Introduction: Portable, Solar 12V Battery Pack

Picture of Portable, Solar 12V Battery Pack

Camping these days usually means bringing along things that need power. Usually I’d just use the cars 12v outlet but I find this a hassle, especially if you have to charge your phone at night.

So, after being inspired by a build my youngest brother did, I decided to build myself a battery pack that would last the whole time I was camping, was portable and also practical.

The battery pack runs off a 12v, SLA battery and has 3 outlets, one 12v cigarette outlet and 2 USB. An 18v solar panel ensures that it is kept charged throughout the camping trip and there is also LED lighting on the side with a dimmer. To regulate the power from the panel, I used a solar panel regulator. Lastly, I added a mains power switch to make sure the battery isn’t drained when not in use.

You can also charge the battery via a couple of lugs that stick out the side. I added these as an afterthought so you won't be able to see them in the images below. However I will add another step so show you how I did this soon

I use the power pack to run the shower (yes I have a portable, hot water shower. Nothing better than to have a hot shower after a couple days camping!), blow-up mattresses, charge up my portable speaker and phone, and whatever else that needs power.

The build isn’t very difficult; it does however require a little knowledge of electronics and some basic soldering skills. I’ll take you through all aspects of the build so anyone should be able to put one together.

Step 1: Parts and Tools

Picture of Parts and Tools


1. 12v, 7ah SLA battery – eBay

2. Project or power box. The size I used was 85mm x 230mm x 150mm. You can buy these from electronic shops (Jcar in Australia) or eBay

3. 18v Solar Panel – eBay

4. 12v Solar panel regulator – eBay

5. On/off switch – eBay

6. Momentary switch – eBay

7. Red and black wire

8. LED strip – eBay

9. 12v Dual USB / Cigarette Charger – Ebay

10. Dimmer – eBay

11. Aluminium bar (for handle)

12. Double sided tape

13. Velcro

14. Various nuts and bolts


1. Drill

2. Angle grinder

3. Files

4. Hot glue

5. Soldering iron

6. Screwdrivers and Philips heads

Step 2: Attaching the Power Adapter

Picture of Attaching the Power Adapter


1. Remove the voltage meter and power adapters and use the cowling as a template for the holes you need to drill into the project box

2. Mark out the hols onto the lid of the project box

3. Drill out the holes. I used a … sized hole bit to make the holes. They are slightly larger than needed to be so I had some room in case the drilling was off.

4. Next put the voltage meter and other adapters into the cowling and secure onto the lid with the plastic washers that they come with.

5. Screw the cowling to the project box lid

6. Lastly, drill a hole near the volt-meter and attach the momentary switch

Step 3: Attaching the Solar Panel

Picture of Attaching the Solar Panel


1. Make a template out of a piece of paper, the same size as the solar panel

2. Mark the 2 solder points on the paper and stick it with tape to the lid.

3. Next, drill out the area where the pads are and remove the paper template

4. The solar panel that I used didn’t indicate which pad was negative and which was positive so I just used an LED, touched it to the pads, and put it up to a light source. Solder a couple of wires to the pads.

5. Attach some double sided tape to the back of the panel, thread the wires through the hole in the lid and stick the panel into place

Step 4: Adding the Mains Switch

Picture of Adding the Mains Switch


Mains Switch

1. Drill a hole in the side of the project box big enough to fit the switch into

2. Secure into place

Step 5: Attaching the Dimmer

Picture of Attaching the Dimmer


1. The dimmer switch comes in a small case. You need to remove the pot and circuit board from within.

2. First, un-screw the 4 screws holding the lid on

3. Next, remove the bolt holding the pot onto the lid

4. Carefully remove the lid and un-screw the circuit board from the case

5. Drill a hole in the side of the project box and attach the pot with the nut.

Step 6: Attaching the LED's

Picture of Attaching the LED's


1. Drill a hole in the project box for the wires on the LED light to go through. Remember to have the light close to the dimmer switch

2. Attach the LED’s to the project box. I had to modify my LED’s so they fitted correctly which meant that I couldn’t screw them in any longer to the project box. Instead I used some epoxy glue to secure it to the box. The LED’s also came with their own on/off switch so I didn’t have to worry about adding one. You may however need to add a switch if the ones you have chosen don’t have one

Step 7: Attaching the Handle

Picture of Attaching the Handle


1. I used a piece of aluminium strip to make the handle. First you need to bend one end.

2. Next, measure where to bend the other end, stick the aluminium into a vice and make the bend.

3. Trim off any excess aluminium

4. Secure it in place with some screws and lock nuts

Step 8: Wiring - Part 1 Battery

Picture of Wiring - Part 1 Battery


1. The first thing to do is to secure your battery to the bottom of the box. Add some Velcro to the bottom of the battery and stick into place.

2. Next, you need to attach a wire from the positive terminal on the battery to one of the terminals on the main switch.

3. Another wire then needs to be attached to the other switch terminal to the solar panel regulator.

4. Lastly, attach a wire to the negative terminal and to the solar panel regulator

Step 9: Wiring Part 2 - Socket

Picture of Wiring Part 2 -  Socket


Ignore the LED wiring for the minute. I go through this in more detail in a couple of steps

1. Connect each of the terminals on the USB and 12v socket. Solder wires to each of the positive terminals and also the negative ones.

2. Solder another wire to one of the negative terminals on the socket to the terminal on the voltage meter.

3. On the other terminal on the voltage meter (positive one) solder a wire to it and then to one of the terminals on the momentary switch.

4. Solder a wire to the other terminal on the momentary switch and then secure this in the solar panel regulator as shown in the below image.

5. Attach wires to the last terminals on the socket and also secure these to the solar panel regulator.

Check out the diagram below to help you out with how to wire this section up. It’s pretty straight forward but might be a little confusing to a novice.

Step 10: Wiring - Part 3 Solar Panel

Picture of Wiring - Part 3 Solar Panel

I have done some calculations which can be found below on how well the panel will charge the battery. If you got ideal sunlight for 6 hours, you should be able to recharge the battery by 25%. This should be enough to top-up the battery each day


1. The wires that you soldered to the solar panel now need to be attached to regulator. On the regulator, there is a picture of a solar panel where you need to attach the wires (couldn't be more straight forward!)

2. Secure the wires (polarities the right way...) to the regulator

Thanks it!

Step 11: Wiring - Part 4 Dimmer and LED Light

Picture of Wiring - Part 4 Dimmer and LED Light

Last thing to wire-up is the dimmer.


1. Attach the wires from the LED light to the output section of the dimmer switch. Make sure that you have the polarities right.

2. Next add a red and black wire to the input section on the dimmer. These then need to go into the solar panel regulator as shown in the diagram below.

Step 12: External Lugs (For Charging)

Picture of External Lugs (For Charging)

There might be a need to top-up the battery now and then. I decided to add a couple of lugs to enable a battery charger to be attached. I didn't include these initially but after some comments, I thought it would be a good idea


1. Drill a couple of holes into the side of the case. I made the holes slightly smaller than the screws (lugs) so I could add a thread to the inside of the holes.

2. Add a couple of bolts to the screws. these will be used to hold the wire to the screws.

3. Screw the screws into the holes.

4. Now attach a couple of wires to the battery terminals on the regulator and then attach them top the screws by wrapping them around them and tightening the bolts

5. Lastly, I added a couple of rubber covers I found at the hardware store. It's best if you can cover them when the battery is live as you don't want to accidentally short anything.

Step 13: Test and Close-up the Box

Picture of Test and Close-up the Box

Now you have everything wired-up, it’s time to test and make sure all the electronics work. Plug the battery in and test that the power sockets are working. You should see a light on the USB 5v ones come on. Check the light as well and make sure it also comes on. If you can, test out the solar panel and make sure that the battery is getting charged. Lastly, make sure that the wires to the battery are secure and won’t come off if handled roughly.

Close-up the box and screw together.



gillagilla (author)2017-07-23

Great project. Useful, adaptable and robust. Two things that I have noticed:
1. I am getting back flow from the device being charged to the charger it self . This must be happening when battery of charger was very low.
2. A cut off would be good to stop the SLA running below capacity.
Over all great idea though.

That's interesting about the back flow. I wonder if it is due to the solar panel regulator in some way?

maddixke (author)2017-01-18

I read this is used to control a chicken coop door.

I'm looking for something to power a drinker heater using 12V, 5W (it's freezing over here and I don't have power anywhere close to the chickens) like this one:

It only has to heat from dawn till noon. Will such a solar pack do the trick, should I build 2 and alternate day by day or does the heater simply use up to much energy to be powered by such a solarpack? (Electric novice, but I do love the animals who can't drink on dry icy mornings when I'm at work. I guess my previous electronic attempts proved I can set up a light sensor to have it automatically start heating at dawn.)

lonesoulsurfer (author)maddixke2017-01-23

Hey there,
for what you want I would use something different. I built a auto chicken coop door sometime ago which used timers and this would be more suited to what you want to do. here is the Instructable:


BaelRathLian (author)2017-01-16

Thanks for the cool info. I love natural energy projects. I am curious, how much would you charge to make one of these for someone else? Also an idea for a future project : Keep everything you have here but add a wind dynamo with a bit larger box.

Juanma232 (author)2017-01-06


How can the battery measure 150.1 mm. Long and can be put into a box that has 150 mm. Of outer width.

Errol1951 (author)2016-12-28

I built one a bit larger for my daughter for the same thing and what I setup for charging was an external input plug so that I could either plug a larger panel or a 12volt plug pack to give me a bigger variety of options to charge and you could even plug it into your car from the cigarette lighter socket I also put a small radio from ebay with blue tooth on the radio for entertainment with a builtin usb charger port

JC81 (author)2016-12-25

Can I use 11.1V Lipo Battery instead of 12V SLA battery? That can make a lot lighter and smaller pack.


timothybil (author)JC812016-12-25

All batteries sag voltage a little when in use. 11.1V is already low for a nominal 12V setup, so I would use a 14.4V LiPO instead. Don't forget you should really use a balance charger for best results in charging a multi-cell LiPO battery.

JC81 (author)timothybil2016-12-26

I can't find the enclosure case. Can you point me where I can find? I'm from US.

lonesoulsurfer (author)JC812016-12-27

Check out the link in the parts section. Alternatively, you can just type into eBay - "230 x 150 x 85mm Project Box" and it should come up with a few

D BE (author)2016-12-25

Raise the voltage and separate better battery banking from solar cells charging facing South with plug & play devices connections. Pure sinewave inverter split phase in either single or 3 phase that can be stackable for pairael AC amperage increases. Throw in a small windmill and you then have a mini microgrid.

blackvyper (author)2016-12-25

Nice build! It reminds me of the 2 versions I built. If I build another I'm going to use a lithium ion battery.

Mjtrinihobby (author)2016-09-09

Impressive project!

kellyt18 (author)2016-09-03

Instead of lugs, could I put a cigarette lighter port on the side and charge it in the car while driving?

PawanL2 (author)2016-08-31


This is exactly what I have been looking for since quite some time now. I'm not good with solar or electrics but this look do-able even for a rookie like me. Thanks a lot mate.

I have a few questions and I really hope that you can help me out on this.

1) Do you think that I can add one or two more batteries in parallel or even try working it a larger one for more usage?

2) By adding more solar panel in a foldable manner will it reduce charging time?

3) You said you had a shower heater for camping. Is it a diy project or something you bought?

4) My first 2 questions was basically focusing on increasing usuage capacity and reducing charging time. So if you could help me out it would be great?

5) There was a comment saying there was a mistake in a diagram for wiring. Have you updated that?

Thanks a lot.

Keep building such awesome stuffs.

lonesoulsurfer (author)PawanL22016-08-31

Hey there. Anytime!

I'll try and answer your questions as best as I can:

1. Definitely. You can also purchase similar sized battery with higher amperage which also might be an option.

2. Yes it will. If you have more amperage though it will take longer to charge.

3. The shower is something that I purchased. The battery runs the water pump for me.

4. It's a trade off really. If you have less amps, then the battery won't last as long but you will be able to charge quicker with less panels.

5. I haven't updated the diagram yet. I'll let you know when done

PawanL2 (author)lonesoulsurfer2016-09-01

Hi Lonesoulsurfer

Thanks a lot for all the info.

Now I know how to work through it. Thing is when we go camping its usually 8-10 people so with all the charging and usage being done I really needed a heavy duty stuff. Now I can mod ur model and add maybe two higher amp batteries together and a foldable solar panel.

Both the solar and the batteries should be in parallel right?

And again about the shower, does it also have the heater function?

If possible let me know where you bought it, live in Australia for 2years have a few friends who can find it there.

Thank again mate

lonesoulsurfer (author)PawanL22016-09-01

Don't mention it.

Yep - both the batteries and panel should be in parallel. You want to keep the voltage at 12v but up the amps so the power lasts longer. What you could look at doing is finding a 12v battery with high amps. You could look into batteries from these guys - who do a great battery at good prices. You'd never be able to power it up with a solar panel but you probably would have to as it would last the whole trip!

In regards to the shower - I purchased this from a store called anaconda. The water is heated with gas and the water is pumped out with a small 12v pump.

Good luck!

PawanL2 (author)lonesoulsurfer2016-09-02

Howdy Mate

I was shopping online for a few stuffs to start my build and I can across a solar panel regulator and I got a bit confused. Well read a lot about both systems the PWM and the MPPT one.

The MPPT seems to be the best choice but as I am only beginning my 1st solar project the PWM looks good for a start. But the real dilemma started when I had to choose between 3 models of PWM.

They are as follows:

1) PWM 10a
2) PWM 20a
3) PWM 30a

I figured the 'a' stands for amps.

But what does it really mean and which one should I choose?

An additional info might be that I am planning to buy 3 sets of 18V 5W solar panels to go with that.

I would like to apologise before hand for bothering you so much Lonesoulsurfer but you are really the only one who has been and can help me out.

I would like to thank you in advance for your great help.

Thanks Mate

NathanR97 (author)2016-09-02

I didn't quite understand on the 'ible instruction on the lug part, how exactly did you wire the lugs into the system? Also, do you think there would be any problem if I put a battery maintainer into the system permanently? I figured it would go battery>maintainer> female 120v plug to female 120c computer plug that would poke out on the outside of the case.

JanS151 (author)2016-08-30

I am pretty new to instructables. One question I have is .. Is there an estimate on $$ required to acquire all the parts. Great looking device and exactly what I need. Thank You

AnandN13 (author)2016-08-25

love the project. i have actually one xtra sla battery lying around. if i dont use the solar panel what i can reduce from the list? thanx

lonesoulsurfer (author)AnandN132016-08-25

If you don't use the solar panel then the build becomes a lot easier. All you need is the project box, battery, mains switch, and the USB and 12v charging ports. The LED's are also optional too

AnandN13 (author)lonesoulsurfer2016-08-29

i am thinking to plug into 220 volts or charge thru car plug.

1. how do i make sure that the battery is not over charged?

3. how do i plug to 220volts , by adapter?

AnandN13 (author)lonesoulsurfer2016-08-29


hispanickausinpanik (author)2016-08-23

Nice build, great job !

Nice tidy build 'surfer !

I may have to look into this for my tiny floating home .

Thank you for the good presentation.

Wow what a build! Fantastic job. When do you think you'll have it on the water?

Hi Surfer.

Regarding your question about when I will be finished on my project .....I don`t know really, its a big job , and I need to re-stock some more funds.

Keep up the good work , its appreciated.

Thanks for the reply.

I am going to use the same idea to charge car battery in my car because I don't travel far to keep the battery at full capacity this would be ideal only instead of a project box I would mount the sockets and gauge panel in the dashboard, also how about adding a wind up charger to the box as an extra

Drsch (author)2016-08-28

maybe a beginner electrics coure is in order? how to use a multi-meter!


Drsch (author)2016-08-28

hi folks

One more thing... solar panels work in low light also, at lower voltage!

more light=more volts/, less light=less volts, total darkness=no volts

Dawsie (author)2016-08-28

nice instructable it has helped me a lot as I have been looking into this sort of thing getting lost most of the time :-) but electronics and solar are not my major :-) but I am going to show this to a friend of mine who is a electrician and see if he can make it for me :-) as it will be perfect for what I need it for :-)

Thanks for a great instructable :-)

Drsch (author)Dawsie2016-08-28

hi folks,

a 12 volt battery+ volts average each of the 6 cells is 2.5 volts, 14.7 volts is the max.

regulators are good to have in the circut,un less you want to over charge the battery(not good)!

MikeOfAllTrades (author)2016-08-25

I love how many people comment on 'ibles without checking their facts first. 2 seconds of research would have told all these self professed solar experts that a 12V solar panel produces greater than 15V, specifically for charging a 12V battery... changing the 12V panel to an 18V panel has only cost you money, as the 12V regulator is now throwing away 10+V of wasted energy. You should now buy an MPPT to utilise your extra voltage as increased amperage. And no the regulator does not trade amps for volts unless it has a transformer or buck converter in it, the one listed clearly has neither, hence why they call it a regulator. I think this 'ible is great, but people commenting should spend at least 10 minutes learning about solar before asking you to change your build. Thanks lonesoulsurfer for posting from a Aussie Elec Engineer.

Hey there.

Whenever I do post a project similar to this (electrical) there's always mixed suggestions. There definitely have been some good ones (and some not so good). I'm going to do some tests first before I do replace the 12v panel but I don't there is any harm in pumping in extra v's using a 18v one. I've also had a look at changing the regulator to something which has MPPT included. These are very cheap (under $10) so I might also do this in the future. I have built an auto chicken coop door and that uses an 18v solar panel to charge a 12v through a regulator and this works a treat. I find that the 12v battery (SLA - the same as the one in this project) holds about 13 to 13.5v and then the regulator must kick in.


mscott41 (author)MikeOfAllTrades2016-08-26

gotta love the helpful constructive criticism

MikeOfAllTrades (author)mscott412016-08-26

Helpful constructive criticism is what takes a good thing and helps it become great, im certainly not complaining about that, but for any criticism to be helpful and constructive the "facts" supplied by the critic need to be correct. Fuses should be added = helpful, and constructive; regulator not needed = incorrect and therefore not helpful or constructive.

mscott41 (author)MikeOfAllTrades2016-08-27

without your comments, I (not being an electronic expert,) would have made the assumption that more is better, and the regulator, design to handle the input load would take care of the outgoing load.
your comments make sence to me, and I see there is a better solution. Would not have thought to consider different types of regulator/solar panels otherwise.

hence, gotta love the helpful constructive criticism ?

MikeOfAllTrades (author)mscott412016-08-26

Helpful constructive criticism is what takes a good thing and helps it become great, im certainly not complaining about that, but for any criticism to be helpful and constructive the "facts" supplied by the critic need to be correct. Fuses should be added = helpful, and constructive; regulator not needed = incorrect and therefore not helpful or constructive.

Hello yes the solar panel does go to a higher voltage But from what have seen on mine When i used that solar charger it brings it down to 12v.

If you are using a PWM regulator like the one listed above then 12V is the average voltage your voltmeter is reading, with an 18V panel that means the regulator is turning on at 24+ volts then turning off again all very quickly to average out at a suitable charging voltage. The higher the voltage of the panel the more off time required to bring it down to the correct charging voltage, and hence less time spent charging the battery. This is equivalent to lopping all the extra voltage off the top.

If using an MPPT these are basically a DC to DC converter which means that any extra voltage can be converted into extra amperage. This has multiple benefits, ie more current availability which means faster charging, a constant DC voltage which is recommended for charging SLA batteries and if the MPPT can step up voltage it means better charging in the shade.

shortw (author)josephchrzempiec2016-08-26

A PWM charge controller will bring it down to 12 volts or current battery voltage.

But, when the batteries are charged up and still hooked up to the panel and the sun is still out, you should have about 13.8 volts on the batteries.

Do you have any links to some good MPPT charge controllers that work well with small panels?

Cant say Ive spent the days it would require to go through every charge controllers datasheet. I wouldnt have even commented about an MPPT if somebody hadnt convinced lonesoulsurfer an 18V panel would be better as his original 12V panel with the 12V regulator was a good build. Personally I wouldnt spend the money on the MPPT anyway, I would just make my own with a buck converter and microcontroller, or for even better use of the panel in the shade a buck/boost converter. That in itself is a whole other instructable, although really not that difficult.

deke07 (author)2016-08-26

Do you see a problem adding extra batteries in parallel? I want to be
able to operate a laptop and cell phone (to provide a WiFi hotspot)
from a campsite for a few days. This would be about the only way that I
could go on vacation currently. What do you think?

WannaDuino (author)2016-08-26

i love iT do

WannaDuino (author)2016-08-26

i have 3 things for you so iTS 100 %

You forgot to put fuses between battery and the powerbutton.

And you have to put a block diode on the solar panel. So iT can not drain by the panel.

And you can put a fuse between the 12 v prevent short out

About This Instructable




Bio: I've always liked pulling things apart - it's the putting back together again that I have some issues with.
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