Why MHs should have Digital Voltmeter's in the Cab

Kevin McCloud

Sir Liamalot wrote: »

2.3L but there's a 90Ah starter battery,

Did you fit that by choice, what cranking amps is that battery?

No idea, 600CCA on the label maybe, I'll confirm tomorrow.
Biggest I could shoehorn in there. I think she's 75Ah from factory.

Kevin McCloud

What was factory wiring to starter 16 - 20²?

50mm² from the battery, a feed from the busbar, and a send to the rearward loom iirc.

She's old, copper was cheaper 20 years ago.

Kevin McCloud

It had a 50mm² cable going to the starter motor, what make camper is it?

Yup and it's still working too!
Mercedes T Series

Wiring doc here, see M1 pic. 5

Kevin McCloud

Talk about overkill to say the least.

moodrater

Kevin McCloud wrote: »

Talk about overkill to say the least.

They were old armature type starter motors driving up to 5 cylinder 3 liter engines with 22:1 compression ratio 35mm2 would probably have sufficed though.

With modern low compression DI engines and permanent magnet starters you can get away with higher voltage drops and piddling cables.

Kevin McCloud

Well it seems to work tickety boo. No belt squeak.
Seems to happily hold 14.5V down to 10W load. I didn't check the no-load threshold because that'd take all day as I forgot to turn the split charger on a few days ago. (That needs a self-reseting 10A fuse I have to turn it off to crank the engine because it's only rated for solar charge not battery 2 battery antics)

I guess there was a difference of opinion between the engineers and the mechanics because my B+ goes direct to the starter and then branches out.
Wasn't able to get cable and gubbins today. I asked for 35mm square in one place and they told me they only had round cables (€10 per meter :eek:).

Kevin McCloud wrote: »

what cranking amps is that battery?

Battery: 800CCA
Glow plugs: ~70A load
Warm starting load: 400A

Kevin McCloud

Sir Liamalot wrote: »

Battery: 800CCA

Alot of people dismiss this cca value, they say its a meaningless figure that there is no standardised measurement of it. What is your views?

moodrater

Kevin McCloud wrote: »

Alot of people dismiss this cca value, they say its a meaningless figure that there is no standardised measurement of it. What is your views?

There is an EN standard for batteries made for european market its very specific. SAE standard is used elsewhere also.

It is meaningless as a measure of quality/longevity which is the mistake Joe Public usually makes higher cca for same size usually means thinner plates and shorter lfe.

Kevin McCloud

moodrater wrote: »

It is meaningless as a measure of quality/longevity which is the mistake Joe Public usually makes higher cca for same size usually means thinner plates and shorter lfe.

When you say size are you referring to physical size or AH size?

Gibbo, SmartGauge

Well it is a non-standardised benchmark.

I've never paid too much attention to it, I only care for deep cycles really. Fit a big stoopid starter battery and just let it do it's thing and try not to upset it. It's not like you find deep cycle batteries masquerading as starter batteries to worry about.

Last one I had was 75Ah lasted 5 years, watered it once, ran the radio off charge for days on end and now it's serving as a workshop start the jalopy job. Only reason I changed it was because the holding volts were too low for comfort to be leaving the radio on in the Winter and I didn't want it pulling down my deep cycles and postponing float across a split charger.

I suppose it might be an interesting comparison to see if you can get different CCA with the same Ah.

My thoughts are I fit same or bigger batteries what came with the vehicle. I just get cheap starter batteries, don't overly abuse them and use a real charger every now and again not just an alternator. Might even equalise them once in a blue moon if the cells are out of balance.

As to whether a CCA label is a considerable factor...not as much as weight and reputation (If you are willing to pay for it).
Rule of thumb would be if it can't start the engine from resting at 12.4V then the battery is too small. If it drops below 9.0v cranking or 8.5V sub zero then it's too old.

Gibbo, SmartGauge wrote:

It is the highest current that the battery can produce, at 0 degrees Farenheit for 15 seconds without the battery voltage falling below 9.5 volts. (you may also see MCA, which is Marine Cranking Amps, this is effectively the same thing, but measured at a higher temperature and the terminal voltage has to remain above a slightly higher voltage)

A word of clarification is in order here. There are actually around 10 different specifications for cold cranking amps. Different organisations, different standards (by definition that must be a joke) bodies and different manufacturers all seem to have their own version. The only thing they all agree on is that the measurement is at zero degrees Farenheit. Some state the terminal voltage must remain above 7.2 volts, others state 8.4 volts, some go for 9.5 volts and yet others prefer 10.5 volts. Some state 10 seconds, others 15 seconds, some state 30 seconds, some state 60 seconds and one states 180 seconds. If we average them all out we end up with 9.5 volts for 15 seconds.

You could if you wanted, measure the cranking current, then get a battery to cover this plus your safety margin and spec. it to this, although generally the vehicle manufacturer has already done this and it needs to be a big margin to compensate for age and disingenuous ratings by battery manufacturers.

If you do bring a battery in to get CCA tested in a motor factors and they show you it's way down on their fancy tester, ask them to test the new battery they are selling you too just to see what it says, but do bare in mind it won't be fully charged off the shelf.

Kevin McCloud

Sir Liamalot wrote: »

I suppose it might be an interesting comparison to see if you can get different CCA with the same Ah.

According to battery manufactures the higher quality battery will have a higher cca with same AH.

If you do bring a battery in to get CCA tested in a motor factors and they show you it's way down on their fancy tester, ask them to test the new battery they are selling you too just to see what it says, but do bare in mind it won't be fully charged off the shelf.

What motor factors in the country has cca testing?

Kevin McCloud

Kevin McCloud wrote: »

According to battery manufactures the higher quality battery will have a higher cca with same AH.

According to Mr. M it's vice versa and I'd agree come to think about it. CCA comes from high plate surface area which means thin plates that corrode quickly. If it was physically larger it could have dense plates with a large surface area. Or simply put it'd be heavier.

Kevin McCloud wrote: »

What motor factors in the country has cca testing?

Sher loads.
http://www.ebay.co.uk/sch/?_nkw=battery%20cca%20tester&clk_rvr_id=803943818258

Then all you have to worry about is who do you trust your old battery or their tester.

Strictly speaking any test equipment should have either traceability or be verified by something with traceability.

Kevin McCloud

Sir Liamalot wrote: »

Sher loads.
http://www.ebay.co.uk/sch/?_nkw=battery%20cca%20tester&clk_rvr_id=803943818258

Then all you have to worry about is who do you trust your old battery or their tester.

Strictly speaking any test equipment should have either traceability or be verified by something with traceability.

Is it any wonder cca is disbelieved when one believes in them fisher price toys, are you for real or having a laugh?

I don't trust them particularly, I'd have no use for one either so I couldn't recommend a reliable one.

I prefer the resistor voltage drop test myself, but the best one is the: will it start the vehicle or not test.

Kevin McCloud

Its fair to say you don't know the criteria of cca battery testing.

Not unless the manufacturer states it's parameters and you have a control ie. set charge level, test it on tester 1.
Reset to same charge level, verify tester 1 with tester 2.

So easy sell bad batteries even when you can prove they're sub-par they can always say it's something you did.

Kevin McCloud

Sir Liamalot wrote: »

Not unless the manufacturer states it's parameters and you have a control ie. set charge level, test it on tester 1.
Reset to same charge level, verify tester 1 with tester 2.

So easy sell bad batteries even when you can prove they're sub-par they can always say it's something you did.

CCA is the following,

The industry recognised standard for defining starting power is Cold Cranking Amps (CCA). The battery’s ability to perform is measured by the amount of current the battery can deliver at -18°C over 30 seconds, while maintaining a voltage equivalent of 1.2 volts per cell or higher.

What kind of mens shed theory are you trying to employ?

moodrater

Sir Liamalot wrote: »

I asked for 35mm square in one place and they told me they only had round cables

That was my first lol of 2015. Youll have to go back and ask for four candles.

Kevin McCloud

Kevin McCloud wrote: »

What kind of mens shed theory are you trying to employ?

And you would test it different how?

Kevin McCloud

Sir Liamalot wrote: »

And you would test it different how?

Why should i as a consumer have to test a battery?

Mostly refitted now, ran out of cable because I forgot to designate some for the grounds on my deep cycles and shunt.

Just the 250A relay left to sort out now.
Preliminary tests; all working fine, 5mm shorter belt did the trick for the smaller pulley. Holding no load voltage @ 14.5V and dispenses electrons as required...I'll let yee know what max. load is in December.


So I've figured out the cause of the over-voltage. Drum roll....

effin' regulator after all and an otherwise too clean electrical system. :rolleyes: Contrary to popular belief they're not as interchangeable as one might believe. Not one of them was a reliable OEM regulator of the 3 I tried. 1 spurious, 1 BMW & 1 battle weary.

Same thing happened on the 150A alternator with a 115A regulator (I rathered it for the meatier brushes). Alas..

ahem..2.1kW MWAhaha!!

I ended up having to do mathulations in the end:
I was getting some squeak cold starting under load.

Stock pulley Ø: 55mm
New pulley Ø: 47.5mm

Belt travel; half of circumference.

Stock belt travel
(2r)/2
r
= 86mm

Belt travel over new pulley = 74.5mm

86- 74.5 = 11.5mm

10mm shorter belt now and seems happy enough.

My automatic adjuster is more of an automatic damper.

I had enough of that junk cig. lighter voltmeter with it's RF and occupation of my GPS power port, that and the +150mV calibration error annoyed me.

Now I know digital is really the only way to go for a voltmeter but they're just not as pretty, and I haveta admit with my "new" alternator working great there's not really much need to monitor my bodgineering in that department.

...but dear forum members I'd never let logic stop me from installing meters where-so-ever I can.

I got an analogue meter just for the craic. This one seemed ok; large scale, reasonable price, not naff. VDO do nice ones too for 4 times the price.

Outta the box it was ~300mV low of calibration. :rolleyes:

Never trust a meter without a calibration cert...(unless it's a third hand Fluke on factory cal. that agrees with your other Fluke and or TriMetric )

So I opened it up to see if I could poke it in the gubbins.






Thankfully it had a variable resistor for calibration so it was a simple matter to adjust it to spec. (beware viewing angle, neddle moment (gravity) and static friction are all working against you with analogue)

I put it back together and stuck a cig lighter plug on it to check the radio interference... bloomin' dreadful...
The easiest way to check this is plug it into the same power source as an analogue radio and listen for signal degradation. There was so much the tuner couldn't find a station. :rolleyes:

Easy fix. Found an inductor and a low ESR cap both salvaged from a cheapo Chinese boost regulator I let the smoke outtov previously, and combined these to make an inline low pass filter. Don't ask me what the component values are I've no idea...enough... the meter uses 100mA to operate, the board I salvaged them from was spec-ed as a 150W regulator.

Clean as a whistle now..,once I turned the LC the right way around...
..or perhaps that's the wrong analogy....





Of course I had to recalibrate it then to compensate for the inductor voltage drop.

I also clamped the cables to the arm by the terminal blocks after that photo was taken.

I know I said no splicing conductors for power which is good advice but I chose to ignore it.

I made an adapter from spade crimps and insulated females so I didn't have to hack the stock loom and piggy-backed the power off the temp gauge.

51mm hole saw, some careful measurification and it wasn't hard to install.



Jaysus wouldya look at that colour temperature. Feckin' awful 'innit.



There'll be no 6500°K luminaires on my watch! Making all my other tastefully lit gauges circa 1980 look dated. Psah!

No, no, no that won't do at all! Too schlick lookin'!


I cracked it open again and slipped a cut of Lee 287 in there.



Perfect. :cool:

A caveat about how I wired this. It really only tells me if I'm overloading my alternator (which I haven't the imagination for), the cranking voltage drop, the bank paralleling voltage drop (because mine is manual), the nominal alternator charging voltage and probably when those 4mm brushes I never bothered to replace are going to fail to meet the slip rings (but the battery light does than anyway).

Because I wired it ignition-switched it cannot tell me the OC voltage because it always comes on under load (glow plugs). Of course I have the TriMetric in the living area for this information.

This model does a range sweep on startup to keep the rude boys happy I suppose, so if you start the engine too soon you'll not learn anything from it. The illumination is always on, which is kinda cool as it's the first thing in the dash to come alive at night (as it should be when I turn the key).