So do you plug in your charger and then turn the power switch on to act as your anti spark? Is your board then on whilst you charge?
Parts List:
Battery: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=56840
Power Switch: http://miamielectricboards.com/shop-1/120amp-12s-power-switch
Used These to make the 4S to 8S adaptor: http://www.ebay.com/itm/10pcs-JST-XH-4S-Connector-Adapter-Plug-W-Wire-For-4-Cell-14-8V-Lipo-Battery-/111578260237?hash=item19fa95230d:g:jHAAAOSwx~JWEz1q
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You dont have too. The switch supports regenerative power. So power can flow back to the battery without the switch being on. It will still act as an anti spark. Other BMS have a chargingnterminal what would be wired differently. This was just for the BMS that i used.
Yeah nice, is that switch something you had custom made?
Would a bms that had a charge terminal still only pick up the battery negative directly to the bms and have the balance lead positive still being the only positive connection to the bms?
quick question:
i accidentally touched the black cable to another black cable, whilst chatting to my wife about our holiday. big spark. i shat myself.
[lesson: don’t discuss toddler travel tactics with your wife whilst trying to connect batteries.]
should i expect everything on that circuit to be fried, or should it be ok once i connect everything up the right way? will the battery still be OK?
have ordered a multimeter which arrives tomorrow, so going to use that to check the various connection points to see whether anything else is shorted / buggered, but wondering whether i’m wasting time / have to think about anything else… ?
@Heavy1 Nope it’s pretty much the same as all the other power switch on the market. as for the BMS there are a couple different ones. some can integrate both positive and negative terminals for charger, others are just negative. you would have to look at the schematics for the BMS you purchase.
@oneafrikan depends. Look around you bms… if anything is burn or swollen or just smells really bad the bms is probably ruined. the multimeter will be a great tool to check if your batteries are still being balances by your bms. I would be careful in using it though, you do not want it to ruin your batteries further. a shoer can really hurt your batteries.
@oriol360 - how would you ruin the batteries with a multimeter?
Sorry, I meant careful using the BMS.
@oriol360 What kind of hubs are you using for this build?
gotcha, thanks.
I didn’t want bother with power switch…so I chose hobbyking esc…8s…is alot of power and speed
Would there be a way to bypass the max discharge limit on this BMS? I might be wanting to hook up a motor with a higher max rating than 60A. Is there a way to do this?
@tijmen, The way I did it was to simply not hook up the battery negative to the P- terminal. Instead simply wire the VESC (or switch) negative directly to the battery negative. Hope this helps.
I just want to add, even if the max rating of the motor is higher, i doubt you will ever use this much. I would recommend trying it out, before bypassing the BMS.
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So what you’re saying is that when using the system, the batteries would be hooked up directly to the ESC or switch, but when charging the power would go from the BMS, back through the ESC and then into the batteries? And good idea about the max amp draw. The motor I’d be getting (not sure on which one), will most likely only be 5 amps more than the max draw limit of the BMS
@ flatspot is absolutely right, you probably won’t pull that many most of the time. I bought a very cheap bms for now which is only rated at 15amps discharge. So I went ahead and bypassed it. I updated @oriol360’s original post showing how he wired to illustrate how you would bypass the discharging function but still allow for charging of the batteries. No electrons pass through the vesc when charging on the way to the battery. I hope this helps. Forgive my crude MS paint editing methods. 
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Could anyone please advice with the following setup?
I have a 12S setup with 3 lipo’s of 4S. I have this BMS I use a simple 50,4V charger
I only want to use my BMS for charging. Not for discharging.
Is this the correct setup? Will it work correctly?
Also I have a question about the balance leads.
I have a 4S lipo, with a 5-Pin balance connector. The first is red and is off course positioned before the first cell. The last is black and is positioned behind the last cell. The other three are between each cell.
That’s 15 balance wires in total for the Lipo’s
The BMS has 12 balance wires. And 2 negative connectors on board. B- and P-.
The charge port connects to the P-, and the + of battery 3.
I assume that’s why I can discard the red wire from the balance cable from te lipo (the first pin) and use pin 2,3,4,5 from Lipo Nr3 for the first 4 balance wires from the BMS.
As pin 5 from lipo 3 is the same as pin 1 from lipo 2 I can again discard the red wire (pin 1) from lipo nr2’ balance connector en connect pin 2,3,4,5 with the BMS balance cables 5,6,7 and 8.
For the last lipo (lipo one) I can again discard the red balance wire (pin one). Pin 2,3,4 will connect to wire 9,10 and 11 from the BMS.
What should I do with pin 5 from Lipo 1?
- Should I connect this to cable 12 from the balance wires?
- Or to B- of the BMS? If I choose option one, do I need to connect B- to the black main cable of Lipo 1, or could I just ignore that connection?
A 4s Lipo has 5 balance wires: Black = ground color= cell 1 color= cell 2 color= cell 3 Red= cell 4 This is the standard for all Lipos. Black is always ground and Red is always the Last cell in the pack. A hobby charger uses the ground wire from the pack your bms does not use the black balance wire but uses the main ground instead, that is why it only has 12 pins for 12s. Here is a diagram of how I connected five 2s Lipos in series to a 10s bms: It’s not the same setup your doing but the principle is the same.
As you can see, you don’t omit any of the red balance wires and you omit all of the black balance wires.
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Your bms is rated for 60a and can handle discharge as well as charge. You really should use it for both. Your Lipos will have more protection that way. if you do charge only, you will need to connect the pack ground wire to B- because the bms uses that as ground for the balance wires.
So instead of discarding the first pin of the lipo balance (the red wire), I shouldn’t connect the last pin (black) to the balance wires and use the red one.
Really think it ain’t necessary to use the BMS for discharge as the VESC is set to a safely cut off at low voltage.