Question How to run a DC-DC PSU on a battery

[Aristotle2019]

Hey guys I want to consider the the possibility of running an HDPlex 800W DC-DC unit or a 400W unit if the former is not possible over a battery so that it's essential cordless for at least an hour at a go with a only little bit to spare.
I've often been suggested that using a large drone battery works, so I want to ask about how I could power this and what batteries work (with model suggestions). With some basic info on the math (please?)
(I'm not talking about a UPS, more like a portable powerful setup - but doesn't have to be completely portable - as in, this is similar to a VR backpack)
Thanks in advance !

 

[sizzling]

I think you would need at minimum something like a 12 cell LiPo of a least 10Ah. I found this, you could run 2 in series. Although rated at 22.2v that is nearly discharged and fully charged each pack would be 25.2v.

I am thinking (22.2v x 2 x 10Ah) = 444Wh

https://hobbyking.com/en_us/turnigy-high-capacity-10000mah-6s-12c-multi-rotor-lipo-pack-w-xt90.html

You also going to need an expensive balance charger.

 

[Aristotle2019]

I think you would need at minimum something like a 12 cell LiPo of a least 10Ah. I found this, you could run 2 in series. Although rated at 22.2v that is nearly discharged and fully charged each pack would be 25.2v.

I am thinking (22.2v x 2 x 10Ah) = 444Wh

https://hobbyking.com/en_us/turnigy-high-capacity-10000mah-6s-12c-multi-rotor-lipo-pack-w-xt90.html

You also going to need an expensive balance charger.

Ah ok so this means I can run a a 400 W DC-DC PSU with this? Niceee - so it will connect to the power-in plug of the DC-DC PSU unit?
So.. how long will it last though? I don't mind more expensive options though, as long as they are reliable and serve the purpose.
Thank you very much!
What is a balance charger btw?

 

[Aristotle2019]

I think you would need at minimum something like a 12 cell LiPo of a least 10Ah. I found this, you could run 2 in series. Although rated at 22.2v that is nearly discharged and fully charged each pack would be 25.2v.

I am thinking (22.2v x 2 x 10Ah) = 444Wh

https://hobbyking.com/en_us/turnigy-high-capacity-10000mah-6s-12c-multi-rotor-lipo-pack-w-xt90.html

You also going to need an expensive balance charger.

I also checked out what LiPo and LiFe batteries are after going through that hobbyking.com site. I read that LiFe can have more endurance and are surer to not short circuit or die if completely discharged - good LiPo maybe also give that but LiFe is sure to. So shud I he checking out similar LiFe battery packs ?
And through what idea did u come to a conclusion for a 12 pack configuration? Like, how does the no of packs affect the battery's performance.

 

[sizzling]

Ah ok so this means I can run a a 400 W DC-DC PSU with this? Niceee - so it will connect to the power-in plug of the DC-DC PSU unit?
So.. how long will it last though? I don't mind more expensive options though, as long as they are reliable and serve the purpose.
Thank you very much!
What is a balance charger btw?

I don’t know how long it will last. I doubt you will be taking a constant 400w or will you? You must not completely discharge a LiPo so you are unlikely to see full 10Ah and I have no idea what other inefficiencies there might be in what you are trying to achieve. As long as you take less than 400Wh from the battery you should get 1 hour or more.

LiFe are very good but have lower operating voltage so you may want to use more cells. There are just less options available too. However they are safer to operate but then again I’ve been running LiPo in model aircraft for years and taking far more current (for shorter durations) and never had an issue.

A balance charger monitors each individual cell and adjusts the charge to that cell to ensure they are all equally charged and of equal health. A pack that suffers an out of balance cell can quickly become damaged. These chargers also have other safety features. I have not used this charger but here is one I found that is suitable. I don’t use batteries of this size, mine are 6S (term for 6 cells in series) and 5000mha or less.

https://hobbyking.com/en_us/skyrc-u...-charger-discharger-power-supply-eu-plug.html

 

[Aristotle2019]

Ah ok thank u!
No, I don't think I will take a constant 400W, but I think at the most at the most 350W. RTX 2060 Super+Ryzen 7 3700, which is too much, I can always dial the CPU back to a Ryzen 5 3600 and RTX 2060. That's the most hardware I could go up to.
So. LiFe gives lower voltage ok.

Turnigy High Capacity 20000mAh 6S 12C Lipo Pack w/XT90

Looking for RC drone batteries? Turnigy High Capacity batteries are lightweight lipoly battery packs available online at HobbyKing for the lowest prices.

hobbyking.com

how is this one.
This guy in this video says he is using a 20k mAh battery with a DC-DC convertor .

View: https://youtu.be/rt6QB81RFpA

 

[sizzling]

Ah ok thank u!
No, I don't think I will take a constant 400W, but I think at the most at the most 350W. RTX 2060 Super+Ryzen 7 3700, which is too much, I can always dial the CPU back to a Ryzen 5 3600 and RTX 2060. That's the most hardware I could go up to.
So. LiFe gives lower voltage ok.

Turnigy High Capacity 20000mAh 6S 12C Lipo Pack w/XT90

Looking for RC drone batteries? Turnigy High Capacity batteries are lightweight lipoly battery packs available online at HobbyKing for the lowest prices.

hobbyking.com

how is this one.
This guy in this video says he is using a 20k mAh battery with a DC-DC convertor .

View: https://youtu.be/rt6QB81RFpA

His battery is basically the same Wh as I suggested. I suggested 12s 10Ah which has twice the voltage but half the capacity whereas his is 6s 20Ah. No idea if there is a benefit in power conversion of 6s 20Ah. His prediction of 3hrs under full load seems unbelievable as that would require an average load no higher than 130-135Wh.

 

[Aristotle2019]

His battery is basically the same Wh as I suggested. I suggested 12s 10Ah which has twice the voltage but half the capacity whereas his is 6s 20Ah. No idea if there is a benefit in power conversion of 6s 20Ah. His prediction of 3hrs under full load seems unbelievable as that would require an average load no higher than 130-135Wh.

Yes I think it's because he using an Intel NUC with an i7 and integrated Vega right ? I suppose it has low wattage consumption
Btw, that 20,000mAh battery link I sent , can that be daisy chained into two?
I also found a 22,000mAh, and a 24,00Ah, and a 30,000 mAh one from Turnigy alll operating at 22.2V

 

[sizzling]

Yes I think it's because he using an Intel NUC with an i7 and integrated Vega right ? I suppose it has low wattage consumption
Btw, that 20,000mAh battery link I sent , can that be daisy chained into two?
I also found a 22,000mAh, and a 24,00Ah, and a 30,000 mAh one from Turnigy alll operating at 22.2V

That might explain the lower power consumption. You can run 2 packs in series (6S+6S) for 44.4v, this is often done in larger model aircraft. You just need to be carful to ensure both batteries are fully charged to the same voltage. If you have found cells of 22000, 24000, or 30000 they will give you longer running times but be careful to read reviews as some brands do over advertise their mha.

 

[Aristotle2019]

That might explain the lower power consumption. You can run 2 packs in series (6S+6S) for 44.4v, this is often done in larger model aircraft. You just need to be carful to ensure both batteries are fully charged to the same voltage. If you have found cells of 22000, 24000, or 30000 they will give you longer running times but be careful to read reviews as some brands do over advertise their mha.

Ok great ! Thanks a lot for all your help @sizzling and I will be sure to check them out, btw, is running dual batteries in series a feature or can be done anyway ? And is 44.4V recommend for a PC? I'm not sure what voltage a PSU is designed to take, I do know that it delivers different voltages to different components

 

[Aristotle2019]

That might explain the lower power consumption. You can run 2 packs in series (6S+6S) for 44.4v, this is often done in larger model aircraft. You just need to be carful to ensure both batteries are fully charged to the same voltage. If you have found cells of 22000, 24000, or 30000 they will give you longer running times but be careful to read reviews as some brands do over advertise their mha.

If I use theoretically, 22.2×2×20 it gives me 888Wh and then I can run an 800W PC for an hour. Or 22.2×2×30=1332Wh so somewhat less than 2 hours . And of course, even if I use a 95W or 100W i7/i9/Ryzen 7/Ryzen9 (not that i would due to cooling constraints) with let's say when a max 400W 2080 Ti, I should be good . Lovely.
Thanks a lot , really. @sizzling

 

[sizzling]

If I use theoretically, 22.2×2×20 it gives me 888Wh and then I can run an 800W PC for an hour. Or 22.2×2×30=1332Wh so somewhat less than 2 hours . And of course, even if I use a 95W or 100W i7/i9/Ryzen 7/Ryzen9 (not that i would due to cooling constraints) with let's say when a max 400W 2080 Ti, I should be good . Lovely.
Thanks a lot , really. @sizzling

Theoretically but as there are some unknowns you should add an allowance for inefficiencies.

 

[Aristotle2019]

Theoretically but as there are some unknowns you should add an allowance for inefficiencies.

Ok.. even that way .. dual 30Ah gives me 1332W and my system takes 550? At least somewhat less than two hours . Cool.
Does 44.4 V DC output make a difference to the PC? It won't damage the PSU or anything na..?