External circuit breaker to generator

[CompNeuroDev]

I have a Duracell PowerSource 660 all-electric generator that supports daisy-chaining batteries to it. I am going to connect a 12V 55Ah SLA battery (like a car battery) to it and I read adding a single circuit breaker to the connection between the generator and external battery could help with safety. I am a novice here, so I wanted to check, simply plugging in a 250A circuit breaker (for example the one here: [1] (Amp size I read is recommended for the size inverter I have [2]) with 2 or 4/0 gauge AWG wires in between the generator terminals and the external battery is safe? Should the breaker be connected to the positive or negative terminal connection on the generator? Is there any general safety advice for working on this? E.g., some kind of work gloves should be worn when working on this to avoid one's body accidentally picking up any electricity?

Thanks!

[1] https://www.amazon.com/ANJOSHI-Circuit-50A-300A-Inverter-Protection/dp/B07VY91V4Q/
[2] https://www.altestore.com/howto/recommended-inverter-cables-sizing-and-breakers-or-fuses-a62/

 

[jay32267]

I'm reading to use 2 AWG cable and a 200 amp breaker or fuse.

See here where it says attaching an external battery.

https://cdn.shopify.com/s/files/1/1...S_UserManual_ENGLISH_Outlined_20190326.pdf?15

Hook the negative post of the external battery to the negative terminal of the inverter.

Connect the positive post of the external batter to the breaker or fuse and the other side of the breaker or fuse to the positive terminal on the inverter.

 

[CompNeuroDev]

I'm reading to use 2 AWG cable and a 200 amp breaker or fuse.

See here where it says attaching an external battery.

https://cdn.shopify.com/s/files/1/1...S_UserManual_ENGLISH_Outlined_20190326.pdf?15

Hook the negative post of the external battery to the negative terminal of the inverter.

Connect the positive post of the external batter to the breaker or fuse and the other side of the breaker or fuse to the positive terminal on the inverter.

Thanks! I ended up doing some more reading about circuit breakers and got one that is 20 Amps. I read it can handle 80% of max amperage listed before I assume it trips [1]. Since the generator I have has a peak of 1800W and a continuous load of 1440W then 1800 (W)/120 (V)=15 (A). The circuit breaker tripping at 16 Amps seems to be a good point for that to occur.

I got 2 AWG cables like you mentioned (2 1fts, and a 3ft, and length does matter in safety), even though those are rated for up to 95 Amps, they didn't seem much more in cost than higher gauges and I read having greater amperage capacity does not cause issues. It is more than needed, but in case I ever want something more powerful in the future, those might be nice to have.

[1] https://www.homelectrical.com/understanding-capacity-your-circuit-breaker.6.html

 

[CompNeuroDev]

Thanks! I ended up doing some more reading about circuit breakers and got one that is 20 Amps. I read it can handle 80% of max amperage listed before I assume it trips [1]. Since the generator I have has a peak of 1800W and a continuous load of 1440W then 1800 (W)/120 (V)=15 (A). The circuit breaker tripping at 16 Amps seems to be a good point for that to occur.

I got 2 AWG cables like you mentioned (2 1fts, and a 3ft, and length does matter in safety), even though those are rated for up to 95 Amps, they didn't seem much more in cost than higher gauges and I read having greater amperage capacity does not cause issues. It is more than needed, but in case I ever want something more powerful in the future, those might be nice to have.

[1] https://www.homelectrical.com/understanding-capacity-your-circuit-breaker.6.html

Well, I found out I was wrong about this. I was told "You calculated 120v from the output (the inverter), not the external battery, and you need to calculate it based on the battery voltage, which is 12, not 120. 1800(w)/12(v)=150 amps." Therefore, because of 80% efficiency with a circuit breaker, I should get a 200 amp breaker and AWG cables more than capable of handling at least 160 amps of current. You were correct @jay32267 about the breaker size. I think, however, at least 2/0 (00) AWG gauge cables or lower gauge is advisable for the type of cables.

 

[jay32267]

Thanks! I ended up doing some more reading about circuit breakers and got one that is 20 Amps. I read it can handle 80% of max amperage listed before I assume it trips [1]. Since the generator I have has a peak of 1800W and a continuous load of 1440W then 1800 (W)/120 (V)=15 (A). The circuit breaker tripping at 16 Amps seems to be a good point for that to occur.

I got 2 AWG cables like you mentioned (2 1fts, and a 3ft, and length does matter in safety), even though those are rated for up to 95 Amps, they didn't seem much more in cost than higher gauges and I read having greater amperage capacity does not cause issues. It is more than needed, but in case I ever want something more powerful in the future, those might be nice to have.

[1] https://www.homelectrical.com/understanding-capacity-your-circuit-breaker.6.html

Yeah but the battery is 12 volts.....not 120.....and needs a DC circuit breaker and not an AC circuit breaker.

 

[CompNeuroDev]

Yeah but the battery is 12 volts.....not 120.....and needs a DC circuit breaker and not an AC circuit breaker.

Thanks @jay32267, I made sure to get a DC circuit breaker for 200 amps that with about 80% efficiency matches coverage for 1800W/12V=150A. I also got a solid plastic (UHMW) block to store the breaker on to avoid any surface with electrical or thermal risk.

 

[CompNeuroDev]

Another issue I am having is many circuit breaker products' posts to connect wire ring terminals don't offer enough room (post and surrounding plastic or other material) to fit the terminal (e.g., [1]). What product can extend the posts' connection points to plug a wire terminal into? I am thinking of something like terminal clamp connectors but they need to be the right size to fit such circuit breakers (e.g., [2]). I will be using 2/0, 3/0, or 4/0 AWG gauge wire (not 2, 3, or 4 gauge) and a 200 amp breaker.