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>> Home > Tags > lipo charge

lipo charge
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lipo charge
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lipo charge
Battery problems by RNinMunich Sub-Lieutenant   Posted: 4 days ago
Hi Patto, forget the 'watt meter' and consequent P=IV -> I=p/V conversions! What you need to measure is the actual current drawn, especially the stall current, if you can manage that without getting any fingers chopped off 😡 On the lake anything can choke the prop so just testing 'free running' is not the whole answer. Sounds to me simply that your setup is drawing so much current that any battery or accu will go flat in a few minutes. Your example of a 5300mAH (i.e. 5.3AH) means that in perfect (!) condition, fully charged and almost zero internal resistance (int. cell resistance wastes power so buy the best quality you can possibly afford) it can theoretically supply 5.3 Amps for 1 hour. or 53 Amps for ~ 6 minutes (1/10 hour). and so no. LiPos with C values of 130 sound great BUT the discharge C value is related to the AH rating. So taking your example of 5300mAH = 5.3 Ah 130C = 130x5.3 = 689Amps! The Accu would supply that for ~ 27 seconds before departing to the great recycling centre in the sky! If you ever decide to try such an experiment PLEASE let me know in advance and I'll fly over the record the event for posterity 😉 Seriously though folks: I can't comment on the prop/motor setup, one of my weaknesses - I always check my stalled motor current draw with an ammeter before selecting the ESC - but as an electronics engineer I do have some idea about power supplies and circuit requirements etc. Can't imagine that your setup exceeded the 160A (short term remember!) rating of the ESC so that seems to be faulty, but you still need to find out what current your setup will draw under severe load i.e. stall. If just holding the boat cause blow ups then something else is fundamentally wrong 🤔 Bit long-winded perhaps, much of the above makes sense but not the whole story, time to cut to the chase I thought. MEASURE THE CURRENT! Good luck. Doug 😎 By the way the above comments about lead acid & hi current are OK. They are more useful for long term supply of low to medium currents. I still use them in some larger scale models (~ 1.5metre naval ships) as they provide useful ballast (i.e. payload) instead of JUST ballast! The 20HR of your lead acids refers to the Hourly charge Rate, i.e 1/20 of the capacity in AH, in your case 7/20 = 0.35A or 350mA.

Li-Poly batteries by RNinMunich Sub-Lieutenant   Posted: 4 days ago
and Good So! I think a lot of people (without the benefit of a long career in electronics) needed a 'Wake Up Call' on the dangers of and correct handling of LiPos. When possible try to find the manufacturers specs. in the net. I only buy from dealers who also post the specs. as PDF. No Spec. No Buy 🤔 The best manufacturers also print the max charge and discharge rates on the LiPo / LiFe etc pack itself. Rule of thumb: Max charge 2C, Max discharge; depends whether you want to run for ca 1sec or an hour or two 😉 Remember: 1000mAH (or 1AH) means the accu (strictly speaking LiPos etc are accumulators and not batteries 😉) can theoretically deliver 1Amp for 1 Hour IF hi quality and in perfect condition 'In this the most perfect of all possible worlds', or 2Amps for 1/2 hour and so on. But if you 'drain the tank' completely it will probably be ruined. Cheers Doug 😎

Li-Poly batteries by rolfman2000 Chief Petty Officer   Posted: 5 days ago
My use of lipos involves drones (racing and camera), fpv fixed wing long range aircraft, and boats (mostly reasonably fast electrics). And my charging regime is to number all my similar cells, so all can be rotated, evenly used and charged. I normal charge twice, then balance charge the third. This has kept all my cells with even capacitance and in good condition. I say that, so far (touch wood) that I haven't managed to puff or blow any packs.

Li-Poly batteries by pmdevlin Fleet Admiral!   Posted: 8 days ago
to add to that, its also regarded as good practise to balance charge the lipo, using the balance lead, and and appropriate lipo charger, I believe all lipo chargers have this facility. This means the cells are all equal when fully charged, and you can view this on the charger display. It also means that none of the cells will be overcharged, and risk fire etc. The down side is that as the charger enters the final stage of balancing and achieving fully charged, it takes a while, as the current reduces, so patience is a virtue, and never leave unattended whilst charging, that applies to all chemistry, I have seem a nihm explode due to over charging, its not just this lipo myth that is risky!😉

Battery problems by HoweGY177 Lieutenant   Posted: 9 days ago
Hi Patto, Sounds like you aught to be running on a decent lipo. The motor is probably taking more amps out of the battery than it can maintain. Lipos are much much lighter than lead acid and can give a higher discharge rate. The dicharge rate is the 'C' rating of the lipo, the higher the number the greater the discharge capacity. If the 'C' rating is too low the battery will start swelling up and its life expectancy greatly reduced. Go for the highest you can afford with the greatest capacity and always use an alarm with the battery, it plugs into the little white plug and can be set so when the battery gets to a set voltage an alarm sounds indicating to stop using it until it is recharged. A 3 cell will give you the required 12volts. The 'C' rating now goes up to 130 in the more expensive lipos but an 80 will probably suffice. The higher the amperage of the lipo the longer running you will get. A 2500 may only give you 8-10 minutes whilst a 4500 (cost just under £50) will give you up to 20 mins. You will have to check your speed controller to make sure it is compatable with lipos, a few are not. Remember you will need a balanced Lipo charger, I only spend about £20 or less but they only charge lipos, quite often the more expensive ones will charge a variety of battery types. I'm not an expert on electronics my knowledge comes through personel experience. With the lipo you will get better performance as the lead acid weighs the boat down. Good luck.

Li-Poly batteries by nasraf Commander   Posted: 10 days ago
The link to rchelicopters.com that pmdevlin has indicated I found very informative and I think should be read by all those using lipo's. In addition if they follow its recommendations is likely to save them a lot of money as to the life they will get out of their batteries. One thing I discovered was the meaning of the two "c" values shown on the batteries which from what previous contributors have said looks a bit confused. From the web site article the lower of the two numbers is the maximum charge rate that can be applied to the battery without causing its immediate destruction i.e. assuming a capacity of 1000 ma.hrs and a "c" of 5, 5 amps would be the absolute maximum charging current. However if this rate is used the number of charging cycles that can be done before the battery is seriously damaged would be greatly reduced. The author of the article recommends that the rate should never exceed 1 c if you want to get a good life. The higher "c" rating is in general better understood and is an indication of the maximum short term discharge rate that can be drawn. Going back to an example of a 1000 ma.hr battery a "c" of 25 would give a discharge current of of 25 amps but not for long and the internal battery heating would not do much for the battery life.

Battery problems by Dave M Fleet Admiral!   Posted: 11 days ago
Hi Patto I agree with what has already been posted, but it would help if we knew the size and type of prop you are running with your brushless motor. Fast large racing props do not work well with brushless unless your battery can provide the very heavy sustained current required. As Haverlock suggests a Wattmeter will allow you to select the best prop for your set up. LiPo power will give you all the speed you need but at an initial high cost as they require special chargers and correct management. You could use NiMh batteries which are lighter than SLA and are more suited to high discharge currents. You can get these in 12v packs and 5000mAhr would be a good starting point. If your motor is cutting out it is more likely the ESC is the culprit due to too high current draw. Another possibility is that the propshaft is too tight, it should turn freely with no tight spots and have thrust washers at both ends. Dave

Battery problems by Haverlock Admiral   Posted: 11 days ago
A quick check on the specs of your motor /esc combo states its good up to 5s LiPo. So step 1 get a watt meter ( cheaper than burned out motors ) Step 2 check with your bank manager ( or wife) for available funds Step 3 buy the biggest 4s or 5s LiPo you can fit in the available space. you will also need a LiPo charger do not attempt to skimp on that step LiPo batteries need special handling and can be spectacular if you do it wrong. You have not mentioned the prop your using if you use the watt meter you can play around with different props so the current used by your setup heads towards the point you pick twixt performance / running time. If you do go LiPo you will also need a battery monitor part of the careful handing includes not discharging them below around 3.3 Volts per cell. 3s =3cells 4s=4cells etc. So if you go 4s then you should not discharge below 13.2V. http://www.rchelicopterfun.com /rc-lipo-batteries.html http://www.4-max.co.uk/pdf/pro long-life-lipo.pdf some text on the care and feeding of LiPo batteries. The reason for your problem is a simple case of battery chemistry a lead acid accumulator cannot deliver a high current for extended periods gasses on the plates prevent the electrolyte coming in contact so the battery loses power. After a while the gasses are re dissolved and the battery can then go on providing power. Nothing wrong with the battery its just a case of wrong tool for the job.

Li-Poly batteries by pmdevlin Fleet Admiral!   Posted: 11 days ago
thats prety much it Alan, but be warned, chinese c rating and mah tends to be overstated, the bottom figure being exagerated, and the top one really only there for very short bursts, its more abount the make of the lipo If your present packs have puffed, one or more of the cells has either over discharged, or couldnt take the draw, once puffed, its pretty much had it. I have used slightly puffed lipos oin a boat, but would never use them in a plane, its just not worth the risk if it fails, and it probably will

Motor Mounts by pmdevlin Fleet Admiral!   Posted: 12 days ago
Mtroniks do have lipo friendly vipers, they are call "tio" I recall, if that is written on the cover you can set upo for lipo, if not then its imperative you have some sort of alarm as dave says, they plug into the balance lead on the lipo, and are current sensitive, so need to be the right way round to work. The ones I use are here, and also can be pre programmed to sound at a given low voltage. I use 3.7v on a boat, and 3.8v on a plane. Ant lower and they take longer to charge. If over discharged they are generally finished. There are ways to recover them, but its regarded as bad practise. Nims can be discharged fully, but are now really yesterdays technonlogy, heavier, and not any cheaper these days! https://hobbyking.com/en_us/ce ll-checker-with-low-voltage-al arm-2s-8s.html Paul

Motor Mounts by Dave M Fleet Admiral!   Posted: 12 days ago
Hi Steve Yes I intended to use silicon to fix the motors on the Perkassa. Works well and acts as a damper to any noise. The battery really depends on your speed controller as that may have a max voltage of say 12v. It's not a big model so I suspect a 3 cell 11.1v at 2200/3000 mA would suffice and provide plenty of power for the two motors. If you have a 7.2 NiMh available I suggest you try that and see if its fast enough. A 7.4 LiPo will give more endurance and speed so a 2 cell may suffice. LiPos do need protecting from over discharge so make sure your ESC has such protection or buy an add on unit that warns you when the battery voltage is too low. The ESC version is better as it cuts or reduces the current before damage is done. The Amp/Hr rating gets dearer the higher you go, so its down to you as to what you buy. Higher ratings will give you more speed but also longer running times. Glad the coupling worked. Dave

from the Philippines by Dave M Fleet Admiral!   Posted: 2 months ago
Hi Wellard I think we need a bit more info to give helpful advice. Electric or Gas depends on the noise level nuisance. May not be a problem for off shore use. Probably greater endurance than with electric but not as good for the speed you envisage. As speed is not important (3-4Km/h) then a brushed motor may be preferable to brushless. Generally the prop should be about the same diameter as the motor case. Larger props will require some form of reduction unit to reduce the load on the motor. Sounds like there will be plenty of room in the hulls to carry a good power source and as you are operating at some distance SLA is possibly better than say LiPo where discharge voltage is important. I think you may have a problem with the range (20-30Kms) as this is somewhat greater than the normal range of domestic RC sets. As you are off shore there may be additional problems with wave height as the signal may be obscured when the model is in a deep trough between waves. At the end of the day you need a motor prop battery combination that will move the craft thro the water at the required speed and last for the full duration of each sail. It's quite a large model and I suspect will need say two 800 size brushed motors to allow for wind/waves and current. I suggest you come back with your thoughts as you may have specific requirements to fit in with other equipment you are instaling. dave

cabin cruiser by Dave M Fleet Admiral!   Posted: 2 months ago
Hi I avoided mentioning LiPo as you are handing the completed model to possibly a novice. NiMh would be my choice and depending on the budget I would get the highest amp and voltage you can manage. There may be a min voltage requirement depending on the ESC you choose. She will also need a charger for the NiMh and possibly the Tx/Rx if no BEC on the ESC. Sounds like you will achieve your goal and I am sure the lady concerned will be well pleased. Dave

Battery Life by Dave M Fleet Admiral!   Posted: 4 months ago
Hi Keith I see you have a 2 cell Lipo battery of 5100Ma. The charger shows Li 2S charging at 1amp with the overall voltage of 7.43volts on the charge so far. Your charger need to be set to the correct battery type if your battery is to be fully charged safely. You have a balance lead connected so the charger will take care of the process if correctly set up for the battery. There are several flavours of Li batteries so your charger need to be set for LiPo which appears to be the 2nd setting. I can't quite read the writing but suspect it is Lion, LiPo and LiFe. Your charger supports charging up the 5amp and I suggest you use this for your battery which is 5.1amp. As the charge proceeds your charger will reduce the current as full capacity is reached. My charger then flashes a message to say charge end and stops any current flow. Your may have a similar message or indication. When fully charged your battery will have a voltage of about 8.4v. You should not discharge below 6.3v which is probably where your ESC shut down power to your model. LiPos should not be stored fully charged. The safe storage voltage is 3.7v per cell or 7.4v in your case. There may be a setting on your charger that allows you to charge to this level. If you are still unsure please ask. A copy of the charger manual would help. Hope this helps.😁

raf crash tender by pmdevlin Fleet Admiral!   Posted: 4 months ago
Hi Dave, good to hear from you (sorry to hijack thread). 4 footer came out two years ago, Huntsman once in 2016, Its over 3 years since the 3 footer got wet! Orca once in 2016. I did build the PCF which I really liked, but it went immediately as too many people messaged saying they wanted it, so it funded some RC plane gear, which I am really into now. I sold a load of bits and bobs at the Blackpool show a few months ago, didn't renew with St Helens in 2015, or 2016, and wont this year. However.... Robs excellent blog has got me interested again, and Stephen kindly did a bespoke 3 d printing project on something rc related, info and pics to follow when its finished! Back on track... George, I'm going to advise only things I have done, or used, I'm not one to say do this, or that, but actually I have not done it myself. No doubt others will disagree, but this is my opinion only. Best performance in terms of speed is brushless, and lipo. Forget fear of fire and explosions, this only happens with abuse, and they are the common use with rc planes, helicopters, cars, its only boats that are really stuck in the dark ages with technology that have this big fear of brushless systems and lipos! However, to get initially set up, they do take more understanding and initial cash outlay, as you need a specific charger for one, and you do need to understand what you are doing. Brushless motors will unlease the power far more than brushed, and are usually lighter. https://hobbyking.com/en_us/tu rnigy-t600-brushless-outrunner -for-600-heli-880kv.html This motor is an example, there are much cheaper ones with similar specs, but I have used this motor in various applications, the most similar to your boat being my large Huntsman, with this motor on 6 cells lipo I achieved 25mph, but speed might not be what you want. So if you have the fast engine in your car, say a v12 Ferrari, if you run it on cheap fuel, it wont perform, same here, nicads and nimhs batteries are easy to maintain, you can drain them dead flat, but will give cheap fuel performance, like a bath tap trickling when the shower is on at the same time, and as they are dying technology, are expensive for what they are. Lipo is like turning up both bath taps and the force floods out, but now the tank will empty quicker, so you have less run time 😊 If brushless, its a specific speed controller, https://hobbyking.com/en_us/ho bbyking-50a-boat-esc-4a-ubec.h tml and you pay extra for reversing (other rc disciplines don't need reverse) and a marine esc might need to be water cooled, however, decent brushed motor speed controllers are not exactly cheap, so now you know why budget is important to give advice, you could be spending £100 here just to get up and running. Look at my 4 foot fireboat build blog, as its twin screw (personally a boat this size is better twin screw) you can get by with cheaper motors, mine where £30 the pair, I use lipo for all my boats, so I have the batteries, and are familiar with using them, the speed controllers where about £40 the pair, and if I was buying batts then probably another £40, so it all adds up! Single screw, less batteries. You could power with nimhs, and it might be acceptable ,performance for you. If your location is Ellesmere Port, have a Sunday morning drive to Hoylake, then New Brighton, and maybe take in St Helens Liverpool, and Runcorn, see boats in action, see what sort of performance suits you, and rethink the budget, what do you want to spend? Then you need the transmitter and receiver (if you don't already have these) the fittings (see Robs build blog) a prop shaft, and a suitable propeller I am North Wirral, you are more than welcome to come and have a chat and see some boats, but unfortunately I'm deep into another rc project for the next few weeks, once that is done I can share some time, if you want! Don't worry, I'm not all about speed, I can do brushed motors and nimhs and get a result, Any questions, just ask, Paul PS... Looks like a nice clean boat you have there😉