General Battery charging problem

[timgarman]

Hi Folks

I have a problem with the battery not charging.

I've looked into this and had the generator cleaned and reconditioned with new bearings and brushes. But I have the same issue.

The battery was dry recently but is now topped up and I'm getting a 12volt charge across it.

I've installed a separate generator LED on the dashboard and initially this was going out on high revs, but now isn't.

Haven't touched the voltage regulator yet but any advice on where the issue might be?

Many thanks

Tim

 

[cambio]

Have you got a mechanical regulator?
check the voltage from the dynamo at idle and with the engine set at higher rpm (use the cruise control cable!) by measuring it to the earth (engine casing. If its kicking out a good voltage (>14v) then i would look at replacing the regulator. Replacing with an electrical one really is a fit and forget job.

 

[timgarman]

Have you got a mechanical regulator?

The regulator in the car when I got it was a Lucas. I've replaced this with the original Fiat type.

Tim

 

[phoenix1]

Hi . When you said your battery was dry did you mean totally dry if so it means usually it has been overcharged and will now probably be useless.
Have you got the wire going to the ignition warnibg light connected and is the bulb ok.

 

[timgarman]

Hi . When you said your battery was dry did you mean totally dry if so it means usually it has been overcharged and will now probably be useless.
Have you got the wire going to the ignition warning light connected and is the bulb ok.

Battery looked pretty dry but not sure if it was completely so. It has been on charge often.

I've replaced the original Fiat dash with a new array which doesn't have the generator warning light. We've fitted a new LED in the dash to measure this. I know LED can have issues themselves so will be looking into this. Currently (no pun intended) it stays on.

 

[Vitesse]

Battery looked pretty dry but not sure if it was completely so. It has been on charge often.

I've replaced the original Fiat dash with a new array which doesn't have the generator warning light. We've fitted a new LED in the dash to measure this. I know LED can have issues themselves so will be looking into this. Currently (no pun intended) it stays on.

Tim you won’t get an LED to work for the generator warning light. As pointed out by Andrew I recall previously. LED’s have an anode + and a cathode - so they are polarity sensitive. For them to work they need a + 12v to the + side and 0v to the negative side.

With the generator warning light it works with 12v to one side of the bulb from the voltage regulator, which ultimately comes from the generator output and the other side comes ultimately from the battery, which of course is 12v, so they cancel each other out. No potential difference.

When you see the generator warning light flicker dimly at idle, it because the output from the generator has dropped by a couple of volts and therefore there is a potential difference of a couple of volts compared to the battery output. Therefore the generator light will come on dimly. You will only get it work properly with a conventional filament bulb.

 

[F123C]

Your battery may be toast.

Usual advice is to fully charge the battery and check that it is accepting and holding a full charge before testing the charging system.
You'd feel somewhat foolish if you had just spent a lot of time and money on the rest of the charging system only to finally realise that the battery was faulty.

Iirc battery should come up on charge to approx 13.2 volts (maybe a little more, depending on charger output etc.), and when removed from charging and left for a while, voltage will likely drop to c. 12.8 volts. You could also have the now fully-charged battery load-tested to check it's satisfactory and that there are no faulty cells.

Next, carefully check all battery leads, including earth leads/braids from battery to bodyshell and engine/gearbox to bodyshell. Pay particular attention to the battery posts and terminals. Then check all leads in the charging system. All corrosion needs to be removed. If you have and can use a multimeter, check for resistance at all connections (with power off) or do a voltage drop test with power applied.

When all of the above has been proven to be okay, then you can move on to checking the charging rate and system.

In my experience, on older vehicles, batteries and connections give more trouble than generators and voltage regulators.....

AL.

 

[timgarman]

Thanks Al and Tony.

I dom recall the conversation about the LED and I'm looking in to it. It's something to change but not the full problem.

The battery may be closer to the truth. I'll let you know when we've done some tests.

Tim

 

[Vitesse]

Trickle chargers are your friend. They carry out all sorts of charging cycles that maintain the battery in a decent state and increase the life span.

I have my 500 on one constantly and one of my moderns, well it was modern 12 years ago, but is garaged and has very low mileage. It was on its original battery until this year but eventually gave up the ghost after 12 years!

 

[timgarman]

Tim you won’t get an LED to work for the generator warning light.

Hi Tony. To add to my confusion, my 500 is at the Auto-Electrician's today. They tell me that an LED will work with a generator but not an alternator.??

 

[Bambino]

Hi Tim,

I talked to an Autoelectrician mate of mine today and he said that once a wet cell battery is dry for any length of time either through spill, evaporation or overcharging, it's probably stuffed.

The contact with the air apparently irreparably effects the plates - ? oxidises them.

You can refill the battery with distilled water and recharge it, but more than likely it won't hold a charge.

He also said that the current through the alternator lamp is used by the rotor winding until the alternator can supply enough itself and that using a LED in place of a filament bulb may not permit enough current to let this happen. A generator is different though and as long as you get the polarity correct, it should work OK.

Chris

 

[Vitesse]

Hi Tony. To add to my confusion, my 500 is at the Auto-Electrician's today. They tell me that an LED will work with a generator but not an alternator.??

As Chris has already said about the LED. I was wondering myself after I posted whether it would work with an LED, if there was a small potential difference across the LED rather than the full 12v. Unfortunately my HND in electronic engineering doesn’t get used much these days and I can’t remember TBH!

 

[timgarman]

Now returned from the auto electricians.

I have a generator with an LED mounted in the dash. This seems to be working fine. Stays on at low revs and goes out about 1100rpm.

The previous issue was the wiring to the generator which was the wrong way around and had fried the regulator. New (old) regulator fitted. (Incidentally, the guy at the workshop said if I wanted to spray the regulator cover, don't take it off, since it changes the magnetism (I think that's what he said anyway).

Not sure on the condition of the battery.

Next job will be to solve my bonnet issue.