BMS as anti spark
- Thread starter Zambam
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Epithemeus
100 W
Yup, this is how I do it. Kind of annoying since I can only turn the bms on and off from the phone app over Bluetooth, but I only disconnect like... Once every three months maybe?
Once every 3 months? You don't charge more often?
Annoying? My JBD BMS takes under 30 sec to turn it on/off via phone app. I see it as an anti theft feature compared to a physical switch which is easy to hack.
Epithemeus
100 W
I don't need anti spark when I charge? Only when I plug or unplug the controller itself. Which is almost never.
It's more annoying than just plugging and unplugging. And I have to remember that it's turned off, which is challenging for me. And the app is awful for connecting.
It's more annoying than just plugging and unplugging. And I have to remember that it's turned off, which is challenging for me. And the app is awful for connecting.
I use a CC/CV adjustable power supply set to 75.9 V to charge my 22S LFP battery. It sparks unless I turn off the BMS first. I suppose there's big electrolytic capacitors in the power supply which cause the spark?
What kind of BMS & app do you use?
What kind of BMS & app do you use?
Epithemeus
100 W
Daly bms and it's corresponding app.
The power supply is already on though so any caps it has would already be charged. I'm guessing it's just that your battery has a very low internal resistance. Do you get less/no spark when the battery is fully charged and as such the voltage difference between battery and the supply is smaller/0? What's the current limit set to on your power supply? You might be able to avoid the spark by setting it to near zero then ramping it up after plugging it in. Though it could just be that the power supply current limit takes too much time to kick in. I'm just pondering out loud, at least you've got a good workaround figured out.
The power supply is already on though so any caps it has would already be charged. I'm guessing it's just that your battery has a very low internal resistance. Do you get less/no spark when the battery is fully charged and as such the voltage difference between battery and the supply is smaller/0? What's the current limit set to on your power supply? You might be able to avoid the spark by setting it to near zero then ramping it up after plugging it in. Though it could just be that the power supply current limit takes too much time to kick in. I'm just pondering out loud, at least you've got a good workaround figured out.
The power supply was off when connecting to the battery and it always sparked. Just tried it with supply on and there's no spark. I will do that from now on.
Why didn't I think of that?I use the Overkill Solar app with the JBD bms instead of JBD's Xiaoxiang app. I've read the Overkill app may work with other bms also. Maybe worth trying if the Daly app has issues connecting?
I had already bought a good supply of XT-60 connectors before learning about anti-spark connectors, which is not available in XT-60 size.
I have 2 ebikes, both with XT-60's currently. I already have an anti spark solution. It does not make sense for me to switch to XT-90S with adapters to XT-60.
I also have trouble remembering to turn off the BMS with the app before plugging in the battery. Just added this reminder label next to the battery connector.
Add "please" for good measure
Have you got your sparking under control?
Yes I have a switch on my battery to turn off the bms
I think the spark is now across your switch contacts. Switch may fail in time.
edit: I had a factory circuit breaker switch between the 60V SLA battery and the moped controller before I built the battery with the JBD bms. The circuit breaker eventually failed open.
The small switch shuts off the mosftets of the bms
Then you should have no more problems with sparks. What kind of bms?
Never opened the battery, no idea
How did you know where to add the switch to control the FET's?
Have you checked the battery voltage after turning off the Daly bms? Mine reads 38.2 V with JBD bms off (I was expecting 0) and 72.5 V bms on. I put a 60W incandescent bulb load across the 38 V and it drops to 0 V immediately, remove the load and it rises to 38.2 V. Very little current on the 38.2 V so no spark.
Battery came with a switch like that already installed into the casing
Epithemeus
100 W
This is pretty common. It's just leakage voltage. Transistors aren't perfect insulators due to quantum effects. No real current can flow as you discovered with the lightbulb. Even the microamps the multimeter draws measuring the voltage is enough to drop the voltage by half.
OneAcre
1 µW
My Ego BMS only works when charging (learned that here). I use anti-spark xt90's like Neptronix. You can't see the other end in the controller bag, it's a standard xt60. If you can solder, a short pigtail adapter is easy to make. I like the larger xt90 anti-spark connector, it's easier to grab when plugging and unplugging.
The pic is from one of two identical etrikes just completed. I joined the forum to learn how. Thanks to all!
The pic is from one of two identical etrikes just completed. I joined the forum to learn how. Thanks to all!
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