Low voltage warning

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rudderonlybird
Posts: 37
Joined: 17 Feb 2018, 05:07

Low voltage warning

Post by rudderonlybird »

Phil...or anyone. Is there some kind of a low warning system for the single-channel rudder-only emulator? I'm doing a Futaba FT-3A 2.4 conversion, and space limitations require an oblong 9v battery. I'm concerned about battery life, and would install a meter, but again, no room. An alternate would be some kind of LED circuit for a low voltage warning.

Any ideas?

Marc
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PaulJ
Posts: 598
Joined: 16 Feb 2018, 19:01
Location: Ipswich, UK

Re: Low voltage warning

Post by PaulJ »

Marc, I don't know which Tx module you are using but I used an Orange DIY and yes, it took a bit of planning but it all went in in the end. I started out with a 2S 350 mA lipo which went in the top of the case.
IMG_0153.JPG
This had plenty of capacity for the amount of flying I do in most sessions but then, for peace of mind I found a 450mA lipo that went in neatly on top of the Tx module.......
IMG_20181210_085951.jpg
I don't know if you actually NEED 9V but a fully charged 2S lipo is at very nearly 9V and indeed you can buy "9V" lipos that are actually only 2S (nominally 7.4V).....
https://www.ebay.co.uk/itm/2-9v-Lipo-Ba ... 3409c145aa

Paul
rudderonlybird
Posts: 37
Joined: 17 Feb 2018, 05:07

Re: Low voltage warning

Post by rudderonlybird »

Cool, Phil, thank you. I hadn't thought to spec the FrSky DIY RF module is used. There seems enough room for everything, and I'm only waiting for a new slide switch and microswitch to arrive from DigiKey. I found the original switches were intermittent and simple to change out. Unfortunately, the original on-off switch is a rocker and seems to be proprietary to Futaba, so it gets a standard slide switch. At least the mounting holes line up :) I'll post some pics when the mod is underway.

Marc
AndyS
Posts: 42
Joined: 12 Oct 2018, 19:03
Location: Biggleswade

Re: Low voltage warning

Post by AndyS »

What is the best way to charge the 'EBL PP3' type lithium battery?
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Phil_G
Posts: 596
Joined: 15 Feb 2018, 23:32
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Re: Low voltage warning

Post by Phil_G »

Hi Marc, I dont bother with battery alarms, these 2.4g sets use so little power and batteries are so good these days that a 'top-up' charge after a full days flying rarely exceeds 100mAh. I use a lot of the PP3 size 2S lithiums, search "EBL PP3" on ebay, they're a genuine 600mAh the size of a PP3 and I defy anyone to flatten one in a day! In larger trannies my standard battery is now 2x 18650 cells, these have huge capacities and easily last me a season. Its not like the bad old days, generally I've found that battery level isnt a concern any more Image

I ordered my EBL batteries with a twin charger, it just has the two press-stud connections, no balance lead, balancing is internal and the charge current is deliberately low (80mA) so the internal balancer can 'keep up' :D
I would have thought that any lipo charger set to '100mA unbalanced' should be ok.

You can buy the chargers separately, eg: https://www.ebay.co.uk/itm/2pcs-600mAh- ... 2694788427

Cheers
Phil
IMG_20191214_230238.jpg
AndyS
Posts: 42
Joined: 12 Oct 2018, 19:03
Location: Biggleswade

Re: Low voltage warning

Post by AndyS »

Thanks for your reply Phil. After I made my post I did a bit of internet research and found out about the critical voltage requirements. I have on order a similar charger.
jackdaw
Posts: 165
Joined: 16 Feb 2018, 20:30
Location: Wet and Windy North Wales

Re: Low voltage warning

Post by jackdaw »

Got to add that I use these batteries all over the house/place; digital scales in the kitchen and hobby room, DVM, smoke alarms, frequency counter, etc. So, I bought quite a few of them and to charge I got one of these https://www.ebay.co.uk/itm/EBL-8-Slot-F ... SwJxRcqwmD
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