Start bike when cold

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pitintheuk
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Start bike when cold

#1 Post by pitintheuk » Mon Jun 19, 2017 12:00 pm

For about 2 years, my CBF600, when starting cold in the morning, struggles a bit sometimes = would takes 2-3 tries before it starts. I thought that might be old spark plugs responsible, which I changed 2 days ago... and still exactly the same issue. Thus is not the spark plugs. Also if it does anything I had a year ago the carburators aligned, which also did not have any impact on the start issue. I just did a oil and filter change, still nothing different.

I am wondering... before I take it into the garage. If someone would have an idea?

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Re: Start bike when cold

#2 Post by Mississippi Bullfrog » Mon Jun 19, 2017 4:57 pm

Is the battery fully charged? A weak battery will cause slower starting.

Remember that the charging system on most modern bikes does not bring the battery up to full capacity even on a long ride. They only replace the charge used to start the bike. (Old dynamo systems on cars did fully charge batteries which is why people think a long run will fully charge a battery.) I find I need to give mine a routine top up charge to keep the battery at peak level or it tends to drop to the point where first thing in the morning takes a couple of cranks before it fires up.

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Re: Start bike when cold

#3 Post by Mr Fro » Mon Jun 19, 2017 6:43 pm

Mississippi Bullfrog wrote:
Mon Jun 19, 2017 4:57 pm
IRemember that the charging system on most modern bikes does not bring the battery up to full capacity even on a long ride. They only replace the charge used to start the bike.
Have you got any reference for that statement?

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Re: Start bike when cold

#4 Post by Mississippi Bullfrog » Mon Jun 19, 2017 10:30 pm

Years of working on classic and modern cars. There was an article on the subject in one of the journals a while back but it would take a while to reference.

Over the years I have acquired dozens of batteries from cars which people have jump started, driven a fair distance, then found the car still won't start, so they assume the battery is dud. Most of the time the just need a proper charge and they are good to go.

Classics fitted with dynamoes will fully charge a flat battery, alternators won't. The battery will still fire the engine but it won't be brought back to maximum capacity.

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Re: Start bike when cold

#5 Post by pitintheuk » Tue Jun 20, 2017 7:34 am

Hello and thanks for the suggestions.

I don't think it is the batterie because there is a 1 yo one in the bike, and the issue existed before, and continued after I changed it.

I need to MOT it, I will also ask to check the bike.

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Re: Start bike when cold

#6 Post by Mr Fro » Tue Jun 20, 2017 8:01 am

@@Mississippi Bullfrog - I'd like to have a shufti if you could dig that out at some point.

The system will (should) just plonk charge in to a battery until it reaches an equilibrium point. My understanding is that alternators are favoured as they are more efficient/reliable than a dynamo.

Alternators replacing only what is used during the starting procedure would require them to "know" the state of charge of the battery prior to starting.

It may be that a quality charger will recover more charge in a flat battery mind you (remember when you had to keep an eye on them and switch them off when the battery started to boil :-)).

@@pitintheuk - sorry for the hijack!

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Re: Start bike when cold

#7 Post by Mississippi Bullfrog » Tue Jun 20, 2017 9:33 am

Mr Fro wrote:
Tue Jun 20, 2017 8:01 am
@@Mississippi Bullfrog - I'd like to have a shufti if you could dig that out at some point.

The system will (should) just plonk charge in to a battery until it reaches an equilibrium point. My understanding is that alternators are favoured as they are more efficient/reliable than a dynamo.

Alternators replacing only what is used during the starting procedure would require them to "know" the state of charge of the battery prior to starting.

It may be that a quality charger will recover more charge in a flat battery mind you (remember when you had to keep an eye on them and switch them off when the battery started to boil :-)).

@@pitintheuk - sorry for the hijack!
Given the number of journals on my shelves that will take some considerable time. If I can find it I'll try but no promises. It's pretty well recognised is most classic car circles as we tend to notice the difference between dynamos and alternators, most folks who have only dealt with modern stuff don't realise the difference. But if you can access a car fitted with a dynamo it's easy to demonstrate. Take a battery, run a bulb on it until it's dead, fit it to the car and jump start it. Drive it 100 miles and measure the electrolyte in the battery. Do the same with a car fitted with an alternator. The specific gravity will be different.

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Re: Start bike when cold

#8 Post by Mr Fro » Tue Jun 20, 2017 12:12 pm

Mississippi Bullfrog wrote:
Tue Jun 20, 2017 9:33 am
Given the number of journals on my shelves that will take some considerable time. If I can find it I'll try but no promises. It's pretty well recognised is most classic car circles as we tend to notice the difference between dynamos and alternators, most folks who have only dealt with modern stuff don't realise the difference. But if you can access a car fitted with a dynamo it's easy to demonstrate. Take a battery, run a bulb on it until it's dead, fit it to the car and jump start it. Drive it 100 miles and measure the electrolyte in the battery. Do the same with a car fitted with an alternator. The specific gravity will be different.
Just if you happen to come across it - would be interesting to see.

If you measure the electrolyte/voltage of two different systems then different results should be expected.

A dynamo outputs DC - alternator outputs AC which is converted to DC via the reg-rec. How is one DC preferable to another DC?

If we're talking charge state after x period of time then the differentiating factor is charge rate, surely.

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Re: Start bike when cold

#9 Post by Mississippi Bullfrog » Tue Jun 20, 2017 10:07 pm

Not the article I was thinking of but along the same lines..... The bit it doesn't cover it what happens when a battery is not brand new and doesn't perform in peak condition. That's when bike batteries, which are not huge in the first place, can get a bit marginal on starting grunt. Assume a new battery is charged to 70-80% capacity then an older one could be well below that which is why I prefer to give the battery a very low amperage charge whilst the bike isn't being used. it raises the battery back to its maximum charge and I find I get much better starting.

Anyway - for what it's worth......

An alternator will not charge your battery fully.......It pays to look at the original engineering criteria of what the vehicle manufacture wanted to achieve.

FYI... A starting battery has only one goal in life and that's to supply enough energy to start the engine with in a given time frame of around 5 to 15 seconds.... after that it has very little more to do.

When they design a charging system for a vehicle there are many aspects to consider.... what climate is the vehicle going to be operating in.... what conditions is the vehicle going to be operating in.... how long is the vehicle going to be run.... how long is it going to be to start the vehicle.... what load is going to be placed on the battery when the vehicle is not running.... when will the vehicle be run again.... what type or manufacture of the battery is going to be used in the future.... what quality of battery is going to be used in the future.... is the battery going to be maintained correctly.... and what effect on fuel usage and emissions is it going to have.

As you can see there are many criteria the engineers have to deal with, and there are many different charge conditions that have to be addressed.

A vehicle charging system has two goals.... firstly it must supply amply current and voltage to run the vehicle and everything factory fitted under all conditions.... the second thing is to charge the battery enough to enable the vehicle to start the next time.

The second one is the hardest criteria to design with so many unknown variables to consider, there has to be a big variable in charging the battery to not undercharge it or to over charge it, this is where this "a vehicle battery will only charge to 70-80% SOC".... 70-80SOC is reconsigned as a safe limit for charging battery's under most conditions, it enables the vehicle to start quickly, gives OK battery life, has ample reserve and places less load on the charging system.

Hence "lets dump big current and volts into a battery for the shortest period so the battery can start the vehicle next time"

Most charging systems fitted to vehicles prior to 2001 are very dumb in what they can do and how the function.... think " I'm not very smart but I can lift big weights".

Around 2001 more and more vehicles started to appear with a smart charging systems where by an ECU with it's own map would process the information and only charge when really needed, modern day charging systems can control voltage, current and frequency..... the down side of this; seeing it was really designed for better fuel consumption, better emissions, more engine power and making the NVH of the vehicle better is they have lowered the SOC of the battery down to 60-70%.... most new vehicle have smart start technology making them start with in 5 seconds of cranking.

Most new vehicle have time driven auto disconnect of factory fitted electrical gear just in case something was left on like interior lights..... they don't have to headroom anymore to get away with it.

As for secondary battery's....... the engineers who designed the charging system had no interest in even thinking someone may add an aux battery..... with some manufactures you can spec an upgraded charging system designed to charge the starting battery more and also charge a secondary battery fully, GM do it in the USA and some of the commercial vehicle manufactures in Europe (ambulance and rescue vehicles) but to my knowledge this is not available to the general public.

As for your 8 amp charger charging it to 100% SOC..... yes they do because the battery charger manufacture know the fixed non variable conditions the battery will be charged under.

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