Voltage at 29-35 Volts with Good Battery

[Leftiebiker]

   I'm really discouraged. I just got the horn and headlight properly installed, the bike was working well and starting to get near finished, and...last night when I booted it up to make sure the horn was still working, the voltmeter read 29-35 volts (fluctuating) and the display showed one flashing bar. This was with the battery still at 49 volts. I've eliminated the battery, and can't see how my main power switch (a 60 amp DC breaker) could reduce the voltage by a third. That appears to leave the controller. Please, somebody tell me I've overlooked something easier to fix than that!

[Bikemad]

There must be either a poor connection somewhere between the battery and the voltmeter (either on the Negative or Positive wire), or your battery's BMS is faulty and not allowing the full battery voltage to be delivered when any load is placed upon it.

If you have a removable bottle mount battery, check the contacts where the battery fits into its mounting plate for loose or burnt contacts.

Are your battery cable connections properly soldered/crimped etc. or could there be a poor connection somewhere on the battery cables?

I once had my motor refuse to start with a freshly charged 48V battery but the LED headlamp still lit up at full brightness when the battery switch was turned On. 
I wrongly assumed that is was not a battery connection as the headlamp was receiving its power from the battery all the way through the controller harness, main control harness and all the way up to the light via the throttle, therefore I thought the entire battery circuit was good.

However, upon further investigation, I noticed a feint buzzing noise coming from the main battery connector which was arcing internally due to a high resistance between two of the contacts.

I cleaned the burnt contacts and closed up the female connectors to make a much tighter connection and the motor then ran properly again.

A poor contact can cause a substantial voltage drop, and in my case it was enough to reduce the voltage of a freshly charged battery below the minimum working voltage setting of the controller, but still high enough to fully power the LED headlamp.

If you measure the voltage across the terminals of your 60A DC breaker, you should be able to confirm whether or not the switch is causing the problem. It should show full battery voltage with the switch in the Off position and ~0V when it is switched On.
If it shows higher than 0.1V across the two breaker terminals when switched On, dirty or damaged switch contacts must be causing the voltage drop.

Check for full battery voltage coming out of the battery when everything is connected and turned On.
If the battery voltage is correct, double check all wiring joints and connectors on the battery circuit until you locate the fault.

If you use a multimeter to measure the voltage between the Battery - connection and all connections/joints etc. along the battery wiring circuit (including the negative battery return circuit) you should be able to locate the exact point where the voltage drop occurs.

If you can measure full battery voltage between the Battery - (Negative) connection and the Red controller (Positive) connection, check if the Black controller (Negative) connection is showing ~0V.
If it shows 14~20V instead of the expected ~0V, the fault will be somewhere on the Black battery return circuit (Battery -) instead of the Red battery supply circuit (Battery +).

Alan
 

[Leftiebiker]

   Thanks for that last part. I was able to swap in a different battery last night, with the exact same result, ruling out the battery. I will reexamine the battery contacts in the holder, and check the breaker. I'm now hoping it's the battery holder, since I bought a new one because I didn't like how weakly the old one holds the battery when locked. I suppose it could also be the XT-90 connection for the main power cable... so are you saying that this isn't a known failure mode for this controller?

[Leftiebiker]

Well, it turned out to be the cheap DC breaker, happily. Voltage going into it was the same as battery output, but the voltage exiting it was the above 29-35. I'm 95% sure that I just need a new power switch. What are you folks using? Here is one I suggest you avoid:

https://smile.amazon.com/gp/product/B08V8JVHBV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Bikemad]

I't's good to hear that you have located the cause of the voltage drop, check out this thread for more details on switches combined with precharge resistors to avoid burning the switch contacts each time the battery power is turned on.

Alan
 

[Leftiebiker]

   I read through that thread. I'm guessing that an AC household breaker of about 30-50 amps wouldn't hold up much better? I've ordered the switch linked below, and I'll look into adding a pre-charge button with resistor to that. It's a shame that "Reention" batteries have such wildly variable wiring for the power buttons: my first one, now worn out, actually turns the output off and on with the power button. The one I bought to replace it just shows state of charge with the button, and is always on. I have a new 17AH one en route - I'll have to hope that that one has a working power button so that maybe I can avoid this issue...

https://smile.amazon.com/gp/product/B0B2ZSJ4RK/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

[Leftiebiker]

   OK, I read up on AC breakers, and I guess I'm looking for a Square D "QO" type. Has anyone used one of these DC-rated AC breakers?

[Tommycat]

I’ve used a “solid state relay” as described below on a 52 volt nominal system for over 4 years. It doesn’t require the precharge hassle because of the elimination of mechanical contacts, but it could be considered a bit pricey. I recommend you look into it.
https://electricbike.com/forum/forum/main-forum/diy-discussion/89981-switch-for-48v-25a?p=90041#post90041

Just a bit more on it in my build log…
https://electricbike.com/forum/forum/builds/ebike-building-directions/48457-1st-build-e-bike-rider-magic-pie-v5-rear-bottle-batt-52v-11-5ah-huffy-parkside?p=55270#post55270


Regards,
T.C.

[Leftiebiker]

   I will look into it. I want to see what kind of power switch my new pack will have: if it actually turns the battery output off, then I'll be fine. If, like the current pack it doesn't, then I'll get one of the above, when they get back in stock.

[Bikemad]

I’ve used a “solid state relay” as described below on a 52 volt nominal system for over 4 years. It doesn’t require the precharge hassle because of the elimination of mechanical contacts, but it could be considered a bit pricey. I recommend you look into it.
https://electricbike.com/forum/forum/main-forum/diy-discussion/89981-switch-for-48v-25a?p=90041#post90041

TC, they state that it "May not work with regenerative braking."
Have you noticed any problems with your regen?

They also state that it "does have heat shrink but is not waterproof."
I wonder how long it would have resisted water damage if you had not installed it inside of the battery housing.

Do you know if the push button section of the illuminated switch is waterproof?

If the GND and +12V wires going to the switch are purely for the illumination, it should be possible to re-wire the Horn switch in parallel with the SW+ and SW- wires (assuming that you don't have a horn fitted).
However, that might not be good for the controller if you accidentally pressed the horn button instead of cruise button while riding along at high speed. 

Alan
 

[Tommycat]

Hi Alan,

TC, they state that it "May not work with regenerative braking."
Have you noticed any problems with your regen?

Wow, didn't even see that when I ordered it. 
But no, have had no issues with regeneration at all. As typical it doesn't work near a full charge, and below around a 6-mph speed. And I'm using it at a lower setting of about 20%, as this gives me firm yet not jolting speed braking. I know it's working with the display of voltage (increases by a couple volts) and amperage draw (goes to zero when it typically registers .06A minimum) on my Bayite display. Seen here...
https://electricbike.com/forum/forum/builds/ebike-building-directions/48457-1st-build-e-bike-rider-magic-pie-v5-rear-bottle-batt-52v-11-5ah-huffy-parkside?p=52231#post52231
Toyed with the idea of installing a current direction switch, diodes (not enough current in the sensing circuit...), or adding a separate amperage display for the regeneration back flow, but never did...

They also state that it "does have heat shrink but is not waterproof."
I wonder how long it would have resisted water damage if you had not installed it inside of the battery housing.

This I did see in the description and mentioned by others elsewhere... So as a precaution I filled up the protecting shrink wrap casing from both ends with clear silicone caulk before final installation. This material wasn't mentioned as a solution, but something I have liked using in the past against moisture.
This SSR is NOT water compatible at all! And I keep my rig out of the rain or moisture at all costs.

Do you know if the push button section of the illuminated switch is waterproof?

I would think not, no gaskets and seemingly very open to the elements.

If the GND and +12V wires going to the switch are purely for the illumination, it should be possible to re-wire the Horn switch in parallel with the SW+ and SW- wires (assuming that you don't have a horn fitted).
However, that might not be good for the controller if you accidentally pressed the horn button instead of cruise button while riding along at high speed. 

Many possibilities for this nice remote feature. Hidden actuation switch to using a key switch mounted on the throttle. Unlike with the temporary push horn switch though, you would need a locked on or off switch... more like the light switch provided on an OEM Pie kit throttle. You could always wire the on indicator power to a single panel mounted LED if desired.
https://electricbike.com/forum/forum/knowledge-base/parts-aa/88314-how-to-wire-keyed-switch-into-luna-remote-solid-state-switch



Regards,
T.C.

[Leftiebiker]

   I've been reading replies but not posting. I just ordered this, because it is in stock, and will be here Monday:

https://www.amazon.com/gp/product/B09MD63LY6/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

   30 amps is enough for a Magic Pie 5, hopefully? The current limit is set to 25A. I just tried a "heavy duty" rotary DC battery switch, supposedly rated for 300+ amps. It lasted for one ride, then failed on the second. Hopefully the above will actually perform as advertised...

[Tommycat]

That looks very neat! 

I'd be curious if it requires or draws power when off? Does your new battery have a shut-off switch?

[Leftiebiker]

   No, Reention seems to have dropped real Off switches from the design. Now the button just lights the state of charge lights for a second or two. I asked about consumption when off. Here is the seller's reply:

"Consumption is less than 0.1w when off .thanks ."

   I figure that if vampire drain is an issue, then I can install a low voltage switch to essentially turn off the power switch.

[Leftiebiker]

   I haven't been so much holding out on reporting on the solid state power switch, as I have been recuperating from a BAD fall a couple of weeks ago. I was checking out said switch, later at night, and I got hit with bad fatigue. I was almost home so I tried to Tough It Out. I woke up just as the bike was about to leave the road and head into a low wooded area. So I made the classic mistake of wrestling it back onto the new pavement, but all crossed up. When the tires got grip it was Good Night Irene. Don't worry, the bike is ok - I broke its fall to the pavement with my body.

   Anyway, I started riding again last night, with a moderate amount of pain. This evening I have to test the new battery. The switch, though, seems great. No issues with it at all. I thought it had stopped working once, but it was just the Crappy Reention battery lock failing yet again. For about $25, the switch seems to be a steal - IF you only need 30 amps.