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OK, Understood, I think! If you just want to boost the bow thruster why don't you just fit a small 12V (or 11.1V LiPo) just for that? Frankly I might start with an 9.6V batt before I jump from 7.2 to 12V. I assume it's just either On or OFF, i.e. no ESC. As you can see from the specs of your Booster, as the output volts increase the deliverable current (for a given input volts) decreases inversely, as I predicted! Ya don't get summat for nuttin! Soooo, you need to carefully check the specs of the thruster motor; max voltage, current at maximum efficiency versus volts applied! That will tell you the max volts battery that you can safely and most efficiently use, and you can check if your booster can deliver the required current at the voltage needed. I'd just use a separate battery and a servo operated micro switch, but then I'm just a dumb engineer!😲 Bon chance mon ami👍 Cheers, Doug 😎
A somewhat confused question if I may say so Eric!😲 You can't 'regulate up' only down. The regulator's job is to produce a constant lower voltage from a range of higher voltages. I often use one to produce 5V for the RX and servos from a 12V SLA drive battery. A little 3 legged device (type LM7805) which looks just like the power FETs in a high current ESC. My version of a UBEC! 😉 What is this 'regulator' you have? Type number? Manufacturer? Photo? To get 12V from 7.2V you would need to use a Voltage converter (also known as an inverter). This works by converting the DC input from the battery to an AC voltage which can then be increased using a transformer. More elegant (and expensive!) versions use a transistor oscillator and amplifier. This uses hi-power transistors instead of the transformer. The AC output of the transformer (or amplifier) is then rectified back to DC. All this is very inefficient which is why it is normally only used for very light currents, where the losses are not so significant, and when there is no other alternative, not often the case! You can't beat the physics and you will never get the same power out that you put in. This leads to a basic design question:- What is the total current consumption of the load? I.e. the motors. A simple example:- Let's say that at 7.2V the motors draw 10Amps total, i.e. 72W (or VAmps). Assuming a utopian 100% efficiency at 12V this would equate to 6A. Due to the three stages of conversion; DC to AC, transformation / amplification of AC to 12V, AC back to DC, you'll probably be lucky to get an efficiency of around 60% to 70%. Thus if you stick 720W in you'll get around 430 to 504W out. Not much of a gain is it!🤔 Your battery would be exhausted in about 2/3 the time it is now 😡 If your motors draw more than 10A the problem just gets worse. So what is it you really want to do? If you just want to up the volts to your motors stick a 12V SLA or an 11.1V LiPo (3S) in and hope that you don't cook your motors! Frankly I don't really know why you're bothering, tugs aren't sprinters! If you want more pulling power with the existing setup try experimenting with prop sizes and pitch. Will probably achieve much more than fiddlin' about with voltage converters. BTW: All this assumes that the RX has it's own separate 5V battery supply or from a BEC in the ESC. Some clarification needed from your side. Cheers, Doug 😎
Evening all, I have a voltage regulator I’d like to fit to my Southport tug (currently running on 7.2v Ni-MHs) in order to get it up to 12v. I’m after more speed/power and would particularly like the bow thruster running a bit faster than it does on 7.2v. So, the questions are, where to fit it in the wiring loom, and what will the effect be on the battery life? Advice please! Thank you in advance...
Hi John, that's 0.5A (or 500mA) not 5A! Do you mean 400mAH (which is battery capacity) or 400mA current? If 400mA charge current then use the 15Ohm resistor. If the battery capacity was 400mAh then using the C/10 rule, i.e. 40mA charge current you would need a 150Ohm resistor. And charge for about 12 hours. For a 250mAh battery probably a 180 or 220Ohm resistor. Any chance of a photo showing any and all markings on the 'Wart'? Off to 'Bedfordshire now, I'll do some proper calcs tomorrow. All the best, Doug 😎
Our club recently held a sunset sailing session, its surprising how a cheap set of battery powered lights from a pound shop can add yet another world to r/c boat sailing, so why not have a go at your club too, great fun cheap to do and once finished, you can remove the lights ready for regular sailing.
Your more than welcome TJ. Re paragraphs etc; was a well meant 'Word to the Wise', just to make your interesting contributions easier to read. 😉 Keep up the good work👍 Which configuration did you decide on in the end? On my single screw boats, like my Sea Scout, I tend to just use the BEC from the ESC and no separate RX battery. On my multi screw ships, the majority actually, from two to four screws (PTB to HMS Belfast cruiser) I always use a separate RX battery. On the basis that I reckon that the drive battery already has enough to do 😉 So I use 4.8 or 6V NiMh batteries of around 1500 to 2000mAh. Always put a switch between the batt and the RX. Also a switch and a fuse, approx 5A lower than the ESC max current rating, between the drive battery and the ESC(s). All the best, Doug 😎
I had realised that John, the acronym DEAC had simply revived some ancient memories of my early days in mobile and hand-portable radio engineering. Circuitry and components, early ICs etc, were moving on much faster than battery development could keep pace. Good to hear from you👍 Pecker up old chap, with you in spirit. Best wishes, Doug
Hi TJ, RE: RX battery. Any 4 or 5 cell (4.8 or 6V) NiMh of 1000mAh up will do. Use the biggest one you can without upsetting the boat's trim or reducing it's performance / planing etc. BUT: don't forget to disconnect the red wires between your ESCs and RX to disconnect the BECs in the mTroniks speed controllers!!! Also check that your RX and mixer module etc can handle 6V+! If not use the 4 cell pack. A fully charged NiMh will be significantly above 6V. Some modules; e.g. Action Electronics / Component Shop don't like that 😡 Alternatives are, esp if you need to save weight, 1 use ONE of the red BEC leads from ESC to RX, e.g. the centre one, and disconnect the other two, 2 Use a separate 5V UBEC module to syphon power off the drive battery for the RX, AND disconnect all three red BEC wires from the ESCs. Cheers, Doug 😎
Revell model at stern you see a small servo with micro switch for the Ram whooper sound module. Pic with upper deck on side shows speaker and electronics with 9volt battery power. Moving forward Harbor Models small 6 volt smoker, 3000 nimh 6 volt battery with 2 connectors powers smoker fan and main motor from ESC.
Basically ads is correct, but that's only half the story! The clue is to look for 'LiPo Safe' when buying ESCs. That tells you it has a programmable Cut Off voltage setting to prevent damage to your battery. Default is usually 3.2V per cell. Absolute minimum is 3.0V. Below that you risk irreversible damage to the battery due to chemical changes that can't be reversed. The alternative is to fit a battery monitor which can trigger an audio and/or visual alarm to warn you to 'make nearest port best speed' before your battery is deep discharged, from which it will not recover! Some ESCs have a programmable function which allows to preset a reduction of the max power to the motor (instead of a total shut down) to give you the chance to get home before disaster. PLEASE don't ask me which ones. Check the specs carefully before you buy. Many current TX/RX sets will tell you on the TX display when the battery volts are low. Cheers, Doug 😎
The TIO has a safety low battery voltage cut-off for LIPO batteries whereas the Viper 15 does not have this facility. If you are confident in not running down your LIPO battery to below a 'safe limit' then you should be OK to just use the ordinary Viper.
I'm hoping someone may be able to tell me why it is that on the Mtronics website, the only ESC suitable for a lipo battery is the 'TIO', yet two friends of mine are curently running lipo's with normal 25 and 40 amp Mtronics ESC's with no problems. My question therefor is....Can I or can I not run lipo's with these ESC's. I await any replies with interest. Thanks in advance
[Score: 9/10] 39"/3400g Sir Kay (T241) Capable of 3mph and a runtime of 30mins Single Propellor (3 Blade 50mm) Geared to a MFA Geared 2.5:1 (3 Blade) Powered by NiMH (7.2v) 3Amp/h Batteries Controlled Through Mtroniks (5Amps) ESC - Comments: This is my Sir Kay (T241) - Round Table Class Minesweeper. It is from the Caldercraft range and I was fortunate to recently acquire it - I would have much preferred to have built it but couldn't miss the opportunity of it being given to me by an old retiring modeller. It just needed new RC throughout, a good clean, a tidy up and some fresh paint here and there plus a bit of rigging renewal. Not tried it in the water yet but will do tomorrow at our Club meet. Tried it today and it sailed really well, stable and sits perfectly on the water and one 3000mA 7.2 NiMH battery lasted all afternoon - so pleased with it.
Hi Dick, I have a few tugs and the largest at 49" uses a geared 540 running from a 12v 7ah sla battery giving a good 90mins running time. This model weighs in at 15 kilos ready to sail. I also have a caldercraft model tug Joffre. Which is about 30" long and runs using a 6v monoperm motor and gearbox. 6v 4.5ah sla battery giving about 1 hour run time. Weight is 5kilos ready to sail. Hope this helps. Cheers Colin.