Battery Terminal Connection bolt Size?

[NautiTug]

I am getting a 1/0 AWG battery wire made to connect my thurster battery in to my house battery. I am going to have them crimp the battery connector on. Does any have what size bolt is on the factory AGM battery? 1/4 or 5/16? or something else?

Also I am going to run the jumper wire from the thurster battery to the house and in the middle which is under the aft cockpit seat I am going to put a battery switch so if i ever need to I can isolate them again. Anyone see issue with that placement. Trying to avoid sharp bends in the wiring.

 

[Kevin Lamont]

Hello,

They should be the 5/16 size.

Can I ask why you are wanting to connect your thuster battery to your house bank? You may have some issues with the charging system as we use the ACR's to charge your engine, house and thruster banks. If you have the thruster connected to the house bank and the ACR opens to charge what was the thruster bank it will now charge both the thrustrer and house bank and vise versus when charging just the house bank. If you want more power for thruster I would look into adding a second battery in parallel and/or replacing the battery with a bigger one with higher reserve capacity. Let me know if you have questions and feel free to email me anytime, my email is below in the signature.

Thank you,

 

[BB marine]

Battery switch terminals are 3/8 lugs. The positive battery terminals are 3/8 and Negative are 5/16. I don't think with the installation you are doing requires negative terminals just positive. I would have 3/8 terminals installed on the cables.

 

[tugnnaweigh]

I did this on my R25 and R29 but without any switch as there’s no draw when thrusters are not in use and I like big wire that carries big amperage to only have connectors on each end. I think of it as adding 25% more capacity to the house and 400% capacity to the thruster and you can tell the difference especially when operating both thrusters simultaneously.

I use wiring that’s tinned, (West Marine, they can crimp too, get yer wallet out) I crimp them on then solder them then shrink wrap them then say don’t rust three times in a row quick, that’s the trick here.

My understanding of factory wiring is there’s three banks of batteries with two of them (thruster and starting batteries) having ACMs whose job it is to isolate them if their voltage drops below a certain point (10.5?) to prevent other banks being drawn down. Then you have to jump an ACM to get voltage to pass to charge them back above the 10.5 so the AGM will stay closed and I’ve had to do that so I made up short jumpers for exactly that.

As for the factory wiring of the charging for these three banks each is individually charged by the shore powered charger and my solar only has two charging leads which you can set to 50/50 or 90/10 and I don’t know how the heck the alternator distributes its energy.

So now you and I have two banks with one bank having two charging inputs from the shore power charger and I’ve set my solar for 90% to what is now house/thruster bank and 10% to starter battery.

I don’t comprehend Kevin s comment on how things have been changed visa ve charging as initially all three banks charged separately and now the only change is that there’s two banks one of them now having two charging inputs when on shore power battery charger.

Is he saying saying with the additional connection the AGM has been defeated and a thruster or house drain has the ability to kill all of the thruster/house bank? Or would a AGM still jump into the fray and isolate some batteries? I got lost in there somewhere.

Anyways, my understanding is with both boats the starter battery remains isolated and my solar is always giving it a bit of a tickle which is good for peace of mind. Unless of course I’m wrong.

 

[BB marine]

When I moved my batteries to starboard compartment. I pre-measured all the cable lengths and ordered pre-made cables from Greg's Marine wire supply.(https.//gregsmarinewiresupply.com) I used all 2/0 AWG wire with 3/8 post Lug. I have a 2000W inverter and this is the cable size requirement for the inverter installation. I used a 4 position battery switch to tie my thruster battery into House battery.OFF battery 1 (house) battery 2 (Thruster) Both. I installed this battery switch in place of the single on/off switch for my inverter. When we are cruising I turn the switch on to power the inverter. I now have the option of using just house batteries or both house and thruster. Using the 4 position switch combines a single on/off inverter switch and the thruster/house cross over switch. This combination will 1) increase the amp hour capacity to the house circuit by 90 amp hr. (1 battery). 2) Thruster circuit 180 amp hour (2 batteries) Group 27 batteries.
Custom Cables

Finished battery installation


Multi-able purpose battery switch

 

[NautiTug]

Thanks All. Yes I was looking at it as Brian mentioned (increasing house battery capacity when on the hook and increasing Thruster battery capacity at the same time)

I will email you separately Kevin but what I believe you are saying is that if the Thruster battery is connected to the house battery and the ACR opens up for the thruster battery and its already been topped off it could cause issues. But I thought the charger would recognize that the now combined house/thruster bank was already charged and not charger any further.

Brian: how do you have your ACRs set up? I believe I have 2 (one connected to house and engine and one to thruster) but need to double check next time I am at the boat.

 

[stwendl]

Before you add any cables consider the functionality of the ACRs

If you have more than one bank there is a chance you have the banks connected via acr for charging and protection purposes. The ACRs close when they see 13v on any input and disconnect at 12.75v

If you are motoring chances are there is 13v or more on the engine battery. ACRs are close and you have one big bank. That is the time when you most likely use thrusters

On the hook, if you have solar and solar pushes one bank over 13v banks will be connected too.

If during the above uses the voltage drops below 12.75 ACRs open to prevent draining of all batteries at the same time

The scenario is different when charging at shore. My boat has a 3 bank charger which is useless for the same reason. If one bank gets charged the ACRs close and push all that charge to all batteries no 3 a bank separate charging. The ACRs need to be disabled during that time

 

[BB marine]

The combined batteries does take out the function of the ACR’s. This doesn’t cause any electrical issues other then the protection of discharging the batteries is taken away. ( house- thruster) Having a battery switch gives you the option of standard isolation ACR’s and each circuit separated as it is now or combination of the two circuits with switch turned on. In two years of using this I have had no issues.