Generators and Motors
[Home] - [HELP] - [Forums] - [Articles] - [Photo Gallery] - [Groups] - [Chat] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] - [Tools]

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Motors General Discussion > Onan Generators
Forgot Password? Join Us!

Notices

Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

Onan 6.5 NH 3CR/12014D Questions...


this thread has 204 replies and has been viewed 20377 times

Reply
 
Thread Tools Display Modes
  #61  
Old 08-23-2012, 07:19 AM
MBB MBB is offline
Registered-III
 
Join Date: Apr 2009
Location: Elk Grove Village IL USA
Posts: 1,898
Likes: 605
Liked 981 Times in 661 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

I believe John Ward may have a copy. Check out this thread post 30 http://www.smokstak.com/forum/showth...=108617&page=2
Reply With Quote
Sponsored Links
  #62  
Old 08-23-2012, 07:39 AM
Kevin K Kevin K is offline
Registered-III
 
Join Date: Jan 2005
Location: upstate New York USA
Posts: 1,949
Likes: 1,380
Liked 1,683 Times in 976 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

That's the way Onan charged the batteries with these old revolving armature generators. They tapped the exciter voltage, dropped it with a resistor, or in some cases two resistors and a "voltage regulator" to make a two step charger, and let the battery ballast the final voltage. That's why it is so important to NEVER disconnect the battery when the generator is running. You will lose all the regulation the battery is providing. I'm surprised your battery is getting up to 15 volts with only a 1 amp charge.

Another way to control the voltage may be a circuit that switches in a 12 volt load whenever the voltage goes above 14.5 volts. In other words, a shunt regulator.
Attached Files
File Type: pdf Page 3-4 from 900-0196.pdf (93.5 KB, 35 views)
Reply With Quote
The Following User Likes This Post:
  #63  
Old 08-23-2012, 11:17 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

I found the full manual Kevin listed above at ---> http://www.cumminsonan.com/www/pdf/manuals/900-0196.pdf
It talks more about the charging circuit on the next page ( 3-5)

PnishrPW....I am ASSUMING this schematic is what you have in your genset, you should check to see if it is. I don't know!

From the schematic on page 3-4 , it looks like the charger controling electronics are in the lower right 1/4 of the picture (Q1,Q3,Q4,Q5 related)

At bottom of schematic:
-- Coming off gen lead/pin 8 is the low charge circuit ( 1.5 amps)
-- Coming off gen lead/pin 7 is the hi charge circuit (3.7 amps)

The manual implies it cycles bat voltage between 13 and 15 volts. But I don't see that the charge controler circuits have a lead going directly to bat to SENSE it's voltage. I suspect the circuit ESTIMATES bat voltage based on how much current is going to bat. (but I'm not an EE).

Manual doesn't give values for componets. So I have to do some guessing here, just looking at the general circuit layout.
I'm guessing the resistor divider pair (A1R4 , A1R8) and pair (A1R7,A1R9) control the supposed min and max ( or max and min) battery voltages. And possiably zener diode A1CR7.

Could try changing ohms of one of these resistors 5 or 10% and see what effect that has on bat voltage. Would have to run genset through a charge/discharge cycle.

I'm surprised they are running 3.7 amps thru A1Q1... needs a heat sink.

I would be interested in pictures of the charger control board.

IF you do proceed , I would be interested to see what you come up with. I'm always looking for new charger designs.

---------- Post added at 11:17 PM ---------- Previous post was at 11:02 PM ----------

In my above post . Scratch everthing from paragraph 5 on down !!
I just saw how circuit senses bat voltage ..... it's thru A1R5.

I thought the dotted line was the edge of the board. You always notice these things just AFTER you post.
I'll have to think about this tomorrow, now it's time for Leno and BEER.
Reply With Quote
The Following User Likes This Post:
  #64  
Old 08-24-2012, 12:32 AM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

Len, Fig 3-3 is the 859 board I have. I`ll have to de dust my board and snap some decent pix... I also believe A1R5 is B+ sense, I`m thinking drop a pot in place of and retest - reduce value to spoof the charge circuit. Still considering dropping in some add`l resistance between G1R1 pin 4 and term 7 on 859 board.

A1Q1 does need a heatsink, on my board it`s been warm, but not smokin hot. Guess I should hit it w/ the IR thermometer. Problem is, as configured you can only use an over the top heatsink due to proximity to A1Q2. Other issue is limited headroom - ~5/8" at best. I`m either thinking pull Q2, not used in my configuration, mill down an over the top AND an under mount heat sink for clearance. Or other option is to simply remote Q1 off-board and socket/heatsink. I`m leaning toward remote. Research indicates it`s an 2N3055, common and cheap. Off-board mounting would facilitate easy and adequate heatsinking and replacement if required.

Side note: FS board uses a heatsink, Dino doesn`t. FS board does have a pair of 10 turn trimmer pots...
Reply With Quote
  #65  
Old 08-24-2012, 12:43 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

A)***hi and low voltage setpoints***
I still suspect they are as I previously said above ( in post #63)

B) **Charging circuit***
I think the voltage sensing input is the base of A1Q5 (line below it)

I don't think dropping a pot in place of A1R5 is the answer. Because it looks like they allow pin 7 voltage to influence base of A1Q5 also, thru A1R4. To me (A1R4 ,A1R8) and (A1R5,A1R8) look like resistor voltage dividers.
If you want to try anyways I would instead try varing A1R8 a LITTLE (5 or 10% maybe). But it will likely lower BOTH hi and low setpoints. Bats don't like getting too discharged either.

Problem is I'm doing a bit of guessing, it's not that simple of a circuit. Don't know if it would help me much, but if you found the ohms of all the A1__ resistors, that might help the guessing process.

Before you adding resistance to G1R1 pin4, I would be interested in seeing a pic of it. I'm concerned that it's providing the bias voltage to operate A1Q1. Besides if you add resistance I think you would just be changing the charge rate (amps) and not the final voltage.
For pic of G1R1 , I'm mostly I'm interested in where the adjustments are (if any). Also interested in where it's pin 1 goes. Schematic doesn't show lines well. That diode next to it doesn't make any sense , unless pin1 is connected to something else also.

C)***A1Q2 and pin 9***
Looks odd, do you know what it supposed to do?? Kind of looks like a transient suppression circuit for any voltage spikes coming off of the spark coil and fuel pump. ( to protect the other transistors.)

D)*** heatsink***
Remote mounting sounds good. I did that on a fire alarm panel. They had a LM317 voltage regulator (with TO-220 mounting) outputing 1.5 amps with only a small clip on heatsink (disapated ~6 watts). Heat sink was ~242 deg F. The internal die junction (which was even hotter) was only rated for ~160 or 180 MAX!! I put it on a big heatsink, now can hardly feel the heat. Overkill, but easy.
Reply With Quote
The Following User Likes This Post:
  #66  
Old 08-24-2012, 01:46 PM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

A), you may be right.

B), I still suspect A1R5 (5.1k on schematic, I believe has a second resistor piggybacked on the board). G1R1 pin 4 is hi charge/ignition supply voltage, you may be correct on charge rate/voltage. Pin 1 goes to ground, (hard to see...).

C), Pin 9 is starter relay output w/o A3 (1227) board. I touched on that in post #34 of K4JKA`s post "Onan w/ no spec tag", And possibly how to replace the A3 board w/ a relay while still maintaining the start disconnect.

I Pulled this from that post, didn`t feel like retyping...

"Len hit it right on the head, A3 board`s only apparent function is to disable the starter relay once engine is running. My NH has it, but to my eye it seems redundant as this feature seems to be already built into the 859 board.

Quoted from 900-0196 UN gen & controls, P 3-5 "Controls Without Start Disconnect Adapter"

"When the engine starts, generator DC voltage supplied to terminal 8 causes A1CR5 to stop conducting, and turns off transistor A1Q2. this deenergizes start solenoid K1 and breaks the starting circuit."

Am I missing something here or is the A3 board completely redundant?? Or is it a "band-aid" added later? Only possible explanation I see is that K1 combined w/ ignition pulls to much current through A1S2 (5 amp rated) and failures were happening. I wouldn`t suspect it`s to protect A1Q2, a 2N2955 w/ a 15amp rating, only used when starting. Wouldn`t a relay off term 9 been good? Oh yeah, the "solid state" thing... I can live w/ a double click.

The closer I look @ the 859 and 1227 (A3) boards, the quirks do show up - but seem to be easily/cheaply corrected. Minimally harder that a re-pop board, but waaay cheaper... If I can dump my 1227 for a single, cheap relay, that sucker`s history.

Matter of fact... Here`s the quickie 1227 delete as I see it:
Use a 4 or 5 pin Din relay (typical 4 pin Onan will be perfect).
Remove A3 (1227), change connectors as appropriate to fit your donor relay.
Move wire on terminal 16 (859) to terminal 9 (859) and connect to terminal 86 (relay). Terminal 13 (859) to terminal 85 (relay).
Move wire on terminal 2 (859) to terminal 18 (859) and connect to terminal 30 (relay). Terminal K1-5 (1227) to terminal 87 (not "A"!!) (relay).
Now you have deleted the A3 board, retained the engine running starter disconnect safety, and removed the added load from switch A1S2 while starting. Total cost: $0-10. I will guinea pig this on my 859 equipped NH tomorrow and confirm. Might have just boned Dino on selling a few of their ~$100 1227 replacement boards, whoops, my bad...

Interesting note: active device on the A3 board for controlling the starter relay is a smaller TO-66 cased transistor, on the 859 board it`s a larger TO-3 cased transistor (A1Q2, 2N2955). Hmmm..."

D), Yep, gonna pull the trigger on that one.

As I see it, the 859 isn`t really that complicated, I`ve designed/built/worked w/ way more complicated circuits. I`m not an EE, but I often play one in real life, also a former Ham (AE ticket).

If I had a LM317 pushing 1.5 Amps, I`d probably go to a LM117 in a TO-3 pkg, but I`m an ultra-conservative engineer... Well, that and I have a couple of handfuls of Mil-Spec LM117HVK steel`s in my stash.
Reply With Quote
  #67  
Old 08-25-2012, 02:04 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

**Section B above.**
Strange that lead 1 of g1r1 goes to ground. That would put full charging voltage accross the bottom of that resistor which is 8.3 ohms according to circuit diagram (post 62 above). Just loading down the voltage output, lot of power disapation, hot resistor.
In the guy I helped with the MCCK ( post59 above) , the end of that resistor was NOT grounded.
You said pin 1 goes to ground, are you reading schematic or looking at your actual generator?

**Section above C** will read it in detail later. ..... weekend issue.
Bigger cases (To-3) usually have lower thermal resistance (deg/watt) from die junction to case. Run cooler.

**section D**
I did go with a to-3 package, don't remember if I used 117 or 317, they are the same except for ratings. Did the upgrade in ~1987, still going strong. I'm not pulling 1.5 amps, that was just the alarm's rating. So naturally I tested it to full rated output. Called the company for info + gave my findings to their EE , the next year the alarm was only rated at 1/2 output (.75 amps) with heat sink increased in size by 2X. I am a ME and play EE sometimes. Also read lots of EE magazines. My friend at school were into Ham, I was never really into it. Required morse test back them.
Reply With Quote
  #68  
Old 08-25-2012, 07:57 PM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

(B), G1R1 grounds on my NH. I thought it strange also... I`m still wondering about the diode also, looks to be 1N54xx ish. I`ll have to check out the M/CCK schematics, out of curiousity.

(C), Agreed, just seemed odd they would change.

(D), LM317K? I`m not a ME, but wear the hat frequently... Morse is a pain, my Dad taught me when I was very young, he was Signal Corp in WWII. Havn`t used it in ~30 yrs.

A1R5 is a 5.1k paralled w/ a 36K, 4.467K net. Drops voltage to 10% of input value. Odd, now my batt voltage is ~13.9-14.1V after ~30 min run. Same batt, cables - changed absolutely nothing. Did mount an Autometer Voltmeter, just to keep an eye on it.

Did the A3 (1227) board to relay conversion, works perfectly. Locks out starter as it should, no add`l current through A1S2. Anyone need a good used A3 (1227) board?? If no objections, I`ll post the A3 to relay conversion in a separate thread to make it easier to search for.
Reply With Quote
  #69  
Old 08-27-2012, 12:56 AM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

Did figure out one purpose for the A3, provides a slight delay in dropping out the starter relay. Didn`t notice it on a hot restart (restarts instantly), but on a cold start, right as the motor is taking off the starter relay will cycle a couple of times before it starts and goes into lockout. Didn`t get a chance to play much today, but will try a couple of different caps (220, 470, 1000 uF, 25 or 50 VDC or so) from pin 9 to ground (859) to cure. Should provide a slight delay and resolve the issue.
Reply With Quote
  #70  
Old 09-05-2012, 10:36 PM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

1000 uF/50V worked fine, dropped a 2200 on it - no issues. Left the 2200 on it. Yeah, no more A3/1227 board!! Used a couple of 1/4" M/F adapters right on the relay and wired w/ 16 ga to finalize the install, siliconed the cap right to the relay.

Ran it for ~1hr, batt voltage was up at 14.65. Changed A1R5 to a 10 turn 5k pot, set to ~ 4.5k, batt volts were ~ 14.3, I`ll retest when I get more time. One way or another, I`ll home in on this issue - I like the 2 stage charging system. If I dumped the 859 board, I suspect I`d have a serious overcharge issue. If I can find a cheap workable regulator, I may dump the 859 and go w/ relays. I may end up designing something to work, if I have to...
Reply With Quote
  #71  
Old 09-05-2012, 11:11 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

You should still check how low the bat voltage will go, lead acid batteries don't like being too heavily discharged.
-------
If you dump the board and need a charger, few simple solutions.

1) Ac powered battery charger, with built "2-stage type charging.

2) Lead acid battery charger "IC chips" should be a mature technology . Look for a circuit design on website of some of the big chip makers....National Semiconductor, Analog Devices, Maxim, Texas Instruments. In their spec sheets for the devices, they usually also give circuit designs.

Because of the hi no-load voltage ~45V, you will likely end up with a only a hi-power resistor for the low charge circuit, and maybe a resistor assisted, IC -chip circuit for the hi charge circuit. (Using the resistor to disipate some of the voltage/heat so you don't have as much thermal problems in the IC/transistor section due to hi power disipation. )
Reply With Quote
The Following User Likes This Post:
  #72  
Old 09-06-2012, 01:50 AM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

A couple of very good ideas, thx Len! I don`t think low end on the batt is an issue, I`ve got a float charger/maintainer for it already and my genny starts easily/quickly.

I goofed in my earlier post, I`ve got my pot set @ 4.3K, not 4.5K. I`m going to pull the batt down a bit prior to starting to test the setpoints, but I need to heatsink and/or remote A1Q1 first so I don`t have any temp issues while testing.

I`m thinking if I design something, I`ll go PWM instead of linear - it`ll keep power disipation lower across the output device (probably MOSFET).
Reply With Quote
  #73  
Old 09-06-2012, 02:25 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

1) Batterys .... Look on the web. Car bats don't like to be deeply discharge cycled (go too low on voltage) it shortens life. Also they say if you discharge them and let them sit long time, that's the end of them.

2)PWM ..... I saw an Onan design that uses PWM with a high "ON" voltage (20-40V) just AVERAGING out at ~14V. I have some concerns that the bat is not going to like the peak voltage. Whenever bat charging voltage is over ~15-16V (I forgot the #) it breaks down water to o2 +h2.

So while PWM is bettter than steady 17V charging, I would go for a linear design, for a steady voltage ~14 ( you got to lookup actual)

For design I'm reading the specs on an IGBT for something else. It looks easy to design with, ( I think, but I'm not a EE), Maybe operate it in a linear mode ?? 104 watt power disapation rating !! Fairchild # HGTP12N60C3D.

spec sheet ----> http://www.fairchildsemi.com/ds/HG/HGTP12N60C3D.pdf
Reply With Quote
  #74  
Old 09-06-2012, 03:44 PM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

Len, good points to ponder...

1). Agreed, discharged batts die quickly, and are way more prone to freezing (more H2O, less acid). Plus, the cells sulphate up much quicker. Let an Optima sit discharged for a couple months discharged, you can toss it in the recycle - It`ll never come back. Ask me how I know...

2). IGBT may be better, hadn`t considered it. If I use the 12v for something else, the higher PWM pulse may annoy/damage it. However, the batt will introduce a sustantial capacitive effect, smoothing the average. That, combined w/ a LC component may prove very effective. Also looking at solar charge controllers, tons of designs out on the net, both PWM and linear. Max theoretical Onan charge rate ~5 Amps, 15-20 Amp controller should have a good safety margin. Any option is better than 15+ v boiling out the batt.

With the right reg setup, I should theoretically be able to pull significant 12v amps off that circuit, which would be handy in some cases. As those windings are used for starting, they are pretty beefy. Still trying to figure out the purpose of the diode on the bottom end of G1R1, makes no real sense.

As always, thanks for the ideas Len, you always have a great insight.
Reply With Quote
  #75  
Old 09-06-2012, 04:49 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

Bat "Capacitance" ..... Depends on whether it comes from actual capacitance or "chemical" equivelent capacitance. From large spacing of bat plates I suspect it's chemical not actual capacitance, thus susceptible to ripping water apart to o2 + h2.

PWM .... maybe a PWM design , with a low pass filter on output.

Diode ..... Suspect it's either:
1) a free wheeling diode to protect electronics (like the ones they put across relay coils that are driven by trasnistors.
2)OR it's to do something magnetically in the gen to lower bat charging output voltage.

IGBT... I was impressed by its power disipation rating !! 100+watts

---------- Post added at 04:49 PM ---------- Previous post was at 04:39 PM ----------

Maybe a switching power supply with a constant ~13.6 volt output , with low pass filter.
Reply With Quote
  #76  
Old 09-06-2012, 11:04 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

Diode..... I saw a similar diode, but in a different place on a MCCK ?? schematic. It was in series with the shunt winding. A schematic is on Page 43 of manual at -----> http://www.docstoc.com/docs/34443851...Parts-Catalog? Guess they were playing with different designs thur the years.
Reply With Quote
  #77  
Old 09-07-2012, 12:24 AM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

Batt capacitance: Actual Vs. Chemical? Please school me on this one...

A lot of solar charge controllers use a PWM scheme to charge LA/SLA/Gell cells. I`ve been doing research online, and more than not seem to be this way these days.

On the diode, looked at the schematic you referenced, definately an odd place for a diode also. On my NH, from the configuration, I`d have to suspect a freewheeling diode as with your first guess, but to protect ?? Only thing I could possibly come up w/ is inductive kickback from starting?? I`m at a loss, never recall seeing anything configured like that in over 35 yrs of playing sparky... But then again, why ground the tail of G1R1? Short side/long side makes perfect sense for hi/lo charge. But, then again, these are designs from the tail end of the hippie yrs, far out man...

I`ve worked on some strange electronics (try an 1981 Chrysler Imperial w/ stock OEM electro/mech fuel injection and stock digital dash, THATS an exercise in crazy. Electronics supplement alone seems to rival a New York city phone book in size. And there maybe less wiring on the space shuttle... But man I love my Frank Sinatra Edition Imp!!), but for a low component count system - Onan did some strange engineering!
Reply With Quote
  #78  
Old 09-07-2012, 11:03 AM
grif grif is offline
Registered-III
 
Join Date: Oct 2011
Location: Yakima, Washington
Posts: 675
Likes: 157
Liked 146 Times in 112 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

So it looks like the upper left corner is alive and well ;-) I'm over on the dry side, several intermittent service tractors, wind machines and farm stuff over the years.

Was going to make a comment that an onan conversation on 80 meters might be fun over the winter.

FYI, I don't know what I know about Onan using the battery as part of the regulation circuit. For intermittent use, I'm just a clip the charger on the battery post untill equipment needed sort of guy.

Lead acid wet batteries.

Battery Tender from WallMart. I'm sure there's better options, but we got full life out of the batteries, and they don't boil dry over the winter, available and cheap enought.

And a comment about faston (spade) connectors. Yes I use them. Not even a love/hate thing,,, mostly hate. Almost as bad as the old school molex connectors. good for about 5 disconnect cycles and junk.
Reply With Quote
  #79  
Old 09-07-2012, 12:57 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,888
Likes: 84
Liked 2,094 Times in 1,597 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

***Capacitance
The way I look at it lead-acid (car) batteries have 2 types of capacitance.

1) Traditional capacitance, where capacitors are defined as energy stored as an electric field between conductors. Such as between parallel plates with uniform spacing model, capcitance= k A/d where, A=area of plate, d=distance between plates, k=constant.

2) Electrochemical action that makes battery behave electrically similar to a very very very large cap. You put current into it and voltage rises and vice versa, just like a cap does (within limits). So I call it equivent capacitance, as it's physical source is not derived from a stored electric field between conductors, but a chemical one.

The contribution to capacitance from the parallel plate model is likely low, as the separation between plates is pretty large vs real caps with ~.001 inch spacing, or less. (I have not done the calcutlations.) Plus with 6 cells in a 12 V battery, the 6 series connect caps would have even less capacitance.

So I'm guessing the major contibutor to capacitance in a car bat is from "equivelent" capacitance (from electrochemical action). Thus susceptible to ripping water apart to O2 + H2, if voltage is over ~15 to 16V.
---------------

***PWM + bat chargers
PWM is popular these days for a lot of stuff, more energy efficeint. They are probably using a PWM with a peak voltage of say 17 volts, that should be alot kinder to the bat than a 45 V peak (gen output), IF you don't use a low pass filter on it's output.

It might be good enough, but I think PWM should use a low pass filter ( say parallel cap then series inductor ) to lower the peak voltage presented to the battery. Even if it is for a few micro or milliseconds. Besides you need a low pass filter to keep the RF output down to pass FCC noise issues.
------------

**Diode
"..freewheeling diode as with your first guess, but to protect what ...." If that then likley the transistors. When you use semiconductors have to think about protection, or you end up replacing them. But it just doesn't look right, maybe a 1/2 hearted attempt. They didn't bother with heat sinks , so ....
Reply With Quote
The Following User Likes This Post:
  #80  
Old 09-08-2012, 02:03 PM
PnishrPW PnishrPW is online now
Registered-II
 
Join Date: May 2012
Location: Western Washington
Posts: 404
Likes: 203
Liked 147 Times in 96 Posts
Default Re: Onan 6.5 NH 3CR/12014D Questions...

Battery capacitance: Thx for your insight, I`d always just considered it as raw capacitance, w/o consideration of the actual mechanism.

PWM: I am looking at it for efficiency`s sake mostly, and I have a fair bit of experience w/ PWM. Agreed on the LC component, smooth the ripple and for noise. Virually all modern float chargers/maintainers are PWM, along w/ the vast majority of modern higher amperage solar charge controller circuits I`ve researched online. A few of the low amperage >2-3 amp circuits are linear in nature. Just out of curiousity, I put my scope on the float chargers I have, definately all PWM...

Diode: Yeah, looks strange to me too. Only reason I can see is to protect A1Q1-2-3. But the configuration just doesn`t look to be a particularly effective/efficient one. A1CR4 & 10 are definately freewheeling diodes.

Going to try to get some testing time in on my charging circuit issue later today, anxious to see if my A1R5 pot is going to be the solution. Did come up w/ a novel way to shorten test time: Marine battery selector, 1/both/2, main batt on 1 - small motorcycle batt on 2. This way I can switch w/o totally removing the batt from the circuit, discharge the small batt while out of the circuit to simulate a charge cycle, and the small batt will charge much faster to greatly reducing testing time. I was thinking of using a smaller 6-12 AH gell cell for an even faster cycle time, but I`m not 100% sure the results will translate completely/effectively to a car sized batt.

Still trying to get the whole unit down to my buddy`s shop to bend up the exhaust, but have to do it when the owner isn`t around. Bossman seems to believe I`m the Antichrist, I don`t know why...
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
having trouble with an Onan 6.5 NH 3CR 12014D LesBerg Onan Generators 26 04-10-2013 05:35 PM
onan 6.5nh3cp/12014d 12v issue killswitch Onan Generators 10 09-23-2012 09:04 PM
Onan 6.5 nh-3cr/12014d no auto choke mech and low voltage froggy4873 Onan Generators 6 08-09-2012 02:16 PM
6.5-NH-3CR/12014D Information Please GHunter Onan Generators 13 05-09-2009 08:16 PM
Onan 6.5 NH CR3/12014D "No Spark" Paul Kogut Onan Generators 3 10-21-2007 09:10 PM


All times are GMT -4. The time now is 10:17 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark
A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2014 by Harry Matthews
P.O. Box 5612 - Sarasota, FL 34277