Re: [electricboats] Controller overheating

Hi all,

Thanks for your suggestions.

I did check the connections with an IR thermometer and they all seem to be at the controller temp.

What temperatures do your controllers run at?

Thanks Dan, I noticed that my conversion underperforms.

Those RPMs are motor RPMs without any reduction gear.

Direct drive, so motor = prop RPM

I have a 16 /14 RH two bladed prop which is the old prop that came with the 20 HP Bukh diesel and the boat.

I swapped to a smaller 3 bladed prop just because that was lying around.

However, that ran at much higher RPMs and the old prop shaft was making a lot of noise at RPMs over 800.

The prop shaft had only ever been up to max 800 RMP with the diesel.

The prop shaft turns quite easily by hand and doesn't heat up.

So I changed back to the original 2 bladed prop.

I attach a graph of the 2 different props below.

Unfortunately there isn't any room on the keg to swing a bigger prop. Going up to a 3 bladed prop of same size would impair the sailing performance.

I'm with you, sailing comes first.

I guess the heat generated by the controller is not enough to explain the performance loss?

I wonder if the nearly 10 foot beam might contribute?

I am keen to improve the efficiency so I can feel safer out in the Pacific.

Thank you so much for your thoughts

Cheers

Mich

On 1 Feb 2022, at 5:25 am, Dan Pfeiffer <dan@pfeiffer.net> wrote:

Agree about checking connections That Seek sensor looks very interesting though a bit pricey?  I have Klein IR thermometer that's quite handy though not as cool as the Seek.
https://www.kleintools.com/catalog/infrared-thermometers/infrared-digital-thermometer-targeting-laser-101
https://www.amazon.com/Klein-Tools-IR1-Thermometer-Non-Contact/dp/B0873T6SGR?ref_=ast_sto_dp&th=1&psc=1


Your power consumption on the Roberts 29 seems quite high for the speeds you are reporting.   I am seeing speeds of almost 2x at the same power levels in a 6 ton 33' boat.   
At 28 amps (1300 Watts at 48V) you get 2.0 knots.  I am seeing more like 3.8 knots. 
http://dan.pfeiffer.net/10m/electric_drive_performance.htm
A shorter boat will be a bit slower but not that much?  Seems like there is something wrong somewhere. 

What are the prop dimensions and the reduction gear?  Are you running a reduction gear?   You RPM's seem quite low for the speeds if those are motor RPM.  If it's prop RPM it's fine.  But I don't know what the revs for that motor should be to get into the high efficiency range.  I know my ME1616 would be quite unhappy with those loads at that low RPM. 

You have really good battery capacity and should get excellent range from it. 

Dan Pfeiffer


Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

On 2022-01-31 12:22 pm, James Sizemore wrote:

 

Before doing more advanced trouble shooting, I would first check that the lugs on your cables are not getting hot from bad crimps and internal arcing. Also check andvmake sure the nuts are clean and snug.

 

You would be surprised how much heat a bad connection can generate.

 

I use a Seek thermal sensor to check for heat distribution, that can save lots of time trouble shooting and are fairly cheap. 

On Jan 31, 2022, at 9:48 AM, Mich Pop <michpop@gmail.com> wrote:

Hi all,

I wonder if you could please come up with some thoughts as to why my controller overheats at relatively low currents.
Once it reaches 90 Celsius it downregulates the current which can be dangerous in some situations.
Latest example: running at 450 rpm = 30 amp for an hour
when the controller downregulated to 200 rpm for 10 minutes before resuming at 450 rpm.
Ideally I would like to be able to run at 200 amps for 90 minutes.

Heat dispersal is optimised in regards to airflow and a fan that starts at 50 Celsius.

The controller is an older model and I'd be happy to get a new one.
I'd like to hear what kind of controller you suggest.

I've got a 4.5 ton 29 Roberts with a 48V 15s 4p 450 Ah 21.6 kWh LiFePo battery. (usable 360 Ah  = 17.3 kWh)

The controller is a Kelly
KAC72601-8080I
1 Minute Current600A
Continuous Curent240A
Voltage24-72V

The motor is a 7.5 KW, 4P, 415V, AHE132M4, 3PH, MEP S2
rewound to 30 VAC, air cooled
The motor doesn't get hotter than 80 Celsius

Here is the average performance I get with a hull that could be cleaner.

Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

Thank you so much for your thoughts

Cheers
Mich