twin screw brushless/lipo set up now has wierd problem please help!

[pmdevlin]

interesting Lenny, thanks, I use deans on pretty much everything thinking they were tight connectors and could handle the amps, I take it I am wrong, I do have 5.5mm on my huntsman 28. Just programmed out the lvc and auto cell count, and checked programming on a pair of old cc barracudas as a back up, so hopefully will sort this out, pity link didn't work, the video has two mini cameras on board, and the shoreside camcorder

Paul

[NativePaul]

Thanks for the memories Pmdevlin, my dad had a similar Vosper MTB that looks to be about this size that he powered with a pair of Irvine .40s back in the day.

It sounds like driveline binding or motor issue to me, as nice and neat as the long motor/propshaft combo is, you are bound to get some water up the shaft into the front motor bearing which could easily have rusted the bearings in storage, with the motors in situ the cogging of the motors wont let you tell if there is any binding properly. Regular use will stop deep pits of rust forming and will make the bearings last longer, drying and oiling the bearings after each day of use is the answer but is unfortunately not very practical. Hopefully the new motor bearings will get you going again for quite a while.

Check the drivelines for binding again now you have the motors out.

How big was the amp spike at the start of the run, circa 75A or more? Was that a full throttle holeshot and was it the only hole shot you did? A full throttle holeshot is always the biggest amp draw a boat will see, a prop has its highest load when spinning full speed at a standstill and unloads as the water speed nears the pitch speed, I typically see around double the ampage in the holeshot than I see at top speed.

The Video works for me, but I am in Great Britain too.

[pmdevlin]

Hi Paul

I have stripped it all down, and was surprised to see how much gunk had travelled up the tubes, after only a few runs. One motor had a slightly tight front bearing, so its all lubed up and free now. The amp spike was approx. 60a, boast usually peaks at 40a ay biggest speed, this was at a low speed. I don't punch the throttle, feed gently. Drivelines are very free, so hopefully the bearing clean up and replacement, and the esc changes will give me some positive results at the weekend, weather permitting!

[siberianhusky]

What does the Eagletree say the voltage is doing? That will tell you a lot about what is going on. You should be able to see what the voltage is at when the escs shut off as well as how well the batteries are holding their voltage under load.
One thing I noticed is you said batteries were at 3.8v/c, showing that voltage at rest means the packs are very close to 20% remaining capacity which for all intents and purposes means they ARE discharged for a lipo.
On all my 5000mah packs if I show 3.7V/cell at rest it takes about 4000mah to bring them back to full charge. Voltage under load is much lower.
The more I think about this the more it looks like batteries, you'd be drawing a lot more amperage than you are if you are going from a fully charged pack to 3.8V in a minute or less, that 3.8 resting voltage also tells me the esc isn't cutting anything off early, sounds like it's working properly to me and cutting the voltage at 3.2.
How many MAH is it taking to charge the packs? If you are getting a full charge and dumping the packs to LVC in 1 minute it has to be the batteries. Otherwise you are drawing somewhere in the vicinity of 240 amps!
@ 60 amps steady draw with a 5000mah pack you would see about 4 minutes of runtime or 1 amp per minute usage. My ballpark theory for determining runtime based on amp draw.