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Battery life

Just a best guess will help us!

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Paul T27/04/2021 14:35:00
7304 forum posts
1228 photos
2 articles

Hi Brian

It would be worth researching your batteries and looking at the manufactures test results for things like power drop off and core heat generation.

Then look at Internet for independent reviews from testers who have pushed the batteries at full draw for extended periods.

This level of research will better inform you as the results are taken from actual tests rather than a desk top study.


Brian Porter 227/04/2021 15:48:20
20 forum posts

Hi Paul,

Interesting, never done that before but will certainly try. Thanks for the advice.


Dave Cooper 628/04/2021 22:53:08
290 forum posts
29 photos

Another good test would be to find out where the BEC (Battery Eliminator Circuit) cuts in - assuming you're planning to use one that is.

This is essential on RC aircraft to get them down safely after the motor(s) has been cut. On boats, less so perhaps, but, could save your boat hitting the bank /another boat etc. whilst it still has substantial way....

I think I would set a timer on the Tx to chime in about 10 minutes, or so, before the BEC is due.

The experts may disagree !

ashley needham29/04/2021 08:43:01
7218 forum posts
169 photos

I would not disagree with any of the previous comments as I am not an expert. However.

Nimh batteries tell you when they are low as the boat slows down. Usually you have to then get the boat in straight away, however the battery voltage is unlikely to dip below that required for the BEC to work, especially if you conserve battery voltage by using minimal throttle to get back to shore.

A wattmeter is invaluable here and will tell you more than any amount of theorising....not that you don`t want to theorise, far from it, but having an actual sight of whats going on is a must.

The Component shop sells them, they are inexpensive. or e-bay


Brian Porter 229/04/2021 10:34:49
20 forum posts

Dave & Ashley,

You're going to have to slow down now, remember this thread is in the Beginners section!! Wattmeters I can understand but the BEC cutting in is, as yet, a bit beyond our understanding. I know they're in the two Mtronics ESCs but that's it. If you're able to explain the basics here that would be great. We're slowing advancing up this ladder one run at a time!

Not sure what you both think of this but as a visible warning, our electrics are being designed so the continuous working radar (a microscopic 3v motor) automatically stops, as a visual indicator, when the main 12v batts drop to 10.5v at which point we can shut down everything except motors to bring her home.

Also, in the early days of our marine adventures we'll be experimenting with her use & bring her home often to check the batts so to understand the battery life.

Thanks guys, all advice & criticism welcomed plus any micky taking accepted!!


ashley needham29/04/2021 11:27:16
7218 forum posts
169 photos

Brian. Scroll down on the right to members articles, click on that, scroll down to hints and tips and there, somewhere, is an article the late Dave Milbourn regarding electrics. He was the guru and I think you may find all the answers in the scribbling.

Basically the BEC (battery elimination circuit) in an esc provides power for the receiver at approx 5v through the centre red wire, and this saves you having to use an external battery pack for the receiver. If two esc are in the circuit, one on the ESC red wires must be disconnected for reasons unfashionable to me but just do it.

As the BEC voltage is about 5v it stands to reason that if the main feeding battery voltage drops to around, or below this value, the esc will not be able to provide 5v and so the receiver will not function.

You can over complicate things however, and after a few runs you will know when it is time to come in without a lot of gizmos. However, obviously the gizmos are very handy so I am not saying you should not go down this route.


Edited By Colin Bishop on 29/04/2021 12:23:58

Brian Porter 229/04/2021 14:42:26
20 forum posts

Ashley, Ah, got it. I thought it was more complex than that!

Thanks for the info & will also take a look at the article.


Dave Cooper 629/04/2021 17:23:01
290 forum posts
29 photos

Hi Brian,

I forgot to welcome you to the forum (talk about getting things backwards !).

Yes, Ashley has it in a nutshell. The BEC is just an electrical safety feature. Some of them are 'programmable' but, that's getting ahead of ourselves, and, as you quite correctly mention, this section is for beginners (that's me too !).

The alternative is to have a separate battery supply for the receiver (Rx). Not a bad idea actually although I think wiring etc. is best kept simple in the early stages...

One thing I would include is a suitable fuse in the main power lead. I think Dave M gives chapter and verse on this in his article.

Have fun and do ask about anything that's not understood,

Dave C

Brian Porter 229/04/2021 20:39:31
20 forum posts

Hi Dave,

Don’t worry about the welcoming, I (we) have had the best welcome possible - plenty of help & very informative advice from supportive members.

Programmable BECs - woh there, we’ll learn to walk first!!

Battery for the RX - Although I tried it during our first attempt at set up when we innocently wondered blind into the world of interference (what a nightmare & what a learning curve that was!) we now no longer need it. Point of interest though, Carson say not to (14ch RX).

Fuse - Proud to say we’ve included it in our design plans - impressed? No? Ah well.....


Dave Cooper 605/05/2021 22:40:04
290 forum posts
29 photos

Hi Brian

Looks like you're on the right road ( / lake).

Keep on 'trucking'...and, enjoy your build,


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