Why MHs should have Digital Voltmeter's in the Cab

moodrater · 09-02-2015 7:58pm

Sir Liamalot wrote: »

Too late took a punt on a petrol model before it occurred to me. I imagine the gearing is on the pulley size and seems there's a lot of vehicles running similar alternators on different fuels.

The thick plottens.

Which dya reckon are better? OEM bearings with a few hundred thou miles on or new cheap and nasty Chinese ones? :pac:

Neighbours merc is on 380k miles with original bearings. Obviously water, dirt ingress, standing periods etc can knacker the bearings too.

Smaller pulley will turn the alternator 33.3% faster than the big pulley. But diesel engine will be turning on average slower than the petrol and never hit the high revs.

Ratio in the car was 3.64 in your van it would be 3.97 with the larger crank pulley.

*Kol* · 09-02-2015 8:11pm

As a matter of interest how much is a new OEM alternator?

moodrater · 09-02-2015 8:16pm

*Kol* wrote: »

As a matter of interest how much is a new OEM alternator?

The oem one is archaic and the external fan is useless.

[Deleted User] · 09-02-2015 8:16pm

Larger crank pulley, larger alternator pulley. Gosh you do your homework!

There comes a time in life M. where calculations slow ya down. Slap it together, fire it up and stick a finger on it to see how hot it's getting at full load! (My life anyways)

I've no problem with a 55A alternator at the end of the day, but seeing as 60A extra was the same price as a diode pack (not inc. cable + maybe recon kit) seemed all round better than bodging semiconductors in the nethers.

Less I have to current limit the TS the easier.

[Deleted User] · 09-02-2015 8:30pm

*Kol* wrote: »

As a matter of interest how much is a new OEM alternator?

€120 last time I priced one. Just a Bosch though not OE.

Why's the E280 double rated? 70-115A

moodrater · 09-02-2015 8:33pm

Sir Liamalot wrote: »

Larger crank pulley, larger alternator pulley. Gosh you do your homework!

There come's a time in life M. where calculations slow ya down. Slap it together, fire it up and stick a finger on it to see how hot it's getting at full load! (My life anyways)

I've no problem with a 55A alternator at the end of the day, but seeing as 65A extra was the same price as a diode pack (not inc. cable + maybe recon kit) seemed all round better than bodging semiconductors in the nethers.

Less I have to current limit the TS the easier.

I have a tons of pdf catalogues on a drive here takes a couple of seconds to find a part or dimensions. I'm usually bodgiing something onto something else.

The problem with the 55A is the cooling hardly any of the air actually goes into the alternator. The design goes back to at least the early 60s it was rubbish back then too

moodrater · 09-02-2015 9:02pm

Sir Liamalot wrote: »

€120 last time I priced one. Just a Bosch though not OE.

Why's the E280 double rated? 70-115A

1800rpm and 6000rpm divide by 4 for your pulley ratio. Now I have to do some actual work.. boring

[Deleted User] · 09-02-2015 9:26pm

moodrater wrote: »

The problem with the 55A is the cooling hardly any of the air actually goes into the alternator. The design goes back to at least the early 60s it was rubbish back then too

Always suspected as much I never used more than 50% rated under 80kmph.

moodrater wrote: »

I have a tons of pdf catalogues on a drive

I keep asking Mercedes for those and they keep laughing. They'll only give me a page per part I buy.

[Deleted User] · 09-02-2015 9:40pm

moodrater wrote: »

Smaller pulley will turn the alternator 33.3% faster than the big pulley.

Shorter belt so.

I'll save you the maths because I have one 5mm shorter in stock so lets try that first.

Automatic tensioner anyways probably no need.

[Deleted User] · 15-02-2015 10:19pm

Rather spectacular fail I'm afraid.

Took my relic off. Fitted the w210 alternator, mounted perfect, wee bitta slack on the belt but nothing to worry about. Fired her up and got nothing.
Waited a bit longer then still nothing. Turned off the engine the starter battery was 10.4V and my battery light was still on.

I pulled the D+ diode outtov the fusebox; battery light stayed on.
Got out, looked at the alternator and it was bellowing magic smoke.
Grabbed a side cutters and snipped the wires off.

Old alternator B+ #1 and B+ #2 combined on new alt. B+.
D+ to D+.

It was still warm to touch 30mins later.

Autopsy reports; coils ok, bearings not bad, slip rings down 70%, rotor paint chipping and flash rust, brushes on the limits of serviceability, one burnt to a crisp diode on two phases; failed closed (perfect previous to install), another diode on the remaining phase damaged, forward biased resistance much higher than the survivors. Diode trio intact. Didn't see any zeners...except inside the regulator.
So this manifest as dead shorts across the three phases.

While I had the relic off I gave it a beating trying and failing to crack it open with all the wrong tools. I don't know if it was the problem but seems my steel cable retention clip has the ability to wander and create a short off the B+ if so inclined. I was reading a short between a B+ and ground (one of 2) which is particularly strange because it seems the B+ terminals are in parallel in a later test (educated guess says one's headed for the starter motor then battery and thuther is headed for the +ive bus then fusebox).

The relic is refitted and working, I don't know if it's still over-voltage because I haven't charged the starter battery fully after it powered my little alternator bonfire. The loom looks fine. Connector to alternator little worse for wear but serviceable.
See how it does in a while.

moodrater · 16-02-2015 2:23pm

Such short. Very smoke. Wow.

Unlucky it must have had mega hours up on it to be that worn. I suppose with unknown providence its worth bench testing with a drill.

Hows the old beast holding up today?

[Deleted User] · 16-02-2015 3:51pm

Bench tested resistance fine on everything.
I was getting reversed biased resistance but it was in the order of MΩ

I'm still trying to figure it out, and debating whether it's work spending €25 on a new diode pack for a €40 alternator than still needs a set of slip rings and brushes and all the while may still explode again.

I needed two 9.5mm male blade crimps to connect into the old loom B+ (for test purposes only before new loom was made). Couldn't find them, tried Halfords, Maplins, 2 others, so i just stripped 4mm² wire back 15mm and marmaladed it into the connectors which was a sloppy fit but did work (i think). Then lecky taped them in.

However if it went no load over-voltage I would have expected the D+ to have briefly gone out then pop the dash bulb. Considering how melted my bodge wires were I expect they were making connection.

Which beast? The W210 alt. is stripped to the stator pending further investigations.
The Merc lump is bulletproof.

My stock main +ive and -ive are ~80mm²...shorts don't bother them a whole lot.
Split charge relay is currently topping up the starter after yesterday's endeavours off PV. I won't know until later in the week whether I did any good beating on my stock alternator.

FWIW my brake light (fluid switch and pad wear switches) are also tied to the D+ somehow, every time I lose a regulator the brake light comes on with the battery light.
Also depending on the regulator sometimes my oil pressure light doesn't illuminate (W210 reg. being one of these).

moodrater · 17-02-2015 12:54pm

Definitely not worth putting a diode pack in it. Ask for your money back and get another one. Definitely bench test the next one

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[Deleted User] · 17-02-2015 5:16pm

Yeah probably not. I was in the supermarket the other day trying to figure out where I'd get 600V to insulation test the coils. I decided to focus on the cheese I wanted instead of microwave transformers for health reasons.

I'm a bit sceptical that it was faulty in the first place, and more inclined towards something I did fried it.

I've been re-inacting my bodge connection under vibration testing and dreadful as it was it should have handled a flash few amps.
Hard to tell if it was arcing, but I reckon you need >30V to make an arc.

Not sure if there's much point sending it back, the rectifier stinks of fried silicon, the connections to the phases are cut, and the rectifier pack has been forcibly split, and stud diodes cut at the legs. It's clearly been tampered with.

Do you reckon that there's no good installation reason for it to fail like that? That it was the alternator?
Seeing as I've already spent the price of an alternator on new loomage I'd be almost tempted try another.

moodrater · 17-02-2015 9:59pm

Just tell them you hooked it up and it self destructed would they have another one. I doubt they'll be looking for it back probably at least offer you a partial refund.

Unless there was a massive short on the b+ or theres something really funky about your d+ I can't see what would have caused it. You could bypass the van d+ with a bulb.

Just had a quick google and it looks like d+ just goes through the bulb to ignition no shennannigans although it is very fuzzy:
https://services.ubal.to/mercedes/Mercedes-207-208-210-307-308-310-408-410D.pdf

Also looks like one b+ is to the solenoid and battery as you suspected and the other is to the ignition.

re: insulation don't you have a megger?

I just moved up the directory tree and he has other diagrams:
https://services.ubal.to/mercedes/Mercedes-schema-207D.pdf
https://services.ubal.to/mercedes/Mercedes-schema-208D.pdf

[Deleted User] · 17-02-2015 11:53pm

What would happen if you parallel the D+ and B+? Just a thought....battery light would come on with no key for one...hrmm wasn't that so.

moodrater wrote: »

Just had a quick google and it looks like d+ just goes through the bulb to ignition no shennannigans although it is very fuzzy:

https://services.ubal.to/mercedes/Mercedes-207-208-210-307-308-310-408-410D.pdf

Ha! I have the paper copy of that and it's never made any sense to me...those diagrams are too bloomin' cluttered, conductors running off the page never to be seen again. I was looking at it before you posted and just discarded it.

moodrater wrote: »

...he has other diagrams:

I just finished translating that to English.

K4 is the D+ relay. Let me know if you can make any sense of it...or no worries if you're not bothered either.

7-15%20Diesel_zpslr9yyx6h.jpg?t=1424129632

moodrater wrote: »

Also looks like one b+ is to the solenoid and battery as you suspected and the other is to the ignition.

Well it's loomed in the opposite direction through the firewall and if I turn on the vehicle electrics I don't get any reading on the clamp meter at the battery which leads me to suspect it's T'd between starter motor -> battery and auto-electrics (on 2 x 32A cable

). That or it's T'd at the starter motor and doubles back on itself after.
I guess all I know for sure is the starter battery is the end of a stock circuit.
{EDIT} They're both going to the +ive bus twould seem. I guess they were trying to be a fancy Mk-1 3 wire alternator.

moodrater wrote: »

re: insulation don't you have a megger?

Nope never needed one. Most days all I take to work is a Sharpie, adjustable spanner and a multitool.

moodrater · 18-02-2015 12:46am

K4, B5 etc is all optional for heated rear windows. If you don't have heated windows then you can ignore the 122 connection and d+ should just go to one side of the bulb and the other to the switched live on the ignition.

Russek is missing a few wires alright, but the merc schematic though I'm sure electrically correct is crap as it doesn't indicate where all those dot junctions actually take place.

I reckon they've incorrectly dotted the line from 122 to the relay coil. was reading it wrong.

[Deleted User] · 18-02-2015 1:37am

No heated windows, interior light (it's there but never worked and I never fixed it), clock (now hotwired off hazards I think), tacho, tilting headlamps.
Can't find 122 but I've no idea how to read this once a conductor leaves the page. I know what you mean though.

The D+ shares F15 ("diode monitor") with the brakes. (see beside K4 relay 30 terminal) If I pull that the pre-ignition indicator lights go out.

moodrater · 18-02-2015 12:32pm

122 is 120 on the schematic you posted its a reference to the vertical coordinate on the schematic where the wire is headed.

Across the bottom of the schematic is numbered linearly

107 108 109 110 111 112 113 114 115 116 117 118 119 120 etc.

So when the wire is headed off you look along the bottom of the schematic for the number e.g. 120 you'll see a wire heading off for 7 which is where you came from so thats the wire you want.

F15 shouldn't knock out the charge light according the diagrams wit should get switched live direct from the ignition and earth via the d+ until the alternator is charging.

[Deleted User] · 18-02-2015 4:22pm

Yup my bad.

If I pull this D1 diode the brake light warning turns off pre-ignition.

[Deleted User] · 18-02-2015 4:35pm

moodrater wrote: »

e.g. 120 you'll see a wire heading off for 7 which is where you came from so thats the wire you want.

There's two 7's beside K4

moodrater · 18-02-2015 10:36pm

Sir Liamalot wrote: »

There's two 7's beside K4

Yes one is 120 the other is 123 the 123 one goes tot he mysterious x2 block which I assume it plugged into the fuse box?

[Deleted User] · 19-02-2015 1:15am

The X2 block is the +ive bus bar. Just a big copper block with spades and lugs buried behind the fusebox and relays in the passenger footwell, bittova mission to get in there on the street. Leave it with me, Cheers for the pointers.
Still have to test the relic and I'm in negotiations for a W202 alternator.

Compared the regulator resistances and they were slightly different but I expect that's normal given they're for different field windings.

The reason I'm suspicious about the brakes is the battery and brake light come on together with an alternator fault, but I guess the brakes need to be held high on both sides too, to illuminate off the disc when it finds ground.

moodrater · 19-02-2015 1:44am

Sir Liamalot wrote: »

The reason I'm suspicious about the brakes is the battery and brake light come on together with an alternator fault, but I guess the brakes need to be held high on both sides too, to illuminate off the disc when it finds ground.

If k4 is present then the brake lamp would be grounded via 30 and 87a of that relay.

moodrater · 27-02-2015 11:13am

Any more fireworks on the agenda ?

[Deleted User] · 27-02-2015 7:31pm

Belt powered bonfires I like to call 'em.

Yeah I hate to disappoint.

Negotiations fell through on the 'nother alternator for obvious reasons. Chalk this one up in the bad bodge column methinks.
Laying a hardwood floor and skirtings in a double room without right angles at the moment so it'll be another week or two.

Living in a house these days. Don't care much for it myself but can't convince swmbo to see reason!

The relic is still misbehaving.

Dozer Dave · 08-03-2015 12:06am

I would preference on of the following, temperature gauge, oil presssure gauge or turbo boost gauge over a volt meter any day.

[Deleted User] · 08-03-2015 12:54am

It's not an or situation.

Dozer Dave · 08-03-2015 12:56am

Ok well i see no reason to install a volt meter.

[Deleted User] · 08-03-2015 1:53am

Fair enough.

Reasons off the top of my head;
Alternator failure, alternator malfunction. Alternator overloading.
Cranking voltage drop (starter battery health).
Unloaded charge voltage (starter battery DOD)
Parallel battery drop (Auxilliary bank DOD).
Left the lights on and engine off and didn't open the door?
Fridge left on and engine off?
Want to use the cab radio for a few hours but not past 12.5V?
Unfused short circuit (main starter motor conductor).
Battery resting voltage (age, health, parasitic drain); Saves one cranking and further damaging a flattened battery.
Electrical diagnostics.

I also have a compass and a GPS
I have a hard time convincing myself I don't need another ammeter. :pac:

Why MHs should have Digital Voltmeter's in the Cab

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