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Member postings for Chris Bott - Moderator

Here is a list of all the postings Chris Bott - Moderator has made in our forums. Click on a thread name to jump to the thread.

Thread: Which version of S8R v2.1.0 firmware?
09/07/2020 10:59:16

It's mostly great gear at excellent prices but FrSky don't do themselves any favours with "support" like this, do they?

Is there a version with and one without V tail?

Could they possibly just be talking about quick mode and the full mode?

Thread: LiPo over-voltage
09/07/2020 07:59:57

I'm sorry Richard but that's incorrect again. As soon as the ESC is connected, ALL cells see the same DISCHARGE current which is in the opposite direction to a charge current so all will start going down.

While I agree that most lipos will stay in balance for a number of unbalanced charges and some will for many charges, any that are out of balance are likely to have that imbalance become slightly greater at each charge cycle.

This is why balance charging was invented in the first place. Early lipos had no balance lead, early chargers had no balance facility and people had fires!

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. Very little time is spent in the balance part of the charge so my charges take only as an unbalanced charge.

For anyone to suggest that balance charging is unsafe and that it's safer to charge without balancing (because of one event that was in effect a fault situation) really is dangerous talk and is doing a disservice to beginners reading this forum.

Of course anyone can make their own choices. But balance leads are there for a reason and I will always use them. I also charge in a safe place and carefully monitor my charges too and I use a separate device to check voltages before and after charges and flights.

Thread: Mini flight stabilisers
09/07/2020 07:45:33

If I remember correctly a 3 axis gyro has 3 attitude sensors which will tell the unit which way up it is. But these are slow to respond to the slight changes that we need our gyros to correct. So 3 accelerometers were added hence the term 6 axis.

Thread: LiPo over-voltage
08/07/2020 20:19:06

If the cells are in series, the charge current through each cell will be precisely the same. Without balancing, the charger will only know the pack voltage.

So it will limit the pack volts of e.g. a 4S to 16.8V.

But if 3 cells are only at 4V when one is at 4.2V the pack voltage will be 16.2V and the charger will keep pushing current in to get volts up. By the time it gets to 16.8V they might be at 4.15, 4.15, 4.15, 4.35 - an unbalanced charge causing overcharge of one cell. 

Edited By Chris Bott - Moderator on 08/07/2020 20:40:25

08/07/2020 19:57:17

I agree with Tim and think that charging without balancing has more potential to overcharge a single cell than balance charging. So I'll continue to balance, every charge.

08/07/2020 18:41:15

I don't understand Andy48. If it was reading over 4.3 on the charger screen then it knew it was going past 4.2 and shouldn't have charged it further.

If a bad connection meant that the reading in the charger was actually 4.2 when the battery was over 4.3 then you'd have seen 4.2. I'm missing something, aren't I?

08/07/2020 18:25:44
Posted by Phil Green on 08/07/2020 10:44:44:

I'd go further than that LHF, I would have hoped that on a public forum, mods would remove dangerous advice.

I'd suggest that this is similar to the club arena where "everyone is a safety officer". If you see something that's unsafe you say or do something about it.

That's exactly what's happened here. Well Wefore any of us mods looked in.

My take, BTW is that I balance every charge to make sure no cell goes over 4.2V. if I watch cell voltages on my charger, balance charging a poor battery, as soon as any cell starts to go over 4.2v it appears to be clamped at 4.2 by the discharger being applied to that cell and the overall charge current is reduced to a level where that load can cope.

I wonder if some chargers are better than others at accurately measuring cell volts. I think it's likely that each tapping point is measured from the 0v connection and some maths done to calculate individual voltages.

I also agree that as current is reduced then connection resistance would have less and less of an effect and the over volts should be spotted. If I saw issues like this I'd be suspicious of either my charger or whatever device I'm checking with afterwards.

Thread: S1581 Hawker Nimrod MkI
03/07/2020 10:01:08

Eric can you get your video onto YouTube? Either on your own YouTube account or through someone else who has one? You need it there to be able to post it here.

Thread: OpenTX not displaying sticks
02/07/2020 14:49:34

OK that's fairly typical of OpenTx, when a short press will take you one way through a group of pages and a long press will take you back through them.

02/07/2020 14:05:55

As Matty says, on OpenTx screens there are a number of "home" pages, you just need to find which is PgUp or PgDn buttons to scroll through them.

Thread: Build your own telemetry sensors.
27/06/2020 17:38:07
Posted by David Wilkinson on 27/06/2020 13:29:28:

Hi Chris,

Seems like I'm very late to the party. Just started with Arduinos a few weeks ago, and am building a vario sensor based on the OpenXSensor page.

Do you have any of the PCB boards left? Don't worry if not.

Was there anything in the magazine article that you've not covered here. I've tried to get hold of a back issue, but there doens't seem to be any available.

Many thanks.

David

Hi David

Yes I'm sure I have PCBs still. Certainly the fully functioning but incorrectly printed ones. Almost certainly some correct ones too. If I can dig out the mag I could photocopy the article and include that as well.

Thread: The great i.c. / electric finger chopping debate
18/06/2020 21:04:03

Whilst I agree that an IC engine is not dangerous while it's not running, and that it only takes the combination of a couple of mistakes for an electric motor to start unexpectedly, that's surely not the end of the debate.

IC prop strikes dominate, in my experience, and that's because engine adjustments or removing the glow clip can require you to put your fingers perilously close to the prop. A moment's lapse in concentration can see you reaching through the prop too. I've even seen a loose tether cause someone to put their hand out to stop the model as it took up the slack and travelled towards him when he'd just started it.

Thread: FrSky Neuron ESC
14/06/2020 22:26:01
Posted by Geoff S on 14/06/2020 22:00:26:

Just setting up to use my Neuron 80 in anger. The motor I'm using is an old one and doesn't seem to be drawing as much current (and hence power) as my records indicate it did when tested it several years ago. I wondered if perhaps the throttle calibration is out and I've connected to BLheli32 to see.

Minimum throttle is set to 1040 and seems to be OK (ie the motor stops when I shut the throttle) but maximum is at 1960 (presumably milliseconds pulse width) whih is less than the usual 2 mS. Just wondered what settings others have used as I think I may not be getting full throttle.

Geoff

Geoff if your Tx is going to 2mS then it's going past 1960 (uS), so should be producing max power just before the stick gets to the top, anyway.

Thread: Simples anyone?
13/06/2020 20:18:08
Thread: Seagull 80" DH Chipmunk
12/06/2020 12:02:09

Here's a typical 6 minute flight on 6S, using 1357mAh. Peak power read 1121W

chippy 6 min flight.jpg

12/06/2020 11:21:49

Prop is a 15x10 APC-E

12/06/2020 11:17:51

This is the motor I'm using, Martin. With 6S 4500 lipos. It would easily take higher capacity ones too. I'll have to check prop size.

Plenty of power and excellent duration. 2 flights per pack, quite often.

screenshot_20200612-111307.jpg

11/06/2020 14:26:56
Posted by Jon - Laser Engines on 11/06/2020 13:57:31:

The sea fury does have quite short wings. I always notice that when i fly mine.

They look great though, just a shame they dont make any noise.

Lack of noise is a huge bonus for me. Each to their own, eh?

11/06/2020 13:14:53

All documented in this thread, Jon. You can see how long we've had them.

I'm just converting mine to 6S Lipo with the battery hatch being the exhaust deflector area.

Thread: 1S Wattmeter
09/06/2020 13:15:53

Excellent, it's really nice to see the fruits of a design when it's put together by someone else. Thanks Phil.

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