Low glow issues with rechargable JP Glow Starter

[Jonathan M]

Got one of those 'handy' JP Glow Starters with a rechargeable 3800mAh NiMH cell, but don't seem to be getting much glow out of it after a few starts?!

Abandoned using it at the field yesterday when it failed to get the plug hot enough - luckily a mate had a lead clip plugged into his 12v power-panel.

At home the battery registered 1.27v on the multi-meter, which went up to 1.35v after 3 hours charging (240v wall-charger rated at 1.25v 170mA, however 1.85v on the multi-meter), then 1.41v overnight and finally 1.43v after 24hrs.

Do these voltage levels make sense? Even after a full charge, the unit's integral meter needle is barely out of the red-zone. Surely a 3800mAh battery should hold a heck of lot of capacity, and the meter should read higher?

[Martin Harris - Moderator]

Assuming it's the unscrewable type, it might be worth cleaning the battery contacts? I doubt that the integral meter is anywhere near calibrated so this may be a red herring...

[eflightray]

If I remember correct back to my Nicad/Nimh flying days, those types of cell do not really like long low amp charging, they soon start to drop the voltage under load and wont hold the capacity.

If the cell is suitable, then a high current charge may reinvigorate the cell.

[Denis Watkins]

Hi Jonathan, as you have found, the voltage does not guarantee the punch needed to light a glow. You put a 1.5 v AAA onto a glow and it will barely show. OK, that was a very small volt increase after 24 hours charging and I would not recommend more than 10 hours on a NiHms anyway. You need a new cell buddy

[Denis Watkins]

To add, 170ma is not the way to charge a 3800ma NiHm. More like 380ma to make headway over 10 hours. I would charge that battery at 3A, that is 3000ma

[Shaunie]

The terminal voltage of a NiMh is only a nominal 1.25V anyway, perhaps 1.4V when bursting at the seams.

Does this go straight on the plug or via a lead? It doesn't take much lead length to lose a significant amount of voltage when you've only got 1.25V to start with.

What plug are you using? Enya No3s work well on a NiMh glow stick as they are 1.3-1.5V rated. A 2V plug driven by a NiMh on a leaded glow clip is never going to end well, in the winter anyway. The other thing is I never expect my plugs to glow bright yellow, reddish orange is fine for me. Too bright a glow can make an engine over-advanced when starting and make it bite back.

Shaunie.

[Jon H]

The meter on the end means nothing and only moves when current is flowing through the plug. To check its power you need only connect it to a spare plug and look at the element. if its orange you are good to go.

With your charge rate of 170mah and a capacity of 3800 a 24 hour charge is going to be about right. charging at 3amps will have it done in an hour but over time that will toast the cell. Also most delta peak chargers struggle with single cells so I wouldn't recommend it.

I have a bunch of similar sticks and charge them on the 240mah chargers they came with. they rarely give any trouble, although the meters are useless

[Former Member]

[This posting has been removed]

[Jonathan M]

Thanks for the various observations - good to know the meters are all pants.

Clean unit, direct clip-on, barely used. Plug is a new ASP unit for 2 or 4 strokes (used in an ASP 70 FS).

Interestingly, a few hours now since ending the 24hr charge, I've just checked and the voltage has fallen back to 1.38v. Will check again tomorrow morning where its settled.

Could get a couple of replacement cells and hot-wire (excuse the pun) the charging-head and leads from the wall-charger to my proper charger (Pb/LiPo/NiCad/NiMh) and select an appropriate charging capacity.

Or - more reliably - I've decided to complete my flight-box properly with a 12v power-panel with adjustable current to a lock-on glow-lead!

Cheers

Jon

Edited By Jonathan M on 19/12/2016 22:40:26

[Jonathan M]

Posted by eflightray on 19/12/2016 20:41:27:

If I remember correct back to my Nicad/Nimh flying days, those types of cell do not really like long low amp charging, they soon start to drop the voltage under load and wont hold the capacity.

If the cell is suitable, then a high current charge may reinvigorate the cell

What charge would you suggest?  Using the hot-wire method above, I might try to resuscitate the 3800mAh NiMh cell...?

Edited By Jonathan M on 19/12/2016 22:43:12

[Martin Harris - Moderator]

I wouldn't worry about the voltage drop since charging - that's normal. Did you check for a good internal contact between the cell and its contacts? It's possible that if the unit has been hanging around for a few years that there may be some oxidisation limiting the current flow. As Jon advised - whip the plug out and check what the glow is like. While it's out, you might consider trying an OS F plug if you have one to hand...

[onetenor]

2volt plug and 2volt cell

[Jonathan M]

Hi Martin - Contacts completely clean, voltage same when measured at head and at battery terminals. Just ordered a couple of OS F plugs as spares, so can compare them in use to the ASP plugs.

By the way, when the glow was powered from my mate's power-panel the engine started with a hand flick first time, whereas this was never possible with the battery-stick even when fully charged.

[Braddock, VC]

I've had the same problem, twice. For some reason the clip is extremely "picky" where it connects, in both cases (a jp self contained and a lipo powered glow igniter from sussex models) I have to ensure when using them that the clip part fits exactly on the hexagon of the plug, a bit of a faff with the engine being inverted.

My solution was to buy a couple of those self contained glow drivers that plug into the rx, press a button and bingo, 15 seconds of power to the plug, never fails.

[Peter Christy]

A typical glow plug will draw somewhere between 2 and 4 amps. What is important for a good glow is not so much the voltage, but a low internal resistance in the cell. In practice this means using a physically large cell - sub 'C' at a bare minimum.

A good NiXX sub-C or larger cell will be quite adequate to light any plug - be it 1.5 or 2V - with the added advantage that it won't be possible to overheat the plug, and thus shorten its life.

I've been using single-cell NiXXs as my glow-plug drivers for over 20 years now, and during that time I have never actually blown a plug! Yes, they've eventually died of old age - usually the warning sign is when the tick-over or pick-up from tick-over becomes unreliable - but not actually burned out. Nor have I ever had any problems starting an engine using a single NiXX cell, either 2-stroke or 4-stroke.

On the other hand, fellow club members, using 12V power panels, seem to have to change plugs at regular intervals!

I use a home made glow driver, comprising a plastic box from Maplins, a single sub-C cell, and a 5 amp meter from an old car battery charger. The meter is an very good guide to what is going on in the engine.

Once you have established what the normal current draw of your preferred plug is - most easily checked before you put a new one in the engine - any variation from that figure will tell you what is happening. If the reading is high, it will be because the plug is wet and cannot get up to temperature. If it is normal, but goes high when cranking the engine, it is dry and the dry charge passing through the engine is similarly cooling the plug.

You will only see these changes on a decent size meter. The tiny little edge-wise meters on most commercial glow drivers are too small to read with any accuracy, and are just a go - no go device.

The problem with power panels are two-fold. Firstly, the regulator device is often a low value variable resistor. This has to handle the high currents drawn by the plug, and often in an oily environment. As a result, they wear very quickly, and can become difficult to adjust smoothly and accurately. Over-driving a plug will shorten its life dramatically.

The second problem is the temptation to wind the current up to "clear" a flooded plug. By the time you see the current start to rise as the plug clears, it is too late, and the plug has already been over-driven.

A plug works not just by glowing, but by the catalytic action of the platinum on methanol. Simply dipping a piece of platinum wire in liquid methanol at room temperatures and pressures can be enough to ignite the vapour! Of course it is more reluctant to ignite when compressed, which is why we need to heat it.

In days of old, plugs were made with almost pure platinum wire. But then the car industry was forced to use catalytic converters to clean up exhausts, and the price of platinum - already very high - sky-rocketed. Modern plugs tend to be platinum coated. If the coating flakes off, the plug becomes useless - even if it still glows.

You can tell if a plug is flaking, as it develops a smoky grey appearance, rather than being shiny. Two things cause flaking - old age, and over-heating. And it is power panels that are predominantly responsible for the latter!

Use a good quality sub-C - or larger - cell, place an ammeter in series with it to accurately read your plug current, use decent plugs and glow-clips, and you will rarely have any problems starting. And your plugs will last a LOT longer!

As for charging sub-C cells (or similar), as stated earlier in this thread, I would recommend using a 1C charge rate, ie: charge in 1 hour, rather than trickle charge.

--

Pete

[YakMad]

If it's the JP Glow with the Red Plastic cover/grip I would recommend opening it up (split the plastic cases at the welded seams) mine decided to fry itself at the field one day and only the fact that the very low grade wiring inside melted, stopped it turning into a blob of plastic. When I opened it up I was stunned at the poor quality wire and the shocking soldering, the meter was toast as well and I am amazed the thing worked for as long as it did. I found out the problem was the wiring was so stiff that the brass contact which engages with the top of the glow plug was being pushed forward and shorting out against the external body of the glow clip. I replaced all the wiring with silicone insulated cable and replaced the meter from an old glow start and it works perfectly now. I passed on my findings to the online shop where I bought it but heard nothing back from them. I've had a few glow starts from different manufactures lately and all seemed very poorly made.

[Stuart Z]

For info, my glow starter is only 1400mah and the maker's instructions recommend 4-5 hours topping up charges periodically, so perhaps all the feedback is telling you how to get a very useful help without being "hooked up" to a power panel.

S

[Tim Flyer]

I prefer using my panel and long lead. I change plugs every now and then about 3-6months depending on model, just because I want to prevent dead sticks. When I used to run high rpm piped 2 strokes a plug would last a couple of weekends( that was in the days of Taylor) . The superb (and dear)OS plugs these days plugs hardly ever seem to fail totally , but I do change them as the filament certainly does still get worn out. I do have a small battery glow start but use that just for spare and lending to other club members😊

[Denis Watkins]

Don't forget Peter Christy's comments, that could easily form a magazine article as it embraces all the important points of adequate amperage and sufficient charging, as well as plug condition. This article will be printed out for my flying colleagues, thanks Peter

[Brian Spearing]

I junked my unreliable glow sticks and now use a 5 AH Cyclon cell with a metre of servo wire or similar to drop the voltage to the glow plug. Totally reliable.

[Stuart Z]

So again, we all have our preferences, I started using a glow starter when I found my power panel glow circuit ran at 12v, no wonder the engine started quick, I also had to use a lot of plugs. No more.

Based on my experience only.

[Jonathan M]

Excellent explanation Peter, thanks, and Stuart et al also. Every component in a chain is always a complete new learning curve!

Already ordered a power-panel. Useful however to know the built-in meters can't be relied upon, but this can of course be periodically checked/calibrated at the plug end of the lead with a hand-held multimeter.  Don't want either 1v or 12volts!

Have also ordered a 2000mAh sub-C replacement for the little JP unit as a backup power at the field. Will see how charging and ability to hold the charge works.

Edited By Jonathan M on 20/12/2016 13:06:37

[J D 8]

To check output of power panel you just need a glow plug, dull orange not enough oomph,bright orange good, heading towards white hot too much and a soon to be dead plug.