick]

If your bike always runs when you get over 3,000 rpm, then your alternator is doing what it is supposed to by producing enough juice to run the bike. You are doing the wrong tests.

All of our bikes only produce enough juice to run the bike and charge the battery over 3,000 rpm. Below that, the battery is bolstering your electrical system. This juice is then replaced when you get over 3,000 rpm again. Do you lug the bike a lot? These engines are designed to sing, not hum. You also need to check the voltage being produced by your bike. A alternator with stock electrical system will produce 14.7 volts at 3,000 rpm. I understand some aftermarket regulators limit that tp 13.5 or so, but you need it to be that high.

With the system you described, assuming all components are operating correctly, I would look at the battery, if the voltage is getting to appropriate levels. For some reason you are not charging as you ride.

Patrick

[RAFster122s]

My bet is a cell is going bad or has gone bad and you are getting a surface charge that quickly craps out when load applied, thus repeated dying you experienced last. Once the battery gets too low you won't be able to sustain the motor running even when attempting to keep revs above 3k when a cell in the battery has gone south. Heat is very hard on batteries, as is extreme cold.
Won't be able to say if you have other problems until you have a good battery in the bike to test with... Sounds like your resistance and voltage tests are good, missing the voltage reading when reving the motor of course.

Ensure you don't have a parasitic loss in a ignition switch that is failing, especially if an Emgo switch. Test keyed voltage black wire for voltage when bike is turned off, key out... Should see 0v, if you see anything then you have an issue with the switch.

Best of luck sorting this out...
Sounds like you will be near Addis Ababa for a bit until you source a new battery.
Might be wise to monitor your battery voltage for a bit after replacing the battery with meter taped or tied to the handlebars. It can give you advanced warning before things get critical.

David

[jgger]

Sean, if you have a lead/acid battery you can check the cells one by one. Remove all the caps and put your black meter lead on the negative post. Then the positive ( red) lead dipped into the liquid in each cell . If you use a wire attached to the lead you won't damage the probe, and don't  touch the plates inside just the liquid. You should have a 2v.  reading on the 1st cell closest to the neg. post. This should go up by 2 volts the farther you get from the neg. post. 6 holes times 2 volts = 12 volts.

That may help........I hope.

BTW enjoying the journey vicariously, good luck.

[Henning]

Lots of good advice above and yes, it won't run properly at low revs if the battery is bad. Worst case just go and buy a car battery and strap it on the bike somewhere; it doesn't need the identical amp hour rating as the original. And if it's still not charging, you can top it up with electricity while you're topping it up with fuel. :-)

Well done on getting as far as Ethiopia! Where to next?

[scottly]

Black wire shows battery voltage when ignition on and nil when off
Green to earth resistance 0.7 Ohms
White wire shows no voltage at all.

The white wire should have near battery voltage when the ignition is on, but since you jumped the white to battery + with no change, there must be something else wrong. With the white wire disconnected from the reg, measure the resistance from the white wire to earth; it should be 7 ohms.
Also, measure the battery voltage after it is charged; if less than 12v with a fresh charge, the battery may have #$%* the bed.

[RAFster122s]

Black wire shows battery voltage when ignition on and nil when off
Green to earth resistance 0.7 Ohms
White wire shows no voltage at all.

The white wire should have near battery voltage when the ignition is on, but since you jumped the white to battery + with no change, there must be something else wrong. With the white wire disconnected from the reg, measure the resistance from the white wire to earth; it should be 7 ohms.
Also, measure the battery voltage after it is charged; if less than 12v with a fresh charge, the battery may have #$%* the bed.

Needs a couple hours after charge to settle, immediately after if it is less than 12V you definitely have a problem.  If a couple hours after charging you test it and it is still 12V or above then it may be OK, but load test will confirm. Problem is most load testers are designed for car and truck batteries, not our small capacity motorcycle batteries.


Hope you can get this sorted soon.


David

[scottly]

Black wire shows battery voltage when ignition on and nil when off
Green to earth resistance 0.7 Ohms
White wire shows no voltage at all.

The white wire should have near battery voltage when the ignition is on, but since you jumped the white to battery + with no change,

If the battery is good, it would take time to recharge, even with the field jumped. Check the output of the regulator at the white terminal with a charged battery.
David, the electric starter is a damn good load tester.

[The Lone Builder]

Thanks for the thoughts folks.

The battery is a Motobatt AGM one, so I don’t think any poss to check individual cells.
The running light is a 4W LED (https://www.ebay.co.uk/itm/T4W-233-BA9S-CREE-LED-SIDELIGHT-INTERIOR-CAN-BUS-OBC-ERROR-FREE-bulbs-E/230864353231?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

The reg and rectifier are individual items; Horst uses the original bodies and puts electronics into them. The regulator is supposed to give full charging current at 2000 rpm. (http://www.cbfourclub.de/boerse/750.htm)

I do have a voltage monitor fitted; (https://www.ebay.co.uk/itm/LED-Motorcycle-Battery-Alternator-Charge-monitor-level-indicator-warning-bike-G/200826330214?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649) It works well, but it’s one shortcoming is it is difficult to see in sunlight. It was flashing red at me yesterday, but I had no choice but to keep going to try to reach a town. It wasn’t much fun negotiating the slow traffic, the cows, goats, donkeys and people while keeping the revs up above 3000!!

Once I get the battery back this morning, I’ll check voltage and try the drop test. I’ll also check the ignition switch. I haven’t measured white to earth resistance but wil do so.

Scottie, I read in one of the troubleshooting docs. I have (can’t remember where I got it now) that the white wire should have battery voltage with the ignition off and the black wire 0V with ignition off and battery voltage with ignition on. I couldn’t quite understand this, but is it right?

As far as the trip goes, on this leg I’ve done about 7,500 km through 8 countries in just under 2 months. The first leg was 4,000 odd km and 4 countries, making 10 in total (been to two countries twice). From here (haha!) it’s up to Sudan and from there it depends on visas and will either be Saudi or Egypt to Jordan; Iran is off the cards for now due to their ban on bikes >250cc, though I did hear that has been lifted. Not quite up-to-date blog at belfast2belfastbybike.com

But that’s for tomorrow; it’s electrics day today. Will keep you posted.

[Spanner 1]

+1 on the battery only holding a 'surface' charge. I think the solid state reg/rect will not supply the White field coil wire with voltage if the battery is below discharge volts.  Discharge voltage for a 12v lead/acid battery is 11.6 v.  Might be time to get  new battery, especially when all your test numbers look correct  . Very best of luck with the rest of your journey ! How epic on a CB 750 !

[scottly]

Scottie, I read in one of the troubleshooting docs. I have (can’t remember where I got it now) that the white wire should have battery voltage with the ignition off

No, the white wire should have 12V only with the ignition on, just like the black wire: 12v in on the black and about 12v out on the white. It doesn't matter if the motor is running for this test. If zero volts on the white, the regulator isn't working. Dave500 in Australia has found a Bosch regulator that is compatible with our CBs, and it may also be available in Africa??

[Spanner 1]

Agree with Scottly, but the reg/rect may not pass voltage to the field coil ( White wire ) if the battery is discharged. The stock electro-mechanical regulator would pass whatever battery voltage is available but not produce a charge  as field energy too low. I still think you need a new battery.

[Spanner 1]

Use your Irish charm and get a loan of a 12ah or 14 ah battery from some biker in town and see if your bike now charges at 13.5v @ 3,000 rpm .

[The Lone Builder]

I’ll go check these out now - in the rain! 

Worst case just go and buy a car battery and strap it on the bike somewhere;

I was offered a car battery as a replacement, but not quite sure where I’d put it! 

Nobody here does anything for nothing; the guy who offered to lend me an old, and I mean old, car battery wanted a deposit of about $75 to make sure I brought it back. But you never know; I’m sure there’s a good soul out there. I just haven’t found him yet

[Spanner 1]

If that rec/rect claims to put out 'full charging '@ 2,000 rpm ( 14.5v ) then your alternator is super stressed as the stock reg. allows 14.5v @ 4,000 rpm. I don't know why folks throw away the 50 yr proven charging components for some new fangled microchip tech that will get fried by our 'old' charging system eventually as not designed for that . Sorry, that's no help in your situation but again you need to find or buy a battery or a loaner to actually test if the bike is charging .

[The Lone Builder]

I got the battery back and it was only reading 11.7V, so I put it back on the charger. Looking at the settings on the charger, I’m not sure he had them right, but maybe changed since he took my battery off.

Anyway after another 2 hours, it was reading 12.4v, so I decided that was enough to finish testing. I walked back and by the time I got there - about 30 mins - it had dropped to 12.1V.

Drop test with starter - it went down to about 10.8 and turned the motor. Only tried this once.

Resistance W to G at the alternator plug was 7.8 ohms; resistance W, at VReg, to earth was OL.

With ignition switch on I got battery voltage at W terminal.

I then ran the bike and voltage went up to about 12.8 at 5,000 rpm but no higher. At idle it dropped to 11.7 I think. Charging current peaked at about 3.5 amps with lights off.

I wasn’t very systematic I’m afraid, but I think from all this that it is the battery.

I’m now arranging, and might have just succeeded in getting bike and me a lift to Addis.

Watch this space.

[PeWe]

The LED voltage monitor is good info. Flashing red is too high voltage.

I had issues with a Honda CB750 regulator that suddenly lowered the voltage. The relay found a middle position. Road bump could get it right. I added a volt meter to supervise better.  Cheap on eBay and really useful. I know when it's time to save the juice even now with a good regulator.

[TwoTired]

A depleted battery will take quite a long time to restore from the bike.  The alternator /vreg does NOT dominate the system voltage.  The battery charge state does.

You do NOT want the battery to change voltage quickly, as that would indicate very high charge or discharge rates.  Its a reservoir, intended to drain and charge slowly.   But, you can watch for voltage trend info.  Trend higher, it's charging.  Trend lower, it is discharging.
The starter draws 25 amps or more out of the battery.  The charge system puts in 1-2 amps under full bike electrical load.  More if you turn loads off, of course.  Takes 10 to 25 times longer to charge than discharge under those conditions.

If the battery only fell to 10.8v during starter engagement, there is still hope for it. (depends on load duration.)   But, it doesn't seem like you are ever getting the battery to full charge.  It should have at least 12.6v after a 2 hour rest, off a fresh full charge.
The charging system is there to maintain the battery, not to charge it from total depletion.  For that you'd need to rev the motor over 3000 rpm for 10 hours.  It's math.  A 14 Amp hr battery will take 14+ hours to absorb 14 amps at a 1 amp charge rate.  While you can restore 50-70% at a faster charge rate, that last 10-20% must be done at a very low charge rate, lest the battery be overheated.  This is because chemical conversion is going on inside and the electrolyte kinda has to stir itself to reach all its contents.

Good luck!

[PeWe]

I have seen that it take rather long cruising time at 4000 rpm to get same voltage level as it was before a shorter city riding using brake and blinkers especially with headlight on that will need time to enter 13.5- 14V area.
This evening I saw voltage drop of 1.5 V with headlight on. 20 minutes at 4000 rpm needed to get 0.7V drop.

[scottly]

If the battery had enough juice to spin the electric starter, even in a run down state, it's probably OK.