Battery questions

Hi so I’m planning on making a battery out of LG HG2 18650 cells. These particular cells are 3000mAh and rated at 20A and if I wired 15 of them in a 5S3P would it be correct in saying each pseudo “cell” would effectively be 9000mAh? Furthermore would that make this pack, 9000mAh @ 18V nominal?

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Correct. Each cell would be 9000mah at 3.6v nominal. Your max continuous would be 60a. Are you going to run two in series? 5S is not much for an ESK8.

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I agree, 5s is very little. If you can, I would recommend buying 5 more cells and making a 10s2p battery.

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Just to confer. 5s is not enough for eskate. 6s is the minimum and doesn’t provide much torque.

Also something worth mentioning is that even though the cells are rated at 20A continuous, don’t plan around a battery design that relies on drawing even close to a cells rated discharge current for long periods of time regularly as you’ll end up generating a lot of heat, get less range out of your battery per cycle and degrade the cell life more quickly.

I think a lot of people here use batteries that generally draw closer to half theirs cells rated current or less most of the time. Obviously if you live somewhere very flat then its not as much of an issue as if you riding up hills regularly.

If cost is a limiting factor, have a look at Samsung 25R or LG HE4 cells, they’re usually a reasonable amount cheaper so you should be able to get a few more cells for the same price and would likely give you very similar per cell range to the larger capacity of the HG2 cells when setup in such a small pack anyway.

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hey…I’ve tried 4s before…feels like yuneec-ego

so…5s will work…just ride flats and small inclines and you’ll be fine

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Yeah, the 15 cells was an example, I was thinking maybe 16 and do 8S2P or like what michaelcpg said, get the 25R or HE2 and get more for the same price.

how to determine how many pack i need for my setup? base on motor AMP or ?

or you could just up the amp limits on the esc if you can. compensate for less voltage with amperage

Do not get 25Rs or HE2. Go with 30Q from nkon, they’re just as good as hg2s but way cheaper

30Q have an even lower discharge rating than the other cells which could be an issue with such a small pack. In saying that, I haven’t personally seen any data comparing their discharge curves to other cells.

They’re still more expensive than 25Rs by a reasonable amount as well. They certainly look like great cells for larger packs though.

Umm no… Don’t go with 30Q cells. Only 15 amp continuous and quite a bit more expensive then 25r. 25r is the best cell for the money 20 amp and cheapest compared to other similar cells. Lg hg2 are a bit more expensive but have 500 mAh more capacity. Lg hg2 cells the same price as 30Q so there is no point in getting 30Q.

ratings mean shit - look at actual discharge curves. 30Q can withstand far more than 15A and have less voltage sag. They might heat up more than the 25R but you are not going to use the full 15A per cell for extended periods of time.

See: http://lygte-info.dk/review/batteries2012/Common18650comparator.php

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I went ahead and bought 20 LG HE2 18650s and will configure them in a 10S2P config

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@Okami, @radium Back me up here… I’m tired of repeating myself…

Do some research. If you just want to be spoon fed answers and follow what people say blindly, you’re going to end up with a mediocre board.

Both @michaelcpg and @jrpwit are wrong, no offense to you two. But it’s my daytime job to know battery technology like the back of my hand. I’ve posted in several threads why the 30Qs are much better than 25Rs, backed up with actual test data and not just numbers from a table I saw somewhere. Have you guys even looked at the actual data sheets??? Do you know where the 15A limit on the Samsung 30Q comes from? It’s got nothing to do with power and more to do with number of cycles you get out of the cell if you push 20+A CONTINUOUSLY through them. Samsung actually tests these up to 25A. Look up the spec sheet, inform yourselves…

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No need to get worked up about it man.

I specifically said in my previous comment that I hadn’t looked at any data comparing the discharge curves and was purely basing what I said off the manufacturer provided ratings which I know don’t give the full story.

If the 30Q’s are comparable to 25R’s then that’s awesome.

Cheers for the link :slight_smile:

Not comparable… Better, much better

I’ll back you up. The 25r is an ok battery, but it’s going to sag more than the 30q and have less capacity overall. If you look on ecig forum you can find information directly comparing the two at a 20A continuous discharge.

I have been looking at the VTC6 and thinking about buying 65 of them soon for a 10s6p pack. The extra 5 is in case there is a couple sub par batteries in the box.

Since you say it is your day job to know about batteries, are the VTC6 better then the 30Q’s? From what I read, VTC6 is the best li-ion 18650 at the moment.

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