battery box - Page 2 - Honda Rebel Forum
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post #11 of 20 Old 11-07-2016, 04:24 PM
 
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Originally Posted by SoakedKarma View Post
can't speak to 125cc charge system but the rebel only puts out 0.9A Max charging current.
a slow charge compared to 2A charge current most phones and tablets now take..
I'd be interested in a further elaboration of this explanation, since my present understanding of the role of the regulator is strictly to limit the VOLTAGE appearing across the battery terminals by partially short circuiting the alternator windings as necessary. The short circuit does not result in the catastrophic result that might be expected from our usual experience of short circuits because of the limited power capability of the permanent magnet alternator. How exactly does the regulator understand the current going into the battery apart from the total current fed to the electrical system?

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post #12 of 20 Old 11-07-2016, 05:31 PM Thread Starter
 
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im glad you didnt ask me that question, i still use a bulb and two bits of wire for all my electric testing lol
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post #13 of 20 Old 11-07-2016, 11:00 PM
 
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I quoted the Honda published 0.9 Amp max current output spec
@Duckster my feeble understanding,,, Amperage or current is regulated by the state of charge of the battery. When battery voltage low, the electromotive force (battery charge) is not strong enough to hold back the current from the alternator trying to recharge the battery.
As the battery reaches a state of full charge, the electromotive force becomes strong enough to oppose the current flow from the alternator, the amperage output from the alternator will drop to close to zero, while the voltage will remain at 13.5 to 14.5. As battery electrical power is used, the electromotive force (voltage) will reduce and alternator amperage will increase.

overcharging/overheat thermal runaway seems to be cause of most Li-ion phone battery melt downs that I have heard about.. hoverboard melt downs seem to be result of cheep battery and circuit design..
@jim ray many a time have I used a length of wire and 1156 or 1157 bulb for testing..
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post #14 of 20 Old 11-08-2016, 06:24 AM
 
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Google helped me find out a little more about this class battery for motorcycles....
Lithium Ion Phosphate, not quite the same formula as explosive cellphone/hoverboard batteries
Integrated charge regulator hidden inside battery case to prevent overcharging...
Shipped at only 30% charge due to hazardous material laws and recommend a 0.75amp tender to fully charge before use.
Wide variety of price depending on what you desire to spend for Cold Cranking Amps (CCA) (juice for the first start), and spend on Amp Hours (AH) (how many times you can try to start before draining the battery).
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post #15 of 20 Old 11-08-2016, 07:32 AM
 
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Forgive me a moment while I put on my "Mr. Wizard" hat...
A Voltage Regulator is a sandwich of silicone & germanium and being semi-conductors has the unique property of shunting excess voltage above its design spec, 13.8v to 14.2v in the case of most car/motorcycle designs. So it's wired in to an alternator across the +/- poles, and stops the alternator from putting out more voltage when you rev the engine, by shorting the extra juice through itself. It doesn't care how much amps go down the line, just how many volts are across itself.
Lead + sulfuric acid + lead oxide = Lead Acid Battery: the acid eats the plates and produces 2v. When you daisy chain 6 of these cells together you get a 12v battery. Bigger plates allows more amps to be pulled out at once. Shoot extra electricity back into the battery and the chemistry goes backwards, the acid gives back the lead and lead oxide it ate, redepositing on the plates, like the way chrome electroplating works. This is why an ordinary battery life is shortened if drained dead too many times, the plates are deformed from being eaten/rebuilt over and over again.
Lead Acid batteries like being overcharged, it forms little bubbles of steam in the acid/water mix which stirs the acid and keeps the dissolved lead in the acid ready to go back on the plates and, once fully charged keeps the acid from eating the plates any more. This is also why you had to put distilled water back into your battery, to replace the lost steam. (maintenance free batteries are just thicker walled and sealed, trapping the steam and letting it condense back to water when it cools down later)
Lithium Ion batteries do not like being overcharged, they heat up, create gasses inside and splitting the case. Lithium, being an alkali metal, is very reactive and combusts explosively when exposed to oxygen (see Mythbusters). Lithium ion batteries need a 'smart charger' that turns itself down as it senses how charged the battery is, from aggressive charge to slow charge to trickle charge, automatically, based on how much juice the battery is sucking down.
The charging circuit in your cell phone is 'smart', which is why it seems to charge from 20% to 60% in mere minutes, but the last 99% to 100% seems to take hours.


A little google research shows that lithium ion batteries designed as a drop in replacement for lead-acid batteries include a smart charger inside the battery case so that you can use it on a 14.3v system without blowing the battery up.


sorry, I'll climb down from the podium now.....
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post #16 of 20 Old 11-08-2016, 09:22 AM
 
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Forgive me a moment while I put on my "Mr. Wizard" hat...
A Voltage Regulator is a sandwich of silicone & germanium and being semi-conductors has the unique property of shunting excess voltage above its design spec, 13.8v to 14.2v in the case of most car/motorcycle designs. So it's wired in to an alternator across the +/- poles, and stops the alternator from putting out more voltage when you rev the engine, by shorting the extra juice through itself. It doesn't care how much amps go down the line, just how many volts are across itself.
There is a huge difference between an automotive alternator and regulator and the permanent magnet type alternator found on the Rebel and other simple motorcycles. Automotive regulators adjust voltage output by adjusting the DC current in the field winding which produces a variable magnetic flux in the alternator magnetic circuit and thus a variable voltage output in response to the load on the system. Automotive regulators send a controlled field current into the alternator field winding to control output. This type of system is very flexible and can provide much better output control and a wider power range than is possible on a simple system like the Rebel's

A permanent magnet alternator has no field windings at all and a fixed magnetic flux created by permanent magnets in the rotor. It's output is inherently not controllable. The only way to prevent overvoltage on the battery once it is fully charged is to short circuit the windings of the alternator using voltage controlled SCR's (silicon controlled rectifiers) . The short circuit does not cause damage because the current output is limited by the fixed alternator field flux and the voltage can be dropped very low to limit the power and heat generated.

This is a comparatively crude regulating system that does not directly control output current of the alternator. It just shifts load to the battery on an intermittant basis to prevent overvoltage on the battery.

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post #17 of 20 Old 11-08-2016, 09:25 AM
 
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Lead Acid batteries like being overcharged, it forms little bubbles of steam in the acid/water mix which stirs the acid and keeps the dissolved lead in the acid ready to go back on the plates and, once fully charged keeps the acid from eating the plates any more.
You have the gist of the idea.. sulfur is transferred from the acid solution to the lead plates not lead..
a battery that has set for to long will form a sulfur crust on the negative sponge lead plate damaging battery.. Known as sulfation..

Overcharging known as boiling a lead acid battery causes the those little bubbles of steam to form within the sponge lead matrix of negative plate and actually blow pieces of lead and sulfur crust off plate if enough amps are applied.. even a Newly filled MC battery can be destroyed or at least life shortened if connected to 6-10 Amp charger for initial charge..

Lead sulfides and oxides blown or lost off plates collect at bottom of cell and can cause a cell to short out..

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post #18 of 20 Old 11-08-2016, 09:42 AM
 
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something I found in my wanderings some time back and had bookmarked.
Crank Amp Ratings for Lithium Batteries
and these guys will explain just about any question for many batteries.
http://batteryuniversity.com

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post #19 of 20 Old 11-08-2016, 12:44 PM Thread Starter
 
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well i now know where to come if my bulb and bit of wire aint solving the problem lol. some interesting reading and broadened my knowledge, cheers fellas
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post #20 of 20 Old 11-09-2016, 08:08 AM
 
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SoakedKarma and Duckster, yes I oversimplified the "quick intro to 12v electrics for non-scientists" lol
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