New Fuses caused new problems - PeachParts Mercedes-Benz Forum

Stoney · #1 04-10-2008, 08:55 PM

I did some basic maintenence this week and in the process ended up with new problems...

there was no reason/fault before the swaps, just the usual "I'm a guy, it's Springtime and I hate Basketball so let's do some basic maintenence on the ride" deal.

The basic Ceramic Fuse Pack sold on Ebay (probably same one sold on Fastlane and FCP) has the std white/red/blue ceramic fuses with a copper colored fuse metal.

The old fuses were same type Ceramic but had Grey lead looking fuse metal

When installed, the new fuses caused the Auto antenna, Alarm and radio itself to become intermittent, along with a few other wonky electrical problems....

I swapped them for new of same type, also cleaned the mating surfaces with Dremel using a stainless steel dome shaped brush. Same thing, same wonky electrics.

Today I swapped the old fuses back in, I didn't so any cleaning of the contact surfaces on the old fuses, nothing...everything came back to life.

WTF?
All fuses were swapped for same rating as installed.
No fuses were blown, none had separated fuse metal.
The damn things just didn;t work like the old ones.

Maybe the Grey lead colored fuse metal is softer and makes better contact? but I cleaned the fuse holder contact surfaces...

Took a Digital Amp meter and checked the resistance...AHA!!

The old fuses had almost no loss across the fuse (volts in vs volts out)...the "new" fuses with the Copper colored fuse metal had a loss of 30 to 40% (volts in vs volts out). Tried cleaning the ends with emery cloth, and they came up to 25% avg voltage loss...

Again ...WTF?

No idea where they were made but I ain't buying them anymore.

kpb · #2 04-10-2008, 09:08 PM

hey stoney, thanx for the investigation. I have five old MBs now and seem to always be tinkering with fuses, relays, etc. This is very useful info.

azurite300E · #3 04-10-2008, 11:28 PM

In February I bough a set of brass/copper fuses like the one you describe from an ebay seller called "fastvw99", but didn't get yet a chance to replace my old aluminum ones. I really don't have any reason to suspect that mine could also be bad ones, but I'll keep an eye on them for any problems like it happened to you, and just in case will definitively not change them out all at once like I had planned.

In any case the same seller is still offering them as item # 300213444711

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=300213444711

Do these look like yours?

BTW, how did you test for electrical losses on the new fuses? did you measure the voltage across the fuse while current draw was flowing through it?

280EZRider · #4 04-10-2008, 11:51 PM

I have found that a lot of the newer fuses are junk. The metal connectors are just copper / brass colored. The color fades fast the minute current is run these P O S.

azurite300E · #5 04-11-2008, 12:18 AM

Quote:

Originally Posted by 280EZRider

I have found that a lot of the newer fuses are junk. The metal connectors are just copper / brass colored. The color fades fast the minute current is run these P O S.

That makes sense, the brass/copper is just a thin plated on layer and the base metal is pure junk. I'm going to check filing down one of mine and report back the findings.

azurite300E · #6 04-11-2008, 01:27 AM

Tested the fuses by hooking them in series with a 55W 12V bulb with a set of "alligator" clip cables, and powered it with a 13.7V 20-amp power supply. According to ohms law (I=W/V) a 55W bulb should draw 4.01amps if fed 13.7V, which is exactly what I measured. 55W/13.7V = 4.01A.

Next I connected one fuse at a time in series without altering any other aspect of the circuit, and measured the voltage drop across the fuse itself. Again using ohms law I determined the internal fuse resistance by using the R=V/I formula with the known 4.01A current in the circuit.

Fuse ---- Voltage ---- Resistance
----------------------------------
8A red --- 0.083 V -- 20.69 milliohms
16A blu -- 0.043 V -- 10.72 milliohms
25A wth -- 0.032 V -- 7.98 milliohms

These resistance values appear to be quite consistent according to the metal cross section of the fuse. The larger the fuse rating, the larger it's metal cross section will be, and consequently it should have a lower resistance.

Now by using the known estimated internal resistance of each fuse, one can calculate the estimated actual voltage drop across it when subjected to its rated current rating, which would be pretty much the worst case scenario. For this I used yet another version of the ohms law formula: V=IR.

8A x 20.69 milliohms = 0.165 V
16A x 10.72 milliohms = 0.172 V
25A x 7.98 milliohms = 0.199 V

These IR (voltage) losses seem to be very reasonable, and should be proof that in my case I seem to have gotten good fuses from the "fastvw99" ebay seller.

Due to the overly positive test results, I did not bother to compare them to my existing aluminum fuses, but might do so later on just for the fun of it.

azurite300E · #7 04-11-2008, 12:31 AM

I just filed down one 8-Amp brass, and one 25-Amp copper fuse, and it appears that so far the "fastvw99" fuse sets seem to be the real thing, as there was no change in color of the metal at the filed down part.

I will now do some electrical tests in order to determine their internal resistance, which I estimate will be of very low value, and not directly measurable by a regular DMM in order to compare them to a known good original fuse.

But by running a known current through them and measuring the resulting voltage loss across the fuse, one can easily calculate its resistance, and so have a way of comparing them.

jhodg5ck · #8 04-11-2008, 10:21 AM

Flosser...I 2nd their products..I use their fuses and bulbs for the past 3 years with Very good results!!

Jonathan

Arthur Dalton · #9 04-11-2008, 10:29 AM

Quote:

Originally Posted by jhodg5ck

Flosser...I 2nd their products..I use their fuses and bulbs for the past 3 years with Very good results!!

Jonathan

Yeah...we used their automotive relays on commercial water equipment controls b/c they outlasted the original ones that came with the equipment..so that is as good a testament as one can get..
They have tied up with Littelfuse now..Littelfuse/Flosser.. both good companies.

Dee8go · #10 06-20-2008, 08:10 AM

It sounds like Flosser is the brand to look for. I need to buy some spares to keep on hand. Are Flosser fuses readily available? Would I be likely to find them at an Auto Zone or Advanced Autoparts, or do you have to order them?

jhodg5ck · #11 06-20-2008, 11:02 AM

Flosser is what I have in my kits

Jonathan

94Wagenmeister · #12 06-20-2008, 02:56 PM

I asked my dentist the other day how best to take care of my repaired tooth.

He replied, "Flosser".

(hey, it's Friday afternoon...)

Arthur Dalton · #13 06-20-2008, 03:00 PM

He said " Flossmore"..

..after the Dentist , go visit the Hearing guy......

TGIF

Gilles Kay · #14 06-22-2008, 02:25 PM

Just bought some parts for my '92 300E from ******** Arizona (www.***************) which included some fuses for preventative maintenance like the original post. They appear to be the Flosser fuses as shown on the ebay site for fastvw99. You can order any quantity and amps and the prices are great. Their service is also great.

Oldwolf · #15 05-16-2009, 09:03 AM

Just as a follow up, I am wondering if any of you copper fuse converts are having any problems now that a year has nearly passed us by?