My lightweight portable power station build

[NCblueridge]

I am building a small portable power station that will be used as a power source for my kayak's trolling motor and fish finder as well as a small backup system for power outages.

For my kayak uses, this will plug into a single outlet on my Slayer Propel 10 kayak and suppy power for a 12 volt, 30 amp trolling motor (Newport Vessels 36lb. thrust Kayak Series), a low power GPS/sonar unit (Dragonfly 5) some USB convenience connections I am adding to the kayak in conjunction with this project. I will probably do a post or two about that in this thread also.

For power failure situations, my primary needs are USB charging for my laptop, phone and iPad (I am a career long web developer and manage 19 individual data driven dynamic websites so access is critical), DC power for my fiber modem and router (both adapted to allow direct DC inputse) and power for a couple of DC fans and LED lighting. I also have a small external 750 watt inverter that will plug into the unit should that be necessary.

Charging sources for this station will consist of a Victron Bluesmart 12V/17Amp AC unit for regular use and (2) portable 100 Watt mono panels (or optionally (4) portable/stationary 100 Watt panels in a 2P/2S configuration ) with a small Victron 100/20A MPPT charge control which could possibly be integrated into the pack also.

The batteries I am using are (4) 105 AH Shenzhen Luyuan 3.2 Volt packs in a 4s configuration. I chose these for their light weight and size although the threads are fairly small as was pointed out in one of Will's build videos on youtube. I sourced the batteries from Power BLS on aliexpress since they have a US warehouse and offered free shipping for around $450.00. I wasn't happy with the mismatched cell voltages initially but otherwise they were new and the vendor has assured me that if there are any issues they will take care of them - I will know more after some capacity tests and use but for now they seem ok. I have top balanced these in parallel using a 100/30 bench power supply at 3.65v. I am using an Overkill BMS which I have been impressed with so far - more on that shortly.

So let's get started.

Battery specs:

 

[NCblueridge]

These cells weren't even close to matching on delivery (3.298,3.288,3.248,3.184) so they have been top balanced with my bench PS and then setup in series and the OK BMS added. No problem installing the software for the BMS although I did pay a small fee for the licensed app, hopefully that is a one time charge so I can use it with other packs I build in the future.

 

[NCblueridge]

One option for the housing box is an Eylar 3.37 inch 11.62 inch 6 inch case. The inner deminsions are 11.81" x 8..87" x 5.18" which actually fit the battery pack and BMS but it's tight on the 5.18 width, but acceptable and there is also a little room to spare.

Now this box is waterproof and thick so there is really no airflow and only a small pressure release valve. This may be a concern and I would love any feedback. I have another box wich is not waterproof but is large enough to add fans. I don't plan on putting an inverter inside but the Victron charge controller would fit if needed - again though, no air flow and I wonder about continious use at 30a with the trolling motor or using a small external 730 watt inverter and the heat generated on the battery with that. I do have BMS protection settings that could go into effect but would hate to be stranded on the water in that situation. I think I am going to do some tests with the inverter and watch the temp to see where those busbars go. While it would be great to have a small waterproof unit, I do have a medium size water resistant case I can use that isn't that much bigger and can accomodate a couple of fans with a themal controller as an option as well.

Any thoughts are greatly appreciated on this.

Pics attached, open/closed with pack and BMS inside.

 

[svetz]

I'm so jealous! I want to do this too, but with a solar panel too as posted in Flexible Panels hit Prime Time? Please post how it goes, love to know your range/speed.

 

[NCblueridge]

I'm so jealous! I want to do this too, but with a solar panel too as posted in Flexible Panels hit Prime Time? Please post how it goes, love to know your range/speed.

I'm going to keep this up to date and add a lot of photos and detail as I go forward...some questions for those with experience also.

It's sad you have to run down manufacture data in FL just to put a trolling motor on a kayak, we don't have that nonsense in NC...at least not yet..

They should just be honest and say, "this is about tax revenue, we charge X dollars in taxes for a kayak with a 'motor'" ($10/12$25..whatever) and leave it at that, would at least make things easier for FL residents with an unregistered kayak and a trolling motor.

 

[NCblueridge]

Quick update, even after top balancing in parallel, at peak voltage, the individual cells were still a little off in voltages once I connected in series and added the OK BMS (one in particular). I did a rundown to @35% with an inverter and my heat gun on high speed, low temp for many hours. They are pretty close now. I'm gonna run it up to 100% in the morning with my new victron 12/17 charger and then do a full rundown after that to see where things are, my concerns about maybe having a bad cell are fading but we will see.

 

[svetz]

...It's sad you have to run down manufacture data in FL just to put a trolling motor on a kayak, we don't have that nonsense in NC...at least not yet...

Actually it's to circumvent theft. Since you can't register a boat or trailer without it, no one will buy any sort of boat/trailer without the paperwork so there's no longer an incentive to steal them. Kayaks don't need to be registered unless you put a motor on it, so a lot of owners misplace their original paperwork. Then you're in a catch 22 and can never get it registered.

 

[NCblueridge]

Also, pulling 30 amps (which is the most my trolling motor typically pulls), I felt no heat on the batteries or busbars so I may be ok with this enclosed case. Any thoughts from others welcome.

 

[NCblueridge]

Actually it's to circumvent theft. Since you can't register a boat or trailer without it, no one will buy any sort of boat/trailer without the paperwork so there's no longer an incentive to steal them. Kayaks don't need to be registered unless you put a motor on it, so a lot of owners misplace their original paperwork. Then you're in a catch 22 and can never get it registered.

Oh ok, I figured it was just a way to require people to formally register a kayak so you can get yearly tax bills

 

[NCblueridge]

Looks like I've hot a roadblock with one of the cells in this pack, I posted info in the general area about this issue so hopefully I can get it resolved.

 

[NCblueridge]

Everything resolved and finishing this project up (hopefully this week). This is the smaller unit of 2 I am doing - this one is very portable and lightweight and for marine use my Slayer Propel a kayak, powering a trolling motor and electronics.

 

[floridianman27]

nice set up. still itching to build mine like this. right now i am looking for Valence U27-12XP 135ah used batteries around $400.00+/-. Already purchased 2 Valence batteries. i do need to get a BMS for these as the XP series batteries do not have an internal BMS. I wonder if the Overkill BMS will work on Valence batteries. I only need three 12 volt batteries to run my 36 volt trolling motor. do i need to use all four wires from the Overkill BMS. i will have another 12 volt lithium battery just for my 3 fish finders and one livescope. I am unsure about connecting the forth wife from the Overkill BMS to a stand along lithium battery.

 

[Gazoo]

nice set up. still itching to build mine like this. right now i am looking for Valence U27-12XP 135ah used batteries around $400.00+/-. Already purchased 2 Valence batteries. i do need to get a BMS for these as the XP series batteries do not have an internal BMS. I wonder if the Overkill BMS will work on Valence batteries. I only need three 12 volt batteries to run my 36 volt trolling motor. do i need to use all four wires from the Overkill BMS. i will have another 12 volt lithium battery just for my 3 fish finders and one livescope. I am unsure about connecting the forth wife from the Overkill BMS to a stand along lithium battery.

You might want to ask in the Valance XP super thread.

Valence XP Super Thread

#1: I'll try and keep this organized. We're limited to 10,000 characters so this will be a multi part post. If you have an XP battery or a bunch of them this will be a good thread for information on how to treat them properly. We'll discuss what the Valence Brand U-BMS actually does and how to...

diysolarforum.com

 

[-C-]

Hello- I'm planning on doing something similar. Has this been working out OK for you?

How did you end up housing everything and end up orienting your cells? I read (under Mechanical Installation here) that it's not a good idea to lie cells down unless they're designed for it, which messes up my design ideas of using a Peli case similar to yours. Or have you found some that are OK with this?

 

[NCblueridge]

Hello- I'm planning on doing something similar. Has this been working out OK for you?

How did you end up housing everything and end up orienting your cells? I read (under Mechanical Installation here) that it's not a good idea to lie cells down unless they're designed for it, which messes up my design ideas of using a Peli case similar to yours. Or have you found some that are OK with this?

For this smaller unit, the case locks the 4s pack in place when closed. I just received a replacement for a rogue cell from China so I will post the final build soon with the replacement done.