John Helling Posted January 21, 2016 Share Posted January 21, 2016 Hi All What is the difference between a 7.4V 2s 1300mAh and a 7.4v 2s 3300mAh. could the 3300mAh be used to replace the 1300mAh or would that burn out motor and ESC John H Quote Link to comment Share on other sites More sharing options...
Julian Holder Posted January 21, 2016 Share Posted January 21, 2016 Hi John, the difference is in the capacity of the battery, ie how long it will last. Yes the 3300 battery can be used in place of the 1300 battery with no damage to motor/etc and will theoretically last about 2.5 times longer on a charge. Although the 3300 battery will be a bit heavier which might be an issue if being used in an aircraft. Hope this helps. Rgds. Julian Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted January 21, 2016 Share Posted January 21, 2016 Same thing John, it's just like having a bigger fuel tank is all, bit heavier/bigger though. John Edited By john stones 1 on 21/01/2016 14:55:08 Quote Link to comment Share on other sites More sharing options...
John Helling Posted January 21, 2016 Author Share Posted January 21, 2016 Hi John Many thanks for that, I know that there is a max flight time due to heat issues but more fuel = more flights per charge, I suppose that is correct. Many thanks John H Quote Link to comment Share on other sites More sharing options...
Geoff S Posted January 21, 2016 Share Posted January 21, 2016 John, if you're going to land and complete a flight (ie not a touch and go) why carry all the extra weight? Unless you need it to get the CoG right (as I have to do with one of my electric conversions) it would be better to use a smaller, lighter battery and recharge/replace each time. That has the advantage that you know the battery state every time you fly. Otherwise, as the others have said the motor/esc doesn't 'know' how big the battery capacity is as long it's the right voltage, which, if they're both 2S, it is. Geoff Quote Link to comment Share on other sites More sharing options...
MattyB Posted January 21, 2016 Share Posted January 21, 2016 Posted by John Helling on 21/01/2016 14:59:47: Hi John Many thanks for that, I know that there is a max flight time due to heat issues but more fuel = more flights per charge, I suppose that is correct. Sorry, but no, not really. Max flight time is not defined by "heat issues" - it's about the battery capacity (equivalent to the fuel tank size) and the rate at which the battery is depleted (the current in amps, equivalent to the fuel consumption). Heat only becomes a factor if the current drawn was too much for the ESC or motor, which then got too hot and burns out, terminating the flight. Not something we want to happen! What you are looking to do is to deplete the battery at a rate sufficient to give good performance, but not so high as to damage the component parts of the powertrain. This is done through careful selection of the prop, motor, ESC and battery. Re: your comment "more fuel = more flights per charge", again that's not really correct. Given the limits of current battery technology in almost all instances you are looking at depleting the battery "fully" in a single flight. With lipos "fully" means using up ~70% of the rated capacity and no more if you want to keep them in good health. True, some powered gliders have minimal power requirements and benefit form the additional weight in a wind therefore can carry a pack suitable for multiple flights, but most electric models cannot - to do so would be to burden themselves with unnecessary weight. Far better to select your battery and powertrain components to give the desired flight time and performance on one full charge; trying to get multiple flights out of a single battery is a recipe for puffed batteries and broken planes. Quote Link to comment Share on other sites More sharing options...
John Helling Posted January 21, 2016 Author Share Posted January 21, 2016 Hi Matty Thanks for your explanation, I should have said that the model is a powered glider, Phoenix 1600 to be precise. I have been sent the battery by mistake by the supplier from whom I had ordered a 1300mAh 2s. I know nothing about Lipo batteries, so thought I would enquire from model flyers who know than I about such matters. Regards John H Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 21, 2016 Share Posted January 21, 2016 John Whilst the bigger battery itself will do no harm to the motor or speed controller I would be very cautious about using in a glider as it will weight 2.5 times as much as the 1300 mAh one. You have to recognise that the original size battery was selected by the planes designer as being adequate for the purpose. The extra weight of the bigger battery could not only effect the way it flies but might actually overload the structure. I would avoid using the bigger battery in that glider until you were absolutely sure it could safely handle the extra weight Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 21, 2016 Share Posted January 21, 2016 Normally, using a battery with more mAh capacity (like a larger fuel tank) won't affect the way the motor runs. But I do recall reading a while back of an RTF model which was burning out its motor or ESC (I don't remember which) when owners installed larger-capacity batteries. The problem turned out to be that the originally-supplied battery was too small, and/or low C rating, so that it was preventing the motor from drawing the amps it really wanted; using a better/larger battery removed that constraint, and the motor then drew more amps than either it or the ESC was able to handle. The moral is, know the specs. of your motor and ESC, and use a wattmeter to make sure the actual amps -- not the manufacturer's or on-line calculator's figures -- are within the spec. whenever you make a major change to battery or prop. Quote Link to comment Share on other sites More sharing options...
PatMc Posted January 21, 2016 Share Posted January 21, 2016 The recommended batteries for the Phoenix 1600, kit version are 3s1300 - 3s1800. So a 2s1300 is about half the weight of the larger recommended. However the PNF version recommended batteries are 2s1300 - 2s1800 but all batteries shown under "related items" are 3s ranging from 3s1500 - 3s2200. IMO 2s is a typo. My advice would be to fully rig the model without any battery then add some ballast in the centre of the battery area until the correct ballance is attained. Measure this weight & get a 3s lipo close to this. Once you have this battery adjust it's position fore & aft to achieve the correct ballance, if necessary adding extra weight. Quote Link to comment Share on other sites More sharing options...
MattyB Posted January 22, 2016 Share Posted January 22, 2016 Posted by PatMc on 21/01/2016 21:23:23: The recommended batteries for the Phoenix 1600, kit version are 3s1300 - 3s1800. So a 2s1300 is about half the weight of the larger recommended. However the PNF version recommended batteries are 2s1300 - 2s1800 but all batteries shown under "related items" are 3s ranging from 3s1500 - 3s2200. IMO 2s is a typo. Yep, no doubt about it - the Phoenix 2000 and 1600 both need a 3S pack. My recommendation would be to get your supplier to swap the one you have for a 3S 1800, which should be a good compromise between duration and weight. PS - Be aware that the 1600 PNF variant of the Phoenix is well known for having a bell motor that is prone to burning out; there isn't a lot of cooling, and the wires going to the ESC are only connected to the side of the fuse with tape, so if that gives way they touch the side of the motor and nastiness ensues! My recommendation would be to bin the bell motor and fit a standard outrunner from the off; this one is supposed to be a direct swap according to the video below... Edited By MattyB on 22/01/2016 10:15:49 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.