Wires size for Lithium

[Federico993]

Originally Posted by kmacdonald

A 14mm bolt is 14mm. That's bigger than a 1/2" hole the last time I checked. If you get 1/2" lugs you will have to drill out the hole to at least 14mm.

You are right, I need to find the right lugs. Do they exist?

Originally Posted by a64pilot

I don’t believe he is talking about inverters or any other loads etc.
Way I read it is he’s talking about what size wire to run from the alternator to the battery bank.
Personally I connected my alternator to the wire that goes from the bank to the starter and didn’t run a dedicated alternator wire.

I still don't have an inverter/charger, but it can be installed near the house bank, or 2m far away. (Honestly I don't know how much heat it produces, so I need to check where it's better to install on my boat).
The starter will be plugged to the AGM start battery, which will be charged with a DC-DC charger from the lithium house bank, while the engine is running.
So I will run from the alternator to the "Alternator Switch service", then to the "Charge busbar" controlled by the BMS. Here will be plugged all the feeding sources (Alternator, Solar and Charger), then to the house bank.

Originally Posted by kmacdonald

Yes. Most do use the starter wire and that's probably the best way to do it. It's usually the biggest wire on the boat unless there is a large inverter.

How if the alternator is regulated to charge a Lithium house bank and the starter battery through a DC-DC charger?

Originally Posted by s/v Jedi

Okay, I may not have the situation clear. Between battery and alternator, is there just one continuous cable or is there a busbar? How is the switch panel connected?

My recommendation for 4/0 cable and 400A class-T fuse is for the cable from battery to busbar. For the alternator to busbar you only need a 200A ampacity cable and further size for voltage drop of the distance. You can use the tables and apps for that but make sure cable ampacity meets highest possible current which is 200A. This would also be the fuse value.

Is there an inverter/charger? For current only the alternator is discussed but for most boats that is not the biggest current aboard.

With M14 battery terminals you can not use 12mm nor 1/2” cable lugs because they don’t fit. You need 14mm or 9/16” lugs. Drilling out lugs is not recommend because this removes the tinned finish from quality lugs.

The system still need to be built, so I am trying to draw it on a sheet.
The alternator will be plugged to the "charge busbar" which is controlled by the BMS and then to the Lithium house bank.
The Charger will also be plugged to the "Charge busbar".

Originally Posted by boat driver

The wiring is dependant on full capacity use and length and type of material made from- aka the wire type you choose x length (DC or A/c) x maximum draw- the source of power is irrelevant.

Lugs should fit the studs/fastener on both ends of wire as well as crimp/fasten to the wire correctly as designed. The capacity of the lugs is again a manufacture rating- and will be easily determined by above parameters.
Just recognize the tables are minimums- and therefore error to oversizing if in question. Wire is the cheapest to purchase and most labor expensive to install.

The distance from the alternator to the "Charge busbar" will be about 3m.

It's not so easy to think where to put each part of the electrical system on the boat when it's not your job

[kmacdonald]

Can your BMS handle your charge amps?

[Federico993]

Originally Posted by kmacdonald

Can your BMS handle your charge amps?

I will use a REC ABMS.