651LikesSeattle RC Racers/North SeaTac Racing Center
06-20-2019, 09:00 AM
#2133
Steve, it's a wattage formula. Voltage x amps = wattage. And while I am failing at coming up with a proper written formula....if your race pack takes in X mha every charge from a "source", it's in the form of wattage.... the more voltage present along with capacity the less it will take away from your source. Of course the limit is the charger input voltage tolerance. The icharger has a max of 30v. I recall my LRP Touch wasn't going to operate with a particular power supply that had 14.5v.
The other concern is having a sufficient power supply when charging a 16ah 6s. Even at a 10a charge rate at 6s, it will draw at least 25amps from your power supply which only the 75a units tolerate. A Muchmore or LRP power supply will give you 2 middle fingers and say "no".
It's an interesting solution that I only recently was taught.
I checked the junk pile for a 10.5. Sorry. I've cleaned shop too many times.
bb
The other concern is having a sufficient power supply when charging a 16ah 6s. Even at a 10a charge rate at 6s, it will draw at least 25amps from your power supply which only the 75a units tolerate. A Muchmore or LRP power supply will give you 2 middle fingers and say "no".
It's an interesting solution that I only recently was taught.
I checked the junk pile for a 10.5. Sorry. I've cleaned shop too many times.
bb
06-20-2019, 09:35 AM
#2134
I can have a new one if you get back to me within the hour.
Please message on Facebook or call or text
604 612 9507
06-20-2019, 10:56 AM
#2136
Tech Master
iTrader: (6)
Steve, it's a wattage formula. Voltage x amps = wattage. And while I am failing at coming up with a proper written formula....if your race pack takes in X mha every charge from a "source", it's in the form of wattage.... the more voltage present along with capacity the less it will take away from your source. Of course the limit is the charger input voltage tolerance. The icharger has a max of 30v. I recall my LRP Touch wasn't going to operate with a particular power supply that had 14.5v.
Numbers being used for calculation:
- Number of cells in source / (divided by) number of cells in battery being charged
- Size of source in MAH
- Typical MAH being put into your race pack for each heat
- Estimated efficiency (or loss) = 15% this is a high value, but better safe than sorry
4S / 2S = 2
Now I multiply the MAH available in the source pack by 2 giving me 32,000 MAH available for 2S charging.
I typically charge around 2,000MAH into a Stock Touring pack after every run.
32,000 MAH / 2,000 MAH = 16
16,000 MAH 4S charging 2000 MAH 2S = 16 batteries charged in a perfect world. Now figure in the loss with efficiency etc....
16 * 15% = 2.4
Now we subtract 2.4 charges from the original 16 and we get 13.6.
So with this ridiculously ballpark formula we get 13.6 charges into a Stock Touring battery from a 16,000 MAH 4S pack.
06-20-2019, 11:07 AM
#2137
Tech Master
iTrader: (6)
People ogle my battery pack all the time and here's the numbers for it:
It's a 30,000MAH 6S pack.
I charge 1000MAH into my mini 2S battery.
6S/2S = 3
3 * 30,000 = 90,000
90,000 / 1000 = 90
90 * 15 = 13.5
90 - 13.5 = 76.5 charges
Is it worth the money I spent for it? Hell no! Stick with the 16,000's and charge em after each race day. As Brian said, don't charge the source battery above 4.18 per cell and they will last much longer and not "puff" over time. This could change when HV packs become available for these source packs.
It's a 30,000MAH 6S pack.
I charge 1000MAH into my mini 2S battery.
6S/2S = 3
3 * 30,000 = 90,000
90,000 / 1000 = 90
90 * 15 = 13.5
90 - 13.5 = 76.5 charges
Is it worth the money I spent for it? Hell no! Stick with the 16,000's and charge em after each race day. As Brian said, don't charge the source battery above 4.18 per cell and they will last much longer and not "puff" over time. This could change when HV packs become available for these source packs.
06-20-2019, 11:41 AM
#2138
Tech Master
iTrader: (10)
Mike,
30k 6s isn't big enough. You really need this one:
https://www.maxamps.com/lipo-22000-1...v-battery-pack
30k 6s isn't big enough. You really need this one:
https://www.maxamps.com/lipo-22000-1...v-battery-pack
06-20-2019, 11:43 AM
#2139
Mike,
30k 6s isn't big enough. You really need this one:
https://www.maxamps.com/lipo-22000-1...v-battery-pack
30k 6s isn't big enough. You really need this one:
https://www.maxamps.com/lipo-22000-1...v-battery-pack
Maybe i I should ask Stuart...
06-20-2019, 11:51 AM
#2140
Tech Master
iTrader: (6)
As a side note:
When charging your source packs it is "best practice" to only charge at .5C (16,000MAH = 8A charge). So if your battery is completely depleted it would take 2 hours to completely charge your source pack. We get a little carried away in RC with how we charge and discharge our battery packs and it's a testament to how long they stay in "race condition". The true charge rate for a long lasting lithium powered battery is 1/2C as recommended by the "actual" manufacturers and their test specifications. YMMV
When charging your source packs it is "best practice" to only charge at .5C (16,000MAH = 8A charge). So if your battery is completely depleted it would take 2 hours to completely charge your source pack. We get a little carried away in RC with how we charge and discharge our battery packs and it's a testament to how long they stay in "race condition". The true charge rate for a long lasting lithium powered battery is 1/2C as recommended by the "actual" manufacturers and their test specifications. YMMV
06-20-2019, 11:53 AM
#2141
Tech Master
iTrader: (6)
Mike,
30k 6s isn't big enough. You really need this one:
https://www.maxamps.com/lipo-22000-1...v-battery-pack
30k 6s isn't big enough. You really need this one:
https://www.maxamps.com/lipo-22000-1...v-battery-pack
Conveniently, they linked one under the battery...lol...oh wait...it doesn't even do 50V hahaha
Time for a regulator...I got this...hold mah beer
Last edited by Carnage9270; 06-20-2019 at 12:06 PM.
06-21-2019, 07:48 AM
#2145
Yea, that makes perfect sense. I’m going with that.