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what is the best vesc For long-term sea observation

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Thu, 2022-09-22 12:12
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jhgjg
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what is the best vesc For long-term sea observation 
hello can someone tell me what is the best vesc for our purpose for a boat for fish watching for several months in the sea. Longevity and efficiency is the most important thing here,  but also electrical or acoustic interference should be reduced to a minimum (the motors are most likely only operated at approx. 125W and low speed. Motors with sensorless 70kv 48v and approx. 30A should be operated (the manufacturer writes but you should min. 100A esc use why we haven't understood yet)

Our questions would be. The 75/300 has adjustable voltage and amp filters which the 100/250 does not have. The vesc 6 mk 6 also has silent hfi. 
Does this mean the 75/esc is gen 7?
The 100/250 gen8 and the vesc 6 mk 6 gen 9?. 

what would be the best ESC for us the price plays a subordinate role?
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Fri, 2022-09-23 08:49
frank
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For a 48V System you need to know the voltage at full charge level. If it is LiIon, you probably have a 13S system (54.7V fully charged) . 13S is borderline for the VESC 6 and only possible with very short battery cables and if you don't use regeneration (brakes). There is a new VESC 6 HP coming to the market soon. It can push 160A peak and around 70A continuous without additional cooling. And there will be the VESC6/75V controller back in stock soon: https://trampaboards.com/vesc-6-75--p-33322.html

Your best option would be a 75V rated ESC with plenty of headroom. That is the VESC 75/300. It also features phase filters for sHFI operation. I'm not sure if you need Phase filters and sHFI, as a marine propeller typically doesn't need a high startup torque.

The 75/300 has been used a lot for thrusters and is very reliable since it runs very cool at such low power levels. In any case, you need to place it in a hermetically sealed box to avoid salty air surrounding the unit.

 

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Fri, 2022-09-23 12:26
jhgjg
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Hi @Frank , thank you for your response :-)  

we plan to use 14-15s lifepo4 batteries, but if necessary we can use fewer cells. The batteries should also be recharged during operation so that the voltage could be up to 58.4v. but we are worried about whether there is a higher voltage for a short time when the devices are plugged in or when fuses are triggered. Here we want to mount diodes and capacitor banks on each device tvs or would this be unnecessary? At sHFI we hope this makes for smoother running and greater efficiency, or are we wrong here? Do you happen to know when the VESC 6 HP might appear? All electronics are housed in double-walled tubes, filled with nitrogen to prevent fire or similar problems
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Sat, 2022-09-24 17:18
frank
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The 75/300 is probably a good match then. Additional capacitor banks are usually not needed and diodes in between the battery and ESC are no good idea at all, as current must be able to flow back to the battery. If the battery cables are very long, additional capacitors might be needed, but they need to be really close to the VESC. Really close means within a cm away from the housing. The devices should always be connected via a pre-chare resistor, so spikes will not be an issue in that case. sHFI is only for high startup torque or position control. For a propeller not needed. We typically use Back EMFs as soon as possible anyway.

 

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Mon, 2022-09-26 10:08
jhgjg
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Hi Frank. 

the capacitor banks are mounted directly on the esc, as cable lengths of 2 meters are to be expected. the tvs diodes are not connected in series but in parallel because they only become conductive above a certain voltage and short-circuit the voltage peaks. https://www.mouser.de/datasheet/2/240/Littelfuse_TVS_Diode_8_0SMDJ_Datasheet.pdf-1840113.pdf 8.0SMDJ51A for a 48 volt system we would use these diodes because they only start conducting at 56.7V. and a maximum clamping voltage of 82.4V has allowed us to short circuit between 97a and 630a (yes in a very veryshort period of time but for a voltage spike in connection with the capacitor banks this should work. for the pre-charge resistors each connector is designed with xt90 connectors I think they have a 6ohm resistor built in.
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Mon, 2022-09-26 15:44
frank
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Pre-charge is ideally a solution with a relay but the XT90S also work. However, inrush currents can be a bit high for an extended lifespan of a XT90S.

If the system is designed properly, you should not need the TVS diodes. If you use CAN it might be good to add a TVS there. The 75/300 has a footprint for a TVS diode on CAN and it can easily be added.

 

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