Noob question thread! 2020_Summer

Don’t have a limo and don’t really need a soldering iron on the go
So ok with a laptop charger

Got one thing I can use atm but it’s the plug for my bike turbo trainer

Yeah, pretty much, within reason.

Just use a fuse rated for 1.25x to 2.5x the amount of current you’ll charge at. 7.5A is a great fuse to use for 4A charging

I personally use these

7.5A 58V
or
10A 58V

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You should never have to replace it.

But if you do, you’ll be happy seeking one out — because you’ll have a not-junked battery and a not-burnt house.

If you’re in the US, I will send you one for cheap

Basically as a favor :slight_smile:

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Someone posted an email response from Timo saying that DHL screwed him and most of his stuff is still in transit. That was like a week ago.

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That’s very strange. My version of the app doesnt do that. Try increasing the Overvoltage cutoff and see if that allows you to raise the overvoltage release. For example, set overvoltage cutoff to 4.22 and see if that allows you to set the release to 4.17, etc.

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Here’s a list, its a wiki so anyone can add whatever they want. Plus, since this is DIY getting verifiable and accurate data about a lot of this is difficult. So color me skeptical about some of these numbers haha. But here it is.

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Yah you have to set the overvoltage too. It’s weird and feels wrong because sometimes a cell will actually peak at 4.22

Pretty sure I do; I tapped on the ‘polymer normal’ then the check buttons

It does :slightly_smiling_face: (4.169999…) and doesn’t crash the app lol

Would that be too risky to leave the cutoff that high though?

Cutoff should be at 4.25v and release at 4.15v

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I’ll change those settings, thanks!

No, its not really going to hurt anything for your cells to be a few mV above 4.2V for a half second, since as soon as the BMS cuts charging, your cells will equalize below 4.2V.

Really though, pushing to get to 4.2V per cell is not really worth it. Its slightly worse for cell life and is not going to get you any measureable increase in range or top speed, since as soon as you draw current from those cells the voltage will drop. Look at a discharge graph for your cells and you will see how little capacity there actually is in the first .1 or .2 volts.

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looking for a link (uk preferably) to some good (cheaper the better) solder and flux

thanks

not sure which are good and which arent

:arrow_up: this

so much this

And even for LiFePO4, and for li-ion too, they drop instantly from 4.2 (or 3.65), it’s almost a vertical line at that point. You’re gaining nearly nothing in the top end of the charge. Look at the number of amp-hours in the first 0.2V, it’s so small it’s basically 0.000Ah

So you’re not really gaining anything anyway by pushing that 4.2 as @BenjaminF said

btw thanks @Battery_Mooch for these data

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Does anyone know about sounds from hobbywing esc?
I hear sounds like from a computer from the esc on a friends board :joy:
The esc runs prefect so far, just curious about the sound.

@b264 what do you have your battery cutoffs set to for your lifepo4 packs? I just finished my friend’s 12s6p one, and I haven’t set the vesc cutoff voltages yet.

need to know which board it is to know which hobbywing esc its inside, but the latest one does have sound when doing motor detection.

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great question, I use these cutoffs

Do note that unlike a li-ion pack, once these start going dead, they go dead very, very, very rapidly. (compare the mostly-horizontal {LiFePO4} versus mostly-diagonal {li-ion} lines on the two graphs above)
These aren’t li-ion packs. This is both good and bad. You get almost full power (not mushy sagginess) until it’s dead, but then it dies in an extreme hurry.

Stay above 31 for cutoff end. You can lower it a tad if you want. 34.5 / 33 seem to work really well though and I’d use that.

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yeah, thank you…esc is on a wowgo 3 hub motor, dont really know which one this is.

Ah gotcha. Thanks for the info, I am hoping for 20 to 25 miles out of this pack (urethane), we will see though.

I think I’ll just go with what you have since it’s been working for you, maybe I’ll squeak out a little more and set it at 32.5, but I am not sure how much sag to expect, not too much right?