jump starting bike with cables
#11
10-09-2010, 07:01 PM
A pissing match
OK, before this digresses to a pissing contest...
William, you may be dead nuts on target with what you're saying.
Hold that thought...
When I was in college, I had an electrical engineer roommate who was off the chart brilliant; one of those in the top 2 of his class, graduated, taught at a nuclear power base for the navy in Florida, blah, blah. He and I were like Felix and Oscar, but aside from our lifestyles and differences in problem solving, we were a damn good team. He would give me the Stephen Hawking explanation of how things work, and I would give him the functional-experiential explanation. He saw the sky as colorless, but seemingly blue only because of the refractive wavelength of how our optometric cones perceive it.............you get the idea.
To me, the friggin sky is blue. Grass is green.
However wrong or disfunctional my perception may be, I can give you a very working (albeit "confused"..ahem) explanation of what "seems" to happen. I am not Stephen Hawking. Take everything I say with a healthy dose of disbelief, if you choose.
However, what I KNOW, is that if you leave your bike battery connected to a smart charger over the winter, you're GONNA be buying a new battery come spring. If you connect your bike battery to a 12 volt source that has significant amperage, you're gonna toast your little bike starting friend. I have the dead batteries in my garage to prove it! We seem to ALL agree: Don't cross your wires!
William, thanks for reminding me of my roommate.
William, you may be dead nuts on target with what you're saying.
Hold that thought...
When I was in college, I had an electrical engineer roommate who was off the chart brilliant; one of those in the top 2 of his class, graduated, taught at a nuclear power base for the navy in Florida, blah, blah. He and I were like Felix and Oscar, but aside from our lifestyles and differences in problem solving, we were a damn good team. He would give me the Stephen Hawking explanation of how things work, and I would give him the functional-experiential explanation. He saw the sky as colorless, but seemingly blue only because of the refractive wavelength of how our optometric cones perceive it.............you get the idea.
To me, the friggin sky is blue. Grass is green.
However wrong or disfunctional my perception may be, I can give you a very working (albeit "confused"..ahem) explanation of what "seems" to happen. I am not Stephen Hawking. Take everything I say with a healthy dose of disbelief, if you choose.
However, what I KNOW, is that if you leave your bike battery connected to a smart charger over the winter, you're GONNA be buying a new battery come spring. If you connect your bike battery to a 12 volt source that has significant amperage, you're gonna toast your little bike starting friend. I have the dead batteries in my garage to prove it! We seem to ALL agree: Don't cross your wires!
William, thanks for reminding me of my roommate.
Last edited by jeffzx9; 10-09-2010 at 07:02 PM. Reason: Ooops; Freudian slip. Nuclear POWER base, not nuclear POSER base.
#12
10-11-2010, 08:45 AM
Actually I'm a professional electrical and electronic engineer with over 40 years post-graduate experience. I spent about 30 years working on big mainframe computers, including motor alternator back up supplies, and later I worked a lot on UPS systems for server racks.
As you know, these are big back up batteries with integrated chargers and by-pass filters. That gives me a certain amount of professional knowledge about batteries and chargers. The UPS batteries - ordinary 12V lead acid batteries - are permanently connected to their chargers for their entire life.
You're still talking bollocks when you talk about 12V chargers with significant amperage - or perhaps I'm being pedantic about the terminology. The amperage delivered by a charger is a function of the voltage and the battery resistance. As a battery attached to a charger charges up, its internal resistance increases and the amperage as you call it (the current) falls. A 20A charger does not deliver 20A apart from for a very short time on a totally flat battery. And nobody would select a 20A rate for a bike battery - would they?
You can only overcharge by applying too high a voltage which maintains a too high high level of current. Battery chargers don't work like that. It's true that too much current will toast a battery, but that won't happen from any intelligent domestic charger. It can, very rarely, happen with a cheapo 'boost' charger if used incorrectly though. The more usual cause of overcharging of bike batteries is failure of the regulator, allowing the charging voltage to rise over 15V. At that voltage the circuit will push too much current through. It's a bit worrying that Kawasaki seem to think that 15.2V is fine. In my view that's a bit marginal. 14.8v is better as a maximum, and around 13.6 as a sustained charging voltage.
If you're worried about whether your home charger might damage your battery, measure the voltage with the charger connected when the battery is charged. If it's less than about 13.6V it won't do much harm, although again it's not good practice to leave it connected unless it's a type that's designed for long term connection.
A cheapo car charger with a 'boost' setting might deliver higher voltage to boost the current and quick charge the battery. 20A or 50A are common 'boost' settings. That setting shouldn't be used for more than about half an hour at most with a car battery and shouldn't be used at all with a bike battery. I suspect that your experience of cooking batteries is with these cheap chargers, many of which can't be trusted to supply the correct level of voltage.
Optimates and the like are designed to monitor the battery voltage and shut off completely when a particular level is reached. As the battery self discharges over time they cut back in as required to maintain that level. I'm against leaving them connected to a battery on the bike as a matter of good practice, but they are safe enough. They won't harm the battery.
Last point. Apart from the deep cycle batteries on the boat I don't regularly use any kind of charger at home. My wife does a lot of short journeys in her car and needs a quick boost charge maybe once or twice a year. My car and bike are very rarely fired up for anything less than a 20 mile round trip and the batteries never need to be charged or replaced. I last replaced a car battery in 1983, and last replaced a bike battery in 1969. My last car I kept for 7 years. It's now 9 years old, being used by my son in law, on the original battery. My record for a bike battery was about 6 years before I sold the bike. The current one is 3 1/2 years old.
I do have a 120AH deep cycle battery in the garage that I use to power my electric impact wrench. That gets a 6 hour trickle charge once a month unless it's been used and needs a proper charge. With a cheapo battery charger on the 1A setting it draws around 800 mA initially, dropping quickly to about 150mA. I'd be quite happy to leave it permanently attached to the same sort of charger that we have on the boat, except for one thing. Intelligent chargers do consume mains electricity, even when the battery that they're connected to is fully charged and the charger is dormant. Left connected for a full year, as some people do, they'll add £20 - £30 to a year's domestic electricity costs. That's a reason for not using them that I can understand.
Sorry to go on a bit about this, but people must understand the very basic relationship between voltage, resistance, current and capacity to have a real practical appreciation of the external issues affecting battery life.
Rob
As you know, these are big back up batteries with integrated chargers and by-pass filters. That gives me a certain amount of professional knowledge about batteries and chargers. The UPS batteries - ordinary 12V lead acid batteries - are permanently connected to their chargers for their entire life.
You're still talking bollocks when you talk about 12V chargers with significant amperage - or perhaps I'm being pedantic about the terminology. The amperage delivered by a charger is a function of the voltage and the battery resistance. As a battery attached to a charger charges up, its internal resistance increases and the amperage as you call it (the current) falls. A 20A charger does not deliver 20A apart from for a very short time on a totally flat battery. And nobody would select a 20A rate for a bike battery - would they?
You can only overcharge by applying too high a voltage which maintains a too high high level of current. Battery chargers don't work like that. It's true that too much current will toast a battery, but that won't happen from any intelligent domestic charger. It can, very rarely, happen with a cheapo 'boost' charger if used incorrectly though. The more usual cause of overcharging of bike batteries is failure of the regulator, allowing the charging voltage to rise over 15V. At that voltage the circuit will push too much current through. It's a bit worrying that Kawasaki seem to think that 15.2V is fine. In my view that's a bit marginal. 14.8v is better as a maximum, and around 13.6 as a sustained charging voltage.
If you're worried about whether your home charger might damage your battery, measure the voltage with the charger connected when the battery is charged. If it's less than about 13.6V it won't do much harm, although again it's not good practice to leave it connected unless it's a type that's designed for long term connection.
A cheapo car charger with a 'boost' setting might deliver higher voltage to boost the current and quick charge the battery. 20A or 50A are common 'boost' settings. That setting shouldn't be used for more than about half an hour at most with a car battery and shouldn't be used at all with a bike battery. I suspect that your experience of cooking batteries is with these cheap chargers, many of which can't be trusted to supply the correct level of voltage.
Optimates and the like are designed to monitor the battery voltage and shut off completely when a particular level is reached. As the battery self discharges over time they cut back in as required to maintain that level. I'm against leaving them connected to a battery on the bike as a matter of good practice, but they are safe enough. They won't harm the battery.
Last point. Apart from the deep cycle batteries on the boat I don't regularly use any kind of charger at home. My wife does a lot of short journeys in her car and needs a quick boost charge maybe once or twice a year. My car and bike are very rarely fired up for anything less than a 20 mile round trip and the batteries never need to be charged or replaced. I last replaced a car battery in 1983, and last replaced a bike battery in 1969. My last car I kept for 7 years. It's now 9 years old, being used by my son in law, on the original battery. My record for a bike battery was about 6 years before I sold the bike. The current one is 3 1/2 years old.
I do have a 120AH deep cycle battery in the garage that I use to power my electric impact wrench. That gets a 6 hour trickle charge once a month unless it's been used and needs a proper charge. With a cheapo battery charger on the 1A setting it draws around 800 mA initially, dropping quickly to about 150mA. I'd be quite happy to leave it permanently attached to the same sort of charger that we have on the boat, except for one thing. Intelligent chargers do consume mains electricity, even when the battery that they're connected to is fully charged and the charger is dormant. Left connected for a full year, as some people do, they'll add £20 - £30 to a year's domestic electricity costs. That's a reason for not using them that I can understand.
Sorry to go on a bit about this, but people must understand the very basic relationship between voltage, resistance, current and capacity to have a real practical appreciation of the external issues affecting battery life.
Rob
Last edited by williamr; 10-11-2010 at 09:10 AM.
#13
10-12-2010, 10:11 PM
It's a bit worrying that Kawasaki seem to think that 15.2V is fine. In my view that's a bit marginal. 14.8v is better as a maximum
#14
10-13-2010, 07:29 AM
I fully agree with that post.
having expounded at length about the reasons why it's safe to keep an Optimate connected, I don't use one and feel uncomfortable with one - prejudice from the days of cheap inconsistent chargers and high maintenance batteries probably.
My bikes and cars are never connected to a charger and never have batteries replaced. They're just used regularly.
Rob
having expounded at length about the reasons why it's safe to keep an Optimate connected, I don't use one and feel uncomfortable with one - prejudice from the days of cheap inconsistent chargers and high maintenance batteries probably.
My bikes and cars are never connected to a charger and never have batteries replaced. They're just used regularly.
Rob
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