LiPo low voltage warning device.

Ian · 10-06-2006

Just been on the RC group USA forum where there is a very interesting thread on this topic.

A member has designed one at a weight of 4 grams, when the voltage goes down to 3v a buzzer starts and you know it's time to land.
He calls it the "MicroScreamer", for 2 and 3 cells only.
Does anyone know of such a device for sale here in the UK ?

He attached a drawing that - as I type this I'm trying to attach-.

I'm no good at electronics, but I strongly suspect that the device is invaluable.

Any ideas anyone please.

**wonwinglo** · 10-06-2006

Ian,I may have missed the point here, but surely the correct ESC will do the job of shutting off the motor and telling you that it is time to land ?

Ian · 10-06-2006

Nope, you don't Barry, It escaped my attention that an ESC would do what you mention, oh well, we learn every day & I'm gradually getting there. In fact, I'd have found that out 'cos I had ordered an ESC and LiPo's last Tuesday when they were despatched but I ain't got them yet.

I also ordered another item from the same dealer on Wednesday, an item I received on Thursday. Then I again placed an order on Thursday & I got that on Friday, but the ESC & LiPo haven't materialised. So I can't get started on my Fledgling. I have to wait 10 days in case it does materialise.

thanks for your reply, much appreciated.

**wonwinglo** · 10-06-2006

Ian remember the golden rules with Lipo,I learned the hard way-
1/ Always use the correct ESC,this shuts off the motor when the voltage is at its lowest permissable.
2/ Charge up as soon as you have exhausted the pack,but never ever leave them in a flat state,otherwise they are scrap.
3/ Always use a charger dedicated to use with lithium batteries.
4/If you use one of the adjustable versions such as the excellent Chamaleon ISL 6 then make sure the settings are correct,eg 2 cells 800 ma,60 amps,this reads on the grid as -2 LIPO#Go#1=60a,if there are any problems then it refuses to charge.
5/Not tried the new cell balencers yet which jump the cell if it is in overcharge state,the problem is that only the new batteries have the necessary taps,Overlander have the new cells in stock,if anyone has used them then I would be pleased to see a report here.
Thank you.

Ian · 10-06-2006

thanks again Barry,
I have 3 x Dualsky, X Power 2250mah, 1.1V (3s 1p) LiPo batteries that have the taps for a cell balancer, I got my cell balancer from Overlander. These batteries are for my Rainbow, Katana mini, Mustang & Spitfire that I have all ready to assemble when my time to fly them comes around. It's the Fledgling first and then I'm in business. I won't get to try these dualsky batteries untill I get past the trainer stage.

I got 2 x 2 cell LiPo batteries from Overlander with a free battery Guard that connects between the charger and the battery, I don't know what it does but I'm certainly going to use them, they are Kokham guards and batteries on special offer. these are for the trainer.

I should mention that I am a great believer in passing on any hints / tips or info I may come across after I do a search to find out if it has or has not been posted, I have got a vast lot of excellent info in here and I want to repay that if I can.

Your LiPo info is very greatly accepted, and I can assure you I am treading carefully regarding, not only all aspects of R/C, but especially the batteries.

**wonwinglo** · 10-06-2006

***Good man Ian,thats the spirit pass on any updated info,the battery market is in a state of flux at the present time with thousands of un-tapped Lithium batteries on the shelves,Overlander appear to be one of the few suppliers selling the updated versions apart from a few American ads that I have seen,you will be fine going the route that you have taken with proper equipment,by the way the Swedes have developed a wafer thin cell pack for military use,any news like that can only be good for the future of electric flying,the development costs can only be absorbed by the military and we will reap he benefits eventually,just think in a few years time almost anything could be possible in the way of small lightweight models ? battery development has never been as active as at present,the technology is out there,just look at that tiny delta that flew the atlantic last year under radio control,the future is exciting.

Quote:

Originally Posted by Ian

thanks again Barry,
I have 3 x Dualsky, X Power 2250mah, 1.1V (3s 1p) LiPo batteries that have the taps for a cell balancer, I got my cell balancer from Overlander. These batteries are for my Rainbow, Katana mini, Mustang & Spitfire that I have all ready to assemble when my time to fly them comes around. It's the Fledgling first and then I'm in business. I won't get to try these dualsky batteries untill I get past the trainer stage.

I got 2 x 2 cell LiPo batteries from Overlander with a free battery Guard that connects between the charger and the battery, I don't know what it does but I'm certainly going to use them, they are Kokham guards and batteries on special offer. these are for the trainer.

I should mention that I am a great believer in passing on any hints / tips or info I may come across after I do a search to find out if it has or has not been posted, I have got a vast lot of excellent info in here and I want to repay that if I can.

Your LiPo info is very greatly accepted, and I can assure you I am treading carefully regarding, not only all aspects of R/C, but especially the batteries.

**Bluewavestudios** · 11-06-2006

Ian,

That circuit looks quite easy to do and you have the full list of components...all you need to do is find a Maplin store near to you and I bet you could build one quite cheap.

Regards.......Mark

Ian · 11-06-2006

Regarding the ESC cut off points, that isn't always given or even mentioned, e.g., after Barry mentioned it above I went to the web site where I got a Jeti Advanced 30amp one for my AXI brushless motor, cut off was definitely not mentioned.

Then I read the instruction sheet, not mentioned.
So I went to their web site and it was given there and it has a cut off.

BTW, re Saphion batteries, that I am very interested in, here is a little info from Overlander.

I asked what configuration of Saphion would replace a 3 cell 2250 11.1v LiPo pack,
They kindly replied that I will need a 4s2p pack (2400mAh 12.8v) at £64.99.

Methinks that when funds recover I might very probably go that way.

duncan · 11-06-2006

Barry,Never heard of the tiny delta Atlantic crossing, sure it wasnt the Aerosonde thing from Australia ? Ian, be sure to read the "Batteries and Chargers" section of RCGroups, very informative.

**wonwinglo** · 11-06-2006

NASA X-9 Delta 9 inches wingspan,I think that it has solar panels in its tiny wings,crossed the atlantic,midway point take over flying at many thousands of feet,what a feat of engineering,I bet that there are more of these flying midgets that we have never head of ? the first details were leaked and shown in a magazine.
There was another larger long distance design that landed on the roof of a building short of its destination,a phone number on the side stencilled on brings out a team that are on 24 hour standby to retrieve them.