Bms cutting out in rain

[jbalat]

I managed to get about 100 meters from work and BMS decided to shut down in a light drizzle
Had to peddle the beast home for 17km at a top speed of about 14 km per hr Lol
Anyway all working again after it has dried off and no way any water can get onto the D166 BMS
So any ideas what the main culprit could be?

 

[dogman dan]

How sure are you it was the bms? Sounds to me like water may have shorted a halls wire.

 

[jbalat]

How do you tell? Does the controller cut power?
I used to have my voltage display coming from the BMS and it would just drop down to some really low voltage.
What would the voltage look like if the controller cuts out?
Makes the brain hurt....

 

[dogman dan]

Generally when a bms pops,, the only way to get going again is to unplug the battery, then plug back in. This resets the bms somehow.

The display goes dark, and won't light up again.

If the display goes dark, but you can start up again with just the on off button on the display, or it goes dark then lights up again by itself, then you are just bouncing it of the controller lvc.

If the display stays lit, but the bike won't run, its a problem somewhere in the wiring of the kit. the 5v circuits,, halls in the motor and hall in the throttle, are the most vulnerable to poor contact problems. But it could easily have nothing to do with wet. Random bad connection problems get maddeningly random.

 

[jbalat]

Firstly thank you both for taking the time to respond.

Remember I just changed all my batteries just recently because I was getting cutouts that I attributed due to cold weather. Only 4 out of 10 lipo batteries were not bulging and were about 3 years old so well worth the changeover. In fact it may be nothing to do with cold weather or rain since I had this cutout in rain with the new battery and previously I had cutouts in cold weather and no rain with the old batteries. Alternatively the two may be unrelated and the cutout in cold weather is no longer an issue and I still get cutouts in the rain.

So yes I have a voltage display like the one in my icon on the right of this post. When the power cuts out it slowly drops to zero volts and dies. If I pedal it does come back on approx 1v per km/HR. I was running the display from the bms side, now I run it directly from the battery, so when my bike cuts out the voltage remains unchanged. I might rewire it back the other way.

The only way to get it going again is to unplug the battery from the bms and reconnect it. Occasionally it will restart but most times it won't unless I leave it for a few hours and then reconnect it. No charging in between and no fiddling about with wires.

First thing I can try is covering the throttle and switches with a plastic bag when it starts raining and see if that helps...
Next thing is maybe bypass the bms ?

 

[jbalat]

Thanks Nelson,
I have the infenion 12fet controller and half twist throttle and 3 pos switch from EM3EV
The motor is a Crystalite 5404
Batteries are 5000mah 4S Hardcase Hobby King x 10 off (5S2P) 84v
The BMS is a Bestech HCX-D166

In the picture below I just realised that there are at least 3 of the balance connectors exposed underneath which feed directly to the BMS. If these were to short then that would certainly cut the BMS

I'm not sure exactly what would happen if the throttle shorts out. It may cut the controller ? However it probably wont cut the BMS in which case I shouldn't have to reboot the BMS to get it started again ?

The controller is hard soldered to the BMS. I would need to rewire it to be able to Bypass the BMS but will certainly look at this option.

 

[dogman dan]

Ohh, hell yeah,, voltage drop on a balance wire to the bms will do er. And those are,, again,, low voltage wires that are susceptible to a loss of contact when wet, dirty, loose, they may lose contact when its wet because it got cold. All it would take is a poor enough contact to drop the voltage.

I think you may have found one of your problems. But there could be others.

 

[jbalat]

Small victory
not sure I should be dancing just yet, but I did get caught in the rain again last night and no cutout. It was not as bad as the other day but I was totally soaked when I got home.

the night before I sprayed the exposed balance connectors with Plasti-dip which creates a rubbery plastic coating.. and I used silicon spray on all the exposed switches and in the throttle.

Hope this does the trick ?

regarding the LVC question, yes it feels exactly the same, BMS cuts and needs to be unplugged to be reset. I have hit it a few times on the last hill just before home, need to watch voltage doesn't drop below 69-70V. In the cases I am talking about the batteries had lots of charge left and I was just cruising along with hardly any throttle.

 

[dogman dan]

Unplug to reset indicates the bms cut off. It might be coating those connectors will help. If not, consider solid solder connections between bms and cells.

But any other plug loose or just wet, could cause non bms stoppage. Controller LVC usually comes back as soon as the load is removed, resulting in a porpoise effect. on off on off, I call it bouncing off the lvc.

 

[jbalat]

OK another cut out today, just some drizzle so all switches and throttle became wet. The connectors underneath were still dry.

This time was a little different. When I unplugged the power and plugged in back to the BMS I was getting a spark. This to me indicates that the BMS is working, so in this case I suspect the controller.

After a few tries and riding without power I decided to blow between the throttle and grip and woohoo it started working again.

So if it is the throttle then what kind of water proofing techniques do you use ?

I did try putting a bag over the lot but it wrapped around and throttle got stuck open which nearly gave me a heart attack.

 

[jbalat]

this did the trick this morning in the rain. Its just a kitchen food handling glove and I cut 2 fingers off.

 

[jbalat]

Just in case anyone is interested this plastic bag did the trick today in the rain. No cutout might have this thing licked
I thought with the em3ev throttle being popular that others may have come on that have the same issue?

Anyway be careful that when you cover the throttle that it is dry first