Power supply questions
10-16-2015, 10:03 PM
#1
Power supply questions
Ok so I'm not new to rc but lipo in still a bit been on. More charging than anything. But my questions boil down to this. ....first can you power multiple chargers (2 in my case)from one power supply. Chargers in question would be a venom 2-10 dual and a regular pro charger. The power supply is a bulldog series rdc-30.output on supply is 13.4v 30 amps.this is my first experience with a power supply like this. My pro charger has the external but if I can run both on one it clears up some space.ty in advance for any help
10-17-2015, 03:21 AM
#2
In general yes one can run multiple chargers off one power supply. It's very common practice.
Do need to stay within the power output of the supply though, there is a limit of how much it can do. All depends on what size packs, 2S, 4S, etc, and what amps you want or plan on charging at. The dual charger is the key since it's capable of much more power than the pro charger.
If only doing 2S packs there is no limit, you would be fine.
3S packs are approaching the limit if using 10A on the dual. I would recommend no more than 8 amps each to leave a safety factor/headroom.
4S packs around 8 amps each is the limit, I'd suggest 6A, and so on.
If interested I can post up the maths.
Do need to stay within the power output of the supply though, there is a limit of how much it can do. All depends on what size packs, 2S, 4S, etc, and what amps you want or plan on charging at. The dual charger is the key since it's capable of much more power than the pro charger.
If only doing 2S packs there is no limit, you would be fine.
3S packs are approaching the limit if using 10A on the dual. I would recommend no more than 8 amps each to leave a safety factor/headroom.
4S packs around 8 amps each is the limit, I'd suggest 6A, and so on.
If interested I can post up the maths.
10-17-2015, 06:31 AM
#3
In general yes one can run multiple chargers off one power supply. It's very common practice.
Do need to stay within the power output of the supply though, there is a limit of how much it can do. All depends on what size packs, 2S, 4S, etc, and what amps you want or plan on charging at. The dual charger is the key since it's capable of much more power than the pro charger.
If only doing 2S packs there is no limit, you would be fine.
3S packs are approaching the limit if using 10A on the dual. I would recommend no more than 8 amps each to leave a safety factor/headroom.
4S packs around 8 amps each is the limit, I'd suggest 6A, and so on.
If interested I can post up the maths.
Do need to stay within the power output of the supply though, there is a limit of how much it can do. All depends on what size packs, 2S, 4S, etc, and what amps you want or plan on charging at. The dual charger is the key since it's capable of much more power than the pro charger.
If only doing 2S packs there is no limit, you would be fine.
3S packs are approaching the limit if using 10A on the dual. I would recommend no more than 8 amps each to leave a safety factor/headroom.
4S packs around 8 amps each is the limit, I'd suggest 6A, and so on.
If interested I can post up the maths.
10-19-2015, 07:46 AM
#4
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volts X amps = max watts
any math you do will boil down to some version of that equation.
watts / amps = max volts
watts / volts = max amps
any math you do will boil down to some version of that equation.
watts / amps = max volts
watts / volts = max amps
10-19-2015, 08:24 AM
#5
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iTrader: (31)
Join Date: Nov 2008
Location: RIP 'Chopper', 4/18/13 miss you bud:(
Posts: 15,482
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In general yes one can run multiple chargers off one power supply. It's very common practice.
Do need to stay within the power output of the supply though, there is a limit of how much it can do. All depends on what size packs, 2S, 4S, etc, and what amps you want or plan on charging at. The dual charger is the key since it's capable of much more power than the pro charger.
If only doing 2S packs there is no limit, you would be fine.
3S packs are approaching the limit if using 10A on the dual. I would recommend no more than 8 amps each to leave a safety factor/headroom.
4S packs around 8 amps each is the limit, I'd suggest 6A, and so on.
If interested I can post up the maths.
Do need to stay within the power output of the supply though, there is a limit of how much it can do. All depends on what size packs, 2S, 4S, etc, and what amps you want or plan on charging at. The dual charger is the key since it's capable of much more power than the pro charger.
If only doing 2S packs there is no limit, you would be fine.
3S packs are approaching the limit if using 10A on the dual. I would recommend no more than 8 amps each to leave a safety factor/headroom.
4S packs around 8 amps each is the limit, I'd suggest 6A, and so on.
If interested I can post up the maths.
10-19-2015, 04:04 PM
#6
First sorry for the late post, busy few days playing with a couple of energetic grandkids.
This is working backwards from most calculations since you already have a power supply. Which is rated at 400 Watts per the Bulldog literature.
First point, frequently overlooked, is this does not mean 400W of charging power. The chargers consume some power themselves, aka charger efficiency. Modern chargers are generally in the low 80s% to about 90% efficient. I recommend a slightly conservative estimate of 80%.
400W power supply x 80% = 400W*0.80 = 320 Watts of charging power.
If I'm not mistaken the Venom Pro charger is a 50 Watt charger. In many cases these chargers are ran close to max if not flat out.
320W - 50W = 270 Watts available for the 2-10 Dual charger.
Split that into 2 channels = 270/2 = 135 Watts for each dual channel.
Much of a lipo charge will be close to and at the full charge voltage of a 4.2 Volts per cell: 2S is 8.4V, 3S is 12.6V, etc.
2S: 135W / 8.4V ≈ 16.1 Amps, well over the 10 Amp limit of the charger, no limitation.
3S: 135W / 12.6V ≈ 10.7A, just slightly over the 10A limit.
4S: 135W / 16.8V ≈ 8.04A.
Based on a decent amount of experience with several types of power supplies for various uses, I've personally not had a lot of success running them at full power reliably. Leaving a little headroom I rarely have issues. For example major manufacturer MeanWell recommends 30% extra for continuous operation. Thus I recommend slightly lower values for reliability.
Can one go a little higher, in some cases yes. I try to offer suggestions that are likely to work without many issues, not just for one poster but for anyone else that may be reading this.
In fact your case is one that may allow for more aggressive settings. If I'm not mistaken the Bulldogs are based on Iota power supplies which are well regarded for capability. Keep a watch on temperatures and perhaps going closer to the max is reasonable.
Also please note that some of the bigger chargers require a higher power supply voltage to achieve full power. To the best of my knowledge this is not a limitation for your situation.
This is working backwards from most calculations since you already have a power supply. Which is rated at 400 Watts per the Bulldog literature.
First point, frequently overlooked, is this does not mean 400W of charging power. The chargers consume some power themselves, aka charger efficiency. Modern chargers are generally in the low 80s% to about 90% efficient. I recommend a slightly conservative estimate of 80%.
400W power supply x 80% = 400W*0.80 = 320 Watts of charging power.
If I'm not mistaken the Venom Pro charger is a 50 Watt charger. In many cases these chargers are ran close to max if not flat out.
320W - 50W = 270 Watts available for the 2-10 Dual charger.
Split that into 2 channels = 270/2 = 135 Watts for each dual channel.
Much of a lipo charge will be close to and at the full charge voltage of a 4.2 Volts per cell: 2S is 8.4V, 3S is 12.6V, etc.
2S: 135W / 8.4V ≈ 16.1 Amps, well over the 10 Amp limit of the charger, no limitation.
3S: 135W / 12.6V ≈ 10.7A, just slightly over the 10A limit.
4S: 135W / 16.8V ≈ 8.04A.
Based on a decent amount of experience with several types of power supplies for various uses, I've personally not had a lot of success running them at full power reliably. Leaving a little headroom I rarely have issues. For example major manufacturer MeanWell recommends 30% extra for continuous operation. Thus I recommend slightly lower values for reliability.
Can one go a little higher, in some cases yes. I try to offer suggestions that are likely to work without many issues, not just for one poster but for anyone else that may be reading this.
In fact your case is one that may allow for more aggressive settings. If I'm not mistaken the Bulldogs are based on Iota power supplies which are well regarded for capability. Keep a watch on temperatures and perhaps going closer to the max is reasonable.
Also please note that some of the bigger chargers require a higher power supply voltage to achieve full power. To the best of my knowledge this is not a limitation for your situation.
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