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Post  Iceberg on Tue May 12, 2020 7:33 pm

Wanted to ask the knowledge.

Sometimes glow plugs take a much stronger battery than others. Usually we discard these plugs right? Well my question is the "weak" plugs that take brand new batteries to start (but with older batteries are terrible to start a motor}. The ones we discard. IF the motor starts. Do these "weak" plugs also run cooler when the motor is up to RPM or are they the same because now they are heated by the fuel and combustion? I sometimes seem to think they burn cool even when under compression as well??

Thanks
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Post  Iceberg on Wed May 13, 2020 12:41 pm

So nobody has a thought?
Thanks
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Post  Surfer_kris on Wed May 13, 2020 12:58 pm

Iceberg wrote:
Sometimes glow plugs take a much stronger battery than others.

I have lots of thoughts all the time, but here I do not even understand the question. What do you mean with a "stronger battery"?
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Post  balogh on Wed May 13, 2020 1:06 pm

I guess I understood Darren. Older plugs and glow heads with the white deposit on the filament take higher amper to glow in orange color. In my experience once the engine runs even these older plugs and heads sustain the same or only slightly reduced engine output. I use the heads and plugs until they blow, no matter if they take more juice to start an engine.
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Post  davidll1984 on Wed May 13, 2020 10:11 pm

y understood Darren lets say yes old plug change temp wit good batry it wil run yes some time engine output can slightly change try 4cycle fuel ad nitro and castor oil 4cycle fuel wit 15%mix low oil let place for more castor oil les sintek oil wil help engine if plug run bad just chage for new y use os no8 wit a good adaptor no chage in comprestion like other wil... now start bether wit 1 sub c batry cox dont start to good wi just 1 c use 2 +to + -to - if run cold wit good result stay wit dont change setup Very Happy Babe Bee .049 RC Plane
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Post  Surfer_kris on Thu May 14, 2020 12:23 am

I still seem to have a language problem here.... Huh...
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Post  ffkiwi on Thu May 14, 2020 2:29 am

The material used in plug elements varies from manufacturer to manufacturer-in a variety of ways-the actual alloy, the gauge of the wire, the length of the coil-so it is only to be expected that plugs require different currents to operate-then on top of all that-for the same brand and type of plug....eg a Cox head....the element will age with use-depending on what it sees in terms of fuel composition, fuel impurities, engine wear. Most of us who have been at this game longer than 5 minutes will have plugs that still glow fine-but on which the engine refuses to run-or runs poorly/indifferently.  In some cases-even the fuel bulb the fuel is stored in whilst running the engine can have an effort (ask a few Norvel owners!).....lean runs...mechanical problems, or mishandling (ie the classic 'ground up backplate' from excessive starter useage) can result in metal depositing on the element....this rarely (Ok...I'm joking...never not rarely! ) improves operation!

Anytime the element attracts foreign material-or suffers physical damage (the 'cold solder' crystalline appearance you see sometimes)-you can expect the efficiency to fall-and the current to creep up. In 50+ years of operating glow engines (and diesels....not that that counts in this specific instance)-I've never encountered a situation where the current required to produce a good orange red glow got less as the plug aged....!

Finally-some plug manufacturers use a base metal core with the active materials: platinum-rhodium-iridium plated on the base metal core; others use a proper alloy wire of the Pt group metals-the latter is expensive-so plugs made this way are a lot more expensive than the former sort....it doesn't take much imagination to see that a thin layer of plating is going to be less durable-and prone to 'poisoning' that a full diameter of pure alloy wire-though the actual physical strength of the plated wire may be the same-or even better than the pure alloy...so such cheap plugs may be just as durable-in terms of lasting as long-as a better quality element wire plug-but suffer from a faster decline in operating efficiency.....but again this is going to be influenced by multiple factors...

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Post  balogh on Thu May 14, 2020 2:45 am

Thanks ffkiwi that is a comprehensive explanation!

Yes, I remember the NV engine manual states that syringes with the black rubber plunge should not be used to fill the tank....despite this, I use the syringe with black rubber plunge (in lack of any other 60 ml syringe available) , on my COX engines, and so far have not experienced any accelerated glow element deposition. Neither experienced any performance deterioration with deposited filaments, albeit they draw more current. I remember one high compression TD 049 head I used for many-many hours, with the dome of the head completely discolored brown due to the castor varnish, and while the filament glowed very dimply at 1.5 Volts and 3 Amps or so (I have cranked the Hobbyco starter panel knob to peak glow current) , once the engine started, it revved the same as with a brand new head ...who knows, maybe the high compression ratio itself keeps chamber temperatures hot enough not to deteriorate engine output even with cooler filament with deposits on it?
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Post  ffkiwi on Thu May 14, 2020 4:40 am

Yes for those of us who use power panels-or one of the other clever devices for powering up a glowplug for starting-increased current draw is not really an issue-but for someone trying to get by on a couple of size D Duracells it is probably IS something of an issue....there's no real way round it, its just life when operating a glowplug engine-plugs or heads age as they are used-at different rates depending on the engine, the fuel, and the competence of the operator-and eventually their performance drops off to the point the owner spits the dummy and fits a new one...or burns the plug out in an attempt to increase the current sufficiently to get a good hot glow...

I have fond memories-as a junior-of using two of those big 'bell batteries' -wired in parallel-as the glowplug lighting source-the big ones-used in telephone exchanges and doorbells-weighed about a pound and a half each...big mothers about 9' tall and about 2-1/2" across....a pair of those lasted for a couple of seasons providing you were careful-and being 1.5V they lit off a Cox head perfectly...I had a 4-bottle milk bottle carrier-made in school woodwork class-with two of those batteries on one side-and a bottle of glow and a bottle of diesel on the other side; a coupke of screwdrivers, a small crescent wrench, a spinner tommy bar and a couple of spare props-and that was my field box!

further to my earlier reply....at least some of the early Japanese made glowplugs-especially in the 1950s-and some of the european ones as well just used nichrome wire as the element-to keep costs down....and yet the engines still ran-albeit probably not as well as with a decent plug element....

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Post  Levent Suberk on Thu May 14, 2020 5:34 am

You can make a replica of this battery. Pdf file here:

https://kd4hsh.homestead.com/Battery-Art-26.html

Glow Plugs Weak Or Strong Sf-no610
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Post  Levent Suberk on Thu May 14, 2020 6:38 am

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Post  Ken Cook on Thu May 14, 2020 1:55 pm

The EN6 battery is being produced once again in carbon form. Exell makes them also designate BR40.
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Post  ffkiwi on Thu May 14, 2020 2:52 pm

Yes-those are the big dry batteries I recall from my teens.....they were great for starting Coxes...

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Post  ian1954 on Thu May 14, 2020 3:32 pm

Glow plugs need some care in both choice and maintenance.

I always find that it is a good idea to clean the glow plug after use. I flood it with isopropyl aclcohol or straight methanol to remove any castor oil residue before it gums.

I also use dedicated plugs for running engines in, a new engine can quickly contaminate a plug,

I prefer Enya and OS plugs, I find that they last quite well, Where I have bought cheaper plugs (Hobbyking), they have had quite a short life.

Because I remove plugs regularly to flush them, I also anneal the copper washers to soften them. They work harden with constant tightening.

Different makes of plugs and different temperature plugs draw different currents. Not all batteries can supply the demand. I use 1.5v NiMh batteries (rechargeable) as they tend to not drop voltage until very discharged. Disposable batteries (carbon and alkaline) tend to drop voltage rapidly.
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Post  Oldenginerod on Thu May 14, 2020 5:34 pm

Ken Cook wrote:          The EN6 battery is being produced once again in carbon form. Exell makes them also designate BR40.

These are available out here, although getting less common. They are the carbon type that Ken mentions
Glow Plugs Weak Or Strong At-1_510

They last quite well if you can find a fresh one.  I've had them swell and leak within a month or two of purchase.  For the cost, I now use 2 D cells.
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Post  Iceberg on Fri May 15, 2020 12:47 am

Thank you all for the replies. Happy to see a nice question period finally:)

Balogh I think that is very true that like your old TD head some heads will continue to run well even though need strong battery to start. Your comments are always very helpful and full of facts. Yes likely the hot nitro keeps the filament going hot no matter the resistance in the platinum wire.

Often any heads that took too much current to start I drilled out and tapped to accept the fireball inserts. They glow red and hot easily with low current and run like stink with the heads slightly higher compression than before as I screw the insert in to almost touch the piston top.

I have run a number of NV inserts and found them a touch too high compression & needed a number of copper gaskets.

Thanks again all appreciate the many interesting and helpful comments.
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