How do you increase the engines idle speed. This is accomplished by the pulley sizes. Alternator output is most definitely determined by alternator speed. The curve is not straight either. At idle, the amp output is low, and this is normal. EDIT: Problem was fixed, it was the ground cable. Or a weak relay if somone added one. New patented technology: The unique use of permanent magnets enables the high output Eco-Tech 305-I alternator to generate 260 Amperes (135 Amperes for 28V versions) at 1,800 Alternator RPM as compared to 2000 RPM, the idle speed most often quoted by competitors.This high-at-idle alternator is a unique solution to achieving high output at low RPMs. Mark is actually dreaming. Although alternator manufacturers, rebuilders, and suppliers typically refer to the rated output in promotional materials, both the ISO and the SAE require a format of “IL / IRA VTV,” where IL is the low, or idle, amperage output, IR is the rated amperage output, and VT is the test voltage. Alternator Output. Alternator output is on demand when there are loads detected or the battery needs to be charged. Perhaps as low as engine idle speed on many cars. Overrunning Alternator Pulleys (OAP) are used on a number of late-model import and domestic vehicles. If your idle speed is below 1200 rpms, that will reduce a modern alternator's output even further. Should be around 14 Volts. Discussion Starter • #1 • Jan 3, 2017. The smaller pulley turns the alternator faster at lower speeds thus making more power. There are several ways to get more power at lower engine speeds. Best-in-class IdlePro Extreme alternators feature an array of engineering benefits that enhance electrical system and engine performance to extend battery life and increase vehicle uptime. The lights may dim but they should not go out at all weather the alternator is putting out or not. The most important thing is that the power goes in one end and exits the other. And does that mean my alternator is outputting good power? If you only require a little more power at lower engine speeds you may be able to use a smaller pulley. 2) Could a bad ground cable be responsible for the described issue? alternator output power at idle speed without violating thermal. 13.90 alternator case and block idle. I thought the curve was versus engine speed, forgetting about the small alternator pulley. 3Amp better alternator output at idle speed range that is roughly equivalent to the necessary output … Save Share. Often times the battery is taking up part of the load. Testing Alternator Amperage Output. Idle speed and alternator pulley size can also affect alternator output. The least expensive upgrade from the 10-DN would be to step up to a 10-SI or 12-SI. Generally 1200 rpm's = 10amps, 1500rpm's = 20 amps, and 2000rpm's = 35 amps, max output is reached at 4500 rpm's (51 amps). Actually there could be 3 things. Reply. 208 Posts . Burned stator windings are common, in applications that continuously require a high amount of alternator output, and so are heat-damaged rectifiers. Remember, this is alternator-not engine speed. If you run a 600 RPM with blower, wipers, A/C, rear window defoggers, and headlights, the alternator will put out about 30-40 amps. You should see the difference. If the alternator output voltage is fluctuating it's likely to be a fault in the solid state control pack, usually integral with the alternator. or current limits of the alternator. While use of an SMR and load matching control enables large improvements in output power at cruising speed, no extra power is obtained at idle. With my factory idle speed of 865 RPM and crank/alternator pulley ratio of 130/80=1.63, my alternator should be turning 1405 RPM at engine idle. (Seems a little low too). 12.44 battery, alternator, idle under load. An alternator reaches max output at a relatively low RPM. If the application calls for considerable output at idle speed, but not especially a high gross output; then the souped-up 10SI may also live a long life. This is a 4M40, series 1. 5,712,786, proposes an engine idle speed control method that employs, among other features, a map related to engine idle speed and alternator field duty cycle to determine alternator output current without using a shunt. Think lights on and engine off. Probably 3:1 so a 2400 rpm alternator shaft speed would translate to a 800 rpm engine speed, but I certainly am not sure of the Alternator Shaft ratio to Engine Crankshaft Pully ratio. The new Leece-Neville IdlePro Extreme™ series alternators offer industry-best output at low engine speeds, utilizing a high-amp, brushless design. So an engine that idles at 700 rpm with a 3:1 pulley sizes can have an alternator spinning at 2100RPM when the engine is idling. The new modulation scheme. In addition to testing the output voltage of an alternator, checking the amperage output is also vital. The specifications you see on our website reflect results as follows: Advertised Idle Output @ 2,400 RPM. Alternator slippage and undercharging can also be caused by a bad alternator pulley. Check the amperage output at the rear of the alternator and see if it is more or less than the amperage coming out of the battery's positive cable. 12.23 alternator case and block idle load. Most systems are designed to create just enough power at idle to keep running. No alternator can output it's full amp rating at idle. Most belt driven alternators in cars and trucks are not driven 1:1 at engine speed. A failing alternator will cause many problems for a vehicle and will eventually result in the engine stalling or being unable to start. Depending on ambient temperature, charging voltage varies. Idle speed will be your lowest output voltage, and by 1000 RPM you should be at full output. Newly designed ventilation which cools the coils better; Advantage. But it is safe to keep a few pointers in your mind. In the case of a 12-volt applications much of this wisdom also applies. 13.50 case and block 1,500 rpm's load. As long as the engine is on, the alternator will keep on charging the battery. Happy New Year to you all. If the voltage is especially low, the alternator may be bad. 13.80 battery, 13.83 alt 1,500 rpm's. This alternator (10-DN), uses a flat, two-prong connection at the back of the alternator. Constant regulated output regardless of driven speed. So my question is this. The rest will come right out of the battery. Advertised Maximum Output @ 4,800 – 5,200 RPM. With 12+ volts in the system the lights should be on. It could very well be 2:1, which would put the engine speed at 1,000 rpm for a Alternator Shaft speed … The alternator spins at a higher RPM than the engine. Testing the voltage output of the alternator is one way to detect problems with the alternator. The alternator should be tested with the engine idling and electrical accessories, such as the radio and headlights, turned off. Lastly you need to consider the idle speed of your engine. We know for example, that a 1950 Chevrolet has an idle speed of about 700-800 rpms. Using @landphil number of 3:1, just over 750 rpm engine idle speed would be about 2250 alternator rpm on the curve, which shows exactly 200 amp output. An alternator should put out between 13.5 and 15 volts of power. The original 1960’s GM alternator employs an external voltage regulator. For example, Ueda, U. S. Patent No. Our alternators are tested on our test bench to provide the best output for most driving conditions including low speed or idle operation. Then when you increase RPM, the alternator will put out more amps to recharge the battery. The alternator, on the other hand, is driven by the engine in your car. It is a give and take sort of relationship between the two. Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30497 Post Options A reduced output may be a sign that the alternator is failing, but the drive belt and wiring should be inspected before replacing the alternator. Once you ve reached the peak alternator rpm, in this case at 4,000 rpm, increased speed doesn t create more power output. An alternator should put out between 13.5 and 15 volts of power. Typically a 12 volt DC unit will begin making power around 1000 rpm's. Vehicle is a 2000 Acura TL. SUPERIOR AMP OUTPUT Delivers higher amps at idle and cruise speed compared to the competition. This document introduces a new SMR modulation strategy capable of improving alternator output power at idle speed without violating thermal or current limits of the alternator. If I increase the RPMS a little the alternator kicks in. If you are having problems with overall alternator output or charging at engine idle, maybe a smaller pulley is all you need. Low voltage may also be caused by poor electrical connections, a loose drive belt, low engine idle speed, and a number of other issues. Worth noting that an alternator (AC output) does not have a speed/Voltage relationship. These figures are alternator RPM speed. 1) Is my method of testing alternator output correct? Thank you. There are two things that will cause this. 13.93 battery, 14.00 alt running idle. One way to test your alternator's output voltage (crudely) would be to throw a multimeter across the battery posts with the engine shut down, then start it up and take another reading. Improved Output at Low-Engine Speeds Minimum of 90% output of unit’s rated maximum output at engine idle speed* provides efficient, battery-saving performance Premium Brushless Design Best-in-class brushless performance without the weight & size downfalls of conventional alternators The alternator will turn at idle but does not produce the maximum current. The alternator needs enough output at engine idle speed to keep the electrical system of the vehicle functional. It just doesn't seem to charge at an idle. Improving Alternator Output at Idle Speed . Can provide useful charge at idle speed Use slip rings , having greatly extended brush life over a commutator The brushes in an alternator carry only DC excitation current, which is a small fraction of the current carried by the brushes of a DC generator, which carry the generator's entire output The alternator pulley is usually smaller, making the alternator turn faster than engine speed. NRMA jump started me and it looks like the alternator doesnt put out proper charge at current idle. OAP pulleys have a one-way clutch inside the center of the pulley that slips and allows the pulley to free-wheel when engine speed suddenly drops. The other main connection on the alternator is the output terminal that charges the battery. Reactions: Dave Z and Bob Lincoln. Below that the power output varies. A bad switch breaker so replace the switch. 13.60 battery, 13.70 alt load 1,500 rpm's. Alternator Output at Idle Speed. may be implemented with simple control hardware, and without. n0 for the Mahle 120A AAK alternator is 1400 RPM, meaning that no output current should be expected from it at that RPM. The connection was corroded very badly -- keep your grounds CLEAN.