Author Topic: Toss that Battery!  (Read 479 times)

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AzCal Retred

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Reply #15 on: March 24, 2021, 03:57:41 pm
 I can see that someone here is a candidate for a community college electricity/electronics course!

" I'm having a hard time understanding why a parallel cap would help prevent the regulator from overcharging the battery? "
It doesn't. It can't. I am having a hard time understanding why we're asking that question. The point I was making was that there is no harm & possibly some small benefit in pre-positioning a "Black Start" (dead battery situation) cap in the circuit, you would just need to pull one fuse to isolate the battery. I carefully explained that what comes out of the reg/rec has a small amount of ripple, the cap might dampen that. Again, no harm no foul.

"The data sheet for your Mallory 8900uF says its Equivalent Series Resistance rating is 0.034 ohm at 120 hz. and gives a multiplier rating for higher frequency of around 1.25 for frequencies in the range that would be produced by an engine turning at Bullet engine speeds coupled to a 3 coil alternator. "
A capacitor is an open circuit in a DC scheme. The min/max voltages tell you the useful operating levels and the level beyond which you can expect failure to occur. If you are talking frequency, you are talking impedance values. A capacitor is a "short circuit" in a AC scheme, it doesn't impede current flow but does displace it in time, changing the circuit power factor or providing other useful functions to the circuit designer. The only AC here is upstream of the reg/rec.

A battery is conductive in either AC or DC circuits. It isn't a capacitor, it's a chemical power source.

" I'm thinking that the fuel pump draw will be the difficult obstacle.  It's gonna be tough to get 3 or 4 seconds of multiple amps of 12V power out of what I'm envisioning. "
Put a DC ammeter on the circuit & measure it, it's not that hard. Get a value. Find a source you are happy with that produces maybe 1.5x that and try it. It only needs to put out for maybe a minute, whatever amount of time it takes to start the machine. Those giant audio caps look promising.

Nitrowing - Don't panic. The cap was for trail use to lose weight and promote vibration resistance. The 16V overcharging is endemic to the older Bullets charging system. If you desire a battery, the EZ solution there is to use a battery that tolerates 16V. The iRobot Dirt Dog has a $20 Nickle metal hydride battery that seems happy from 14V - 22V, so that is also an option.

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A brace of 1999 Bullets: 1 Red Deluxe, 1 Green Standard. Also, 1 wee orphan 1956 Fire Arrow project.


Nitrowing

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Reply #16 on: March 24, 2021, 04:13:09 pm
 
Nitrowing - Don't panic. The cap was for trail use to lose weight and promote vibration resistance. The 16V overcharging is endemic to the older Bullets charging system. If you desire a battery, the EZ solution there is to use a battery that tolerates 16V. The iRobot Dirt Dog has a $20 Nickle metal hydride battery that seems happy from 14V - 22V, so that is also an option.

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My first thought was "fit a decent reg/rec" - I fitted a few Honda ones to my Suzuki's over the years.
My second thought was "fit an AGM or LiPo" as they're maintenance free. I've also fitted these to various vehicles.
Capacitors?!?  ::)
No wonder we no longer have a motor industry


AzCal Retred

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Reply #17 on: March 24, 2021, 04:57:59 pm
Batteries already exist that can deal with the Bullet's vague voltage control, so you can keep the electrical side relatively stock by using a more appropriate battery. The Bullet reg/rec is cheap and a bolt on, mine seem to be reliable enough. The Dirt Dog NiMH battery is cheap also, it's small and can be made waterproof. The kickstart Bullet isn't very demanding for battery capacity. A "low hanging fruit" fix?  ;)
A brace of 1999 Bullets: 1 Red Deluxe, 1 Green Standard. Also, 1 wee orphan 1956 Fire Arrow project.


axman88

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Reply #18 on: March 24, 2021, 06:45:52 pm
" I'm having a hard time understanding why a parallel cap would help prevent the regulator from overcharging the battery? "
It doesn't. It can't. I am having a hard time understanding why we're asking that question.

Probably because somebody said,
On my trail bike project I replaced the battery with a Mallory 8.9 uF 16V - 20V cap ...
One of the drivers here was to stop the continuous battery killing 16V overcharging.

"The data sheet for your Mallory 8900uF says its Equivalent Series Resistance rating is 0.034 ohm at 120 hz. and gives a multiplier rating for higher frequency of around 1.25 for frequencies in the range that would be produced by an engine turning at Bullet engine speeds coupled to a 3 coil alternator. "
A capacitor is an open circuit in a DC scheme. The min/max voltages tell you the useful operating levels and the level beyond which you can expect failure to occur. If you are talking frequency, you are talking impedance values. A capacitor is a "short circuit" in a AC scheme, it doesn't impede current flow but does displace it in time, changing the circuit power factor or providing other useful functions to the circuit designer. The only AC here is upstream of the reg/rec.
I would say that a series of pulses with half sinusoidal shape, although it isn't a sine wave, is not DC, and that a cap's ESR would be relevant to its performance in this environment, or even during purely DC charging and discharging.  If a cap was an open circuit to DC, it wouldn't charge.  But it does, current flows, and charging and discharging in a purely DC environment takes time, depending on the resistance, which, as you point out, is frequency as well as construction dependent.  Idealization and simplification are fine, until they get in the way of resolving issues.

Regardless of what you call it, impedance, or ESR at 120hz as the manufacturer specs it, the internal resistance of your Mallory is greater than the internal resistance of a motorcycle battery in good condition.

I can see that someone here is a candidate for a community college electricity/electronics course!
Is there where one learns about swimming pools, pipes and pumps?  Sounds like a lot of fun.


AzCal Retred

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Reply #19 on: March 24, 2021, 07:39:34 pm
1) ( On my trail bike project I replaced the battery with a Mallory 8.9 uF 16V - 20V cap ...One of the drivers here was to stop the continuous battery killing 16V overcharging.) Mission accomplished, overcooking battery replaced by a capacitor that won't cook off.

2) " If a cap was an open circuit to DC, it wouldn't charge. "  A capacitor stores charge as a static electrical field in space. Walking across a new nylon carpet can make you a capacitor, storing charge until you hit the doorknob. Full charge & discharge times are very short. Adding a resistor creates a definite time delay, and RC circuits were routinely used for timing functions until digital electronics created a better way.

3) " Regardless of what you call it, impedance, or ESR at 120hz as the manufacturer specs it, the internal resistance of your Mallory is greater than the internal resistance of a motorcycle battery in good condition. "
This is apples & oranges. Apply a DC voltage across a cap with your VOM and it charges up until it's at "full capacity" for the voltage applied, then current drops to zero. E/I = R, E/0 = undefined, infinite. Infinite resistance. Resistance is a DC function. It'll stay that way until you apply enough voltage to blow it up. AC current flow applied across a cap is limited only by the impedance, the frequency dependent DC resistance analog in an AC system. Those impedance values for caps are the numbers you so correctly pointed out. The fun begins when you look at transformers. The low side coil resistance might be 0.05 ohms, high side 0.5. Put 120VAC across them and you don't see 2,400 amps or 240 amps, maybe 0.1 amp AC. Reflected impedance is the voodoo that makes that work. Short one side, apply 120 to the other and watch the smoke as impedance goes to near zero.

4) As far as Community College Electrical/Electronics, it's a good place to experiment and learn. When you get to the point that you can accurately describe why a single phase motor turns, why a 3-phase motor turns, the difference between AC & DC relays & why, why and how thermistors are used, play with a variac for awhile, learn about step up/step down transformers, inductive phase shifting & how it works, capacitive phase shifting an how that works, maybe look at the relationship between field strength & power factor in a generator, play with relay style controls, figure out PLC driven controls, build some RC & LC circuits, burn up a few transistors & resistors, maybe then you won't be so dismissive of solid basic knowledge, idealized models and simple analogies. Quantum electrodynamics describes the odd goings on at the atomic level as to why all this stuff actually works. That's far beyond most of us, and largely unnecessary just to repair or build functional devices, so we're left with basic knowledge, idealized models and simple analogies.   

https://en.wikipedia.org/wiki/Quantum_electrodynamics.
A brace of 1999 Bullets: 1 Red Deluxe, 1 Green Standard. Also, 1 wee orphan 1956 Fire Arrow project.


axman88

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Reply #20 on: March 24, 2021, 09:15:12 pm
Mission accomplished, overcooking battery replaced by a capacitor that won't cook off.

That's what I thought when I first saw your thread title, but then you said,

Using a cap in parallel with a battery is more about surge capability, as the cap will discharge into a load before the battery as it has less internal resistance. It prevents voltage sags, a useful trait.

With a cap only the voltage regulation will flail about more than with a battery. My casquette mounted analog meter windmills between 12V - 18V on cap only.
Which suggested to me that you also tested the system with cap + battery, paralleled, and that this latter configuration was preferable.

Then there was the fact that the original picture you posted seemed to show the Mallory with a battery in the background, so I started thinking that you were running with your cap in parallel with the battery, which prompted my confusion.

I should have looked at the excellent schematic you provided, right at the start, and would have saved us both a lot of frustration.  Sorry, my error.

I can see any meter, analog or digital, having difficulty giving meaningful voltage readings in this no-battery situation.  Even at idle, that's an ~ 1800 hz waveform it's looking at.

Reading 13 - 18 volts, (15.5 +/- 2.5V) from an analog meter, would seem to suggest that your system is likely experiencing an even greater actual range of voltages, the cap is substantially discharging, and perhaps exceeding the nominal max rated cap voltage on the high end.  I would think it's probably more likely to die quietly from overheating, than to go with a lot of explosive drama, but it does seem to be asking a lot of a 16V rated component.  I'd carry a spare.
« Last Edit: March 24, 2021, 09:48:36 pm by axman88 »


AzCal Retred

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Reply #21 on: March 24, 2021, 11:13:40 pm
The trail bike's just used on my property, always a short walk back to the garage. Hopefully it dies uphill and gravity will prevail! ;D If it croaks I'll get the 25V-30V cap.

Your Interceptor probably has a modern 3 phase system. These Bullets are 3 paralleled coils, 3 magnets, so 3 cycles per crank revolution, 2 wire single phase. At 500 RPM idle that's 1500 cycles per minute, 1500/60 = about 25 Hz. on the AC side. The rectification process converts these to "pure" DC output with possibly a 50 Hz. ripple by virtue of having made each N/S cycle into a pair of NN pulses. Depending on the reg/rec's smoothing & polishing ability, these may possibly be seen by the meter as "DC frequency" where the "humps" cycle between (+10v)---(+20v)---(+10V)---(+20V)---(+10V), doubling the AC frequency. An oscilloscope would be the appropriate tool. But the reg/rec mostly takes care of ripple. Checking frequency with my Fluke to the battery on my other bike shows maybe 3 - 5 Hz., so whatever is passing through is probably below a reliable measurement threshold. The battery helps stabilize the system, acting like a buffer for voltage excursions. The cap has nowhere near the stabilizing "volume" of a battery, so voltage fluctuations are more prominent on the cap-only trail bike. The analog electromechanical gauge flails, as once it drives high the weight of the accelerated components keep it moving against the spring until the low pulse comes along to drive it back the other way. A Fluke-style VOM has the speed & filter circuitry needed to record actual min-max levels if desired, but the flailing analog gauge is mostly just guesswork.

Let us know what you come up with, there are a lot of cool power sources out there that should be adaptable to your idea. - ACR -
A brace of 1999 Bullets: 1 Red Deluxe, 1 Green Standard. Also, 1 wee orphan 1956 Fire Arrow project.


AzCal Retred

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Reply #22 on: April 08, 2021, 02:46:21 am
Round Two: The Overcharge Express gets tamed.
The factory voltage regulation on my 1999 Bullets is right at 15.5V - 16V on both machines. The regulators seem to work fine, just at too high a rate to not cook a lead/acid battery. Since we live in the future after all, I shoved a surplus rubber-armoured 4AH Milwaukee Tools 18V Lithium in the left hand tool box, resting conveniently on that shelf above the brake light switch. The old battery box lower mount had vibration fatigued anyway, so a great excuse to pare off 6 pounds of cooked lead acid battery and unnecessary bracketry. At 18V nominal output, the Milwaukee battery will never be able to be in an overcharging stress condition. It holds plenty of zap at about 15-16 volts to perform all necessary functions. The ammeter seems to flail less at idle, maybe the Li is "faster" than the lead-acid in charge/discharge. Anyway, for a KS machine it is an acceptable solution and really opens up the carb/coil area.

The battery ground wire is a sore point with me, as both machines had semi-cooked ground wires when I acquired them. I cleaned off the paint at the frame ground point, put some Alox anti-corrosion paste of every flat surface of each lug and went back with 19 strand #10 from the battery to the grounding lug with a stopover inside the tool box at a convenient bolt. Components can burn to the ground, but your interconnecting wiring should never cook off.
« Last Edit: April 08, 2021, 02:57:56 am by AzCal Retred »
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AzCal Retred

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Reply #23 on: April 10, 2021, 03:05:37 am
50 mile back country loop today - no smoke, no drama, all in all the adapted Lithium is a success! On to the next fettle...
A brace of 1999 Bullets: 1 Red Deluxe, 1 Green Standard. Also, 1 wee orphan 1956 Fire Arrow project.