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[Pat-K]

Expert Advise Required - Swamp Boat Refit[/size]Good Morning ShipmatesTook my newly aquired swamp boat (second user) for a test yesterday - unfortunately it did not go well so some advise needed.The problem - if chugging along at half power things are great but the boat is a little slow - so I increase the throttle and affter a couple of seconds the motor cuts out :-( . This is easily reset by just giving it a little kick astern. On trying againg exactly the same thing happens everytime.Hardware - The Speed controller is as in the picture (unfortunately I have no knowledge of these as on my standard models i use either Mtronics or FTX ESC's) - I am using a NiMh battery rated at 7.2v 8000mah (sourced from Aliexpress) - so far I have avoided LiPo batteries - as I have a collegue that has had two workshops burnt to the ground with Lipo batteries although I have no more details than that.My thoughs - Either the ESC is naff or there is a problem using a NIMh battery with the ESC/Motor combination - what are your thoughts - I dont know where I could source another ESC in the UK and how expensive it would be - I dont want to spend a fortune as I cant think of where I would use another ESc of this type. As regards Lipo batteries as I said so far I have avoided the due to the fact they are expensive and I would need to buy a new Lipo charger again an expensive option in the UK but this could be used in other models.Anyway guys what are your thoughts, any advise appreciated.Have a good weekend everyonePat

[JimG]

The likeliest fault is the low voltage cut out in the esc. This will be set for LiPo cells which have a higher voltage than the equivalent NiMh pack. The esc senses the number of cells when first connected and sets the low voltage point from that. A freshly charged NiMh pack will show as a 7.4V Lipo and will work OK while the voltage remains high. Once the voltage drops to the nominal 7.2V it starts looking a bit low to the esc. When you use full power the higher current needed will cause the voltrage of the pack to drop and if it drops below the Low Voltage Cut off value the motor will be cut. At lest you can eset it to get the boat back or run at lower speeds.No need to be frightened of LiPo cells, the fact that your collegue has had 2 workshop fires says more about him than the cells. How many thousands of users have charged LiPo cells without a problem for every one who has had a fire. Even experienced mechanics have blown up car batteries during charging when mishandling them. A decent LiPo charger will safely charge the cells without worries and is not that expensive considering what it is capable of (LiPO, NiMh, NiCd and Pb chemistries) Also no need to treat LiPo packs as potential explosives and store in an external safe. I have been using LiPo packs now for at least 15 years without a single problem. (largest packs are 6S 6000mAH)

[1967Brutus]

Fully agree with Jim.

The options availlable are:
reconfigure the ESC for NiMH use if that option is availlable.
If not, and you insist on using NiMH, increase cellcount to 8,4V nominal (7 cells), or even 9.6 V (8 cells)

Otherwise, just get a 2 cell LiPo, they really are NOT THAT dangerous, and the skills for using them safely are absolutely no black magic or dark arts.

[Pat-K]

Thank you all guys for your advise - much appreciated