Question about rapid charging

I wanted to get some input on charging speed for my battery. I’m somewhat new to this stuff and want a second opinion. I built a 12s5p battery and have a bestech bms with a max charge rate of 20amps. I want to get a second high speed charger for days I want to ride alot and long trips and such. I was on aliexpress and saw a yzpower charger for $93 and I have read that some people here ha ve had a good experience with that brand. Problem is the only option for that charger are 12a,13a,14a,15a. I want a 10amp charger but I don’t knkw about the other brands. I know the 30q cell is rated at 1c so a 5p pack should be able to charge at 15a. I would be using this charge rarely and I would use my 3a charger if I don’t plan to ride anytime soon after the battery dies. What are your options on a 12a charger? Is that to many amps? How bad will it reduce my capacity charging at that current(not using it very often). If anyone knows of a better charger I would love some suggestions thanks!

Interested to hear the results. What BMS are you running?

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The BMS can withstand that, but can the thin balance wires take 12/15/20a?

Make sure to fuse your ports if you’re going that high… I’m getting a 12s7p 30q soon and I’m staying below 8a charging because I’m terrified of hurting something

Then again I’m a wuss, so… :joy:

E: I realize this isn’t how it works.

Well apparently they can. I dont know why they would rate the bms is the balance wires couldnt handle it. I don’t know for sure but the balance wires don’t take the full amperage and just a few milliamps(says 168mA). Then again I hope someone who knows more then me to tell me if it’s ok

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Balance wires has nothing to do with the max amp om the charger. The balance current is set by the BMS. Read the datasheet for your battery cells to deterimine max charge amp. i.e if its 30Q cells the rated charge is around 4A max per cell.

That beeing said. The last 30-40% of the battery charge wont get that much faster. Thats the portion where the cells reach higher IR and current over the cells fall, also called the CV mode. At the end of this part the balancing occurs as well. Atleast for the cheaper china BMS’s that does not use active balancing.

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Most chargers in aluminum cases (likely including the YZPower one) have potentiometers on the board inside that can be adjusted to change the voltage and current limits of the charger - it should be totally possible to buy that 12A one and turn it down to 10. In fact, the ones that are available in multiple current options (4, 6, 8, etc) are usually all the same identical board inside, just set differently and sold for a different price.

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The 30Q can be charged at 4 amps max, as you have 5p that means the max you could charge the pack is at 20amps. The BMS can handle that as you have stated it’s 20amps. I would be concerned about your actual charge port, can that handle that many amps? Some of the basic DC 2.5 mm jack’s get very hot and can’t handle much amps. I’m not sure how much they can handle but I have read somewhere that 8amps is max. Maybe somebody else can shed some light on this?

Also need to check the awg of the wires in the charge port.

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yeah some of the jacks only do 4A lol I wouldn’t push them too hard. I usually use xt-60 as my charge port

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I would be adding a different charge port for the fast charger. I think I was going to use a gx16 plug since that’s one of the pre configured options on the charges. I would also be using thicker wire for the charging plug too.

Thats good to know. Ill grab the 12amp one and open it up and drop the current. Thanks for.the info!

Ya I didn’t think the balancing wires mattered with charge current. I didn’t realize the 30q did 4amps max I thought I read somewhere it was 3amps but if thats the case 12amps shouldn’t be a problem with a 5p configuration.

General rule is to stay away from max ratings in electronics tho. If max is 4 then do 3. Lower current will prolong the life of your pack as well.

balancing current is negligible:

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not 1c, but 4amp, so 5p you can max 20amp, but i wouldn’t:

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if you use a higher amperage charger, just make sure to use lower gauge charge wires. also, the common 2.1/5mm barrel plug is not suitable for anything more than 5A.

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Read my edit xP

I edited it shortly after commenting… Wasn’t thinking about it right

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What would be the highest you would go? I dont plan on charging it at this speed very often, only times I want to ride all day.

Depends on the connectors you’re using.

Like i said before, if youre using barrel plugs, no more than 5A.

I was planning on using a gx16 connector since thats one of the options with the charger.

Edit: I take that back that only does 5 amps as well. It looked to be a more capable port but I guess not.

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It’s 5 amps per pin. If you use a connector with more pins, then you can gang them together to get more current handling.

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just make sure to use wire less than 20awg and you should be fine.

seems you should be able to push up to 10A through that connector, right? not sure, haven’t used one before.