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Engine Specific Info and Questions => IDI Engine => Topic started by: ORCoaster on February 15, 2015, 12:31:06 am
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On my 1981 Rabbit I have the 55 amp alternator. I was wondering if the output is correct for the amps. It seems to charge about 3-4 at idle but once the engine picks up to 1100 RPM or so it drops to 1 or 1.5. Is this normal?
I was in the process of swapping out the voltage regulator as the voltage was jumping around a lot and I got a good deal on the replacement. But my amp meter went south on me just about the time I wanted to check the new equipment. The gauge in the car shows near 30 with the heater on, the high beams on and I just couldn't verify if that was correct with my hand held.
The low values were with nothing on but the engine.
I need another 3 of those 3 volt batteries to get real numbers and that will take me a week to get to the store and pick them up. Have to travel for work this week, no time to play.
Let me know if this is standard behavior or not. Thanks.
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I can't say that I've ever seen any numbers on what the amperage draw should be with just the engine running, but I'd suspect they'd be pretty low. The only things drawing amps would be the shutoff solenoid in the pump, maybe a couple gauges like fuel and temp, a clock if you have one, and the memory for your stereo. I was thinking that my battery charger only charges at 2 amps when I have it on trickle charge, so that number might not be too far off the mark.
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It seems to charge about 3-4 at idle but once the engine picks up to 1100 RPM or so it drops to 1 or 1.5. Is this normal?
No it`s not mr. Gremlin,ON START engine you must have 13.8 v and many A.
Change regulator but bad Accu can be factor also.
See that,because bad acu get fast V up and than you have A down.
Even that,bad accu can fail good alternator.
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Most of the time I use a voltmeter to check my charging system.
I understand you want to know how much load it's under and an ammeter is great for that.
A voltmeter connected at the same time will let you know how well the alternator is handling the load. Also lets you know what the voltage regulator is thinking.
A MK2 90 amp alternator setup is a good upgrade for a MK1.
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I decided to go surfing on alternator performance while I waited for sage or not so sage advice here.
Seems that at idle the amount of amps the alternator will develop is based on need. So if I am not running lights, heater, glow plugs, radio or rear defroster the reading I should see is only what the battery needs to get back what I just pulled out of it to start the car.
Now once it is running if I kick on lights, heater, anything else the amperes will go up accordingly. That is until I max out the 55 amp rating at 6000 rpms. Remember the pulley on that is smaller and turns faster because of it.
So, what I needed to do and couldn't because of a lack of 9 volts in the meter was to watch the change from idle to say 1500 RPM's and see if voltage is in the 13.8-14.0 mark. Then watch the amps as I flip on one after the other accessory. I did see the internal gauges reflect the steady voltage and increased amperage but when you have a 0-60 amp gauge it is kind of coarse measurement. About all I know is that it seemed to hit the 35 amp mark with all lights, heater fan on high and defrost on.
I will update when I can run another better measure but I don't think the alternator is bad at all so now I have to find the drain on the system as the battery is new and the cranking power is becoming weak. Only 3 mth's on battery. Volts on start-up near 9 or less.
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While you're away from the car, I trust the battery is on a charger or the neg cable is disconnected? Not so good to leave a lead battery discharged for long.
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A lot of people mis-understand what amps actually are, but what they do is measure the current flow in a circuit. I run into the thought process a lot that says 'well, I have a 55 amp alternator so I should be reading 55 amps all the time".... Not the case. The 55 amp number is the maximum amperage the alternator can put out. You can roughly compare electricity to the flow of water in a hose, with voltage converting to pressure (psi) and amps converting to a flow measurement (such as gallons per minute ie; gpm). So say you have a hose that has 12 psi on it, but that hose is capped off at the end. The 12 psi/volts has the potential to push the water through, but with a cap on it has nowhere to go so you have no flow. With no water flowing your gpm/amps will be zero. Now put a sprinkler on that hose and your gpm/amps will go up, as you now have water flowing through the hose. That is comparable to say, turning on your stereo. Put 10 sprinklers on that hose and your gpm/amps continue to go up as you add sprinklers, comparable to turning on your lights, heater fan etc etc.
I can't say that I know how much alternator output is devoted to charging the battery, but it's probably not a whole lot. As I said above with just the engine running and nothing turned on, there are not many things drawing amps, so you're reading should be pretty low.
Usually what I do if I suspect I'm getting a battery drain is check each wire coming off the positive terminal of the battery one by one to see which one is drawing amps, that narrows it down to a particular circuit, then I trace it out on down the line. The wire that goes to the 'H' terminal on the fuse box may be drawing a small amount of amperage if you have things like a clock or digital stereo that draw power when the car is off, but that should be less than one amp.
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Right on,accu is JUST for start,after that all juise is from alternator.
for 9 V on start,it `s all about temp.
(http://www.dodaj.rs/f/36/2r/2pEDDP0W/11.jpg)
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Rabbit79, I like the garden hose analogy here. Most folks will get it. I was not sure what the flow of current should be into the battery at idle but I knew it would be low. When the meter was working for me I did measure 0.02 amps trailing out of the battery and the only thing that was drawing power that I know of was the clock for the radio. I might try measuring the radio on and key on for different things. Just for grins and giggles.
As for the battery condition at this time. It is a steady 11.5 volts and I was thinking that for times that I do not use the car that a small solar powered trickle charger would be in order here. They generally plug into the power outlet or a cigarette lighter, do cars even come with those anymore? A 40 dollar option?
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It sounds to me like your charging system is ok. My battery usually hangs out right in that 11.5 volt range as well, and I rarely have trouble cranking unless it's really cold outside and I haven't plugged it in. Was that 9 volt reading while you were cranking? I can't say that I know how much voltage drop you would normally get while cranking, so I just went out and checked on mine to see what it is and my volt gauge dropped down to 10 while I was cranking on it, so 9 might be a little low. My battery is about 3 years old so yours should be in better shape than mine. With a pretty new battery in there I wonder if your starter is beginning to think about failing.
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A nine volt reading is low for a new battery so I did pull the starter to check out the operation outside the housing. Spun up real nice, looked in the housing to see what the bushing looked like and it was not showing signs of wear either. What I did notice was that it was sort of hard to get out, like it was torqued in there or something. So maybe alignment was off. I was trying to correct the shakes out of it a month ago and perhaps raising and lowering the front mount did something to starter.
I have to think that getting the charger on the battery will bring it back to full strength and I can go from there. I might need to advance the timing a tad as it starts less than good when it is in that temperature zone where the GPs don't come on and the engine isn't warmed all the way. An over-ride switch has been mentioned here lately and I might go that route as well. I could confuse the heck out of folks with a big GP button glowing on the dash. Push for luke warm start? We don't get cold weather here unless you count 30 F as cold.
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9v is a dead battery. a fully charged battery should hold pretty close to 12.6v. There are 6 cells in series that should hold 2.1v each in a 12v battery. If I remember right from school .04A or .06A is considered an acceptable current draw on a vehicle that is turned off.
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Clarification to 9 volt number, That was when cranking the 11.5 or so was static charge with no draw other than radio clock.
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11.5v is basically a dead battery
State of Charge Voltage
100% 12.7
75% 12.4
50% 12.2
25% 12.0
Discharged 11.9
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if your alternator is outputting 11.5v with no load (and doesnt increase with rpm) then you want a new alty. Mine was putting out like 12.6v for the past 6 months or so. 2 weeks ago I barely made it home on a 2 hour drive, I had to turn every electronic off on the car other then the headlights (even had to unplug 1 headlight). I was lucky it was still making enough charge to power 1 headlight and the distributor (this is my gasoline vehicle), I did however have to bump start it when I stopped for dinner and to get gas.
New one outputs 13.8v.
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The 11.5 vdc was the reading I got when I popped the hood and slapped the voltmeter across the terminals. 9.0 was what I got upon cranking the starter and it was slow but strong.
My alternator was flipping from 12.2 to 14.2 with a steady 1500 RPM showing on the Tiny Tach.
I swapped out the voltage regulator and the voltage is a steady 13.8-14.0 now even if I rev it up and down. Before it would wander terribly.
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Have your battery load tested, a bad one will kill your alternator, and your starter too.
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B_Y_M, I already took one 84 mth battery back after 3 mths as it was not holding a charge. To date I have had the alternator tested for volts only. 14.2 -13.8 is current output. Not sure of the amps but I will have a better idea of that later this weekend. No rain in the forecast. I have replaced the loose belt and the variable voltage regulator so far.
I parked the car for the week at work and was traveling all week and guess what didn't have enough juice to turn the car over. Almost but not quite. So, I just jumped it but once I got it home I had to put it on the charger for like 6 hrs @ 2 amps to get it to come up on the meter on the charger to better than 75% but not quite to 100%.
Now that I have storage I am going to try to source out the leakage. If I even have any. All I am reading here is that my 0.02 amp draw is within spec. And don't anyone suggest cleaning the terminals or the connections to the body and the starter. They are already shiny and tight.
Very odd that the one car I have that uses the least electricity from the battery when driving is the one that is causing me the most trouble.
Oh, Murphy's law that's it.
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Charge your battery on your trickle charger as full as you can get it. Then leave It disconnected overnight and record the voltage. If the voltage has dropped a significant amount with no load on the battery I'd say it's defective.
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A battery needs to be load-tested, resting voltage is a poor indicator of battery viability and capacity.
20mA draw should not kill your battery in two months much less a week.
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Check the water levels in the battery as well as low water can reduce capacity.
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Thanks for the additional tips guys. I forgot to check the fluid levels for storage capacity. Any time you start having high charge no charge stuff going on those Maintenance Free batteries need maintenance. Why do they call them that? Like a fuel free car? Sure but it only goes 300 miles and you walk from there.
I will try the battery disconnect as well as I have a second daily driver I can use. Any rules of thumb on the loss of voltage over night for reference?
I do have test equipment back in hand and the wife's car is out of the driveway. Time to go try and source out what I can.
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I would not go by overnight reading. Too small a sample and you need to burn off the surface charge first. I'd put the ammeter in series with the battery in the car and look for parasitic losses while the car is off.
If your regulator was bad, that could have killed the first battery.
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Or diode,light is out after start right.
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A dash-mounted voltmeter would be a great help.
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I actually have both an inline Amp and Volt gauge on the dash. Trouble with the ampere one is it is really to coarse at O - 60 at the low end. You know you are on the Positive side but not how much. Am I getting 2 or 12 amps if I turn the lights on.
Volt gauge is much better. It was the one that tipped me off to a bad regulator in the Alternator. It would jump around like it had a bad wire connection in the back on the terminals, but it really didn't.
So this afternoon I strolled out to the mighty VW Rabbit and measured 12.0 VDC on both meters I have and I pulled the negative side of the battery and will let it set for the better part of the week and see what happens. It will get in the 40s at night and 60s in the day time so not much of a swing there but I should be able to find out if it is loosing it on its own and not connected to the battery at all.
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Once you do the standing test, hook the battery back up and turn the lights on. You should observe a very small drop in voltage. If it falls fast, time for a battery.
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Old school battery test for 100 Ah one,
charge to full with 10 A or 14.5 V,next day discharge with 5 A load(1/20),with light 55 W, untill 10.8 V drop,URGENT STOP DISCHARGE then,measure the time.
If you discharge with 5 A for 8 hour, then you have 40 Ah battery.
That is true in my case, so change in shop next day.
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12 volts on a sitting battery is bad.
It should be around 12.7,.. unless it's really cold.
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Day one test one disconnected battery. Still the same 12.0 volts DC I left it at yesterday.
Truck battery also measures 12.0 and have no issue with starting on it. 1 year old. 84 mth battery very similar to VW.
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Your meter could be off. Try a different meter.
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I use two meters, one digital with new batteries and then the old tried and true Analog meter that I have used for 30 years. At the time it was top of the line and I use the 50 volt scale and can be accurate to .5 volt on that scale.
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Did you try your meters on a known good battery? What do they read? 12 volt indicates a bad battery.
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That is why I measured my truck battery. It was less that a few months old and still gave me 12 volts. I will try the wife's car and maybe the guy across the street. Let you know tomorrow as the weekend looks sunny.
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If a recent new battery also reads 12 v, it has to be the meter. Maybe the meter's got a bad battery.
Go here www.dealsoff.com/harbor-freight-coupons/
and prinrt a coupon and get a free digital multimeter at HF.
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I have a HF digital meter with brand new batteries in it. It provides a single volt reading due to selector is at 300 volt scale. It provides me with a 12.0 reading. The other meter I use is analog and the battery voltage again was dead on 12.0 volts as of last Saturday. I will measure in the cool of the morning as that is low volt time. I bet it will be.......you guessed it 12.0 volts DC!!!!
Then I am going to put it on the charger for a bit and see if indeed I can get it to the full potential of 12.7 or so.
So much fun.
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Out in the low 50 degree morning with two meters, the battery charger and an extension cord.
First the measures. HF digital shows 12.0 and so did the VIZ analog. So no surprises there.
Hooked up the battery charger and flipped it to the 10 amp mode and sure enough getting about that into the battery. But only for like 5 mins then the green full light comes on the charger and 0.0 on the amp meter.
So I flipped it to the 2 amp trickle charge and up comes the amps and then it starts to cycle. A few seconds of charge, a few with the full power light on. I let it go that way for about an hour then I noticed that it didn't cycle anymore and a fairly steady 1.5-1.6 amps were registering on the amp meter. I flipped it to the volt side and it was solid at 13 with an occasional flicker to 14. I ran it that way from about 1 till 5 and it was still taking that steady input then.
I finally had to wrap stuff up for the evening and just for grins I cycled the glow plugs and cranked it over. Very strong spin on it and instant on. I looked at the internal gauges I have and I had a positive amp reading and 14 volts on that gauge. I shut it off and did a restart without letting the glows cycle off and the internal volt gauge dipped to 10.5 and immediately came up to 12.5 then 14.0.
I hope that the battery can keep its charge now that it is back up to nearly new. I wonder if putting the trickle charger on it tomorrow if it would go all day or just a few hours?
I will post again if I get another draw down in like two months.
>:(
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If your "new" battery go from 12V to 14 V in 5 min,for me it isn`t good,you can do it with good one BUT for 5 hours.Do you try to desulfate?
I try on old battery,but have some + for 5 days.On new one ,I got after more try much better results.
I think they made poor or from recycled battery todays, battery are mostly bad today.
This is how I did,don`t afraid to hook on 110 VAC,I did on 220 VAC and there is 12.8 V on battery,so it`s safe.Just disconnect one battery terminals for peace of mind your alternator,and go.
I use 16 mF ,from washing mashine,and get 3 A ,but it`s very pulsating curent.
(http://farm3.static.flickr.com/2751/4298679896_499c635e34.jpg)
more from:
" My charger is fused to 5 amps with a neon indicator lamp to show when its hot. Its built in an Army ammo can.
I use a 50 mfd ac motor run capacitor for a 2 amp current limiter, just enough juice for a slow overnight desulfating charge. I used a 25 amp/400 volt bridge rectifier. This charger will charge any lead acid battery, no matter what the battery voltage is ... 6, 12, 24 volt ... it doesn't matter. My cost to build it was $12.
The problem with regular voltage limiter chargers is they cannot equalize a battery or desulfate cells. Not enough electrical pressure to bust up the lead sulfate that's insulating the cell plates.
The power output is limited by capacitor size - 25 mfd per amp output. If you want a 1/2 amp charger use a 12 mfd capacitor, if you want a 6 amp charger use (3) 50 mfd capacitors wired in parallel , ect , ect, ect ... "
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mtrans can you post a picture of your setup?
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I can bUT IT SAME AS PICTURE,I JUST DIDN` PUT SWITCH,BUT IF YOU NEED?
DIY,NOT MUCH T SEE.
BEST
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If your "new" battery go from 12V to 14 V in 5 min,for me it isn`t good,you can do it with good one BUT for 5 hours.Do you try to desulfate?
I try on old battery,but have some + for 5 days.On new one ,I got after more try much better results.
I think they made poor or from recycled battery todays, battery are mostly bad today.
This is how I did,don`t afraid to hook on 110 VAC,I did on 220 VAC and there is 12.8 V on battery,so it`s safe.Just disconnect one battery terminals for peace of mind your alternator,and go.
I use 16 mF ,from washing mashine,and get 3 A ,but it`s very pulsating curent.
(http://farm3.static.flickr.com/2751/4298679896_499c635e34.jpg)
more from:
" My charger is fused to 5 amps with a neon indicator lamp to show when its hot. Its built in an Army ammo can.
I use a 50 mfd ac motor run capacitor for a 2 amp current limiter, just enough juice for a slow overnight desulfating charge. I used a 25 amp/400 volt bridge rectifier. This charger will charge any lead acid battery, no matter what the battery voltage is ... 6, 12, 24 volt ... it doesn't matter. My cost to build it was $12.
The problem with regular voltage limiter chargers is they cannot equalize a battery or desulfate cells. Not enough electrical pressure to bust up the lead sulfate that's insulating the cell plates.
The power output is limited by capacitor size - 25 mfd per amp output. If you want a 1/2 amp charger use a 12 mfd capacitor, if you want a 6 amp charger use (3) 50 mfd capacitors wired in parallel , ect , ect, ect ... "
Where did this idea come from? From what I can tell looking at the diagram, it is a a capacitor current limiter through a full wave bridge, rectifying house current of 120 V AC (in your country 240 V AC). The output is 120 VDC and 240 VDC. I don't know what high voltage like that will do to the battery. Battery de-sulfators use pulsed voltage at some frequency around 4 khz. Your circuit being full wave does not have much pulsing going on at the intended frequency of 60 hz (50 hz).
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Yes you are right,one way of use capacitor is as current limiter,but theory say it`s more than 50/60 hz after cap and diode.
I also don`t believe it can work,but I first test on bad battery and then on "good" one from shop just like ORCoaster,and in both cases I get ~ 14V and 3 A on BATTERY,same after 5 hours of use so...
Only real DC come from dinamo,alternator isn`t,and I don't`have oscilloscope to verify.
For desulfate ,they say,you need strong and short pulses and that give cap,and there isn`t cap AFTER
diode to kill pulses completely.
For real one desulfator,there is a LOT electronic, so this one is good for me.
I need a caple run to see same +++ on new battery,not much on old one.Just do it,it`s easy and helps a lot.
And notice,this isn`t for charging as is for desulfate.
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By the way,ORCoaster because you are there,
put One diode(10A) after 3 small ones and before it go to rotor field,in that direction.I have 13.6 v before and 14.2-14.5 after that operation.I do put swich parallel with add diode,so it`s ON(or close) on start car because I don`t want too mach current to battery on start,but after 15 km I change to OFF (open) so I get more V for rotor.
So,it`s not your privelege for gremelins.
Perhaps you find that usefull.Best
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I just recharge my bad battery and remmember you ORCoaster, so for you one that don`t belive you can conect battery on 220 V AC here...
(http://www.dodaj.rs/f/v/11/2um5SIzk/p1010004.jpg)
(http://www.dodaj.rs/f/y/WB/3xbODxre/p1010002.jpg)
(http://www.dodaj.rs/f/1J/K6/1kMwnwRd/p1010003.jpg)
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So running 220 volts AC through a capacitor and bridge rectifier allow it to be hooked to a DC battery.
Interesting.
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Yes,even I didn`t belive,there is of course special aperture to desulfate but $$$. Good thing for today`s teen plate recycled battery which they sold as NEW,as I read no. 1 reason for that is sulfate that plate.Just use MOTOR cap,not ordinary one and go,you will see big +++++,but as always,it`s better on not totaly sulfate battery.Do it many times it helps a lot,but from grandma can`t be girl.
ps. Old and smart guys tell that in dark and from back you will never see difference.