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[SniperGaulois]

Recenty got a new 35 Amp controller. went for a ride, noticed that max output is 25A, approx 2/3rds of the expected amount. Today, battery was fully charged up to 60 volts, went for a long run... what's this? - it runs out after 12A, 2/3rds of the expected amount. All the solder tabs on the battery measure 3.2... everything looks fine, voltage range of the battery appears normal although gets low faster. i dont understand how it could be the controller, although one thing would be to see the amp hours from the old controller... i'm baffled.

any hints?

 

[recumbent]

I have a 35 amp Clyte controler also, and it spikes over 40 amps, according to my Cycle analyst. And my 12 A/H LIFEPO4 goes for about 50 km (30 mi) before it want's to quit, well over 2 hours rarely pedaling, just for comparison.

 

[dogman dan]

Maybe the battery was not as charged as you think? with Lifepo4 a voltmeter tells you a lot less than with a lead battery. i'd love to be able to measure the watthours actually absorbed by my battery.

 

[Jeremy Harris]

I agree, it sounds very much as if the BMS didn't allow the battery to fully charge for some reason.

What is the battery pack? Does the BMS take a while to balance the cells?

60V implies a cell voltage of just over 3.7V per cell for the CV phase of the balancing charge cycle, which is about right. Have you checked each cell to make sure that they are all sitting at around 3.7V during the final stage of charging? This might give a clue as to whether or not the BMS is working properly.

My 36V, 12 cell, Ping pack sits at around 39 to 40V a few minutes off charge, which implies that a 48V 16 cell pack would sit at around 53 to 54V, rather than 60V.

One other thing might be to check the controller LVC voltage. If this is set too high, then maybe it's cutting out early.

Jeremy

 

[SniperGaulois]

I think I have worked out the only logical solution- the only thing that has changed on the bike is the controller, so it seems logical that the controller must be running at 66% efficiency for some reason. Say there are three phases, maybe something a malfunction in the phase system would work out to the correlation of 66%...say when the psychoanalyst says 20amps the controller is actually pushing 30amps... however with the weatherI haven't been able to go on a third run yet to see the distance from the original controller.

also, I was running without a torque arm and the wheels fell out but fortunately the cable released from the connections and went in a spiral rather than twisting it all... but I still think the controller is a much more likely cause..

 

[Jeremy Harris]

The motor can draw more instantaneous current per phase than the meter will show as being drawn from the battery, but the Crystalyte controllers limit on battery current, as far as I'm aware.

If you had a phase out, then you'd know about it for sure. Are you sure that you're Cycle Analyst is correctly calibrated? As both the current and the measured Ah capacity seems to be about 1/3 down on that expected. I believe that the CA has a means of setting the calibration for the current measurement - it might be worth a check.

Jeremy

 

[SniperGaulois]

with the 20amp controller it went back up to 20ah and 50km, whereas the 35amp controller did about 40km... and 12ah!!!

so the controller seems to be very faulty... i will keep on testing.

hopefully it's possible to see the battery charge by measuring how long it takes compared to normal.

the cycle analyst seems accurate, only odd thing is that going down hills at full throttle shows the same watts level as going up hills at full throttle, even though the power seems to be 10 percent in tangible terms.

odd thing is that the faulty controller is new.

 

[SniperGaulois]

sorry i mean the big new controller does little more that half the distance of the little one, like 28km, and wears out the batter really fast. but i have to do some more trial runs to know for certain.

 

[stew007]

You could test the CA with a multimeter on the amps setting and let the wheel freewheel at full throttle while reading the amps on both the CA and the multimeter, and adjust the shunt resistance as necessary so the both read the same, thats how I calibrated mine.

 

[SniperGaulois]

it's also the bike that does 2/3rds the distance on the 35a controller, not just the reading from CA... i literally run out of energy really fast, also the voltage reading drops staright to 47v generally on the 35a controller compared to 49v normally so it's it's like there's a current draw of 6-7 amps that i cant see... i'm pretty sure the battery is optimal.

 

[SniperGaulois]

is it possible the the cycle analyst reads different ratios from differnt controllers?

 

[Jeremy Harris]

Yes, the CA may well read differently with different types of controller, as it's current calibration is determined by the value of the shunt resistor (if it's using the internal controller shunt).

Here is the section from the CA manual that covers this:

"Set RShunt:
The Cycle Analyst is calibrated by programming a resistance value for the
current sensing shunt. If you are using a known shunt resistor, then as a first
estimate this value can be programmed in mOhm. This will usually get the meter
accurate to within 3%. For highest accuracy, the shunt value should be calibrated
so that the displayed amperage matches that of a known current reference,
which may not be exactly the same as the mOhm rating on the resistor. If the
current is reading too low, then the shunt resistance value needs to be
decreased, and visa versa. Stand Alone Cycle Analysts, and Direct Plug-in units
that are sold at the same time as a controller, are all pre-calibrated to the shunts
with which they were sold.

Allowable values in High Range mode: 0.728 to 9.999 mOhm

Allowable values in Low Range mode: 0.0728 to 0.9999 mOhm

If a shunt value is input that falls below this range, then it will be reset to the
lowest permitted number. "

If you purchased your controllers at different times, then it's possible that the CA may be correctly set for the 20A one but not for the 35A one.

As already advised, I'd do a quick test with an ammeter just to see if the CA current readout is correct when it's hooked up to the 35A controller.

Jeremy

 

[SniperGaulois]

ok i see, thanks!

 

[SniperGaulois]

my multimeter only goes to 2m amps, any ideas what the rshunt value is for a v1 35a controller?

 

[SniperGaulois]

i sound like a bozo from all that explaining! its that there is an illusion made by the amps level being the same and the battery cutting out alot earlier because the current is actually much higher.

 

[Jeremy Harris]

I'm afraid I don't know what the shunt value is on the 35A controller, but I would guess that Justin at ebikes.ca might be able to help.

You're right about the illusion. The reason I suspect that the current might be misreading is because the reduction you're seeing is about a third, both on apparent Ah capacity and on the current reading. This fits pretty well with the true current being about a third or so greater than your reading on the CA. The higher current will inevitably lead to a reduced range, assuming that the temptation to use the throttle is the same.................

Jeremy