For the battery experts… Lithium??

[WiskyDan]

I just bought a battery negative cable off the shelf at Napa - it matched negative that I had in the boat.

 

[FSH 210 Sport]

How did you determine what gauge wire to use for the new negative. I assume it has to be able to handle the full load from all 3 of your system negative wires going into the shunt. I have a 195S, it has the stock negative going to the battery and then a direct run for my amp, 4 gauge 100 amp fuse, also going to the battery. Trying to figure out what gauge I would need to go from the battery to shunt.

So did some poking around to see what size battery cable is used in cars and such and what is recommended. From what I can see you’d probably be fine with #1 copper wire, in fact that is overkill for our engines, and I’d get machine wire which has lots of fine strands which makes it very flexible. The #1 wire I used for my house battery is welding cable which is very flexible.

The engines in our boats probably don’t pull more than 150 amps, check the suggested wire size at this website which makes custom battery cables. Battery Cable Size Chart | Battery & Cable Questions | 2/0 Gauge This custom battery cable shop recommends #2 for four cylinder and small six cylinder engines and #1 for large six cylinder and small V8 engines.

Once you have your shunt installed you’ll be able to see just how much your starter draws when you start your engine, and how much all of your accessory loads really are, and I’m sure quite a few people will be interested in your observed amp draws.

Here’s another wire gauge ampacity chart.

Cerrowire Resources - Ampacity Charts

Ampacity is the maximum current that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Cerrowire's ampacity chart helps calculate the load requirement for a circuit.

www.cerrowire.com

Wire can be pushed to 200% of its rating for short periods of time, like for a starter on an engine, and to 150% for four hours with no damage to the conductor, and those overload ratings are very conservative, some utilities push the 200% rating in open air to 4 hours and the 150% in open air to 8 hours, regularly.

 

[Stealth]

Thanks @FSH 210 Sport for all the great info. I have been following a lot of your posts on batteries while I figure out my plan. What you said is the direction I was leaning in. My only concern is that I added a 4 gauge wire fused to 100 amps at the battery for an audio amp. I'm a 195S with single battery. For now I'm going to keep it that way. So in theory I'm combining the stock negative and 100 amp audio ground to one side of the shunt and sending them down just one wire on the other side. I don't draw anywhere near 100amps for the audio amp. In fact the amp itself has only a 50 amp fuse. But I don't want a fire to start on a short of some sort. I think I may go with a 2/0AWG wire for the short run which should give me about 175 amps continuous (way over kill for sure).

I'll likely swap the single battery for 100ah or 135ah LFP down the road but at the moment I haven't depleted the stock deep cycle durning normal use. The shunt data should be interesting to see just how much capacity I'm using now.

 

[FSH 210 Sport]

Thanks @FSH 210 Sport for all the great info. I have been following a lot of your posts on batteries while I figure out my plan. What you said is the direction I was leaning in. My only concern is that I added a 4 gauge wire fused to 100 amps at the battery for an audio amp. I'm a 195S with single battery. For now I'm going to keep it that way. So in theory I'm combining the stock negative and 100 amp audio ground to one side of the shunt and sending them down just one wire on the other side. I don't draw anywhere near 100amps for the audio amp. In fact the amp itself has only a 50 amp fuse. But I don't want a fire to start on a short of some sort. I think I may go with a 2/0AWG wire for the short run which should give me about 175 amps continuous (way over kill for sure).

I'll likely swap the single battery for 100ah or 135ah LFP down the road but at the moment I haven't depleted the stock deep cycle durning normal use. The shunt data should be interesting to see just how much capacity I'm using now.

The cleanest way to do your grounds is to install a buss bar and land all the grounds on the buss bar that way you only have one cable on each side of the shunt.

I get you wanting to go with 2/0 which is 195 Amps, and while I’m a fan of “overkill is underrated” that is over kill but, if you can get it in there without dramas its certainly not going to hurt anything except your wallet. Having piece of mind is priceless.

Your 100 amp fuse on the #4 is basically an over fuse of 5%, since your amp has its own 50 Amp fuse, you are only protecting the length of #4, so with a 100 A fuse you are fused at 105% roughly.

Here is what I suggest you do with your current (see what I did there?) set up. Install the shunt, get your universal battery cable from the auto parts store to go from the battery to the shunt, and then attach your system grounds on the other side of the shunt being sure to put the largest cables on the bottom and the thinnest towards the top or nut part of the bolt.

Once the shunt is installed and you have installed the app on your phone, turn on each device separately to measure their draws. Then with all devices off start the engine and see how much it draws, the instantaneous amp draw should be recorded in the graphical page of the smart shunt.

By doing the two aforementioned steps you will KNOW exactly how much draw you will have on your battery and can then make educated and informed decisions about how you will proceed with your system design. Not measuring all of those loads / draws will just be a guess or an assumption.

 

[Stealth]

The cleanest way to do your grounds is to install a buss bar and land all the grounds on the buss bar that way you only have one cable on each side of the shunt.

I get you wanting to go with 2/0 which is 195 Amps, and while I’m a fan of “overkill is underrated” that is over kill but, if you can get it in there without dramas its certainly not going to hurt anything except your wallet. Having piece of mind is priceless.

Your 100 amp fuse on the #4 is basically an over fuse of 5%, since your amp has its own 50 Amp fuse, you are only protecting the length of #4, so with a 100 A fuse you are fused at 105% roughly.

Here is what I suggest you do with your current (see what I did there?) set up. Install the shunt, get your universal battery cable from the auto parts store to go from the battery to the shunt, and then attach your system grounds on the other side of the shunt being sure to put the largest cables on the bottom and the thinnest towards the top or nut part of the bolt.

Once the shunt is installed and you have installed the app on your phone, turn on each device separately to measure their draws. Then with all devices off start the engine and see how much it draws, the instantaneous amp draw should be recorded in the graphical page of the smart shunt.

By doing the two aforementioned steps you will KNOW exactly how much draw you will have on your battery and can then make educated and informed decisions about how you will proceed with your system design. Not measuring all of those loads / draws will just be a guess or an assumption.

Thanks again, I got the shunt in this morning. An idea what settings should be used with the stock deep cell? Interesting from a quick test the audio amp uses way less power then expected. 75 watts at a loud but not max "boom boom" level.

 

[FSH 210 Sport]

Thanks again, I got the shunt in this morning. An idea what settings should be used with the stock deep cell? Interesting from a quick test the audio amp uses way less power then expected. 75 watts at a loud but not max "boom boom" level.

So I want to understand your question correctly, you are asking what the settings should be on the shunt with a flooded lead acid battery?

Thanks for the info on the amp consumption, (I’m not surprised by the low level of draw) can you please share with us the make / model and watt output of your Amp?

 

[Stealth]

So I want to understand your question correctly, you are asking what the settings should be on the shunt with a flooded lead acid battery?

Thanks for the info on the amp consumption, (I’m not surprised by the low level of draw) can you please share with us the make / model and watt output of your Amp?

Yes that is correct. This is the battery I have:

Salesforce B2B Commerce

www.fleetpride.com

I can't find a capacity but I'd guess 60-75ah. How do you determine the shunt settings for such a battery?

The amp is the Wet Sounds HTX-4. Bridged sub set to max at 300 watts, and the 4 stock recon 5s set for about 60 watts each. We don't blast music and only listen to it in the boat. No desire to make other people listen to our music.

 

[FSH 210 Sport]

Yes that is correct. This is the battery I have:

Salesforce B2B Commerce

www.fleetpride.com

I can't find a capacity but I'd guess 60-75ah. How do you determine the shunt settings for such a battery?

The amp is the Wet Sounds HTX-4. Bridged sub set to max at 300 watts, and the 4 stock recon 5s set for about 60 watts each. We don't blast music and only listen to it in the boat. No desire to make other people listen to our music.

Let me see what I can come up with…you do need to know the Ah of the battery though.

 

[Stealth]

Let me see what I can come up with…you do need to know the Ah of the battery though.

I'm still trying to find the exact number. I have guessed 60ah to be on the safe side for now.

 

[FSH 210 Sport]

I'm still trying to find the exact number. I have guessed 60ah to be on the safe side for now.

Okay, cannot find the Ah listing from Deka, but, I found a reserve min calculator to Ah calculator, looks like 130 reserve minutes is 54 Ah. Which seems about right since this is a starting battery not a deep cycle battery. The best I have seen from a group 24 FLA deep cycle battery is 72Ah, which I find HIGHLY dubious.

Reserve capacity to amp hours

Convert reserve capacity to amp hours

www.convert-formula.com

I have a call into Battle Born to have them give me the settings for this battery.

In the mean time, check to see if there is a lead acid battery set up in the drop down settings in the device, I’d be surprised if there isn’t a pre programmed setting in the shunt.

 

[FSH 210 Sport]

Here’s the manual, go to section 7 for the Peukert setting and other settings related to your battery.

https://www.victronenergy.com/upload/documents/SmartShunt/9172-Manual_BMV_and_SmartShunt-pdf-en.pdf

 

[WiskyDan]

Battle Born is running a 15% off flash sale..........very happy with mine.

Battle Born Batteries | Reliable Lithium-Ion Batteries

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