40 amp luna cycle controller specs? Shunt mod?

Hi guys, I have a cyclone middrive kit from Luna Cycle which came with their 40 amp motor controller. Does anyone have experience with shunt modding these? How much power can they safely handle? Anyone know how many fets do they contain? Edit: Opened it up, contains 12 fets. I'm hoping to bump it up from 40 amps to atleast 50 with the shunt mod, does that sound reasonable?

It is reasonable. You need little mod to the shunt resistance to gain only 10 Amps. If there is a parallel group of shunts, like 4 side by side, then you can add one and you will gain about 25% extra power.

Can your battery safely handle a 50A request from your controller?
Does your battery have a BMS if so whats it rated for, if its 40A then its a no go on the shunt mod.

Add a shunt, or add a bit of solder. If its a cheap controller, solder or if you want to wait for a shunt from mouser but theres no way of knowing what the value of the shunt itself is thats in the controller. I would just buy a cheap controller thats 60A, more then you need because its always better to get more then you really want, if your battery can handle it. Then revert back to the first 2 questions.

You can measure shunt impedance with a multimeter, and manage with try and error, to lower impedance to 3/4 of its actual value.

Of course, your battery must be able to supply the extra Amps.

MadRhino said:

You can measure shunt impedance with a multimeter, and manage with try and error, to lower impedance to 3/4 of its actual value.

Of course, your battery must be able to supply the extra Amps.

Click to expand...

Can you measure a shunt accurately thats already in a circuit?
Does a normal multi-meter go that low for resistance/impedance measurement?

markz said:

MadRhino said:

You can measure shunt impedance with a multimeter, and manage with try and error, to lower impedance to 3/4 of its actual value.

Of course, your battery must be able to supply the extra Amps.

Click to expand...

Can you measure a shunt accurately thats already in a circuit?
Does a normal multi-meter go that low for resistance/impedance measurement?

Click to expand...

Not sure if this is considered normal, but I ordered one of these the other day after doing some quick research. Hard to beat for $25 if it turns out to be good:
https://usa.banggood.com/ANENG-AN8008-True-RMS-Digital-Multimeter-AC-DC-Current-Voltage-Resistance-Frequency-Capacitance-Test-p-1157985.html?utm_source=googleshopping&utm_medium=cpc_organic&gmcCountry=US&utm_content=minha&utm_campaign=minha-usg-pc&currency=USD&createTmp=1&utm_source=googleshopping&utm_medium=cpc_bgs&utm_content=frank&utm_campaign=frank-ssc-us-all-1108&ad_id=395572890419&cur_warehouse=USA

Lots of youtube reviews:
https://www.youtube.com/watch?v=eyYm5b-y9ZY

I don't think it can go lower than 1 mohm though.

EDIT: never mind. the ohm scale doesn't have a lower range.

Okay so I did the shunt mod yesterday and I think it was successful! After two tries I got it to peak at exactly 50 amps up a steep hill according to the cycle analyst. I just decided to add a little bit of solder to the shunts. The motor controller doesn't seem to heat up much more than it did before, but of course it's been a day so reliability wise I'll have to see if the thing lasts, but the bike feels peppier than I thought it would and can get up hills more easily than it could before. Btw yes, the reason I didn't want to upgrade to a 60 amp controller is because my battery's max continuous output is 50 amps and I didn't feel like spending $70-80 more if I didn't need to.

E-HP said:

Not sure if this is considered normal, but I ordered one of these the other day after doing some quick research. Hard to beat for $25 if it turns out to be good:
https://usa.banggood.com/ANENG-AN8008-True-RMS-Digital-Multimeter-AC-DC-Current-Voltage-Resistance-Frequency-Capacitance-Test-p-1157985.html
I don't think it can go lower than 1 mohm though.
EDIT: never mind. the ohm scale doesn't have a lower range.

Click to expand...

Unfortunatley, that kind of meter wont' go that low. It's just a "normal" multimeter; it's lowest resolution is 0.01ohms, or 10 milliohms, according to it's specs here:
imgaz.staticbg.com/images/oaupload/banggood/images/D9/A0/988b1c75-b4d4-4cb2-a8aa-1b4d8cea2756.jpg

The cheapest thing I found that *actually* measures low resistances is the DE-5000 Handheld LCR Meter:
https://www.amazon.com/gp/product/B00S298KJO
https://www.deree.com.tw/de-5000-lcr-meter.html
And in regular resistance mode it still only does 1milliohm resolution, so it is still not good enough to measure shunt resistances accurately.

Measuring ultra-low ohms resistance.

https://streampowers.blogspot.com/2012/06/measuring-milliohms-with-multimeter.html

https://hackaday.com/2011/08/17/milliohm-measurement-made-easy/

amberwolf said:

E-HP said:

Not sure if this is considered normal, but I ordered one of these the other day after doing some quick research. Hard to beat for $25 if it turns out to be good:
https://usa.banggood.com/ANENG-AN8008-True-RMS-Digital-Multimeter-AC-DC-Current-Voltage-Resistance-Frequency-Capacitance-Test-p-1157985.html
I don't think it can go lower than 1 mohm though.
EDIT: never mind. the ohm scale doesn't have a lower range.

Click to expand...

Unfortunatley, that kind of meter wont' go that low. It's just a "normal" multimeter; it's lowest resolution is 0.01ohms, or 10 milliohms, according to it's specs here:
imgaz.staticbg.com/images/oaupload/banggood/images/D9/A0/988b1c75-b4d4-4cb2-a8aa-1b4d8cea2756.jpg

The cheapest thing I found that *actually* measures low resistances is the DE-5000 Handheld LCR Meter:
https://www.amazon.com/gp/product/B00S298KJO
https://www.deree.com.tw/de-5000-lcr-meter.html
And in regular resistance mode it still only does 1milliohm resolution, so it is still not good enough to measure shunt resistances accurately.

Click to expand...

Ya, I got it for the resolution on voltage so I can fine tune the calibration on my lipo charger that goes to 3 decimal point plus a millivolt setting. This had some good reviews and cost less than a decent set of leads. I mistakenly assumed that the resistance had a similar resolution.