Sparks when connecting battery

[Magzy]

I'm connecting a ping battery to the controller.

I'm getting a blue spark when I touch the connectors, is this normal?

there's also a "switch" cable connected to the negative (red) cable on the controller.

how do I utilise the switch  with a ping battery?

Also, just to double check, the "black" cable coming out of the external controller is the positive one right? (there's a label on the black lead  with a "+" on it)

I don't want to connect the wrong way and blow it.

[Cornelius]

A spark are not uncommon, but...

It's very rare that the black are + and red -; it's usually red that is the positive and black that is negative...
Doublecheck and triple check this before proceeding; it might be wrongly labeled.
Check the labels on the controller itself where the + and - leads are connected...

[Dummy Dave]

A spark are not uncommon, but...

It's very rare that the black are + and red -; it's usually red that is the positive and black that is negative...
Doublecheck and triple check this before proceeding; it might be wrongly labeled.
Check the labels on the controller itself where the + and - leads are connected...

Yes, the colors are strange.  But we have a member on this forum who ignored the +/- labels and melted a connector.  In his case, the +/- was true, the colors were not.
That was quite a while ago...  Maybe we can hear from someone who knows how it is wired now.

I think they all spark to charge the capacitors.  There was a clever post showing a resistor to slow the current during that charge.  Search the archives.

[Magzy]

I can confirm that as of last week a new MP with external controller ships with the black cable labeled as "+". (which goes against all EE principles)
However, I recall seeing a thread on here somewhere that this is the case.

I was just worried about the sparking but I just googled the "correct" procedure fo connecting a battery and it's positive FIRST then Negative.

I was connecting negative first, then positive.

can anyone say anything to the contrary?

[Dummy Dave]

I can confirm that as of last week a new MP with external controller ships with the black cable labeled as "+". (which goes against all EE principles)
However, I recall seeing a thread on here somewhere that this is the case.

I was just worried about the sparking but I just googled the "correct" procedure fo connecting a battery and it's positive FIRST then Negative.

I was connecting negative first, then positive.

can anyone say anything to the contrary?

On a negative-ground system, you're right; it's best to connect the positive first, so that you don't accidentally arc against bare metal with the positive lead.
Either way, the capacitors will charge and draw lots of current for a short time.
Bikemad posted a clever solution back in March.
I found that link: http://goldenmotor.com/SMF/index.php?topic=1834.msg9558#msg9558
The resistor would work on whichever lead is connected last.  The only time it's in the circuit is when you are actually making the connection.  Just make sure it can't short out against anything (like the frame). :^)

[MonkeyMagic]

Hey guys

Thought I would reinvigorate this topic and add a site I found searching around:

http://www.scriptasylum.com/rc_speed/_nospark.html

And this -->

http://endless-sphere.com/forums/viewtopic.php?f=2&t=18572#p332056

[Leslie]

I'm connecting a ping battery to the controller.

I'm getting a blue spark when I touch the connectors, is this normal?

there's also a "switch" cable connected to the negative (red) cable on the controller.

how do I utilise the switch  with a ping battery?

Also, just to double check, the "black" cable coming out of the external controller is the positive one right? (there's a label on the black lead  with a "+" on it)

I don't want to connect the wrong way and blow it.

Hi Monkey.


The best and easiest precharge circuit I have made is based on a solid state relay.  With a resistor set to allow 10ma and a small 10uf cap you can ramp up the voltage on the control inputs.

I literally can connect up the the relay inputs to the pack with pie attached via a connector and I get no spark, man I don't even need a switch.

[MonkeyMagic]

Hmmmm sounds tasty

What kind of SSR are you using there Lesmeister?

Sounds like a charm!

[Leslie]

Here is a diagram on my junk.  Um maybe not the right word anyway.



This has been been reliable for 500kms now. I have managed to get regen but not what I call a real test.  But on the heat sink it never even gets warm.


Funny when I originally connected the motor up and the pack was the last step and I didnt realise the relay was on.  I was getting this tiny spark when I connected the pack.  So I went to switch it on and, Oh it was already on.


Umm I though something was wrong.  Nope it works as a precharge protection for any connection before the relay control switch on or off.  Any connection after the relay will spark if the control switch is in on position.

Sometimes the CA catches the voltage ramp up on the precharge and I get min volts 12.7v and stuff.

[Leslie]

Hmmmm sounds tasty

What kind of SSR are you using there Lesmeister?

Sounds like a charm!

Im using this one from the AE ebay dealer on Ebay.

http://cgi.ebay.com.au/Brand-New-Solid-State-Relay-SSR-3-32VDC-24-220VDC-40A-/370412364820?pt=LH_DefaultDomain_0&hash=item563e4c2414

This can have up to a 32v control current up to it.

I set it at 10ma I think about 7v, and that was good because I didn't have to use a big cap.

If you wanted to just use a resistor I would use about 4.5k and test the control voltage with probes.

The LM317L chip doesn't need a diode as there is no path to ground after the switch is opened.  I used one anyway.

[MonkeyMagic]

Thanks mate, I'll pick up one of those for sure
And you're right, you would need about 5K for a 5v @10Ma sink. Do you know if your LM317 draws any current?

I have a circuit in mind, driven by a PIC that I can update as necessary. What is will do is basically switch output pins on a delay, and input pins will check for voltages present etc. ensuring there are no mishaps.

Not trying to go crazy, but the setup will include 2 x 6S1P25C/5Ah (long LiPo packs I got the idea from Alans mention of hobbyking in another post).

Sniffing around I found a reverse polarity protect circuit and a precharge circuit using a relay to switch. I basically just joined the 2 together after a delay switched relay circuit I came up with (that could be driven easily by NE555 and 2 push buttons but I'll use a PIC with GUI)

Although there looks to be alot of relays here, they can be changed to a handful of fets but I chose this because I have some decent 30A relays that I feel won't have a problem with the current passing through them at full power. Relay rating is for a switching current. As the bike will be stationary, or zero throttle/load I'm tipping this will be okay. I won't be switching them with any substantial current passing through them.

There is already a latching relay built into the GM battery, so the code will just check there is not voltage present on the GM battery output before attempting to switch on the backup packs. This will eliminate any worry of both the packs switching on at once, and stop any problem should R6 fail for some reason, and both battery sets arch and connect.

Anyways, what do you think of this? Still needs a few things added...

far left -> series/parallel switched relay circuit (relay coil connections removed to read easier)
middle -> reverse polarity protect
far right -> precharge auto switch on

Why?
-Switches between backup packs and gives option to series/parallel connect matching packs
-Can use 3 completely different packs altogether, and switch between them individually
-Parallel mode for matching packs for greater range
-Can use battery monitors to auto switch off depleted pack and switch to fresh pack without having to touch anything
-No sparks lol my Anderson connectors are covered in ox

Estimated current draw from added components (relays switch with around 10mA)
-> GM battery = 0
-> Backup battery series/single mode = < 50mA
-> Backup battery parallel mode = <100mA

Parts I need:
3 fets I have all the rest gathering dust
The battery from hobbyking (around $100 or so for both)

Compared to buying a frog pack for backup, I put my hand scales in the air and $270 for a 10Ah 24V I can guarantee will have a far less discharge rating than 25C. My thought is to use the backup pack for takeoffs/hills and switch to the GM pack everywhere else. I assume I can near double my range

Not tested at all, and I'm sure I'll find some discrepancies in my circuit.... It's a fun experiment!

MM

[Cornelius]

Just out of curiousity MM; which pic do you favor?

I've fallen in love with the PicAxe pic's http://www.rev-ed.co.uk/picaxe/; it's so simple an yet so flexible...
Those, and some Xbee's? http://www.digi.com/products/wireless/point-multipoint/xbee-series1-module.jsp#overview

[MonkeyMagic]

I guess it depends on the application. I'm no super wizz at PIC's but I do know BASIC to some extent, which allows me customise my projects.

Really I just use rs232, LCD interface and interrupts from a variety of input sources such as push buttons or incoming data, voltage readings etc. So I'm not really into some of the newer chips that have huge memory, ethernet or web interface etc. I still use old 16 & 18 series hehe

The PicAxe are awesome but I don't really like spending the coin on those. Plus funny enough a heap of the gear comes from UK and I pay a bit for shipping that way. Same story in retail stores (australia).

So I opt for PIC's such as 16F628A or 18F877 or similar. They go for around $10 so I go with those

During testing there is always the risk of burning one for some reason so I buy 2 every time I make a project haha I still have some I can use for this. Anyways they are a good hobby to have, and everything you do makes you think to yourself (I wonder if I can fit an LCD in there and do this blah blah blah) lol

MM

[Cornelius]

I guess shipping from UK to AU would be higher than to here (Norway; £5) but the picaxe's themselves are cheap, ranging from £1.70 to £5.50... I ordered 10pc of the 08M when I first ordered; that way, I have some to play with, and some to burn (as you said. Though, they're tough, I haven't toasted any yet... ), and it justified the shipping

And you're right; i'm often thinking 'hey, that would be a nice job for a pic...' My latest project are a temperature compensated dumpload controller for my windgen... (using an DS18B20 digital temp sensor which the picaxe have native support for... )

Edit:
Sorry Magzy; didn't mean to hijack your thread. (Though, your questions has been answered... )

[MonkeyMagic]

Corni what have you done you have me looking at PicAxe's now!!
Lol I should be finishing my build


Magzi --> your google search is right. Negative connected first as this is 'GND' and generally connected to a chassis or earthed through the power line.

This means that hooking up negative first, and then positive reduces any problem whilst powering up a device.

It won't really matter what you connect first with the PIE as it is not earthed (the spark is the sound of the electricity current 'jumping' Across the terminals, at the speed of light, obviously breaking the air creating the 'zap' sound)

Also has a bit to do with resistance. So something like 12KV and <1A would go BANG while our MP's have a 'click' sound.

This is weird > My front motor has a tiny spark when connected, plugging in the rear motor while the front motor is already plugged in will just about light up the sky!! It has a pretty big ZAPPPP I should record it.

I think I'll try one of Les's solid state relays and see how that goes, I plug and unplug my anderson connector which isn't really fun, and if I do it on the train before I get off everyone looks at me cos of the sound lol