Battery charging, is this normal ?

Alty Ian · Post by **Alty Ian** » Fri Sep 25, 2015 12:26 pm

With a fully charged battery, whenever the engine runs the ammeter goes right over to C and stays there, the only exception being when the engine revs drop when setting off when it reduces a bit.

I know the 4TF voltage regulators are problematic, but everything is new on this car having just been rebuilt and if this behaviour is abnormal I dont want to fry the new battery !

Gfhug · Post by **Gfhug** » Fri Sep 25, 2015 12:36 pm

Ian, have you driven many miles after starting? Certainly after a few miles the charge should drop to very little. If it isn't then be very careful.

Geoff

Post by **Heuer** » Fri Sep 25, 2015 12:51 pm

Put the battery on charge overnight, check it is fully charged and try again. It can take a long time to re-charge a half depleted battery from the alternator, even more from a dynamo.

Alty Ian · Post by **Alty Ian** » Fri Sep 25, 2015 1:24 pm

Heuer wrote:Put the battery on charge overnight, check it is fully charged and try again. It can take a long time to re-charge a half depleted battery from the alternator, even more from a dynamo.

Dave, thats what I did. Fully charged battery, just one touch of button starting the engine then it shoots to C and stays there.

Drove the car yesterday a mile or two and kept waiting for it to drop, it didnt.
How long would it take before the battery fries?

christopher storey · Post by **christopher storey** » Fri Sep 25, 2015 2:00 pm

Ian : check the voltage at the battery terminals with the engine running at say 2000 rpm and all other electrics switched off. If it is in the region of 14.5 to 15 volts then you need not worry about frying the battery . If it is significantly higher than that then there is a charging problem. In general terms , however, it requires rather more than a mile or two to top up a battery which has just provided a cold start ( particularly with a very new stiff engine which comes close to representing a dead short ) . If the voltage test is satisfactory , I would not worry about the ammeter reading unless it persisted for say 20 minutes after a cold start . Furthermore, if this is a new battery then depending on type they also take time to "run-in" through quite a number of charge/discharge cycles before they assume normal characteristics

Post by **Heuer** » Fri Sep 25, 2015 2:14 pm

Personally I would ditch the ammeter and install a voltmeter instead. The former is useless in an alternator equipped car, as you are finding out!

"Which is better for monitoring a vehicle's electrical system - a Voltmeter or an Ammeter? Short answer: A voltmeter, by far.

Electrical guru Mark Hamilton of M.A.D. Enterprises points out that amperage is a measure of current flow, so an ammeter is actually a "flow meter" that's intended to measure current flow to the battery (under normal conditions) or discharge from the battery (in the case of alternator system failure). On a typical flow meter, all output must be directed through the device to obtain an accurate reading. In the ammeter's case, that means all the alternator output used to recharge the battery must first be routed through the ammeter under the dash. Which requires a heavy-gauge cable and presents a possible fire hazard. And the ammeter itself must be able to handle all this current flow, so it must have a higher current rating than the alternator's maximum rated output.

All this might be worth the hassle if the ammeter produced reliable information. But the ammeter can only measure the amount of current output to the battery for recharging purposes: When the alternator recharges a "low" battery, the ammeter indicates a high charge rate; with a fully charged battery the voltage regulator reduces alternator output, and the ammeter is supposed to indicate a very low charge rate. But how can you really tell the regulator has reduced alternator output because the battery is fully charged? Maybe a diode in the alternator rectifier failed, or the alternator belt slipped after it warmed up, just as if the battery were fully charged. Or maybe the meter indicates a medium charge rate most of the time-does the battery want this much or could the voltage regulator be overcharging the battery?

On the other hand, a voltmeter works like a fuel pressure gauge-but instead of measuring fluid in psi, the voltmeter measures electrical system pressure in volts. Just like a fuel pressure gauge, a voltmeter only needs to tap into a circuit; all the fuel (or electricity) does not have to detour through the gauge itself. Voltmeter installation is easy, quick, and safe: It hooks up to a fused, ignition-switched "off/on" source and does not require any modification of the circuit used to recharge the battery or any part of the alternator/regulator system. In short, the voltmeter installed at the dash will be a stand-alone circuit.

The voltmeter directly measures the result of charging-system performance. With normal alternator/voltage-regulator function, battery voltage is maintained at 14.0 to 14.5 volts-and this is reported directly by the voltmeter. In the event of alternator-system failure, voltage will be low and continue to drop as the battery discharges. In the event of an "overcharge" condition, the voltmeter will climb above its normal zone. In summary, there is no chance for misinterpreting a voltmeter's readings as can happen with an ammeter."

Full installation details here: viewtopic.php?t=166

Alty Ian · Post by **Alty Ian** » Fri Sep 25, 2015 7:35 pm

Great advice Dave, I was thinking about doing that as I have always had a voltmeter in my S3 and it has always been an excellent way of monitoring the power system and has saved me once or twice as well.

I have ordered one from Merlin.

Post by **Heuer** » Fri Sep 25, 2015 7:53 pm

Caerbont, who bought the rights from Smiths. Details in the Upgrade Forum link I provided.

Alty Ian · Post by **Alty Ian** » Tue Oct 06, 2015 6:04 pm

christopher storey wrote:Ian : check the voltage at the battery terminals with the engine running at say 2000 rpm and all other electrics switched off. If it is in the region of 14.5 to 15 volts then you need not worry about frying the battery . If it is significantly higher than that then there is a charging problem. In general terms , however, it requires rather more than a mile or two to top up a battery which has just provided a cold start ( particularly with a very new stiff engine which comes close to representing a dead short ) . If the voltage test is satisfactory , I would not worry about the ammeter reading unless it persisted for say 20 minutes after a cold start . Furthermore, if this is a new battery then depending on type they also take time to "run-in" through quite a number of charge/discharge cycles before they assume normal characteristics

Chris

I just did what you suggested and the voltage is 12.26V from the battery which is new and charged up, when I start the engine it runs at 18 volts or even higher if I rev the engine. No wonder it is constantly on C when it runs, never drops at all.

In addition, the dashboard voltage regulator which is new doesnt deliver any voltage (supposed to be 10V) to the water or fuel gauges at all which suggests to me its failed? maybe caused by excessive voltage?

Does it sound like my 4TF (which is also new) has failed?

Ian

Post by **Heuer** » Tue Oct 06, 2015 6:19 pm

Yes - failed 4TR, which seems to be a regular occurrence with the new stock. Do not run the car until you have fitted a good working one (order two!) or you will overcharge the battery and cause either the acid to boil over or the battery to explode. You will also need a new VR by the sounds of things. Maybe time to consider fitting the Nippondenso alternator as well? viewtopic.php?t=6668

christopher storey · Post by **christopher storey** » Wed Oct 07, 2015 3:51 pm

Ouch !! 18 volts is so far off the scale that it would fry anything- and seemingly already it has buggered your 10 volt reg . If your 4TR has no potentiometer ( and most modern replacements seem not to have a pot) then you're stuffed and the only option is yet another new one or , as David has said, an alternator with built in regulator.

Or, if you're going to Stoneleigh on Sunday, perhaps worth looking for some NOS original Lucas 4TR

I have wondered whether one could build an adjustable regulator fairly easily ? Any electronics experts out there ?

Alty Ian · Post by **Alty Ian** » Wed Oct 07, 2015 6:23 pm

I have taken Dave's advice and ordered TWO !

Plus a new stabiliser.

Oh well, auto electrics and me dont seem to gell

Will fit them and see what happens this time.

Alty Ian · Post by **Alty Ian** » Thu Oct 08, 2015 3:51 pm

To prove my point above,.......... the new Caerbont voltmeter arrived and guess what ? Its faulty, tested it and it just climbs off the scale with 12.25V across it!

I wanted to fit this before I tested my new 4TR which just came too.

Edit. Well something's gone right for once.

Voltage 14.5 - 14.8 now when engine runs and the ammeter is only slighly charging now.

Also, the new dashboard stabiliser output is 10.4V so looks like its fixed

Alty Ian · Post by **Alty Ian** » Thu Oct 08, 2015 8:11 pm

Toying with the idea of leaving the ammeter and fitting the voltmeter as well in the glove box next to the USB charging unit upgrade. Then I will have the best of both worlds powerwise and if I didnt like its appearance I could fit a dummy panel over them.

Thoughts?

Gfhug · Post by **Gfhug** » Thu Oct 08, 2015 8:29 pm

Ian, glad to hear you seem to have found and fixed your problem. I can see no harm in your belt and braces approach, though I'm sure others may suggest otherwise. But, importantly, you seem to up and running properly, good news.
Geoff

Post by **Heuer** » Fri Oct 09, 2015 10:10 am

Seems a lot of work for no useful purpose - the voltmeter will tell you everything you need to know!

Alty Ian · Post by **Alty Ian** » Fri Oct 09, 2015 1:54 pm

Heuer wrote:Seems a lot of work for no useful purpose - the voltmeter will tell you everything you need to know!

Fitting a simple gauge into a glove box I havent yet fitted is easier than modifying the ammeter and cabling etc. Its less work, but may look quite odd so I think I will leave it for now and do it later, by which time I will have changed my mind

:?

Post by **Heuer** » Fri Oct 09, 2015 2:37 pm

You could buy one of these: http://www.ebay.co.uk/itm/DIY-Car-Motor ... 5d5df34e32 or one of these: http://www.ebay.co.uk/itm/12V-Dual-Car- ... 5b1a9f0c0f for the glove compartment.

Even simpler: http://www.ebay.co.uk/itm/12V-24V-Car-B ... 4af1e1a445

Gfhug · Post by **Gfhug** » Fri Oct 09, 2015 5:48 pm

We can't win can we Ian?
Firstly he shoots the idea down, then he finds the way to do it!

Alty Ian · Post by **Alty Ian** » Fri Oct 09, 2015 6:07 pm

We would be lost without his encyclopaedic knowledge, memory and wit,... err oh shut up Ian :)

I came home from work and the got the plates so just put the new age related number plates on my car and popped out to the garage for fuel and to pick up the curry in it!

I still havent recovered from the shock that everything now works and couldnt resist just giving it a few beans at the lights, just WOW

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Battery charging, is this normal ?

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