[-dirt-]

I didn't think this was possible, but after some Google-ing it appears, this may be doable after all (without extra electronic gadgets like a Trollbridge)...

Does anyone on here run their main engine, accessories, etc. off of the "1st" battery in their series of batteries?

Found here: http://jgdarden.com/batteryfaq/carfaq7.htm

My idea is to have the regular stuff hooked up as shown as Load 2...

Think this should work?

 

[jb-hunter]

Not sure but it all looks like it will work fine. The challenge will maintaining even drain across all for the 24V and 36v drain and if you are going to be charging using Converter you are (according to Powermax) supposed to us a charger same voltage as drain. In your case, that would be impossible.

 

[JPHolla]

It'll work, but it's not optimal. Like it says, the loads need to be equal which you are not doing. When one battery gets discharged more than the others, The others will be "charging" it when you run the 36v circuit. In theory, the batteries will wear out faster. As long as you don't discharge it too much it probably won't hurt much. A lot of people find it simpler to just run a smaller, cheaper battery for the boat. If it gets too low to start the motor, you can always jump it from one of the big ones.

 

[Delawareriver]

As mentioned above and in the diagram the loads must be the same. I run 12v for all my accessories plus my lights. So I have 4 batteries all to a bus bar then my accessories and light leads off the bus bar. If I had to run 24 or 36v I would try to figure out the math and split the accessories between the batteries for example if I was run 24v I would have the batteries in series for 24v then attach maybe the stereo to one battery then my navigation and stern light to the other battery to try to equal the load to as close as I could get it

 

[garpwacker]

I would keep the main engine cranking battery seperate and isolated from all accessory and trolling motor batteries if it was me......

 

[Delawareriver]

X2^^^ should of said that as well.

 

[-dirt-]

Thanks all one follow-up: would the charge that the alternator puts our mess anything up in this setup?

And I agree, for the extra weight of one battery, its probably worth it to just have separate banks.

 

[JPHolla]

The charge will have an effect. It will charge the one battery and raise it's voltage and make it as if it was bigger than the other two batteries. It would be the inverse of the first situation; now, it would be trying to "charge" the other batteries when the 36v circuit is on. I wouldn't want to run the 36v circuit when the engine is on. When cells are connected in series, they need to be identical. If they are, they work in unison. If not, they fight against each other to some degree. A chain is only as strong as it's weakest link. When a battery goes bad, it is often just one or two cells, and that's all it takes for the whole thing not to work.

 

[Tgarver]

I also had this question but just wanting to run my nav lights off the first battery in a 24v system. Will just the nav lights cause that much of an issue?

 

[JPHolla]

I also had this question but just wanting to run my nav lights off the first battery in a 24v system. Will just the nav lights cause that much of an issue?

Doubt it