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Member postings for Nigel R

Here is a list of all the postings Nigel R has made in our forums. Click on a thread name to jump to the thread.

Thread: Seagull Challenger - First kit Build - First IC
09/07/2020 15:52:46

6oz tank happily runs for 10 minutes with some left in the bottom. Maybe 5oz per flight actually used?

There's about 150fl oz in a gallon.

150/5 = 30 flights.

09/07/2020 15:04:00

I use

Firepower F6 plug

**LINK**

5% nitro mix

**LINK**

Thread: Laser Engines development.
09/07/2020 14:26:33

Now you come to mention it, a fence panel looks sort of like a wing. I wonder...

Thread: Irvine 40 Carb Spares
09/07/2020 11:36:17

I think that may be listed for the older silver made-in-UK engine Denis?

Redline RC have the complete carb on Ebay for Ripmax's suggested price:

OQAAOSw1v9eqqua">https://www.ebay.co.uk/itm/Irvine-Jetstream-Carburettor-1750-X-IRVCJ-1750/202979076659?epid=10024530915&hash=item2f427eea33:gOQAAOSw1v9eqqua

SMC also list if for suggested price:

**LINK**

Thread: LiPo over-voltage
09/07/2020 10:40:11

Richard

The manual for your charger states:

"The balancer can also further ensure that you’ve set the cell count correctly, and as a result
we strongly recommend keeping the balancing turned ON at all times. Please also note that
when balancing is turned ON you MUST connect the balance connector of the battery to the
balance connector adapter board (which must be connected to the balancer/charger) BEFORE
you start the charge process otherwise you’ll encounter a Battery Type Error warning.

However, if you understand the associated risks, accept full responsibility, and choose to charge
LiPo/LiIon/LiFe batteries without balancing/using the built-in balancers, it is possible to turn the
balancing OFF"

Emphasis is as per the manual.

 

Edited By Nigel R on 09/07/2020 10:40:42

09/07/2020 09:03:29

As mentioned above, for good reason I doubt many chargers actually use the individual cell voltages to limit the fast charge.

They do, however, all appear to display what they sense.

Edited By Nigel R on 09/07/2020 09:04:57

09/07/2020 08:43:31

Richard Clark:

"trying non-balanced charging over a long period as I have done?"

I have seen results of this in a professional context. Unbalanced charging does not end with the lithium battery packs magically returning to a state of balanced cells. Quite the opposite, in fact.

" As will the charging current for all the cells (though it won't be the same for each) "

I can assure you they very much will be the same on each cell, a series connection has no other possible outcome.

"Thus the cells are limited by the worst one 'naturally'."

They are not.

"the worst one (which has the highest internal resistance) can't go over voltage if you have entered the number of cells correctly or less reliably (so check), the charger has detected the number."

Chargers (generally, perhaps there are exceptions, but it would be necessity slow the charge process) do not apply the 4.2V target to individual cell readings during the initial fast charge. The high current causes the reading at the cell terminal to be only approximately indicative of a cells state of charge. Age and condition of cell as well as charge current make this worse. It is not something easily compensated for. The charger will not know the age or condition. It will not know how much effect applying charge has.

If the charger misdetects the cell count, then something is badly wrong with your pack, and it needs special attention (the bin, would be my first suggestion, although I have seen suggestions to save packs by stuffing a constant charge in for a few minutes to try and "rescue" a dead cell).

"It's the excessive heat when using and charging the Mojo at the same time is the problem, though Chord say it is fine to do. "

Again, being blunt, Chord are wrong. I would imagine the reason it gets hot is because they do not have a proper mechanism to manage the selection of power input, nor a proper charger. A simple scheme of permanently charging whilst running from a battery just doesn't work on lipo (unless your design goal is to degrade the battery very quickly in order to mandate a frequent replacement cycle).

Laptops (for example) have more sophisticated power management and are quite capable of running from mains whilst the battery is connected, and neither drawing power from the battery nor charging it.

"completing the circuit with the ESC/motor each 'high' cells charges any adjacent low one so it self corrects"

You are, incorrect again. It is impossible for this to happen with a series connection.

I would make the polite request that you stop adding more misinformation to this thread, as your posts seem to demonstrate an incomplete understanding of batteries and electronics.


Allan Bennett: "Like Chris, I don't understand how any charger can display a cell voltage over 4.20v and not figure out that something's wrong."

Cell lifespan effects coupled with high fast charge current will produce a high voltage reading which is at best loosely indicative of the state of charge of a particular cell. The charger does not know what the age effects are and cannot compensate. At best, it can set a maximum limit, but that limit must by necessity be over the 4.20 target if the fast charge is to be effective; when charge current is cut to zero, the cell voltage will gradually drift down over the course of several minutes. Only after that time has passed, with no charging being done, can you get a more accurate reading on each cell.

Chris Bott: "I've heard folk complain that balance charging takes too long. Well, if that happens, it's telling you that your packs are being pushed out of balance by your charge cycles. I balance charge every time. It keeps my packs in balance"

Could not agree more.

Balance every time, do that, and the balance will be quick.

If a particular pack starts taking a long time to balance, that's an early warning on the health of that pack.

Thread: Chris Foss Xtra Wot
08/07/2020 16:44:54

Love the sacrificial plate on the skid. yes

Thread: Need some help please
08/07/2020 16:43:14

Many will be best served by putting on ebay with a low start, certainly the more everyday ones. Those will have been traded on ebay before and completed auctions/sales can be checked for an expectation of value. I have sold quite a few engines on ebay this way and received fair value for them most every time. Maybe others on here can advise, but, my experience suggests:

Worth figuring out where best to sell:

Taplin Twin is quite a gem, GMark twin quite nice, Wain TV72 looks interesting, but don't know if it is a valuable one. The Nano could be worth a bit

I don't know about the following, some rare, maybe worth something (but maybe not):

Rustler 500, Forster 29, MK-17, Modela co2 motor

Most engines you have I would personally go straight to ebay with:

OS Max-III 29 C/L, Enya 19-VI boat engine, Thunder Tiger 15

The CS engines, AM 1.5 diesel, OS MAX 20, Veco 19, K Mills 75, cox peewee .020

RCV, Enya SS 40, Magnum GP 10, the MDS engine

The following lot, Ebay again may fetch a higher price:

MPJet 40, Letmo MD 2.5, MVVS diesel, PAW 100, PAW 149,

Super Tigre 40 rear exhaust (maybe, if brand new it would, I think)

HB 61 PDP marine, as an aero engine might get a bit, not sure about the marine version

Hope that helps

Thread: Martin Baker MB5
08/07/2020 15:47:31

Jet turbines are not without their complexities wink

From the perspective of the time, perhaps those airframes ceased to be promising or interesting?

Supersonic was on the horizon with a whole different set of aerodynamic rules...

Thread: LiPo over-voltage
08/07/2020 13:29:55

I rest my case.

08/07/2020 13:18:09

Yes indeed, current off, wait a bit, then take voltage readings, that is ideal.

I think most chargers follow that method. Perhaps some don't. Both my units appear to, you can watch the current drop to zero for a few seconds every half minute.

08/07/2020 12:02:57

"wondering how a balance-charger could let one cell get so far beyond 4.20v."

Our usual chargers tend to operate in two phases;

First phase performs the fast charge at high current, during this phase only overall pack voltage is examined. Balancing may or may not be performed during this phase.

Second phase performs balancing only, slowly draining any "overcharged" cells by applying a small load to them, potentially at the same time as putting a low charge through the whole pack to bring up "undercharged" cells. This second phase is often time limited.

If a badly out of balance pack is fast charged, then it can easily have one cell go over the high limit. The second phase may not last long enough to bring the pack back in balance. Generally the balancing is quite a slow process and our chargers just "have a go" at bringing things a bit closer. Sometimes that isn't enough. You may have experienced this with an old pack taking two or more attempts to balance out.

However, if Tim's pack was previously quite well balanced then it suggests some error in connection would have affected the voltage readings during the first phase. I don't know the charger in question well enough to comment on the exact mechanism at play here.

08/07/2020 11:54:39
Posted by David Hall 9 on 08/07/2020 11:23:12:

Please excuse my ignorance, but doesn't a LiPo battery charge to it's limit as determined by its chemistry, then generates heat rather than excess charge?

No, they just keep on going. Hence why you never trickle charge lithium.

The limit is a level applied by the charger.

The limit itself is a trade off between desired cell life and total energy stored for a single charge cycle.

08/07/2020 10:42:32
Posted by Tim Kearsley on 07/07/2020 16:46:41:

In my own case, I partially discharged the over-charged battery and then balanced it and finally re-charged. I have to say that it seems absolutely fine and in fact powered a model for a decent flight this morning. I checked the cell Voltages after the flight and all were within 0.01V of each other.

I've always, in my ignorance, balance-charged, every single time, because I didn't see any disadvantage.

Your pack is most likely perfectly ok.

Cell damage is a function of both time, and amount of overcharge (or discharge). So if you get in there quick and bring it back to normal levels any damage will be minimal.

Posted by Tim Kearsley on 07/07/2020 16:46:41:

I've always, in my ignorance, balance-charged, every single time, because I didn't see any disadvantage.

You were doing it right. Lifespan and performance is maximised with balancing.

I would suggest, charge somewhere "fire safe", just in case.

If the charger starts making mistakes with the packs, either fix or replace it.

08/07/2020 10:38:09

"it's not got any facility for balancing at all, so Chord, which is a very reputable company, think it's safe enough"

I work with lithium batteries. Not balancing them has never, ever, been a consideration, as both my work and the client highly values reliability and longevity of battery units. And my place has done a lot of lengthy and very expensive work studying the effects of cell degradation and battery performance.

So I'm afraid I have a very different assessment of Chord's approach. Which is, to be blunt, that it is cobblers.

Given that the first google result for 'chord mojo' is 'chord mojo battery replacement' which seems to be a £100 service on a £400 unit, I'm inclined to think there may be a cynical commercial component to their decision to avoid bothering with balance charging, too.

As for other chemistries. If you trickle charge nimh/nicd/lead (or your charger performs a fast charge then drops back to a trickle) you are balancing them.

Thread: Laser Engines development.
08/07/2020 10:22:55

"The new 200 (30cc)"

are these multis the narrow angle vee you mentioned a while ago?

Thread: Swoop. 1.2m aerobatic slope soarer
08/07/2020 10:04:29

Very nice Dan.

How did you do the rib alignment in the wing? They're all at different angles, is it a self jigging sort of structure?

Thread: Martin Baker MB5
07/07/2020 15:29:16

By comparison, Supermarine managed to turn a trick on the Spiteful development and re-use bits of it as the Attacker.

I'm not sure Martin Baker had the necessary production capability or experience to put the MB5 into proper service?

07/07/2020 12:04:03

Personally I can't really see the Mustang in the MB5 much... MB5 has short stubby wings and a long, long fuselage, most everything a different shape. The MB5 was quite a thing, very sleek. But times changed, and jets were the thing, they all had 100mph on the MB5.

The MB5 must make a great model. No problem with balance. Nice long moment arm, wide U/C, etc.

Edited By Nigel R on 07/07/2020 12:04:46

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