How Good Is This Battery + Alternator Test

[NRX]

Guys!

I use my car once a week for short distance trips ( 25Km max). The battery was dead ( not enough power to crank) twice for the past month and I gave it an overnight charge from a battery joint. After 2 days of being not started I did the following tests. Please help me to identify if there are any issues with my charging system. My battery is a Lead Acid type and at least 2 years old.

Idle = 14.3V

Idle + AC = 13.15V

Idle + Head Light + AC = 12.3V ( Drops to 12V sometimes)

2000RPM =14.2V

2000RPM + AC =14V

2000RPM + Head Light + AC = 13.9V

Battery only = 12.33V

Edited February 11, 2013 by NRX

[Rumesh88]

Your alternator seems quite OK. However, when you have headlights and AC on your idle speed should be in the region of 800 - 1000 rpm, depending on the car model of course, and the battery voltage should be above 13V ( These are of course rule-of-thumb values and should not be treated as accurate readings). If you use your car only once in a week it is mandatory to keep the battery float charged if u expect it to last beyond 2 years.

[harshansenadhir]

Previous instances of not having enough juice to crank happened after a night drive with A/C? looks like the charging at idle with accessories is little less specially if it drops to 12v sometimes.

Battery holding 12.33 after two days of not being started is a good sign of the battery but carry out a battery test at a trust worthy place. they check every cell for the ability of holding power.

carry out following test to ensure that there's no current flaw back to the circuit from battery,

1 . make sure all accessories are properly switched off (not even a door lamp should be switched on when you're doing this test, best of the fuse of the setup also can be taken off as some sound setups take little current to maintain the memory)

2. remove the positive wire connector from the battery terminal.

3. take a 12V bulb with lesser wattage such as a parking bulb (T10) and wire it and test whether it's working.

4. then attach one wire of the bulb to battery terminal and the other wire to the (+) positive wire which you have removed from battery terminal. if the light glows, then there's a current flaw back to the charging system

if this test shows that there's a current flaw back to the system, then that explains as to why the car didn't start. get the charging regulator circuit or regulator cut out checked.

[NRX]

Your alternator seems quite OK. However, when you have headlights and AC on your idle speed should be in the region of 800 - 1000 rpm, depending on the car model of course, and the battery voltage should be above 13V ( These are of course rule-of-thumb values and should not be treated as accurate readings). If you use your car only once in a week it is mandatory to keep the battery float charged if u expect it to last beyond 2 years.

Thanks mate!

Previous instances of not having enough juice to crank happened after a night drive with A/C? looks like the charging at idle with accessories is little less specially if it drops to 12v sometimes.

Battery holding 12.33 after two days of not being started is a good sign of the battery but carry out a battery test at a trust worthy place. they check every cell for the ability of holding power.

carry out following test to ensure that there's no current flaw back to the circuit from battery,

1 . make sure all accessories are properly switched off (not even a door lamp should be switched on when you're doing this test, best of the fuse of the setup also can be taken off as some sound setups take little current to maintain the memory)

2. remove the positive wire connector from the battery terminal.

3. take a 12V bulb with lesser wattage such as a parking bulb (T10) and wire it and test whether it's working.

4. then attach one wire of the bulb to battery terminal and the other wire to the (+) positive wire which you have removed from battery terminal. if the light glows, then there's a current flaw back to the charging system

if this test shows that there's a current flaw back to the system, then that explains as to why the car didn't start. get the charging regulator circuit or regulator cut out checked.

Thanks Harshan. No it wasn't after a night drive, but after few short trips ( 3,4 stops/cranks) within half an hour.

I guess I can do this test with a multimeter as well right ?

BTW could we attibute the low voltage @ idle under load to a weak/failing battery ?

Edited February 11, 2013 by NRX

[harshansenadhir]

Thanks Harshan. No it wasn't after a night drive, but after few short trips ( 3,4 stops/cranks) within half an hour.

I guess I can do this test with a multimeter as well right ?

Yes, can do with a multimeter.

BTW could we attibute the low voltage @ idle under load to a weak/failing battery ?

nope

[NRX]

Yes, can do with a multimeter.

nope

Harshan. I've noticed recently that when I switch on electrical items the RPM doesn't go up, in fact it goes down a bit, as I remember it used to go up. Works fine when the AC is switched on though, ie: goes up ( Doesn't work when only the blower is switched on).

Mine has a carb and there is a little vaccum idle up unit that is connected to the carb and the other end to some wires. If it works for AC I don't know why it isn't working for other electrical loads

Edited February 11, 2013 by NRX

[Rumesh88]

There must be an electrical solenoid inside your carb to rev up the engine when you switch on your head lights. You should be able to see the two wires coming out from the top of your carb when you remove your air cleaner (Pls feel free to correct me if I am wrong). If this mechanism does not work it will not rev up when u switch on you head lights. BTW I get the feeling that the supply to your alternator regulator has dropped on its way from the dashboard. You can check this using a makabaas method (although fully scientific) by starting ur engine in a morning when everything is cold and feeling the connectors under the dashboard for slight heat up. Do not switch on AC but u may keep the headlights on. If you find a connector that is getting heated up you may have to inspect and get them cleaned for proper connection. Also, since most of the connector are of white color you may be able to spot some of them getting a little brownish because of heat produced by less-than-perfect electrical connections.

[NRX]

There must be an electrical solenoid inside your carb to rev up the engine when you switch on your head lights. You should be able to see the two wires coming out from the top of your carb when you remove your air cleaner (Pls feel free to correct me if I am wrong). If this mechanism does not work it will not rev up when u switch on you head lights. BTW I get the feeling that the supply to your alternator regulator has dropped on its way from the dashboard. You can check this using a makabaas method (although fully scientific) by starting ur engine in a morning when everything is cold and feeling the connectors under the dashboard for slight heat up. Do not switch on AC but u may keep the headlights on. If you find a connector that is getting heated up you may have to inspect and get them cleaned for proper connection. Also, since most of the connector are of white color you may be able to spot some of them getting a little brownish because of heat produced by less-than-perfect electrical connections.

You are spot on with the two wires. It is originating from the carb from like a spark plug like connector. I did a carb repair few months back and I guess the idle issue wasn't there before the tuneup :/

[harshansenadhir]

There must be an electrical solenoid inside your carb to rev up the engine when you switch on your head lights. You should be able to see the two wires coming out from the top of your carb when you remove your air cleaner (Pls feel free to correct me if I am wrong). If this mechanism does not work it will not rev up when u switch on you head lights. BTW I get the feeling that the supply to your alternator regulator has dropped on its way from the dashboard. You can check this using a makabaas method (although fully scientific) by starting ur engine in a morning when everything is cold and feeling the connectors under the dashboard for slight heat up. Do not switch on AC but u may keep the headlights on. If you find a connector that is getting heated up you may have to inspect and get them cleaned for proper connection. Also, since most of the connector are of white color you may be able to spot some of them getting a little brownish because of heat produced by less-than-perfect electrical connections.

Harshan. I've noticed recently that when I switch on electrical items the RPM doesn't go up, in fact it goes down a bit, as I remember it used to go up. Works fine when the AC is switched on though, ie: goes up ( Doesn't work when only the blower is switched on).

Mine has a carb and there is a little vaccum idle up unit that is connected to the carb and the other end to some wires. If it works for AC I don't know why it isn't working for other electrical loads

seems the idler mechanism is working as it works for A/C (or are there two separate idle up valves? ) however, the input to the idle up valve from headlight relays/switch may be faulty.

[Rumesh88]

You are spot on with the two wires. It is originating from the carb from like a spark plug like connector. I did a carb repair few months back and I guess the idle issue wasn't there before the tuneup :/

OK NRX. This is why I asked you if your idle is OK in Post#2 above. Did they dismantle the carb while repairing it? If my memory serves right the two wires connects to a solenoid actuator (black plastic part inside the carb) which in turn is a part of the carb mount in the form of a through stud. You have to unscrew the part containing the solenoid to reach one of the carb jets. In doing so if you hold the stud in the wrong manner you would end up breaking the solenoid coil. Check the continuity of the solenoid by removing the connector outside the carb. See if the reading is below 100 ohms. If the coil is open, it is gone for good, and just forget it. If the coil is having continuity then use a bulb similar to Harshan has explained on the other side of the connector to see if the solenoid is powered during idle and when headlight is turned on. (BTW trust you refer to the two wires going right into the carb on top not the one or two wires that connects to idle cut-off solenoid which is visible from outside).

In this carb model the idle compensation mechanism for headlights is not vacuum operated. Only the AC compensation is provided by a vacuum operated dash pot.

Edited February 11, 2013 by Rumesh88

[Sylvi]

Members,

If any member wants to monitor the charging system always can buy a ampere meter. Get that installed correctly to the electrical system of the car.

Clip on ampere meters are available they are expensive but it saves the trouble of wiring. Mostly Electricians use for testing.

Amp meter will cost, with wiring Under 1000.00 Rupees.Then driver on the way can monitor the charging rate on the normal driving conditions.

Motorist wants can fix a DC volt meter. To monitor the battery condition. Volt meters are cheap cost for wiring and meter is not more than 500.00 Rupees.

Both ampere and volt meters instalation has to be done by a qualified electrician for correct amperage wires. If not the system can damage.

Sylvi Wijesinghe.

[akboselk]

Hi

I've purchased below gadget from ebay

http://www.ebay.com/itm/D0X8-Mini-Car-LCD-Battery-Voltage-Meter-Monitor-12V-Black-Red-Digital-Screen-ElR-/230884361330?pt=LH_DefaultDomain_0&hash=item35c1c7c472

[NRX]

OK NRX. This is why I asked you if your idle is OK in Post#2 above. Did they dismantle the carb while repairing it? If my memory serves right the two wires connects to a solenoid actuator (black plastic part inside the carb) which in turn is a part of the carb mount in the form of a through stud. You have to unscrew the part containing the solenoid to reach one of the carb jets. In doing so if you hold the stud in the wrong manner you would end up breaking the solenoid coil. Check the continuity of the solenoid by removing the connector outside the carb. See if the reading is below 100 ohms. If the coil is open, it is gone for good, and just forget it. If the coil is having continuity then use a bulb similar to Harshan has explained on the other side of the connector to see if the solenoid is powered during idle and when headlight is turned on. (BTW trust you refer to the two wires going right into the carb on top not the one or two wires that connects to idle cut-off solenoid which is visible from outside).

In this carb model the idle compensation mechanism for headlights is not vacuum operated. Only the AC compensation is provided by a vacuum operated dash pot.

Yes. They dismantled the carb and did the repair/tuneup. My car is a FB13 imported as brand new (Different Carb may be) and the carb I have in mine is the same one as this article. There are a lot of photos of the carb here.

http://www.justanswer.com/uk-car/27vhf-does-nissan-sunny-suddenly-cut-out.html

[NRX]

Hi

I've purchased below gadget from ebay

http://www.ebay.com/itm/D0X8-Mini-Car-LCD-Battery-Voltage-Meter-Monitor-12V-Black-Red-Digital-Screen-ElR-/230884361330?pt=LH_DefaultDomain_0&hash=item35c1c7c472

Well machan, I also chcked few days ago and the accuracy was a bit low.

[Rumesh88]

Yes. They dismantled the carb and did the repair/tuneup. My car is a FB13 imported as brand new (Different Carb may be) and the carb I have in mine is the same one as this article. There are a lot of photos of the carb here.

http://www.justanswer.com/uk-car/27vhf-does-nissan-sunny-suddenly-cut-out.html

You can find a picture of an internal solenoid similar to your one here.

http://images.oreillyauto.com/parts/img/large/bwd/ecs845_1.jpg

However it is not much difficult to trace the connection and see if the solenoid coil is still intact by measuring its continuity. BTW I find that many mechanics here are really very fond of taking a carb apart even to do a minor clean up. In most cases it is the air bleeders at the top of the carb which get clogged up due to dust. All u need is a good spray of carb cleaner through the air bleeders to clean them. (I remember walking up and down Darly rd and Panchi to find a can of STP carb cleaner - the only brand available here in 1994 AFAIK - to clean a FB13 carb). However, if ur fuel jets are clogged up or if you have a gasket crack then of course u need to dismantle it.

[Sylvi]

akboselk and NRX,

DC Ampere meters are available in Pettah 1st cross street electrical and electronic parts shops from Rupees 900.00 to 2000.00 Chinese and Taiwan.

Meters always go for moving coil. Digital meters do not last very long. I have some testing meters which I bought in UK for very small price.

I still have a Millimeter which I bought in UK after my electrical engineering training and a MYFORD table lathe in very good working condition.

I saw today Indian quality switches and plenty of electrical switch gear imported by a merchant. 1 container load of assortment products, He wanted me to have a look and to give my comments. On those Indian products he informed the costs. He wanted to recommend competitive prices to compete with other products in the market. They had all test reports to international standards.

They are expensive than Chinese, but quality is very much better than any other available in the market cheap switches and other accessories FROM EASTEN COUNTRIES.

Western products were the best at that time. No Ceylonese wanted eastern countries products during my small days.

Today everyone has switched onto Eastern country products and motor vehicles are the market leaders in most developed countries.

Sylvi Wijesinghe.

Edited February 15, 2013 by Sylvi