BMS negative wires and AWG/gauge question

[NCblueridge]

I have an overkill BMS (which I am very happy with), it comes with 10 AWG wires by default though. I can connect directly to the positive side of the battery, but the negative side on the BMS is that size wire. I assume that limits me to around 30 amps max given the Amp rating and wire sizes. This is ok on that battery build since it would only pull 30a max on occasion anyway, but I am doing a larger build and would like to size accordingly since that one will have an inverter. One the 2nd BMS ordered, I added the 8 AWG option.

Anyway and sorry if this is a stupid question, but I assume I am still limited to amp restrictions at 10 or even 8 on the BMS with a 12 volt system with an inverter on the larger system?

 

[MisterSandals]

How many amps is your BMS rated for?

 

[Ampster]

There are three sets of wires in parallel.. Each wire can handle at least 30 Amps so that is 90 Amps. It is probably more since they are not in conduit. Three 8 AWG should easily handle over 120 Amps.

 

[NCblueridge]

There are three sets of wires in parallel.. Each wire can handle at least 30 Amps so that is 90 Amps. It is probably more since they are not in conduit. Three 8 AWG should easily handle over 120 Amps.

Thanks, that is great to know - I'm a newbie and appreciate the explanation.

 

[NCblueridge]

How many amps is your BMS rated for?

Up to 120 amps and that is why I was confused I guess - but as someone else pointed out - each of those 3 wire together are capable of putting out 30 amps each to manage 90 amps...and more if you go with the 8 AWG instead of standard 10. I learned something new today and just in time for a long weekend

 

[Dzl]

Maybe @OverkillSolar can confirm the type of wire used (insulation rating specifically). If it is 105*C or above, quality copper wire, securely connected, 10AWG should be good for 50A+ per wire.

Outside Engine Space = 85*F Ambient
Inside Engine Space = 120*F Ambient

 

[Zil]

I don't understand your meaning "connect to positive" There are three wires on each side of that BMS. They do not connect to the positive. The only wires that connect to positive are the small sensing wires.

 

[Zil]

I don't understand your meaning "connect to positive" There are three wires on each side of that BMS. They do not connect to the positive. The only wires that connect to positive are the small sensing wires.

 

[Zil]

Sorry about double post. Verizon is acting up today.

 

[NCblueridge]

I don't understand your meaning "connect to positive" There are three wires on each side of that BMS. They do not connect to the positive. The only wires that connect to positive are the small sensing wires.

I was referring to a load connecting to the positive terminal on the battery pack itself, unlike the negative which connects to the BMS output wires and therefore would be limited in some manner in amperage based on the wiring present on the BMS.

 

[Ampster]

You should also use an over current protection device such as a fuse or breaker on the positive.

 

[NCblueridge]

You should also use an over current protection device such as a fuse or breaker on the positive.

Yes, it will have that for sure.

 

[Ampster]

Your link does not work since it refers to your C drive unless you want to give us all open access. Maybe post it as an attachment. You may still have time to edit it.

 

[Zil]

UOOPS I will change that file to some persistent, infectious, porno file.

 

[Gazoo]

I have it handy:

 

[Zil]

Thank you for lifting that post.

 

[OverkillSolar]

Maybe @OverkillSolar can confirm the type of wire used (insulation rating specifically). If it is 105*C or above, quality copper wire, securely connected, 10AWG should be good for 50A+ per wire.

Outside Engine Space = 85*F Ambient
Inside Engine Space = 120*F Ambient

The wires that they use at the factory are labeled:
"10AWG 200c 600v VW-1 TYPE TV-3 SILICONE RUBBER I A 200c 600V FT2"

When I do 8ga wires they are rated 105c.

 

[Dzl]

The wires that they use at the factory are labeled:
"10AWG 200c 600v VW-1 TYPE TV-3 SILICONE RUBBER I A 200c 600V FT2"

When I do 8ga wires they are rated 105c.

Thank you! Also, if you wrote (or translated/edited) the manual in your signature), I just glanced at it quickly, but great work!!

 

[OverkillSolar]

I paid a writer/programmer to create the entire manual from scratch

 

[NCblueridge]

I paid a writer/programmer to create the entire manual from scratch

He did a great job. Very thorough explanation of setup as well as all the different settings. I just ordered another one BMS for the 2nd pack I am putting together here.