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diy solar

For RV: A couple of questions on my cheap DIY build

Keep in mind that old microwaves are only 60 to 75% efficient. Add on top of that inverters inverters are 80 - 90% (very good ones can be 95% efficient) and the efficiency tails down typically as the load approaches maximum. Worst case scenario is that depending on your hardware, it could draw almost double the microwave's rated cooking power from the battery. 700w x 2 = 1400w. 1400w / 12 = 117 amps. Old ones have big transformers and a hefty inrush current at startup, too.

I would plan on a 2000w inverter and definitely a better BMS if you want to use a microwave. Headroom is always a good thing.
 
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Ive heard heltic is a good brand BMS but for $20 not so sure. Also sounds like it won't handle your planned load(s). I have a spare 4s 120a jbd bms with bluetooth that i am willing to sell. it would handle your load. Also, the 2 places you absolutely do not want to cheap out on are the inverter and the BMS. Strongly suggest a low frequency inverter (samlex makes some quality ones at good prices, look through their EVO line).

That said, please be careful and make sure you understand what you're doing. Just because you hook everything up and it works, does not mean it will stand the test of time. Make sure your wiring is properly sized and securely installed/attached to correct torque specifications, as well as protected by a class t fuse (for lifepo4 batteries). And yes, lifepo4 are "lithium".

Based on popular use, the renogy dc-dc chargers seem to work well. Just be warned, when it comes to technical support I've heard some horror stories. you really need to know what you're doing.

Feel free to reach out if you have any questions or are interested in the BMS, and good luck with your build.
 
I’m a little concerned with you getting anything bigger than a 1200 Watt Inverter with only one 12V battery. You really need to be careful with that. As long as your biggest load is only a 700Watt microwave you will be fine, but the advice of proper cables and breaker/fuse is spot on. Consider getting an inverter with a remote (wired/wireless) switch so you don’t need to leave it on when not being used. We’ve all gone thru the steps of learning so you’re not alone. The advice in here is invaluable!
You are going to have to spend some money though so don’t cheap out on things.
 
I’m a little concerned with you getting anything bigger than a 1200 Watt Inverter with only one 12V battery. You really need to be careful with that. As long as your biggest load is only a 700Watt microwave you will be fine, but the advice of proper cables and breaker/fuse is spot on. Consider getting an inverter with a remote (wired/wireless) switch so you don’t need to leave it on when not being used. We’ve all gone thru the steps of learning so you’re not alone. The advice in here is invaluable!
You are going to have to spend some money though so don’t cheap out on things.
2000 would be fine with his loads. The battery could easily handle it and as long as he doesn't surge over his planned loads for long periods of time the BMS will handle it too. The BMS will protect with over current protection as will the class t fuses. Of course, I admit my suggestion is a little on the over built side, but beginners trying to push the boundaries may find themselves facing more risk than they understand. 120a bms and 150a class t fuse will keep him safe and avoid nuisance fuse blows. Just because the inverter is rated for 2k, doesnt mean he has to push it there. I suggested low frequency simply for the longevity and reliability of their life span.
 
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Thank everyone. You have convinced me to go bigger. Especially on the BMS.

Current connected has the JBD 150a in stock looks like, otherwise you can get it in the other link on I posted from China and hope it gets to you in a timely manner
Overkill has the 120a model only


I am not seeing that link from China. Would you mind posting it again?
 
heres a picture of me testing the inverter before installing it under my fridge
 

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The Giandel 1500W pure sine inverter is reportedly 15W standby as someone recently posted their 1500W Giandel idle consumption and it was 1/3 less than my 1200.
I have a GoPower 1500W with built in transfer switch. It consumes 24W on standby. Manual claims <.9A in standby/sleep mode. Im experiencing closer to 2.0A though so I don't trust manuals. Not really sure if it is considered low or high frequency. I'll have to investigate I guess.
 
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