Hi guys, im on the verge of possibly keeping my 3rd gen (yehh, again.lol)
But since this morning, if i go to start it, it'll struggle like the battery's low. But it always starts. Also if i turn it off n start it again within 5minutes or so, its fine. and if i just turn the ignition on and wind the windows up and down or use any other electrics, they dont struggle either.

But, when struggling to start, the lights will dim with every turn of the enigne. which im guessing is the starter motor pulling a fair bit of power.

I tested the battery in my other prelude just before i pulled the engine out of that one too, n it seems to be fine.

I duobt its the alternator, cos the battery dont drain,

And since starting is the only issue, Im guessing its gota be the starter motor?

Got one spare too (if i can get it off the spare gearbox's housing), so im hoping its just that.

Cheers,
Baz.

Have you checked your earth connection to the engine, could be rusted away, your starter earths through the engine???

I've copied this from the 4th gen' trouble-shooting guide.
It may give you some pointers.

Starter Cranks Engine Slowly

Battery weak or defective - Charge or replace battery as necessary

Engine overheated - See ENGINE COOLING SYSTEM article

Engine oil too heavy - Check that proper viscosity oil is used

Poor battery-to-starter connections - Check that all connections between battery and starter are clean and tight

Current draw too low or too high - See Bench Tests in STARTER article

Bent armature, loose pole shoes screws or worn bearings - See STARTER article

Burned solenoid contacts - Replace solenoid

Faulty starter - Replace starter

Thanks for your replies. Since ive always used the same oil (castrol magnatec, 10W-40 part synthetic) and only just had this problem now, plus ive tested the battery, ive ruled it down to these....

1. Poor battery-to-starter connections - Check that all connections between battery and starter are clean and tight

2. Current draw too low or too high - See Bench Tests in STARTER article

3. Bent armature, loose pole shoes screws or worn bearings - See STARTER article

4. Burned solenoid contacts - Replace solenoid

5. Faulty starter - Replace starter

6. earth connection to the engine, could be rusted away, your starter earths through the engine?

Since ive got a starter lying around, i'll try swap that first. if it still does it, i'll try the other things. the only thing i wanted to ask, is in number 6 above....wat do you mean by starter earths through the engine?

Cheers,
Baz.

Alright guys, not got round to workin on the car yet, exept for giving it a start....exept that didnt happen. it turned slowly like before, but then choked. did that a few times, but now just barely turns.

BUT, the electrics work fine when the ignition's on.

Also, started it a few days ago and it struggled, but started and then the car started hunting (revs going up n down).
Giving it full throttle calmed it down for a second, and taking it for a drive stopped it hunting. so not sure if this just means taking it for a drive sorted it, or if it means its hunting when cold. couldnt start the car to check again.

Dunno if that helps narrow the culprit/s down?

Baz.

I'd start with the engine earth/s. I use the plural because although there's usually one primary earth connection to the block (commonly a braided tinned copper strap) there are usually several other extraneous return paths ('earths') via the wiring to other electrical engine accessories or structural connections back to the bodywork.

OK now consider that the cranking current for a petrol engine can easily exceed 200 Amps whilst the key is engaged and the starter is churning and that when it first starts to turn against the stationary load of the engine compression and friction the initial inrush current can reach 500Amps:!: That is one hell of a current to draw through wiring from a battery. I won't get too far into volts ohms and amps here (if I can help it) but to cut a long story short; at these current levels even very slight increases in the resistance of the electrical path or the components within it can have serious repercussions on the actual power (the ability to do work) that is received at the business end, i.e. the starter motor's windings.

Right here we go; volts, ohms, amps and electrical 'POWER'

the basics... where the electrical 'power rating' of an electrical device comes from.

POWER (in Watts) = VOLTS (unit = volt) x CURRENT (unit = Amp)

So if I have a heater blower motor I can clip a meter round it's live wire and measure the current flowing down it into the motor. This would probably be around, oh I dunno, let's say 2 Amps. We know the volts, (12v obviously) so we can work out the electrical power of the blower motor as power = volts x amps. Put those numbers into the P=VxI equation...

12 volts x 2 amps = 24 Watts ...sounds about right...

Similarly you can switch that little formula around so that if you know the power of a device you can work out the current to expect in its wiring when switched on and this is where it gets useful in fault finding. the voltage is always a nominal (12v) for most purposes. You just DIVIDE THE POWER BY VOLTS

here I'm going to use leccy terminology; current is written as the letter 'I'

so we know that P = V x I power(P) = volts(V) x current(I)
so transposing it to solve for the current you divide P by V and the formula can be re-arranged as

I (the current we want to find) = P/V

Your headlamp bulb says 50W on the box, how much current will a pair of them draw from your battery or charging system?

...just divide that power figure by your voltage (12) so

50W divided by 12 = 4.2A

There's two of them so they'll draw 8.4A from the battery. If you had an 84 Amp/hour battery and you left them on it would (theoretically) flatten it in about 10hrs! (10 x 8.4 = 84A/hrs)

RESISTANCE (measured in OHMS)

When a voltage is applied to a circuit the resulting current that flows depends on the resistance of that circuit. For 'ontheball247's starter motor prob there will be several elements that make up the whole circuit and each one will add in its own bit of electrical resistance including even the crimp lugs! When the key is turned to start, a relay pulls in the hefty starter solenoid (an even bigger relay), this closes its equally hefty pair of contacts which apply 12v straight from the battery's positive (+ve) terminal onto the terminal of the starter motor, through the carbon brushes, through the windings and the current then returns to the battery negative terminal via the frame of the starter motor to which the other ends of the windings are 'commoned', via the conductive metal mass of the engine block, through the earth strap, into the bodywork to the point where the negative cable is bolted, it then travels up that cable back into the battery's negative (-ve) terminal, through THE INTERNAL RESISTANCE of the battery matrix where the chemical energy of the battery drives it round again in a constant loop. Hence the term circuit!

Resistance is an opposition to the flow of electrical current, a bit like standing on a hose pipe. It's measured in Ohms and abbreviated to the Greek letter omega but I can't find it in the font set so I'll have to write the unit as 'r'. The relationship with voltage and current is such that when a voltage is applied to any circuit the magnitude of the current that is allowed to flow through that cct due to the 'pressure' of the voltage is inversely related to the resistance of the circuit. The more resistance there is the less current can flow, that hosepipe analogy again. Let's put that relationship into real numbers.

OHMS LAW

That inverse relationship between current (I) and resistance (r) is described by the formula...

I = V/R Current = Volts divided by the Resistance

If I apply 12v to a circuit with a resitance of say 2r (ohms) I would expect a current of about 6A to flow I = 12v / 2r = 6A

If the cct had a resistance of 400r then the current would be in the region of...

I = 12 / 400 =0.03 amps or alternatively 30milliamps [you get the idea]

As with the power formula before you can transpose Ohms Law in several ways; if you know two of the three quantities you can re-arrange the formula to find the third figure you want.

V = I x R (if you have the current and the resistance figures by measuring them for instance and want to work out a voltage) more applicable to electronics really!

or...

R = V / I (if you know the voltage [12v] and have a current reading you can work out the resistance of a solenoid coil or whatever and for instance compare it to a value in a shop manual.)

OK; BACK TO THE STARTER MOTOR PROBLEM

The starter motor needs 200A to do its job. Automotive starting batteries are designed to deliver that with no major trauma although it is quite a feat of chemical engineering when you think about it, to supply that much sheer cranking power from a 10" squared box!

Sticking some numbers into that Ohms Law formula; to get 200A from a 12 volt battery the resistance of the WHOLE circuit must be no greater than...

R = V / I

R = 12 div. by 200

R = 0.06 ohms

That is 60 milliohms and that is not very much at all, pretty much what in simple terms could be termed a 'short circuit'. A smear of insulating engine oil on the main earth clamp could easily add a few ohms at least to the value of the overall cct resistance. Let's say for instance another half an Ohm or 500 milliohms (but it could very easily be more!) Stick that new resistance number into the Ohms law formula for finding current...

I = V / R

I = 12v div. by 0.56R (560 m/Ohms)

I = 21.4 Amps!!!!!!!

So just half an Ohm of extra electrical resistance has cropped the power (the ability to do work) by a factor of TEN!

A layer of carbonized cr@p on the solenoid's internal contacts could easily account for that, a loose engine earth strap, that crappy, oil encrusted, wrench damaged crimp lug that's hanging on by only three strands of conductor....

If you've got two or more of the above in series then they all add series resistance and all turn cranking power into heat not tourque.

Hope it helps in understanding why the integrity of the engine earth is so important.

Also if that strap is open circuited then that cranking current will try to find alternative routes back to the battery through wiring which simply will not cope and very quickly overheat = ner ner, ner ner...

Wow, that was a fair bit to take in, but i fully understand. To think, i just gave a quick look over all the earths that i could spot. I'll see what i can do about a more thorough investigation of the earthing. And i gota thank you for typin all that up, helps alot. Also im sure it'll come handy knowin all that in future.
Only thing is, if i giv the car a jump, i only have to connect the jump leads and turn the key straight away and the car will start immediately. i.e, i dont have to keep the leads on for a while, then turn the key (like you do when the battery's been run flat). Also, if i keep turning it when the car doesnt start (without the jump leads), it starts clicking. duno if that changes anything, but i will have a proper look at all the earths i can find.

Cheers,
Baz.

Na mate, the engine turns really slowly, then might struggle a bit n get started up, or it'll jus start clicking. Where is the main relay tho, anyway, so i can check that over just in case?
N what am i lookin for when looking at the relay?
I kno azz(shyguy) did the relay on his 4th gen, so i could ask him, but mine's a 3rd gen n im guessin there may be some differences in location?

When I had my 3rd gen', I took what I thought was the main relay out and re-soldered it, (dry solder joints).
It didn't fix it, so I think I took the wrong thing out.

I sold the car before I could find out where it was. It's under the dash somewhere, maybe near the steering wheel.

Cheers pushki, i'll have a look in a bit. see what else i can find. gona try gettin that starter motor out too and swap that for the other1....dont look too easy...its got one of the radiator hoses going just above it, so gona have to drain the coolant and disconnect that hose from the radiator to be able to get to the starter motor.
Wish me luck.lol

You might have a dying or dead cell in the battery so the first thing to do would be to verify the integrity of the battery. Measuring the voltage across the two battery terminals might tell you something. If you get something like 10 to10.5 volts it suggests that one of the cells has packed up but... even if you get a reading of 12.5volts that still doesn't mean that all is well. If one of those cells has developed a high 'internal resistance' then that will only manifest when it is asked to supply current. Multimeters won't generally show this up as they work on milliamps

A volt/multi meter has a very high input resistance as a function of its design so that applying a meter to a circuit doesn't impose its own 'load' into the circuit being tested which would distort the true current flow that we want to measure. (Ammeters for measuring current, conversely, have extremely low resistance for exactly the same reason but let's not go there just now:roll: ) Connecting a voltmeter across the battery terminals whilst cranking the engine draws proper amounts of amps and that is when volts start to be dropped (lost) through any resistances. This should show up any appreciable volt drop but the best and easiest way is to swing by your local exhaust/tyre/battery emporium and ask them to whack a pukka battery load/dump tester across it. This is a known low resistance which allows a proper hefty current to flow and any volt drop is exposed that wouldn't be by a simple check of the unloaded terminal voltage.

They'll usually do it for free hoping to get a battery sale out of it!

Hmm, just seen this thread, when the 3g starts slow/sluggish like that, it's the batt.

Batts tend to die under loading so if it's fully charged and still does it, or does it the day after etc, then yeah, it's a dead batt.

As above, most places will perform a load test on the batt for free in order to get the sale for it.


If it were me i'd just go straight to Honda and order one, it should be very cheap from there.

thanks guys. n maxx, u mean the battery will be cheap? fro, honda? seriously? lol.

But yh, i did the test with a multi meter n thought all was good. but if i leave it lonbg enough, it does show dead battery. no central locking, or lights, etc.

thanks again guys.
baz

Yes, i do mean cheap from Honda, the 4g batt is £42

And, seeing as you said that, the batt is goosed, 99% guaranteed.