#66

Feeling some motivation from this thread, I connected a mock rig with a 50W 12V solar panel, a super cheap MPPT solar controller (boost only) and five 2P10S 18650 battery packs. I’m sure it would be easier and less expensive to buy an off the shelf solution but this feels like more fun. The battery packs were surplussed from hoverboards (probably fire risk recalls) but seem to be pretty good. They are loaded with LG cells and include a battery management system BMS board. The load testing resulted in a capacity of around 4.2AH per 36V (nominal) pack (approx 150Wh per pack) so 5 parallel packs should be 750Wh. In the testing I charged the packs to 42V (4.2V per cell) and discharged to 33V (3.3V per cell). Please let me know if this is too off topic for this forum.

Solar
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#67

Which solar panel is that?

(Seems totally on-topic to me!)

#68

It’s a Kingsolar 50 Watt 18 Volt Flexible Solar Panel. I have not seen it make more than around 25W but it only weighs 2.5 lbs.

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#69

It’s going to be a tight fit to get all the electronics in here but this is 750Wh of capacity in a lunchbox 54hp sized case. I hope to fit a MPPT solar charge controller, coulomb counter battery monitor, cutout protection relay, 12V DC-DC converter, Adjustable DC-DC converter, USB jacks and bunch of connectors for solar panels, and power out. The 120VAC inverter will be outside the box since it won’t always be needed and there is not nearly enough space or cooling.

Battery%20mount
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#70

Reporting back with a word of caution, I did end up purchasing the power supply that @bmoren suggested (link) which works wonderfully with an exception. I was planning on using my grid with it as well and it doesn’t seem like that will pan out unless I get another power supply. I get a high-frequency noise even with the split power cable as outlined in this thread which solved my noise issue on my main rack. It’s kinda a bummer so If you’re wanting a grid (maybe arc) in your mobile setup it would likely be a good idea to go with an alternate power supply.

#71

Here is a tentative plan on how to piece together the portable solar generator. I’m totally new to making something like this so if anyone spots a problem or has a suggestion please share. One potential issue is that if the cell voltage drops below the BMS threshold the pack would need to be bootstrapped through the Solar/Low Volt charge port since the relay would be open. I hope to prevent that by setting the battery monitor low volt cutoff a little above the BMS cutoff.

Diagram
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#72

I started to look up your part numbers and my eyes started watering at the price of the battery packs. I imagine I’m not searching very well. How are you sourcing your batteries?

EDIT: I realized I should search for “1052P” and not “10510P”. Still a sizable investment in batteries, but much more affordable. I’m wondering about downsizing this… (but still want to keep a lunchbox size modular rack and some LED-crazy grids going for 2-4 hours).

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#73

I was able to get these packs fairly cheep ($30) because they were from recalled hoverboards. New 36V 4400mAH scooter packs are around $45 on Ebay. We have a pretty bad dockless electric scooter problem here in San Diego. I’m thinking we are about to see a glut of electric scooter parts in the second hand market because of all the impounded and damaged scooters out there. It would be cool to recycle the battery packs into solar generators. Even if that doesn’t happen $45 for twenty 18650 cells with a BMS is not bad.

I think two 36V 4400mAH packs would still be more than enough capacity for a big portable system.

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#74

Thanks so much for putting this together! I wasn’t aware of the battery monitor, charge controller, dc-dc converter, and adjustable power supply parts. Really amazing how affordable this stuff is getting.

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#76

I want to share some things I have learned the hard way so far (probably more to come). The VAC9010H battery monitor shows a 10-60V rating for the relay connection. I made the connections to a traditional relay and it worked fine for a few dozen on/off cycles then stopped working. After tracing the circuit back to the relay control transistor I found it was using a S9013 NPN BJT with the relay coil from Vbat to the collector. The S9013 has a Vce rating of only 25V! I’m guessing most people are using these in 12V systems and have not seen this failure.

I swapped in a BJT with a 60V Vce rating and everything worked fine. I limited the relay coil current to 100mA which doesn’t sound that bad until you realize that it’s 3.6W of wasted power anytime the output is on. I considered using a DC-DC converter to lower the voltage but that would add complexity and still burn 1.2W @ 12V. Finally, I gave up and switched to a solid state relay SSR with a 5 – 200VDC 40A rating and control port of 3 – 32V. I used a Zener to drop the control voltage by 14V. When on the SSR draws 15mA (0.54W) at 36V. If you go with an SSR make sure to get one designed to switch a DC voltage.

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#77

This is how I ended up mounting the components.

Power_Panel
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#78

Hi guys,

Does any of you have experience with powering and recording your synths outdoors? How do you do that?

I would like to bring my 0 coast and an sq-1 to the river.

Thanks

#79

I use a Bioenno battery with my CL gear. I just needed to add a daisy chain barrel plug cable so I can power them all off of a single battery.

#80

I’ve been powering this little box with this battery for about 5 hours at a time, it has a DC jack on it, so no AC/DC adaptor needed.

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#81

wow, very clean work!

#83

Can that battery power a 7u case?

#84

We tested for a few minutes at the office, seemed to work ok, but the palette case is the only one we’re tried for extended periods of time (4-5 hours at a time)

#85

I’m planning a month long road trip and would like to bring a few of my instruments on the road with me to jam on while I’m layin in bed (back of my truck). Does anybody have any recommendations on power banks or some sort of DIY battery cache I can rig up for power?
I plan on powering a Digitakt, Digitone, keystep, MB33, MS-1 and a small mixer.

#86

I’ve powered 19” of modular, mixer, and PCM recorder off my Jackery when I’ve wanted to “get wild” with my Houseplant sets.

You will want to add up the mA of all the things you want to plug in and then make sure your battery has more than that (ideally a lot more but hopefully someone who knows more about electrical engineering will pipe in). Sometimes this is printed near the plug in thingie, sometimes you need the manual to find out.

#87

i recommend the “mobile modular” thread for some good insights…

john at pulplogic has been experimenting with some cool diy solar stuff:

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