My RV System - Ready to go in

dashdrum · Mar 9, 2020

Everything is ready except for the battery case. As soon as the weather gets a little better I'll be installing this in my travel trailer.

The inverter/generator includes a transfer switch for A/C power. The two empty posts in the middle of the board is where the trailer's DC power will connect.

I'll post another pic after installation.

JoeHam · Mar 9, 2020

Why is the main black wire not attached directly to the battery terminal?

Dzl · Mar 10, 2020

JoeHam said:
Why is the main black wire not attached directly to the battery terminal?

Good question, the first wire looks to be a much smaller gauge too

cass3825 · Mar 10, 2020

JoeHam said:
Why is the main black wire not attached directly to the battery terminal?

I would guess the smaller gauge black and blue wires are from the BMS, likely mounted to the side of the battery (out of shot).

dashdrum · Mar 10, 2020

JoeHam said:
Why is the main black wire not attached directly to the battery terminal?

cass3825 is correct. The BMS cables are smaller than I like to see - 6AWG for 200A continuous. I used 1/0 throughout. However, I don't see a time when I'll be running enough to heat the small wires too much. My tests with a microwave showed no issues. We won't be using the air conditioner of other large appliances in the RV.

I guess I could investigate adding larger or multiple cables to the BMS, but I don't see that it would be necessary.

John Frum · Mar 10, 2020

dashdrum said:
Everything is ready except for the battery case. As soon as the weather gets a little better I'll be installing this in my travel trailer.

The inverter/generator includes a transfer switch for A/C power. The two empty posts in the middle of the board is where the trailer's DC power will connect.

I'll post another pic after installation.

Are you banking on the bms' overcurrent protection circuit?

dashdrum · Mar 10, 2020

smoothJoey said:
Are you banking on the bms' overcurrent protection circuit?

You mean to protect the wires? No, the BMS allows short term bursts of up to 500A, which will protect the battery only.

I'm pretty much a novice with electricity, so I'm at the point where I'm wondering why the BMS is being sold this way. Is it common for customers to replace or augment the cables on such equipment?

John Frum · Mar 10, 2020

dashdrum said:
You mean to protect the wires?

I suggest one of these right on the battery post https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A

dashdrum said:
I'm pretty much a novice with electricity, so I'm at the point where I'm wondering why the BMS is being sold this way.

My guess is because its cheap and they can get away with it.

dashdrum said:
Is it common for customers to replace or augment the cables on such equipment?

Not that common but it is done.
The cheap and cheerful BMS's often are only good for .5x the advertised rating.
This video demonstrates a pretty neat alternate strategy*

*Use in combination with the MBRF I recommended above.

dashdrum · Mar 10, 2020

smoothJoey said:
I suggest one of these right on the battery post https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A

My guess is because its cheap and they can get away with it.

Not that common but it is done.
The cheap and cheerful BMS's often are only good for .5x the advertised rating.
This video demonstrates a pretty neat alternate strategy*

*Use in combination with the MBRF I recommended above.

Thanks. I'll take a look.

My RV System - Ready to go in

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