GQ ign voltage drop when starting

[BadMav]

Put the Pertronix in last september and noticed that the car started really easy, more power etc etc. Economy improved slightly too and has been running sweet up until now.

The aggravation came with cold weather, the car would crank over nicely but not fire. Sometimes just as I let off the starter it would fire while the engine was still rolling. With a 12v jump, she fired on half a turn. It drives fine and revs nicely as if nothing was wrong and when re-starting after a short spell it fires up beautiful too.

It can get anywhere between 1-2 volt drop at the ignition (power side of the ballast resistor). Is this acceptable with ignition on? Can I run a relay and feed power directly from the battery with heavier gauge wires?


Extra info:

The battery is 10 months old and I've swapped coils (I had an accell super coil w/res swapped back to the gt40R w/ res) to no avail.

Any help or ideas are greatly appreciated.

Rowen

[Dooley]

Batteries don't like cold weather... perhaps borrow another battery to rule that out 100%, it may be on the fritz even given it's age. I mean a jump worked fine so maybe that is it... ?

I've been having trouble with the Sierra and a battery that's not even a year old that went flat inexplicably and would struggle starting. I stuck a much larger and older battery in and hey presto... it's sorted. I think... still need to use it as a daily for a bit to make sure.

It's always a good idea to not think of anything as 'known-good' even if it is brand new. A mate recently spent a couple of hundred on an ignition problem only to find out that the broken part he replaced first, well the new part was just as broken.

[BadMav]

Thanks Dooley. I might throw some battery conditioner in it and see how that goes. I didn't suspect the battery as it is @12.26 volts static and the levels are fine along with plate condition. It started this morning on the second rotation, but it is slightly warmer now compared to last week.

Cheers, Rowen

[Clanky]

The aggravation came with cold weather, the car would crank over nicely but not fire. Sometimes just as I let off the starter it would fire while the engine was still rolling.
Rowen

By pass the ballast resistor for a test.
Also check the voltage at the battery when cranking - it may be too low to fire up the ignition.

[BadMav]

The aggravation came with cold weather, the car would crank over nicely but not fire. Sometimes just as I let off the starter it would fire while the engine was still rolling.
Rowen

By pass the ballast resistor for a test.
Also check the voltage at the battery when cranking - it may be too low to fire up the ignition.

Thanks, Clanky, I did that, even tried another resistor. I even pulled the resistor spring out of the original one and cut it in half to reduce the resistance. The total resistance with coil is now 2.6 ohms. It seems to be behaving with the old GT40R coil on it but it breaks down a bit up in the revs, which is why I changed it for the Accel coil in the first place. With help from the Gregory's manual I traced the 12v starter boost wire back to the key and it is working fine. Must be the battery not liking the colder weather. Had some people at work today suggest the same thing. Not sure that being a Century has anything to do with it???

Cheers, Rowen

[JeSTeROCK]

The battery may have a cold cranking problem with a surface charge

Go to a battery specialist and get them to check the cold cranking.
Just did this with my mum's fiesta (high comp motor that is dependant on good battery condition). Standard CCA was 390 but tested at 115.

Has the battery even been discharged lower than 10V ?

Batteries discharge when the casing is dirty so take it out and give it a clean with hot soapy water and clean the terminals

I run a petronix ignitor and a GT40R coil. The total resistance of the coil and ballast resisitor is 3.4 ohm

Other changes made
100AH Calcium battery, 75amp alternator, Top gun ignition leads

[BadMav]

Has the battery even been discharged lower than 10V ?
I run a petronix ignitor and a GT40R coil. The total resistance of the coil and ballast resisitor is 3.4 ohm

Did some research on it and yes, all looking bad for the battery. Yes, it has been run nearly totally flat a couple of times, unintentionally. I've just put two bottles of INOX in but it's still hard to start in the morning and will only hold about 12.15 volts now and drops to around 10.2v when cranking. The battery has been cleaned after every one of "those" outings. I was runnning the pertronix with GT40r too, but swapped the GT40r in favour of the Accel super coil (total res with ballast is 3.2 ohms), although I swapped the points back in this afternoon as the frustration of early morning starts is getting the better of me. I'll chuck the pertronix back in as soon as I get a new battery, but not a bloody century .

[Clanky]

Be aware that Yuasa and Century are the same.

[BadMav]

Yeah, cheers Clanky.

Is there a brand that is worth getting and value for money that you or anyone else can recommend?


Thanks, Rowen

[Clanky]

depends on what you want to spend and what you use it for. winching, camping or just cranking, discharge cycles etc
there are some real good ones for big coins but also some crapola.

I tend to use AGM type batteries as they are fairly robust, can handle the discharge cycling a bit better than a normal cranking battery and dont leak acid everywhere when on steep angles. Of course they cost a bit more than the run of the mill wet cell.

The most exxy ones would be the spiral wound ones, but there are others such as DEKA, Oddysey, Delco etc that are good.

If you are hard on batteries they will suffer in any case, it might be better to buy cheapies and throw them away every couple of years rather than go to a huge expense.

It would be something for you to consider a 'smart' type charger (Ctek, Redarc etc) to prolong the life of your batteries in the event of a deep discharge or to keep it topped up if sitting around. The normal voltage type reg charger such as the standard car type wont recover the batteries as efficiently or quickly as one of the smart types.
I do this after each camping trip to fully charge the batteries again and im into my 5th year with the same ones (Delco AGM).

[bazzle]

Saddly battery.

They will all be ok to purchase.
Just DONT let it go flat again or any batt will loose its edge.

Bazzle

[BadMav]

Cheers guys, I've yet to get a new batttery though I've had the points back in for about a week now and it fires on the first cylinder everytime, no winding needed. I hate points because of the hesitation at 1200rpm, but at least the bastard starts now!

Rowen

[BadMav]

New bigger battery (Amaron combination starting and deep cycle 670 CCA/80Ah) is in as well as the pertronix. Had them put a bottle of inox in too, which will give me another year of warrranty. It spins the engine like it's not there and fires instantly on the first cylinder.

Thanks for your input guys.

[BadMav]

Man just not having any luck, The new battery is going flat and after some elimination, turns out the alternator is just tired and can't keep up with charging the battery fully so eventually it goes flat. I pulled the alternator out and pulled it down, and I couldn't find anything wrong with it (that I could see anyway). I then tested it on the bench and it charged ok (14.2 volts) for a minute, but then slowly dropped to about 13.6 for another minute or so then jumped to over 15 volts and really laboured the drill. I gave it another couple of squirts on the drill but then smoke started coming out, so anyway, a new alternator is on the way.

By the way the old battery (12 months old) is still holding a static voltage of 12.56 volts after sitting for a month un-charged on concrete and easily jumped the car when I found the new one flat. So I guess it will be still be ok for a starting battery and I'll use the new deep cycle combo one for running the fridge.

[Clanky]

Sounds like you have something draining the battery down when parked. I have had this before and usually it ends up being a dodgey stereo install by the previous owner. Might be worth your while to check and see if there is any load on your battery with everything off

[BadMav]

Na, that was one of the first things I checked. It only has 0.02 amps draw with ignition off (alarm system, clock/stereo memory and central locking) and I wouldn't think that would significantly drain a battery overnight, besides that the new battery is a combo deep cycle/starter rated at 80Ah/670 CCA and it's been great for the past month. The battery went totally dead in 2 hours while listening to the stereo in my shed and with a current draw of only 0.45 amps when on accessories, it should theoretically last for 177ish hours when fully charged! I'd also just been down the road in it too so it should have been fully charged. I have noticed the last few mornings though the starter labouring a bit when turning over and the pertronix not firing (like in my OP). I'll get this new alternator and fingers crossed that it's the problem.

Cheers, Rowen

[BadMav]

Update:

New alternator about 2 months ago and you guessed it, the battery was still going flat. As the charge voltage was only around 13.7v, I did the diode trick to the alternator's regulator reference feed wire and walah! I now have 14.6 volts charging the battery after I start it and after about 5 mins driving it drops back to 14.2. No more flat batteries, can have the stereo on for ages and not worry about starting and another bonus, the headlights and spotties are brighter. I was still however getting voltage drop at the coil causing the pertronix to not fire while cranking but I have rectified this by running a relay and dedicated power feed to the it. Starts great and runs great now.

Cheers for your input guys

Rowen

[Clanky]

I re-read all the posts and didnt see it , but im intrigued about this "diode to the alternators regulator reference wire trick?"
DO you have a reference to some info on this?

cheers, and glad you got your probs sorted out

[BadMav]

Where I researched some of the info needed:

http://www.smartgauge.co.uk/alt_mod.html" onclick="window.open(this.href);return false;

Though this one had better pictures:

http://www.detomaso.nu/~thomast/alternator/" onclick="window.open(this.href);return false;

Although the hitachi reg is internal, the reference is still taken from the battery terminal (after looking through the schematic). I simply made up a dummy harness (with diode fitted) to plug into the factory plug and then into the alternator (to see if it would work first with out cutting anything). Of course it did so I went ahead and cut into the feed wire and soldered in the diode. The diode I used has a continuance figure of 684 and induces a voltage drop of around 0.7-0.9v when cold and around 0.5v when the engine has warmed up.

It just "tricks" the regulator so it sees 0.5-0.9v lower than it actually is putting out, but it still "thinks" it's putting out 13.6/13.7v.

[-Scott-]

It just "tricks" the regulator so it sees 0.5-0.9v lower than it actually is putting out, but it still "thinks" it's putting out 13.6/13.7v.

Which is a very conservative figure for charging a lead-acid battery. I can only guess whoever designed the regulator expects the battery to pretty much live at some temperature significantly above 25 degrees C. Great for an engine that rarely switches off, not so great for a daily commuter running 15 - 20 minutes at a time.

Good result.

[Clanky]

Cheers
I am gonna try this 4 sure, as my alternator only output 13.8V too