Glow plugs

[fly boy3]

For years I have used a 2v Cyclon battery for my glow plug power with no trouble. I have now obtained a new one for this season. Plugs are 1.5 volt, battery is 2volts. Am In danger of blowing a plug, or will the resistance of plug drawing about 3 amps. Reduce volts to a safer level.  Thanks

[Martin Harris - Moderator]

The usual advice is to use a fairly long lead - 3 feet or more of reasonably small section wire - to drop the voltage at the plug.  Unless someone can give a recommendation, experiment to find suitable size/length which gives a reasonable red glow at the plug. 

[Christopher Wolfe]

Use a long power lead (about 6 feet of bell wire). If the glow is not bright orange then shorten the wire a bit at a time.

 

With your Cyclon battery you need the wire's resistance to drop about 0.5V.

 

Not too hard as the average glowplug's resistance is about 0.22 Ohms

[fly boy3]

Thanks both for prompt replies. Yes, I agree longer leads can drop the voltage down but these long leads may cause a hazard. I never blew a plug on my old Cyclon battery and I assumed as due to its age the voltage was below 2v anyway.

                 That’s why I thought perhaps incorrectly that the plug ohmic value and current pull of3 amps may have helped to drop just half a volt.  Cheers

         
 

 

 

 

[Andy Stephenson]

You could try a 3A silicon diode, this would drop between 0.6 and 0.7V a 1N5401 would work. This way you could keep the leads as short as possible.

[Martin Harris - Moderator]

You might try coiling or binding the excess cable - I don’t think magnetic effects would be significant. 

[steve too]

5 hours ago, fly boy3 said:

Plugs are 1.5 volt, battery is 2volts. Am In danger of blowing a plug, or will the resistance of plug drawing about 3 amps.

 

Given the current price of plugs, I would suggest getting a subC NiHM or programmable regulator that will go down to 1.25V (search for XL4015 in this forum).

[Brian Cooper]

Alternatively, get a new battery.

[Engine Doctor]

A decent "D" cell NiMh will power a glow-plug for hours with a decent glow, but you will need a lead .Beware of cheaper D cells that have a small cell inside a D case. Also by the "Ready to use" or pre chargedax yhey dont self discharge when not being used . A decent glow stick with a sub c cell is p4obably the best option if you dont want a lead. One thing I have found is that the chargers that are supplied with these are often rubbish . Charge on a propper charger and they work fine , provided the clip hplds them on ok 😉

[BucklandMetcalfe]

If you have a 2 volt battery and need to use it to power glow plugs, using a 1.5 volt plug can be dangerous. Connecting the battery directly to the plug can cause overheating and damage the plug or other components. To reduce the voltage to a safe level, you will need to use an appropriate voltage reduction circuit such as a voltage regulator or voltage divider. These devices will help reduce the voltage to the correct level without the risk of damaging the equipment.

[steve too]

6 hours ago, Engine Doctor said:

A decent "D" cell NiMh will power a glow-plug for hours with a decent glow

 

My current backup.

 

[Peter Christy]

A decent NiMh cell (D or sub-C) will never over drive a plug, and will also be more than enough for 2V plugs. You don't need yards of wire to drop the voltage, and they charge quicker than lead-acid cells. Win-win!

 

The plug does not need to glow orange. It should be a nice cherry red. If you make it glow too brightly, it will start to shed the platinum coating, giving it a dull, grey look. That is when the engine starts to quit at low throttle settings!

 

I can't remember the last time I had to change a plug because it was burned out or gone grey. I have been using NiMhs (and before that NiCads) for decades now, and would never go back to a lead-acid cell. I don't like power panels either, as it is far too easy to overdrive a plug with them and damage it. If you crank up the current, to clear a flooded plug, by the time you see the current rise as the plug clears, it is too late. The damage is done.

 

If you supply a plug with the correct voltage, it will draw the current it needs - it is self regulating - and you will never inadvertently damage one.

 

<Gets off soap-box!> 😉

[BucklandMetcalfe]

My answer turned out to be useless, as I expected🥲

Edited May 12, 2023 by BucklandMetcalfe

[fly boy3]

Not useless at all Buckland. When questions are are asked on the forum, ALL answers are welcome, it’s like a brain storming session where all the answers are read. Sometimes it is not the most obvious answers are first choice too.  I thank you for your informative input.

[Peter Christy]

8 hours ago, BucklandMetcalfe said:

My answer turned out to be useless, as I expected🥲

Not at al! Your answer was technically correct, and a length of bell wire - about 6 ft - will have sufficient resistance to drop the voltage to a safe level. But IMHO, its not the optimum solution. Using a NiXX cell of suitable capacity and low enough internal resistance will do the job better, and be simpler.

 

However, if a cylon battery is all you have, then your suggestion is fine.

 

Use what you have, and upgrade when you can! 😁

 

--

Pete

 

[Don Fry]

I use a 7000 mah Cyclon cell, current unit is 6 or seven years

70 mm ammeter, (to see at a distance), a rheostat,(ceramic wire wound, over 10 watts, 2,5, or 10 ohm resistance,) and 4 mm lead plugs. Second red plug to eft is a charge plug, which allows the charge circuit to bypass ammeter and rheostat. Stick it on a charger every couple of months to top it up. Uses commercial connector leads.

Suits all plugs, because it has enough volts. Will start a twin. 
I don’t use 2 volt plugs nowadays. I always thought 1.2 volt batteries struggle to get them warm enough, but opinions vary, but ohms law suggests I am right. 

This unit gets a lot of use, quite a lot from club mates with small clip on battery units. 

[Cuban8]

On 10/05/2023 at 13:52, Martin Harris - Moderator said:

You might try coiling or binding the excess cable - I don’t think magnetic effects would be significant. 

Particularly as we're dealing with a DC supply and very few coils of wire.

[Martin Harris - Moderator]

Yes - I just wanted to preempt anyone thinking about coiled cable effects!

[Andy Stephenson]

Heating and magnetic effects will be insignificant.

[Andy Stephenson]

I tried to post this before but I just couldn't find the link before so here it is...

https://www.os-engines.co.jp/rule/kinkyuu2021_10_12e.html

For more detail see the link

 

Edited May 13, 2023 by Andy Stephenson

[Engine Doctor]

I use an old MFA glow starter box for standby in case my glowsticks give up , unlikely but you never know. 

The MFA box was popular in the 1970's and  is a neat box that came originally with a built in ammeter,  2v lead acid gel cell and resistance leads for the glow plug. So threw out the cell and leads and replaced cell with 7000 mah Nimh low self discharge D cell. No faffing with resistance wires and can tell at a glance if the circuit is working, charging or discharging. And it will power a glowplug for hours on one charge .

They are often found at swapmeets in junk boxes and can be bought for pennies.

If anyone does use a D cell Nihm make sure its a real D cell as there are a lot of D sized cells for sale that actually have AA cells in a D cell sized case . Choclate teapot comes to mind.

Edited May 14, 2023 by Engine Doctor