Battery recharge

Hi,

I have a Honda CBR 125 (16 plate).

I accidentally forgot to turn off the bike with the remote and drained battery.

Luckily someone helped me push start it.

I'm just wondering running the engine how long would it take for the battery to fully recharge?

You're better off using a trickle charger if you want to bring it back up to full capacity. Otherwise give it a good long ride - but it won't fully charge it.

...but it won't fully charge it.

Why do you say that?

...but it won't fully charge it.

 

Why do you say that?

Most charging systems on modern engines never fully charge the battery to maximum capacity. The old dynamo systems used to which is why people assume that running an engine fully charges a battery. They replace a certain level of charge but if you measure the electrolyte it shows below full capacity even after a long run. If a battery is flattened it's better to bring it back to full capacity using a trickle charger, then the charging system will maintain it at that state of charge.

...but it won't fully charge it.

 

Why do you say that?

 

Most charging systems on modern engines never fully charge the battery to maximum capacity. The old dynamo systems used to which is why people assume that running an engine fully charges a battery. They replace a certain level of charge but if you measure the electrolyte it shows below full capacity even after a long run. If a battery is flattened it's better to bring it back to full capacity using a trickle charger, then the charging system will maintain it at that state of charge.

Didn't we have this debate a while back?

Why do you say that?

 

Most charging systems on modern engines never fully charge the battery to maximum capacity. The old dynamo systems used to which is why people assume that running an engine fully charges a battery. They replace a certain level of charge but if you measure the electrolyte it shows below full capacity even after a long run. If a battery is flattened it's better to bring it back to full capacity using a trickle charger, then the charging system will maintain it at that state of charge.

Didn't we have this debate a while back?

I have read conflicting evidence!

I am yet to see any hard evidence that a battery will charge or will not!

I was only answering the question, not trying to start a debate. As I've said elsewhere there's a simple way to show this effect. Take flat battery, stick it in the bike a ride say 50 miles. Then measure the electrolyte specific gravity.

Then flatten the battery and charge it overnight with a trickle charger. Then measure the specific gravity.

I've always found the trickle charger gets the battery to a higher capacity than the charging system on the bike. ( Same is true of cars fitted with alternators .)

The point I was suggesting to the OP is that if his battery is flat it's better to recharge it using a charger than simply letting the bike idle for period.

idling is no good, at idle my bike puts out 13v-14v, at optimum cruising revs voltage can go up to 16v. Hence why my lights flicker at traffic lights.

So what does a trickle charger do differently that the bikes onboard charging electronics doesn't do?

Ive measured my optimate taking the voltage upto 20v sometimes on really flat batteries which a bikes charge circuit would never do, but do trickle chargers give an extra voltage kick to already full batteries??

So what does a trickle charger do differently that the bikes onboard charging electronics doesn't do?

Ive measured my optimate taking the voltage upto 20v sometimes on really flat batteries which a bikes charge circuit would never do, but do trickle chargers give an extra voltage kick to already full batteries??

There's a variety of answers depending on the state of the battery and the type of charger used. I still check batteries using the old fashioned measurement of the specific gravity of the electrolyte. The latest sealed types of battery prevent this of course but all my batteries are older ones anyway (the one on my bench this morning is 26 years old). Measuring the SG really tells you where a battery is up to in a state of charge capacity.

The on board charging system is designed to keep a battery that is fully charged at that capacity, and it does it very well so you can ride for ages and never need to re-charge the battery off the bike. Since it starts every time you assume the battery is at max capacity - but if you measure the SG of many batteries that work perfectly well they are not at full capacity. Over time they drop a bit but it never causes an issue. It is only when you leave the lights or grips on an flatten it that you get an issue. The charging system will put some charge in but the system is designed to top up a fully charged battery - not fully re-charge a flat one. The regulator design is such that the charge level tails off before the battery is at max capacity.

The classic situation is the car left at the airport during a holiday. It won't start when the owner flies back so they get a jump start off the AA. Then they drive 150 miles home and think the battery is fully charged - next morning the car won't start so they buy a new battery. What annoys me is how many breakdown guys jump start cars and never tell the owner that they need to trickle charge the battery. (This literally happened to one of neighbours last week by the way - he now owns a nice shiny new charger.)

Note that the old dynamo systems will fully recharge a flat battery which is why the habit was formed of going for a long run to recharge a flat battery. (And which some breakdown guys still think it true.)

A trickle charger will keep supplying a charging current up to the max capacity of the battery. It's not an extra voltage kick - it just keeps charging past the point where the onboard system stops supplying a charge current. The bloke who taught me said think of it like this - your onboard system is designed to replace the starting charge, not fully charge the battery.

You also mention really flat batteries - onboard systems and many trickle chargers won't touch a battery that has dropped charge to the point where the overall voltage goes below something like 11 - 11.5v. When that happens you need to raise the voltage by supplying a tiny 'priming' charge - ie in milliamps. Your 'intelligent' chargers will recognise this and lower the input to around 500Ma until the battery reaches 12v again. Then you can start the bulk charge. A much cheaper alternative is a simple plug in gell cell charger. I use a 400Ma unit to resurrect batteries people throw away because they won't take a charge off their usual trickle charger.

I get a lot of elderly people who don't drive over the winter. Come spring the car won't start. A family member or a mobile mechanic comes out - tries to charge the battery which won't take a charge - so they buy a new battery. I use the 400Ma charger on the battery and a few hours later it's connected to the bulk charger and gives years of service afterwards.

Sparky stuff.

I tell you what MB, my zx6r battery has just given up the ghost and it's about a year old.

I'm going to try your method and if it works we'll crown you king of batteries. If it doesn't then we won't.

ZX6R batteries are rubbish, I had to replace mine after a few months on a new bike. After it had been flat it wouldn't hold a charge. It was in 2001 so can't remember what I charged it on. Bought an optimate 3 after and never had a problem since.

Sparky stuff.

 

I tell you what MB, my zx6r battery has just given up the ghost and it's about a year old.

I'm going to try your method and if it works we'll crown you king of batteries. If it doesn't then we won't.

Nope - just call me that tight fisted old git who is too mean to spend money on batteries.

The on board charging system is designed to keep a battery that is fully charged at that capacity, and it does it very well so you can ride for ages and never need to re-charge the battery off the bike. Since it starts every time you assume the battery is at max capacity - but if you measure the SG of many batteries that work perfectly well they are not at full capacity. Over time they drop a bit but it never causes an issue. It is only when you leave the lights or grips on an flatten it that you get an issue. The charging system will put some charge in but the system is designed to top up a fully charged battery - not fully re-charge a flat one. The regulator design is such that the charge level tails off before the battery is at max capacity.

 

Can you explain this bit for me? Is that not an issue regardless of the voltage the battery is being charged from? I'm not questioning you, I just don't understand .

The on board charging system is designed to keep a battery that is fully charged at that capacity, and it does it very well so you can ride for ages and never need to re-charge the battery off the bike. Since it starts every time you assume the battery is at max capacity - but if you measure the SG of many batteries that work perfectly well they are not at full capacity. Over time they drop a bit but it never causes an issue. It is only when you leave the lights or grips on an flatten it that you get an issue. The charging system will put some charge in but the system is designed to top up a fully charged battery - not fully re-charge a flat one. The regulator design is such that the charge level tails off before the battery is at max capacity.

 

 

Can you explain this bit for me? Is that not an issue regardless of the voltage the battery is being charged from? I'm not questioning you, I just don't understand .

When you hit the starter button the energy needed to fire the engine comes from the battery. Once the engine is running the electrical supply for the bike comes from the alternator. The battery acts to smooth the current flow - so for example if you've ever ridden with a nearly dead battery you can sometimes see the lights brighten and dim slightly with engine speed. That's because the power is coming from the alternator without the battery being able to smooth it out. (Which is pretty irrelevant to be honest but hey ho.)

As well as providing the electrical energy needed to run the bike, lights, heated grips etc the alternator also has to recharge the battery to replace the starting charge. The alternator puts out around 14v (usually 14.4v) which is why the voltage across the battery with the engine running is 14v. That 14volts remains a constant. What varies is that the alternator will repond to load rather than actually charge. eg on a car the alternator will do more work as you switch on more electrical gadgets. If you switch on the heated screens at idle you'll often hear the engine rpm drop slightly as the alternator responds to the new load. It's the load that varies, not the voltage.

So within the first 10 minutes or so the alternator will replace the starting charge drawn from the battery - it will then read the battery voltage as having risen to what's sometimes referred to as the floating voltage, just under 14v. At that stage it will stop charging the battery. So it can keep a healthy battery topped up, but it won't fully charge a flat battery.

In fact alternator manufacturers often put a warning on the box telling people to trickle charge the battery before they fit a new alternator. Fitting a new alternator to a vehicle where the battery has been allowed to go flat can kill the new alternator pretty quickly. (eg https://www.optimabatteries.com/en-us/experience/2012/08/fact-alternators-are-not-designed-charge-dead-batteries)

So the rule of thumb is that the onboard charging system can keep a healthy battery topped up, but it won't recharge a discharged battery. Hence a regular routine of trickle charging protects both the battery and the charging system.

The on board charging system is designed to keep a battery that is fully charged at that capacity, and it does it very well so you can ride for ages and never need to re-charge the battery off the bike. Since it starts every time you assume the battery is at max capacity - but if you measure the SG of many batteries that work perfectly well they are not at full capacity. Over time they drop a bit but it never causes an issue. It is only when you leave the lights or grips on an flatten it that you get an issue. The charging system will put some charge in but the system is designed to top up a fully charged battery - not fully re-charge a flat one. The regulator design is such that the charge level tails off before the battery is at max capacity.

 

 

Thanks for that

Can you explain this bit for me? Is that not an issue regardless of the voltage the battery is being charged from? I'm not questioning you, I just don't understand .

 

When you hit the starter button the energy needed to fire the engine comes from the battery. Once the engine is running the electrical supply for the bike comes from the alternator. The battery acts to smooth the current flow - so for example if you've ever ridden with a nearly dead battery you can sometimes see the lights brighten and dim slightly with engine speed. That's because the power is coming from the alternator without the battery being able to smooth it out. (Which is pretty irrelevant to be honest but hey ho.)

As well as providing the electrical energy needed to run the bike, lights, heated grips etc the alternator also has to recharge the battery to replace the starting charge. The alternator puts out around 14v (usually 14.4v) which is why the voltage across the battery with the engine running is 14v. That 14volts remains a constant. What varies is that the alternator will repond to load rather than actually charge. eg on a car the alternator will do more work as you switch on more electrical gadgets. If you switch on the heated screens at idle you'll often hear the engine rpm drop slightly as the alternator responds to the new load. It's the load that varies, not the voltage.

So within the first 10 minutes or so the alternator will replace the starting charge drawn from the battery - it will then read the battery voltage as having risen to what's sometimes referred to as the floating voltage, just under 14v. At that stage it will stop charging the battery. So it can keep a healthy battery topped up, but it won't fully charge a flat battery.

In fact alternator manufacturers often put a warning on the box telling people to trickle charge the battery before they fit a new alternator. Fitting a new alternator to a vehicle where the battery has been allowed to go flat can kill the new alternator pretty quickly. (eg https://www.optimabatteries.com/en-us/experience/2012/08/fact-alternators-are-not-designed-charge-dead-batteries)

So the rule of thumb is that the onboard charging system can keep a healthy battery topped up, but it won't recharge a discharged battery. Hence a regular routine of trickle charging protects both the battery and the charging system.

I'm converted, my bike has been using a solar trickle charger for the past month. It now holds a charge when I go out and I get more than one chance of starting it up before the battery gives up I didn't quite understand everything you said, but will be trickle charging new batteries from now before use.

I don't see this argument.

Any bike built in the last 30 years will have an alternator and that delivers ample charge to fully charge a battery, the manufacturers of bikes and cars don't intend that we have to use a trickle charger. Imagine a car company advising that car owners have to trickle charge their car overnight or it wont work properly, sales would slump.

Manufacturers design electrical systems that don't need trickle chargers to operate satisfactorily and reliably.

As for draining a battery, this is the worst thing you can do, never drain a battery it drastically shortens its life. Only deep cycle batteries can be discharged without risk of damage. A car or bike battery is not to my knowledge a deep cycle battery they must have charge in them or they can be damaged when recharging, they are designed to simply have small discharges and top ups in normal use.

Could it be that for some riders, mistakenly in allowing their battery to discharge fully and then recharging it they have damaged it and it now wont fully charge on the bike so they have to use a trickle charger and the battery then appears to perform better with the trickle charger. The real reason the battery performs better with the trickle charger is that they have damaged the battery by fully discharging it.

I have never used or needed a trickle charger. Manufacturers know what they are doing. If the alternator and bike electrics were not up to the job they would be redesigned.

To answer the op question. If you can start the bike up, go on a ride for at least 30 minutes, don't spend that 30 minutes with the bike on a trickle charger and watching coronation street.

As for draining a battery, this is the worst thing you can do, never drain a battery it drastically shortens its life. Only deep cycle batteries can be discharged without risk of damage. A car or bike battery is not to my knowledge a deep cycle battery they must have charge in them or they can be damaged when recharging, they are designed to simply have small discharges and top ups in normal use.

AGM (Absorbed Glass Mat) Batteries... The most popular brand being Motobatt are as close to a deep discharge. (Deep cycle) battery as is possible to get. And are specifically designed to be used with a trickle or maintenance charger for extended periods, like a 6 month winter hiatus where the bike will have zero use, but it's still desirable to leave the alarm system fully armed.

AGM batteries also have a much lower inherent self discharge rate than wet flooded types. And, as a higher amp hour AGM , the MotoBatt battery can also discharge more deeply and recover repeatedly under vehicle alternator charge or through maintenance charging. A standard flooded cell battery is not capable of withstanding this type of cycling, without pre-mature failure.

I don't see this argument.

Any bike built in the last 30 years will have an alternator and that delivers ample charge to fully charge a battery, the manufacturers of bikes and cars don't intend that we have to use a trickle charger. Imagine a car company advising that car owners have to trickle charge their car overnight or it wont work properly, sales would slump.

Manufacturers design electrical systems that don't need trickle chargers to operate satisfactorily and reliably.

As for draining a battery, this is the worst thing you can do, never drain a battery it drastically shortens its life. Only deep cycle batteries can be discharged without risk of damage. A car or bike battery is not to my knowledge a deep cycle battery they must have charge in them or they can be damaged when recharging, they are designed to simply have small discharges and top ups in normal use.

Could it be that for some riders, mistakenly in allowing their battery to discharge fully and then recharging it they have damaged it and it now wont fully charge on the bike so they have to use a trickle charger and the battery then appears to perform better with the trickle charger. The real reason the battery performs better with the trickle charger is that they have damaged the battery by fully discharging it.

I have never used or needed a trickle charger. Manufacturers know what they are doing. If the alternator and bike electrics were not up to the job they would be redesigned.

To answer the op question. If you can start the bike up, go on a ride for at least 30 minutes, don't spend that 30 minutes with the bike on a trickle charger and watching coronation street.

Did you read the thread? We've got a battery/charging guru who seems to disagree...

Maybe it was a thing in the past (I have no idea), but as above it's not the done thing for modern batteries.

yep I did read the thread, I just happen to have worked for a major car company and I know the extreme lengths that manufacturers go to ensure the reliability and capability of all systems.

The design process of a car for example takes over 7 years and close to 100 million pounds investment. I was a member of a small four man team who took the company I worked for international at a cost of 11 billion pounds. I was responsible for designing the processes to build the assembly plants from green field to commissioned plant and I worked closely with all the design teams including the electrical design team.

The company I worked for employed over 5000 design engineers. They don't consciously under design systems ok maybe a trickle charger will charge a battery more than a vehicles electrical system will, that's for me not the question the question is does the electrical system sufficiently charge the battery for trouble free service and that in my opinion is a resounding yes.

I'm not saying the contributors who declare that a charger will push in more charge than the alternator will are wrong. I simply don't see that the extra charge is required. The alternator will simply charge the battery sufficiently with no external help needed in my opinion.

I agree with the above.

I don't have a automotive background but in power gen where I am now I have involvement with battery power storage, so I can comment on charge characteristics at least.

A lot of what MBF has said is correct. A trickle charger will in general more completely charge a battery than the charging system on your bike, as your bike will have been designed with a regulator that prevents overcharging so it will likely only charge the battery to around 90% total charge to prevent stressing the battery. The trickle charger has the intelligence to back down its power output so that the battery is fully charged.

Where I think there has been some misunderstanding is the idea that a charge system sees the pre-start voltage of a battery and only returns it to this point, thus requiring further charging by a trickle charger. This is at odds with my experience, when I left one my old Honda's lights on yapping to a mate for an hour it was too dead to fire.

I bump started and went on my way, about 20 minutes later at a fuel stop it really struggled to start and I bumped it again before riding it around for a couple of hours. I worried leaving the lights on was a red herring of a failed rec/reg, so measured with a multi-meter and over the next few rides the voltage returned above 14V and was stable there. And in general other cars/bikes I've had where the battery went low (and wasn't old/worn) have all been fine after a long drive to charge it. If you did short journeys this would worsen the situation as you wouldn't be replenishing the power used to start.

Car manufacturers don't invest millions to deliver the best possible machine for their customers. They invest to deliver a vehicle that will sell and survive the warranty period - after that any problems are a source of income for the industry. There are plenty of cases where mediocre quality components are used to save a few pennies when a better quality item would last much longer for very little additional cost.

Yes - modern alternators will keep a battery charged without the driver needing to use a trickle charger. That's not the point. Batteries these days are mainly sealed so very few people check the specific gravity of the electrolyte regularly. If they did they'd find 90% of the cars driving round have batteries running at only partial charge capacity. They are kept at a capacity that will start the car reliably so drivers never notice or worry - there's no need to. But the fact remains that alternators do not raise the battery capacity to 100%. They're not designed to. They're designed to provide sufficient starting charge and then take over the running of the car's power demands.

With bike batteries being smaller the difference between a partially charged battery and one at max capacity is more likely to be noticeable, especially on bikes that are not used daily. The growth in passive electronics - such as alarms - that use battery capacity whilst the bike is stored adds to the issue.

Battery voltage does not equal battery charge - a flat battery can still show 12+v. So if you've flattened the battery and bump started the bike the charging system will put some charge into the battery - all I am suggesting is that if you want to return the battery to full charge you need to use a trickle charger. There's no harm not doing so, the battery will hold a starting charge, it's just not going to be at full capacity. You may never notice - that's fine. But personally I like to keep batteries fully charged for those times when you really need all the juice they can provide.

I walked into that one didn't I - DOH. Must have been itching to tell us your CV.

[mention]Mississippi Bullfrog[/mention]

I'm with what you're saying now. Before I thought you were saying that a charge circuit only returns the battery to a pre-start state, even if that is a low state. When the case is the battery returns to a pre-determined point (say 80-90%) total charge, and can be topped up with a trickle charger.

I'm not sure manufacturers invest in getting things through *just* the warranty period though. Yes it's important, but reliability is important to a brand, which they want to maintain to secure more sales. More often good designs are let down by cost cutting on components.