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diy solar

Ammo can battery with inverter

Semoreo

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Joined
Sep 6, 2020
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I've had this project for nearly a year now but am just now getting to post it. Finished up the assembly a few months ago and I am now using it on the job. The goal is a portable battery with an inverter I could use with me on the job or leave plugged in and charging in my truck. Enough power to jump start a dead truck is a plus but I've not had the opportunity to try this yet.

I'm mostly using it for charging tool batteries but occasionally for testing motorized doors during install. I have a 2000w inverter connected directly to my trucks battery. We used to use this for a lunch microwave and battery charger. We left the inverter on over the weekend too many times and have woken up to a dead truck battery. So I built this tip solve that issue. Isolated from the starter battery, enough power to run multiple chargers, portable so I can bring it inside if needed.

At home testing included plugging in a 500w tower light and letting it run until the bms disconnected it. First run the inverter shut off after 15 minutes overheated. So I just set the inverters case fan on top blowing down on the circuitry to cool it. Using the metal case as a heat sink. Worked great. The light ran for a hour and 15 minutes until low voltage disconnect. The section of the case that has the inverter fets bolted to it got warm, but not hot. Batteries didn't care one bit. The weak link is the 750w Amazon inverter. Might have been able to go up to 1000w but I was worried about space in the ammo can, didn't want to sacrifice storage.

Batteries I got some used 36v medical packs from battery hookup. Used two 36v packs 12s4p 36650 lipo4 that I split into 6 12v bricks. 3 4s4p from each pack. With the cells already connected all I needed to do was attach leads to them. Then I attached 3 12v 4s4p bricks to the 100a low temp bms for 2 12v packs. The packs then connect to the terminals visible on the outside along with the inverter.

Only real draw back so far is no internal charging capabilities. My next one I'll look into an inverter/ charger with an Andersen connector on the outside. This one is not abig deal as I have a bento psu Im using to charge it every other day. A pain but it saves me from buying a dc dc charger isolator, which I'll probably just end up buying anyway. Not sure if I can just direct connect it to my vehicles charging system without roasting my alternator or popping the lipos from over voltage. Not worth the risk.

I think that's it, now for some pics. I didn't think to take pics as I built it until it was mostly complete.




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Nice build

I have a few fan cooled inverters that I've been thinking about opening up to gain access to the heatsink.

They're often built into oversized extrusions... So if you can get the heat away... You can put a whole lot of inverter in a really small spot

...
When budget allows
We use a thermally conductive epoxy to pot the electronics and extract all the Heat. One of the best examples of this are meanwell power supplies. All of their ip64 stuff is just a brick of thermal epoxy inside of an extrusion.

A while back we had to build a bunch of stuff in airtight boxes. You would be amazed how many parts on the board produce heat!

Without the fan throwing heat around in circles... We would get hot spots. Coding something and half a centimeter or a centimeter of thermally conductive glue works like magic

You get the side benefit of being more resistant to shock and vibration, and even ingress and abrasion

-methods
 
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