Technical, Techniques, Hints, and Tips > Batteries & Chargers
Issue when operating with NIMH where I used to use LIPO
goBulawayo:
Hi all, having tried a number of options, it seems that the type of battery is my issue here. I ran my Perkasa on lipos before but recently bought a NIMH battery for the boat. Every time I try it in the water, it cuts out around half throttle. NIMH is 14.4v. When I put back a LIPO (7.2v but boat ran on 11.1 and 14.* LIPO before) no problem. Had the issue on two boats, both with different speed controllers. (photos of speed controllers to follow) running two motors in the perkasa but only one in the Acadamy F1 boat. motors run fine all the way up when out of the water, only cutting when in the water - Most of the time when the motors cut, rudder still works fine
Any thoughts what the issue might be please.
Thanks Wayne
https://photos.app.goo.gl/HREEKbmcYCGLrnLY9
https://photos.app.goo.gl/25B8aVzqWFd51HsGA
Colin Bishop:
Your NiMH cells may be too low capacity and unable to deliver the power the motor needs beyond a certain amperage. LiPo cells have very high discharge rates.
Changing to higher capacity cells will add a lot of weight though.
Colin
goBulawayo:
Hi Colin, by capacity is that referring to the MaH? The NIMH is 2600 - thanks
Colin Bishop:
Yes a 2600 pack is 2.6amps.
There are others who can give you better advice as there could be a number of possibilities causing the problem. Presumably the boat is fitted with a brushless motor and matching ESC. It could be the case that the motor current consumption is causing a voltage drop to the NiMH battery and the ESC voltage monitoring safety function intended to protect LiPos is cutting in.
It would be helpful if you could give details of the motor, prop size and the speed controller you are using.
Also, how big is the boat, is it a kit?
ChrisF:
Agree with Colin's comments here. What was the MAh of the LiPos you were using? 2600 is quite low for a fast boat, especially with two motors, I usually aim for at least 4000.
Have you programmed the ESC so that there is no cut-off voltage?
Chris
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