12s5p 30Qs charge rate?

i wouldn’t charge at max rate. hell, i still use a 2amp charger.

but i think the original question was max charge rate for 30q.

sup dave.

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Since the standard charge current for 30Q cells is 1.5A going to 5x1.5A=7.5A will not compromise cell life. Of course finding the proper charger and connector is another story. Personally I would like to have a 15A charger for those times I need to use the board at the last minute and as usually it sits at 50-70% charge. All the other times a slower charger will be the one I use.

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bet you can charge with very high current when the cells are at a low state of charge

Yeah make sure your BMS wires can handle it. Most BMS come with 22awg balance wires and that’s not enough for 10a. I have a 12s8p 30q battery and I use a 8a charger so I used 20awg silicone with for my balance leads nothing even heats up while charging takes about 3.5 hours to full charge from dead


But as said the balance wires take barely any current when charging


If you wire charge-only (bypassed BMS) it does take place through the balance leads in a lot of ways to wire it. It all depends on how yours is set up. There are certainly many ways to wire it up where charging does not happen through the balance leads but throwing statements out like that could cause someone to have a fire. It’s not true a lot of the time. Even when it does charge through the balance leads though, it would typically only have the full charge current on the end two balance leads and the middle ones would typically be 100mA maximum


Minimum wire gauge for charging:

26AWG: 2.2A continuous 24AWG: 3.5A continuous 22AWG: 7A continuous <-- usually this one 20AWG: 11A continuous 18AWG: 16A continuous 16AWG: 22A continuous


You mean like that? Good job isolating one part of my post buddy. :+1:

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It’s better to be safer, and making a statement like that can lead someone that doesn’t know better to have a fire.

Picture yourself as a noob not knowing what any of the parts do, and read your post. See how you could wire it wrong? That’s why I interjected.

Also it has just as much to do with what BMS you use – as with how you use it. You can wire the BMS up to only the battery with the balance wires only – a very popular way in esk8 – and run the large-gauge wires straight to the ESC not even touching the BMS. This is called bypassing the BMS or running the BMS “charge-only” and is very popular. What you said is dangerous in that context mixed with noob skill-levels.

Bypassing the BMS has nothing to do with charging. The charge function (from an external charger) of a charge/discharge BMS remains the same regardless if you bypass it or not. However I am always happy to gain knowledge so could you please provide a typical diagram of a BMS wired in a way that the charge current would flow through the balance leads?

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“charge-only” or bypassed BMS, the 10AWG doesn’t touch the BMS or charge port, only the 22AWG & 24AWG balance wires 20181003_155339

There are a lot of diagrams in the diagram thread, here is a similar one

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I know very well how to bypass a BMS. This is one of my batteries

I still fail to see how current will flow through the balance leads while charging on the diagram you linked (which by the way is exactly how I have my BMS above setup)

His b- connection on the bms goes straight through the first balance lead so he doesnt need a large cable going to the bms

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That diagram isn’t correct (diagrams don’t have to be functional or correct to be on the thread, and we can’t flag for those errors…) but similar in most ways.

Considering how the large gauge wires don’t even connect to the BMS, I’m not sure what there is to misunderstand.

In the same way that spare wire in my desk drawer isn’t carrying my charge current? In the same way that wire at your house is not carrying my charge current here.

Are you talking about the photo or the diagram? On the diagram the b- goes through the BMS. If you are talking about the photo I can’t see how it is wired under all the tape and fish paper.

Both, either is the same. @b264 has two battery negative wires, a thic 8awg and a small whatever awg. The small one goes to the bms and the big one goes straight to the vesc

If you are talking about this diagram (which you linked as an example by the way) it is correct.

Again what do the large (discharge) leads have to do with what we are discussing here? We are talking about high current charging with an external charger. I say that even if you hook up a big ass charger, provided your charging wires (not discharge wires), port and BMS are suitable you will not have a problem. The small balance leads do not see the charging current. You say this is not correct and that there is a way to wire a BMS that the balance leads will see the charging current. I am still waiting on that diagram.

@pat.speed You are describing a bypassed BMS. I know how it works. Don’t let the 12AWG charging wires fool you on my battery shown above. I used them because I had run out of 18AWG. The discharge wires are 10AWG and are completely separate from the BMS.

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Yeah I’m with the balance leads don’t see the charge current crew until proven wrong.

It’s in the name right? Balance leads. Not charge leads.

It’s not correct because the BMS does not know the voltage of the most-positive P-pack.

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Mine isn’t correct? Tell me whats wrong so I can fix it.

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