LiPo Charging

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Old 01-28-2016, 06:36 AM
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I recently bought a thunder power dual port dc lipo charger that is capable of charging 20A. I will be charging a SMC 6500mah 4s lipo 60C. How do you guys charge your batteries and how do you think I should charge mine? Thanks.
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Old 01-28-2016, 06:45 AM
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BALANCE (always always balance) charge at 1c (6.5a) for maximum life and non-puffing.
Granted if you don't care and want to buy new batteries all the time (and risk them exploding on you) and are just looking for that extra .001 second advantage in stock by all means don't balance charge them and charge them at the max amperage your charger will allow.
Also always take them out of a car and use a lipo bag when charging (you get kicked out of the tracks here if you don't, but when I raced in the US it was NEVER enforced)
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Old 01-28-2016, 07:23 AM
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I would add to look up the manufacturer specs on what the battery can do. I run SPC packs right now, and on their website they state that it's safe to charge up to 2C. So I'm charging at a little less than that: about 1.8C.

Do always charge in a bag, though, and stay in the same room. The fire is what I fear most. Luckily, my RC "shop" is my home office, so I just flip around and peruse the RCTech forums when I'm charging.
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Old 01-28-2016, 08:01 AM
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Just FYI, the speed advantage you get from high-current charging comes from the increase in battery temperature, not actually the increased current. It's just that higher current causes the battery to warm up more.
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Old 01-28-2016, 08:14 AM
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I charge at 1c ( 6.0 amps is all my charger has in it ) , but I don't balance charge every single cycle. I balance charge the night before race day , then during the race day I just charge unless the cells are pretty far off , then I storage charge ( which balances) that night. If I am going to just be goofing off , I balance charge .

The packs charge a bit faster and top off a bit quicker without balancing between heats , and I have not had any of packs (smc) suffer from it. They all still balance out great. I use a hitec x 80 charger fwiw
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Old 01-28-2016, 03:08 PM
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Then what's the point of making 20 amp chargers?
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Old 01-28-2016, 03:15 PM
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Originally Posted by RC Matt View Post
Then what's the point of making 20 amp chargers?
By discharging a pack at a high amp rate you create heat within the cells, then charging at a high amp rate maintains the heat. Heat equals a lower ir in the cells which helps them to release the energy more efficiently. There are numerous threads here that detail the benefits. If done properly there is no increased risk of exploding a lipo...oh and those lipo safe bags you all use, they mean nothing when you are setting them on a towel or next to your flammable tire sauce.
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Old 01-28-2016, 03:44 PM
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I contacted SMC Racing and they said I can charge the batteries up to 6C but found results best at 2-3C. Does that mean I can charge my 6500mah lipo at 20 amps.
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Old 01-28-2016, 03:46 PM
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Originally Posted by RC Matt View Post
I contacted SMC Racing and they said I can charge the batteries up to 6C but found results best at 2-3C. Does that mean I can charge my 6500mah lipo at 20 amps.
6500 at 2c=13amps, 6500 at 3c = 19.5amps. You can do 20.
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Old 01-28-2016, 04:12 PM
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Originally Posted by RC Matt View Post
Then what's the point of making 20 amp chargers?
The main reason for having High Amp Chargers (mine does 30a) for lipos is being able to parallel charge multiple batteries at the same time.

I have 3 5000Mah batteries and charge at 2c (10A). But I can charge all 3 (1500Mah) at the same time 2c (30A) with a parallel charging board.

This means I can charge 3 batteries in the same amout of time and that it takes to charge just 1 battery with the same charger at the same charge rate.
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Old 01-28-2016, 04:21 PM
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Originally Posted by Matt Trimmings View Post
6500 at 2c=13amps, 6500 at 3c = 19.5amps. You can do 20.
How do you calculate that? What is the formula?
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Old 01-28-2016, 04:53 PM
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Originally Posted by RC Matt View Post
How do you calculate that? What is the formula?
C is the mAh rating of the battery divided by 1,000.
Then you charge at 1 x C, 2 x C, 3 x C, etc.

So for a 5000 mAh pack, C is 5000 / 1000 or 5
Then 1C charging is 5 amps, 2C is 10 amps, and 3C is 15 amps.
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Old 01-28-2016, 05:14 PM
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Originally Posted by emerilnut View Post
C is the mAh rating of the battery divided by 1,000.
Then you charge at 1 x C, 2 x C, 3 x C, etc.

So for a 5000 mAh pack, C is 5000 / 1000 or 5
Then 1C charging is 5 amps, 2C is 10 amps, and 3C is 15 amps.
Now I feel dumb that's what I thought then I totally forgot to do the math because I thought it was some super complicated formula
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Old 01-28-2016, 06:24 PM
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charging at 20 amps is relatively safe for most high quality packs. when charging at high amp rates you lower the cycle life of your packs but that means lowering them from 4-500 cycles to 150-200, i would rarely get 100 cycles from a pack before I replace it anyway, and with the low prices of lipos these days its not that big a deal. I used to get 10-15 "good" cycles out of a $100 NiMh pack before it was basically a paper weight and only able to use it once a race day, so at 40-60 bucks for a pack these days, that you can run multiple times per day that lasts you hundreds of cycles???? Charge em like you stole em. I will say this, use a high quality charger and balance ALL the time. This makes a difference in cycle life reguardless of charge amp rate. Also a puffed pack does not mean a ruined pack, as long as the pack balances out and the IR of the cells are not out of whack a puffed pack is fine to use. I race boats and the amp draw in boats is extremely higher than racing cars, and I routinely have puffed cells that I run with no issue. I've been using Lipos for well over 10 years and have owned literally thousands of packs and if you use a high quality charger and balance all the time the amp rate at which you charge at (up to 20 amps or below) should not have any detriment to your cells.
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Old 01-29-2016, 04:40 AM
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What is the point of cycling the batteries and what does it do?
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