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My DIY Portable PowerBox

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#76 SuperJustin

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Posted 16 September 2020 - 03:44 AM

Haven't touched the battery box today but I did end up finishing the diagrams! Let me know what you guys think.

 

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#77 jrsone

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Posted 16 September 2020 - 10:09 AM

Hi Justin,

 

Nice work on all of this, and I encourage you to continue troubleshooting and learning as you have been. I just made a similar custom battery box, albeit much simpler. Because I already have my main power distribution and metering on my tripod, I only needed a few power outlets plus USB for convenience: 

Toolbox turned to 50Ah LiFePO4 battery power station
Toolbox turned to 50Ah LiFePO4 battery power station
Toolbox turned to 50Ah LiFePO4 battery power station

 

I just finished mine, so I thought I would chime in with some useful resources that I found. Will Prowse's YouTube channel talks all about LiFePO4 batteries, charging them, BMS's, etc.:

 

https://www.youtube....ser/errolprowse

 

So for example, you may need to add a BMS to your batteries to keep them balanced (even though they each have their own BMS).

 

Also, I didn't catch what charger you were using, but this one from Victron was recommended to me by Battleborn. It's a little pricey I suppose, but you can choose a standard LiFePO4 charging profile, or it even links with Bluetooth to an app on your phone, so you can make your own custom profile to match whatever the battery manufacturer recommends.

 

I apologize if I didn't get the details why you needed all the regulators, but each stage of regulation will cause losses, so the more devices you can run directly off the batteries, the better. Most of my 12V-powered items (mount, camera, dew heater, etc.) can accept a fairly wide range of input voltages and in fact have their own regulators, so I just let them connect directly.

 

Lastly, if you're in cold weather at all, you have to be careful not to charge the LiFePO4 batteries when they're cold, and adding a heater to the batteries can actually improve their performance in cold temps. I might look at putting some dew heater straps on my battery, with a temperature regulation circuit, but I haven't gotten that far yet!

 

Anyway, keep up the good work, and good luck!

Jeremy


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#78 TelescopeGreg

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Posted 16 September 2020 - 12:09 PM

Haven't touched the battery box today but I did end up finishing the diagrams! Let me know what you guys think.

Nice job with the diagrams!  Took a quick glance...  Didn't you put the battery fuses to be individual per unit, instead of daisy-chained?  Having them in parallel is the more common wiring approach.


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#79 SuperJustin

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Posted 16 September 2020 - 01:46 PM

Nice job with the diagrams!  Took a quick glance...  Didn't you put the battery fuses to be individual per unit, instead of daisy-chained?  Having them in parallel is the more common wiring approach.

Thanks Greg! It’s pretty busy looking I’m sure there is a better way to put this kinda stuff together took way too long lol. Yea I’ve tried a few different configurations but I can’t picture what you mean. I figured doing it this way isolates each battery from each other in the event of a battery failure. The breaker box would hopefully prevent any damage to anything being plugged in if battery I has a failure. The main meter is connected directly so it could be toast potentially. If you don’t mind sketching something real quick so I can visualize it I’d definitely consider changing it if it’s safer!



#80 TelescopeGreg

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Posted 16 September 2020 - 02:17 PM

Thanks Greg! It’s pretty busy looking I’m sure there is a better way to put this kinda stuff together took way too long lol. Yea I’ve tried a few different configurations but I can’t picture what you mean. I figured doing it this way isolates each battery from each other in the event of a battery failure. The breaker box would hopefully prevent any damage to anything being plugged in if battery I has a failure. The main meter is connected directly so it could be toast potentially. If you don’t mind sketching something real quick so I can visualize it I’d definitely consider changing it if it’s safer!

Usually, a long string of daisy-chained devices is going to be less reliable than a configuration where each is home-run individually.  Consider that fuses themselves can fail, even without an actual fault being the cause, and that each battery will individually contribute a different current to the overall load, which, depending on where they are in the chain, may cause up- or -down stream fuses to blow in a chained configuration.  In a chain, the closer to the load the fuse is, the higher rating it must have, and that causes that right-most battery to be the least protected.

 

An advantage of having one fuse per battery is that a battery can be isolated from the set by simply removing its fuse.  This could be useful during repair / replacements scenarios, or to isolate one battery from the set if it were to fail and become a drain on the rest of them.

 

In practice, none of this is likely to be a major problem, of course.  Just a nit.

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#81 SuperJustin

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Posted 16 September 2020 - 02:51 PM

Hi Justin,

 

Nice work on all of this, and I encourage you to continue troubleshooting and learning as you have been. I just made a similar custom battery box, albeit much simpler. Because I already have my main power distribution and metering on my tripod, I only needed a few power outlets plus USB for convenience: 

 
 
 

 

I just finished mine, so I thought I would chime in with some useful resources that I found. Will Prowse's YouTube channel talks all about LiFePO4 batteries, charging them, BMS's, etc.:

 

https://www.youtube....ser/errolprowse

 

So for example, you may need to add a BMS to your batteries to keep them balanced (even though they each have their own BMS).

 

Also, I didn't catch what charger you were using, but this one from Victron was recommended to me by Battleborn. It's a little pricey I suppose, but you can choose a standard LiFePO4 charging profile, or it even links with Bluetooth to an app on your phone, so you can make your own custom profile to match whatever the battery manufacturer recommends.

 

I apologize if I didn't get the details why you needed all the regulators, but each stage of regulation will cause losses, so the more devices you can run directly off the batteries, the better. Most of my 12V-powered items (mount, camera, dew heater, etc.) can accept a fairly wide range of input voltages and in fact have their own regulators, so I just let them connect directly.

 

Lastly, if you're in cold weather at all, you have to be careful not to charge the LiFePO4 batteries when they're cold, and adding a heater to the batteries can actually improve their performance in cold temps. I might look at putting some dew heater straps on my battery, with a temperature regulation circuit, but I haven't gotten that far yet!

 

Anyway, keep up the good work, and good luck!

Jeremy

Thank you and yours looks great. The price tag is huge on that 50Ah! Makes me wonder about my three batteries totaling 48Ah for $150 undecided.gif . I guess only time will tell how they hold up for the price tag! There quite a bit of content on that YouTube channel I'll definitely look through it tonight and see hat jewels I can dig up. Very curious about the possibility of adding a BMS. I think it will be a good idea to add one for sure if I can swing it!

 

I actually only ended up with one regulator in the end that pushes my pocket powerbox on my imaging rig. Really the mini PC is the only device that seemed picky on voltage I don't think anything else really would have minded the little bit extra voltage. Now understanding a bit better how the battery drops voltage under load I might have been fine without the regulator but it would of been tricky getting things fired up creating enough load without the mini pc on already first. I do really like that as the battery gets down to about 25% and starts dropping voltage pretty rapidly I can continue imaging without any worries of low voltage or any fluctuations.

 

A couple post back I linked some amazon chargers I found. I really want to make the 5A work since it was only $35. I ended up ordering a similar priced unit like the one you linked but I haven't opened it. How long is your 50Ah taking to charge and how low do you typically drain it to? Do you actually charge it fully or cut it a bit short? I like the custom charging algorithm feature via bluetooth on that Victrom unit. I will need to replace some of the 18AWG cables if I end if with a 10A charger just to be safe. I'm going to go back to testing here soon so I should be able to decide after the next recharge cycle if 5.5A is just to slow for me.

 

Thanks for the note on cold weather! Unfortunately, here in hot humid Florida I may be on the other side of the spectrum. Pretty nervous for my first real session outside. All my charge/recharge cycles have been inside in ideal conditions! For once maybe I'm fortunate there is clouds for the foreseeable future lol.


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#82 SuperJustin

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Posted 16 September 2020 - 03:07 PM

Usually, a long string of daisy-chained devices is going to be less reliable than a configuration where each is home-run individually.  Consider that fuses themselves can fail, even without an actual fault being the cause, and that each battery will individually contribute a different current to the overall load, which, depending on where they are in the chain, may cause up- or -down stream fuses to blow in a chained configuration.  In a chain, the closer to the load the fuse is, the higher rating it must have, and that causes that right-most battery to be the least protected.

 

An advantage of having one fuse per battery is that a battery can be isolated from the set by simply removing its fuse.  This could be useful during repair / replacements scenarios, or to isolate one battery from the set if it were to fail and become a drain on the rest of them.

 

In practice, none of this is likely to be a major problem, of course.  Just a nit.

Thank you for this. So in your example Battery III would be the first in line for positive and Battery I would be last in line for negative, effectively keeping a "balanced" wiring scheme right? I think this was the point that confused me when I rewired things a bit. It makes sense it would work the same way just couldn't picture it properly. I think it's much better to do it the way your recommending despite not being a major issue. Even if its just for the reason you mentioned, removing fuses and isolating one from the rest! 



#83 TelescopeGreg

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Posted 16 September 2020 - 05:02 PM

Thank you for this. So in your example Battery III would be the first in line for positive and Battery I would be last in line for negative, effectively keeping a "balanced" wiring scheme right? I think this was the point that confused me when I rewired things a bit. It makes sense it would work the same way just couldn't picture it properly. I think it's much better to do it the way your recommending despite not being a major issue. Even if its just for the reason you mentioned, removing fuses and isolating one from the rest! 

To be clear (sorry!), my preference is the upper diagram, where all three batteries are equally treated.  That some of the lines (wires) are slightly longer or shorter is a matter of drawing the schematic.  There's really no "first" or "last", other than the physical position or an arbitrary numbering.

 

Your diagram is what I reproduced in the lower diagram, where there the batteries and fuses are in a chain.


Edited by TelescopeGreg, 16 September 2020 - 05:05 PM.

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#84 SuperJustin

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Posted 16 September 2020 - 05:28 PM

To be clear (sorry!), my preference is the upper diagram, where all three batteries are equally treated.  That some of the lines (wires) are slightly longer or shorter is a matter of drawing the schematic.  There's really no "first" or "last", other than the physical position or an arbitrary numbering.

 

Your diagram is what I reproduced in the lower diagram, where there the batteries and fuses are in a chain.

Yea got that part but I’m wondering about this bit and if doing it like you demonstrated in the top diagram would still have the same effect. Here’s a short excerpt Maybe explaining a bit better then I can.. I think your diagram still keeps thing equalized since the path follows my intent just reversed with completely isolated batteries and better placed fuses.

 

“To join batteries in parallel, use a jumper wire to connect both the positive terminals, and another jumper wire to connect both the negative terminals of both batteries to each other. Negative to negative and positive to positive. You CAN connect your load to ONE of the batteries, and it will drain both equally. However, the preferred method for keeping the batteries equalized is to connect to the positive at one end of the battery pack, and the negative at the other end of the pack.”

https://www.batterys...k-tutorial.html


Edited by SuperJustin, 16 September 2020 - 05:32 PM.


#85 TelescopeGreg

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Posted 16 September 2020 - 05:48 PM

Yea got that part but I’m wondering about this bit and if doing it like you demonstrated in the top diagram would still have the same effect. Here’s a short excerpt Maybe explaining a bit better then I can.. I think your diagram still keeps thing equalized since the path follows my intent just reversed with completely isolated batteries and better placed fuses.

 

“To join batteries in parallel, use a jumper wire to connect both the positive terminals, and another jumper wire to connect both the negative terminals of both batteries to each other. Negative to negative and positive to positive. You CAN connect your load to ONE of the batteries, and it will drain both equally. However, the preferred method for keeping the batteries equalized is to connect to the positive at one end of the battery pack, and the negative at the other end of the pack.”

https://www.batterys...k-tutorial.html

Yep, we're saying the same thing.  All of our diagrams have the batteries in parallel; the difference is in where the fuses are placed.  Again, not the end of the earth, but worth pointing out as there are advantages of the upper diagram for serviceability and resilience when things "go pear shaped".

 

What they are referring to with "connect to the positive at one end of the battery pack, and the negative at the other end of the pack.” is for high current (like, RVs and such) applications, where the resistance of the interconnecting wires can be a factor.  You (I hope) don't have that problem!


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#86 jrsone

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Posted 17 September 2020 - 03:25 PM

Thank you and yours looks great. The price tag is huge on that 50Ah! Makes me wonder about my three batteries totaling 48Ah for $150 undecided.gif . I guess only time will tell how they hold up for the price tag! There quite a bit of content on that YouTube channel I'll definitely look through it tonight and see hat jewels I can dig up. Very curious about the possibility of adding a BMS. I think it will be a good idea to add one for sure if I can swing it!

 

I actually only ended up with one regulator in the end that pushes my pocket powerbox on my imaging rig. Really the mini PC is the only device that seemed picky on voltage I don't think anything else really would have minded the little bit extra voltage. Now understanding a bit better how the battery drops voltage under load I might have been fine without the regulator but it would of been tricky getting things fired up creating enough load without the mini pc on already first. I do really like that as the battery gets down to about 25% and starts dropping voltage pretty rapidly I can continue imaging without any worries of low voltage or any fluctuations.

 

A couple post back I linked some amazon chargers I found. I really want to make the 5A work since it was only $35. I ended up ordering a similar priced unit like the one you linked but I haven't opened it. How long is your 50Ah taking to charge and how low do you typically drain it to? Do you actually charge it fully or cut it a bit short? I like the custom charging algorithm feature via bluetooth on that Victrom unit. I will need to replace some of the 18AWG cables if I end if with a 10A charger just to be safe. I'm going to go back to testing here soon so I should be able to decide after the next recharge cycle if 5.5A is just to slow for me.

 

Thanks for the note on cold weather! Unfortunately, here in hot humid Florida I may be on the other side of the spectrum. Pretty nervous for my first real session outside. All my charge/recharge cycles have been inside in ideal conditions! For once maybe I'm fortunate there is clouds for the foreseeable future lol.

Thanks Justin. Yes, the price is initially high, but in the end, it is cheaper than the equivalent performance in sealed lead acid. If I had known about these used medical grade LiFePO4 batteries, that Will Prowse talks about here, I might have gone that route. They probably are backup for life-support systems, never see a full discharge, and stay in climate control 24/7. Yes, there's A LOT of content on that YouTube channel, but it's a good resource, and this guy is REALLY into batteries! :)

 

Do you have the v1 or v2 Pocket Powerbox? The v1 can accept down to 11V, and the v2 can accept down to 12V (as I'm you probably know). Even at 12V, normal 12V LiFePO4 batteries have maybe 10% charge left. So it might not be worth it to have the regulated output for the Powerbox, which again is a regulator itself. I guess you could try a smaller dedicated boost/buck regulator just for the mini PC, so the losses would be less and you wouldn't have to worry about a minimum load.

 

On the Victron charger, that's a good question! I haven't really used the battery yet! (My telescope is back at Stellarvue for collimation for my new camera setup) Theoretically at 15A from the Victron charger, I should be able to charge mine in less than 3 and a half hours. Battleborn recommends charging to 14.6V, then floating to 13.6V. If I had a 50A charger, the battery is capable of '1C' charging, in which case it would only take an hour to charge it. You may want to have a separate dedicated low-gauge wire harness/connector, so that you could charge at a higher rate if you get a beefier charger in the future.

 

Ah, OK, good for you. I can only imagine winter targets without the winter temps. Yeah, new gear usually means clouds! Well, you're probably discharging slowly enough that you won't need to ever worry about overheating. 

 

Jeremy


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#87 SuperJustin

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Posted 17 September 2020 - 06:29 PM

Thanks Justin. Yes, the price is initially high, but in the end, it is cheaper than the equivalent performance in sealed lead acid. If I had known about these used medical grade LiFePO4 batteries, that Will Prowse talks about here, I might have gone that route. They probably are backup for life-support systems, never see a full discharge, and stay in climate control 24/7. Yes, there's A LOT of content on that YouTube channel, but it's a good resource, and this guy is REALLY into batteries! smile.gif

 

Do you have the v1 or v2 Pocket Powerbox? The v1 can accept down to 11V, and the v2 can accept down to 12V (as I'm you probably know). Even at 12V, normal 12V LiFePO4 batteries have maybe 10% charge left. So it might not be worth it to have the regulated output for the Powerbox, which again is a regulator itself. I guess you could try a smaller dedicated boost/buck regulator just for the mini PC, so the losses would be less and you wouldn't have to worry about a minimum load.

 

On the Victron charger, that's a good question! I haven't really used the battery yet! (My telescope is back at Stellarvue for collimation for my new camera setup) Theoretically at 15A from the Victron charger, I should be able to charge mine in less than 3 and a half hours. Battleborn recommends charging to 14.6V, then floating to 13.6V. If I had a 50A charger, the battery is capable of '1C' charging, in which case it would only take an hour to charge it. You may want to have a separate dedicated low-gauge wire harness/connector, so that you could charge at a higher rate if you get a beefier charger in the future.

 

Ah, OK, good for you. I can only imagine winter targets without the winter temps. Yeah, new gear usually means clouds! Well, you're probably discharging slowly enough that you won't need to ever worry about overheating. 

 

Jeremy

yea very interesting never considered going the used medical route. Looks like he paid $300 for two 40Ah. I still think these 3x 16Ah LiFePO4 for $150 is an incredible deal especially with amazon backing you can ensure you get a good set. I would definitely go with them instead!

 

I am using the V1 but it is just a distro with low voltage and high voltage cut off protection. I'm not sure if the V2 regulates or not either. The v1 does have one regulated 9V port for DSLRs but no help for me lol. I imagined it was regulating to 12V so that's why I initially didn't include one in the battery box design. Once I saw the mini pc was acting a odd power cycling I measured the pegasus powerbox outputting 13.2V and confirmed in the manual it was unregulated unfortunately.

 

I thought you had the 10A model, I just realized they keep going up to 25A! I think I found my charging issue so I'm going to return the 10A charger I bought and keep the 5.5A.. Takes about 10 hours but keeps the overall build cost closer to my initial budget!

 

Hopefully we both will get to use them soon under some clear skies!


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#88 SuperJustin

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Posted 21 September 2020 - 10:10 PM

Hey guys just wanted to provide another update on my project! I think I came up with a decent solution to the main meter needing the LCD screen lit to take measurements. I designed and 3d printed this cover which uses 2x 35mm M3 screws for the hinge. You can use velcro or double sided tape to adhere to the face of the meter. I forgot to take pictures of the final before painting so I included one of the random prototypes where the hinge was on the side. You can download the file here..

 

https://www.dropbox....AZCD9mty8a?dl=0

 

IMG_7758_jpg.jpg

IMG_7760_jpg.jpg

IMG_7761_jpg.jpg

 

Other then that the box has been working great during all my inside tests. I found the issue in my charging which was a polarity adapter I was using. It was a quick fix to one of my earliest blunders wiring the charging cable that I forgot to circle back to. 

 

I have noticed the USB charging ports which are on their own circuit get pretty hot measuring about 75C on a few occasions. I can't think of any issues that could be causing other than usb chargers in general just get very hot! 

 

Not sure if I will come up with much else at this point to add on or modify. I'm pretty happy with things at this point. I wish I had some more practical experience to determine if the loss in voltage I see under load is anything worth rewiring over. Still want to look into the external BMS possibly but it doesn't seem absolutely essential at least for my setup with only 3 batteries. If I come up with anything new I'll report back for now I'll just enjoy the portable power! Hopefully in a month or so I'll have some nights out with it and some pictures to share as well!


Edited by SuperJustin, 21 September 2020 - 10:11 PM.



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