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SDU high current consumptions?
Posted: Sun Aug 18, 2024 3:40 am
by alexbeatle
Hello, everybody.
I'm trying to get a sense whether my drive is behaving correctly. I'm reading what I'd think high currents on my ISA shunt - 40..80A (depending on flat road, uphill or downhill)- at 40mph (miles per hour). Is this normal?
Bellow are some captures from the drive web ui. I can try figure out how to map ISA current reading to drive speed too if needed. Perhaps my parameters aren't quite there.
This is a VW type 2 camper bus.
Thanks in advance.
Re: SDU high current consumptions?
Posted: Tue Aug 20, 2024 6:28 am
by alexbeatle
bump?
Any input is appreciated. Thanks in advance.
Re: SDU high current consumptions?
Posted: Tue Aug 20, 2024 8:22 am
by Bigpie
That seems very reasonable for crusing at 40mph in a brick shape.
Re: SDU high current consumptions?
Posted: Tue Aug 20, 2024 9:24 am
by tom91
You need to graph/log IDC, UDC and speed. A T2 Camper is not efficient at all so will take quite a bit of power to cruise at 40mph or higher.
You mention 40-80 amps, what is the voltage during that draw. Your spot values show 320V so you are talking between 12kW-25kW
Re: SDU high current consumptions?
Posted: Wed Aug 21, 2024 4:24 am
by alexbeatle
tom91 wrote: ↑Tue Aug 20, 2024 9:24 am
You need to graph/log IDC, UDC and speed. A T2 Camper is not efficient at all so will take quite a bit of power to cruise at 40mph or higher.
You mention 40-80 amps, what is the voltage during that draw. Your spot values show 320V so you are talking between 12kW-25kW
Some data of acceleration down the hill close to 40mph. Stopped for the day as my inverter started going into 60C. But another problem I'm noticed is that starting from uphill is difficult - as if starting from the 5th gear in manual when uphill - takes at least 10s to accel.
Re: SDU high current consumptions?
Posted: Wed Aug 21, 2024 6:41 am
by Bigpie
Udcnom as 0 looks off to me, though I don't use the sine firmware. Shouldn't this be your nominal voltage?
Look at catphishs params for reference
https://openinverter.org/parameters/view.html?id=27
Re: SDU high current consumptions?
Posted: Wed Aug 21, 2024 9:24 am
by tom91
No need for that right now, never really ran it on any tesla setups. Unless this has changed in later firmware.
Re: SDU high current consumptions?
Posted: Fri Aug 23, 2024 12:29 am
by alexbeatle
I only found the following reference in the code for the udcnom. Looking at the code and running tests, I don't think it helps with the current consumption as my udc is below udcnom at the moment.
Code: Select all
if (udcnom > 0)
{
float udcdiff = udcfp - udcnom;
float factor = 1.0 + udcdiff / udcnom;
//increase fweak on voltage above nominal
fweak = fweak * factor;
//decrease boost on voltage above nominal
boost = boost / factor;
}
Perhaps this is somehow related.
alexbeatle wrote: ↑Wed Aug 21, 2024 4:24 am
.... starting from uphill is difficult - as if starting from the 5th gear in manual when uphill - takes at least 10s to accel.\
Do you feel like my other parameters seem off for this type of vehicle? Thank you.
Re: SDU high current consumptions?
Posted: Fri Aug 23, 2024 9:22 am
by tom91
tom91 wrote: ↑Tue Aug 20, 2024 9:24 am
You need to graph/log IDC, UDC and speed. A T2 Camper is not efficient at all so will take quite a bit of power to cruise at 40mph or higher.
You mention 40-80 amps, what is the voltage during that draw. Your spot values show 320V so you are talking between 12kW-25kW
Re: SDU high current consumptions?
Posted: Fri Aug 23, 2024 3:21 pm
by alexbeatle
Yes. Thank you. I posted an example of udc, Idc, speed here...
alexbeatle wrote: ↑Wed Aug 21, 2024 4:24 am
Screenshot_20240820_193927_com.android.chrome.jpg
Please let me know if this isn't what you meant.
Re: SDU high current consumptions?
Posted: Fri Aug 23, 2024 3:50 pm
by tom91
Oh the graph is at the bottom, what is the speed ratio? as it continues to climb and current drops. Nothing wierd
50A and 320V is 16kW which is nothing for a bus shaped vehicle.
Re: SDU high current consumptions?
Posted: Tue Sep 10, 2024 6:41 pm
by alexbeatle
tom91 wrote: ↑Fri Aug 23, 2024 3:50 pm
Oh the graph is at the bottom, what is the speed ratio? as it continues to climb and current drops. Nothing wierd
50A and 320V is 16kW which is nothing for a bus shaped vehicle.
Back to testing after fixing mechanical issues...
Speed ratio ~Drive_RPM/96.8 still trying to find the exact constant, as it's off from the speedometer = phone GPS speedometer reading.
I've updated boost=2500, ampmin=5 and throtramp=5 (don't feel much difference after changing throtramp from the previous 20)
Which now feels like a lot smoother takeoff on the flat ground, but this in turn slightely raised the current draw and inverter temp.
But, if I start from the hill (tried 20% and 40% grade), the car barely climbs it even when I floor the pedal. Short hills, but the temps go up to ~60C from ~40C. As if I'm in 4th gear trying to climb a hill.
Any advice, please?
Re: SDU high current consumptions?
Posted: Mon Sep 16, 2024 10:54 pm
by alexbeatle
If at all possible, could somebody please help me figure out the slow acceleration problem? Thanks in advance.
Edit. I have since upgraded the firmware to the latest, added the 10k resistor to one of the channels on the dual throttle and have recalibrated the throttle. My new parameter set and a graph potnom vs. speed (flooring to go uphil).
Also pot, pot2 and potnom graph
Edit2: Lowering udcmin to 240 gave me full throttle! Yay. Though I'm not sure why, as when I was plotting my udc it doesn't have major dips, perhaps invisible due to the sample rates.
Next problem is fighting the inverter temps. The temps of the gearbox heat exchanger recover very quick, but inverter temps recover very very slow and after steep hill, my inverter temp is 50+ degrees C and drop slowly on the flat ground. Though this suppose is a separate topic.
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 9:05 am
by tom91
Yes your potnom clearly was not reaching full.
Check you cooling loop and ensure its vac filled. The inverter on the SDU is known for having issues with trapping air.
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 2:57 pm
by Proton
alexbeatle wrote: ↑Mon Sep 16, 2024 10:54 pm
Edit2: Lowering udcmin to 240 gave me full throttle! Yay. Though I'm not sure why, as when I was plotting my udc it doesn't have major dips, perhaps invisible due to the sample rates.
Next problem is fighting the inverter temps. The temps of the gearbox heat exchanger recover very quick, but inverter temps recover very very slow and after steep hill, my inverter temp is 50+ degrees C and drop slowly on the flat ground. Though this suppose is a separate topic.
If the current parameters work can you post the parameters you are using now?
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 4:48 pm
by alexbeatle
tom91 wrote: ↑Tue Sep 17, 2024 9:05 am
...
Check you cooling loop and ensure its vac filled. The inverter on the SDU is known for having issues with trapping air.
Anyway to *flush* the bubbles without vacuum pump? I simplified my coolant loop over the weekend. Now the fluid goes from inverter to the gearbox, not parallel like before. Was hoping for better cooling, but not really.
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 4:54 pm
by alexbeatle
Proton wrote: ↑Tue Sep 17, 2024 2:57 pm
If the current parameters work can you post the parameters you are using now?
This...
alexbeatle wrote: ↑Mon Sep 16, 2024 10:54 pm
Screenshot_20240916_161631.jpg
But udcmin=240.
Still not happy with the takeoff, accel and regen, so will do some tweaking. It's powerful and fast, but there're nuances that are my personal favourites.
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 5:06 pm
by tom91
Can you share pictures of your coolant setup and the sizing of the pump and rad. How hot is the inverter getting to?
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 8:08 pm
by alexbeatle
This is the diagram of my cooling setup.
The 2x 3-way valves either put all devices on one series loop (green arrow) or divide into two independent parallel loops (grey arrow + blue arrow).
* indicates where I have 5/8 inch ID hoses, otherwise - 3/4 inch ID hoses. Battery boxes use ZeroEV manifolds and blue are 3/8 inch ID hoses.
Coolant heater, not yet installed. Looking for what I can physically fit.
Radiator/fan - giant from Model 3. Blowing mode - pull. The VW bus has the ears on the side where the air is meant to enter, go through the radiator and pull by the fan.
Pumps - Tesla MS/Nissan/Ford pumps.
So far I've been driving with the series loop. Uphilling for 1min makes my inverter linearly reach 50+C and practically
doesn't drop when driving on flat and
doesn't recover quickly on the flat ground. Gearbox exchanger goes to ~60C when climbing uphil, but then quickly recovers to ~25C on the flat ground (and it's downstream from the inverter!). The batteries stay at 16C..18C.
I don't want to damage the inverter so after 50C I park the car. I tried switching to parallel loop and run the pump and fan on my high setpoints when stationary, the inverter temp lineally drops down, but at the rate of ~ 0.25C/sec. Seems slow.
My fan/pump automation (for now just in series loop):
Battery>33C or gearbox>100C or motor >40C: pump=60%, fan=30% (high flow and low fan blow)
Battery>36C or gearbox>120C or motor >60C: pump=60%, fan=50% (high flow and high fan blow)
Battery<30C and gearbox<100C and motor <40C: pump=30%, fan=24% (low flow and low fan blow)
Even at low flow in series I see the coolant flow circulating through the bottle, so it completes the loop without any struggle.
Ambient temp during testing is quite low <20C.
Some pictures.
Bottle:
2x 3-way valves:
Radiator and fan:
Pumps:
Hoses to the front battery box:
Hoses and manifolds going to the rear battery box:
Gearbox side of cooling:
Inverter and OBC side of cooling:
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 8:39 pm
by tom91
alexbeatle wrote: ↑Tue Sep 17, 2024 8:08 pm
I don't want to damage the inverter so after 50C I park the car. I tried switching to parallel loop and run the pump and fan on my high setpoints when stationary, the inverter temp lineally drops down, but at the rate of ~ 0.25C/sec. Seems slow.
Not really bad, the inverter can get a lot hotter. The temp sensor is practically on the hottest point. Cool down is not bad but you want to get more temp measurements in your loops to figure out if the coolant has actually warmed up enough in the motor. It might be you flow to fast.
Which charger you running? The tesla charger is quite a large flow restriction.
Model S had a restricted bypass if one charge is used I believe.
Anyway data is key here, as always more measurements the better.
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 9:56 pm
by alexbeatle
tom91 wrote: ↑Tue Sep 17, 2024 8:39 pm
Not really bad, the inverter can get a lot hotter. .
Isn't max temp = 85C?
tom91 wrote: ↑Tue Sep 17, 2024 8:39 pm
...
Which charger you running? The tesla charger is quite a large flow restriction.
....
Elcon OBC. The coolant fittings do look a lot larger on the outside (20mm) comparing to the inside. Perhaps I should add an adjustable divider valve.
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 9:59 pm
by jrbe
It seems like you have an air bubble in the inverter or coolant is bypassing it somehow. The heat exchanger cooling but the inverter not says this is very likely the case.
You can try to burp it. You need the outlets in the inverter to be the high point, can you jack one side or park on a steep hill to try to burp it with the pump running on high?
I agree with Tom on the vacuum fill. It's likely quicker and less of a headache to drain the coolant into a clean bucket and vacuum fill it with that coolant. Have some extra on hand, it will likely need some more.
The vacuum fill can also help find leaks before there's coolant in the system as a nice bonus.
Re: SDU high current consumptions?
Posted: Tue Sep 17, 2024 10:46 pm
by alexbeatle
jrbe wrote: ↑Tue Sep 17, 2024 9:59 pm
It seems like you have an air bubble in the inverter or coolant is bypassing it somehow.
Not quite sure how this is possible if I have a hose going into inverter, then coming out and goes into gearbox cooler. No alternative path. See my diagram, perhaps I don't see it.
Re: SDU high current consumptions?
Posted: Wed Sep 18, 2024 2:11 am
by jrbe
I'm your image you have the inverter touching the motor but a coolant loop jumping around the bottom. Is the coolant bypassing the inverter there?
And an air pocket means the coolant flows under the air bubble and doesn't have the surface area in the hot spot to pull the heat out.
If the heat exchanger is cooling off the coolant is flowing and moving heat. That leaves an air pocket or a bypass route for coolant as the things I can think of to cause that.
Re: SDU high current consumptions?
Posted: Wed Sep 18, 2024 3:56 am
by alexbeatle
jrbe wrote: ↑Wed Sep 18, 2024 2:11 am
I'm your image you have the inverter touching the motor but a coolant loop jumping around the bottom. Is the coolant bypassing the inverter there?
I see the confusion. No, having the inverter and the motor touching in the diagram simply means they're part of the same package. The cooling is in series only inverter->motor\heatsink.