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Batteries & Wiring Question

Old 03-01-2013, 12:24 PM
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Default Batteries & Wiring Question

In short order I'll be getting the new to me boat ready to hit the water and trying to determine the best way to get the batteries and wiring worked out. Boat is just a small 18' CC.

I want to have a battery dedicated to starting the engine. I also will be running a 24V trolling motor. They'll also be bilge pump, livewell pump etc. I've also got a Garmin 720 and will be picking up a Lowrance HDS12.

Aside from perhaps adding the bilge and livewell pump to the starting battery, I'm not adding anything else. I've done some reading and there are many schools of thought on pulling 12V from the 24V setup for the trolling motor batteries. I've also read that HB doesn't recommend running their electronics from your trolling motor batteries due to possible interference.

I want to have clean power going to the 720 and the HDS12 and about the only thing I can come up with is adding yet a 4th slave battery to run these units. The newer electronics draw more these days and seem to be pretty susceptible to power fluctuation due to low voltage sources etc.

So how about some thoughts and suggestions? Good idea? bad idea? work around solutions?
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Old 03-01-2013, 02:35 PM
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Originally Posted by Badbagger View Post
In short order I'll be getting the new to me boat ready to hit the water and trying to determine the best way to get the batteries and wiring worked out. Boat is just a small 18' CC.

I want to have a battery dedicated to starting the engine.
Good. Do NOT compromise on that.


I also will be running a 24V trolling motor.
This is going to complicate matters significantly.


They'll also be bilge pump, livewell pump etc. I've also got a Garmin 720 and will be picking up a Lowrance HDS12.
All of that (and probably more) should run off a dedicated "House" bank.


Aside from perhaps adding the bilge and livewell pump to the starting battery, I'm not adding anything else.
There is some rationale for running at least one of your bilge pumps off the Starting bank; but there is also a potential down-side to that, so this is by no means a "cut & dry" decision. However, the live-well pump and other accessories have absolutely NO business running off the Starting bank, period.


I've done some reading and there are many schools of thought on pulling 12V from the 24V setup for the trolling motor batteries.
The "Bottom Line" is, DON'T DO IT!

See http://www.thehulltruth.com/5366642-post12.html for more-detailed discusion of the whys & wherefores of that.


I've also read that HB doesn't recommend running their electronics from your trolling motor batteries due to possible interference.
And that is yet another reason.


I want to have clean power going to the 720 and the HDS12 and about the only thing I can come up with is adding yet a 4th slave battery to run these units.
It's not a "slave battery" (whatever that is). But given the scenario you describe, you DO need three separate battery banks.


The newer electronics draw more these days and seem to be pretty susceptible to power fluctuation due to low voltage sources etc.
The sensitivity issue I'll grant you, due to everything being computer-based now. But piece for piece and function for function, modern electronics almost always have far LOWER power consumption than their analog and CRT-based ancestors. It's just that we tend to use a lot more (and more ambitious/elaborate) electronics than we used to, especially on smaller boats.


So how about some thoughts and suggestions? Good idea? bad idea? work around solutions?
Follow the approach I laid out in that post I pointed you to above. Do not forget to dedicate a good high-capacity 24V battery charger (such as http://www.pmariner.com/productFeatu...oductNum=63180) to the trolling motor bank. I would also recommend a separate high-quality 12V charger (such as http://www.pmariner.com/productFeatu...oductNum=63140 or http://www.pmariner.com/productFeatu...oductNum=63160) for the Starting and House banks; but depending on your usage patterns, this MIGHT be less critical.



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Old 03-01-2013, 02:41 PM
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Thanks for the input and I'll read through that post. I currently have a decent charger - Promariner that charges the starting battery and 2 12v batteries for the TM. I'd invariably need one more charger.
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Old 03-02-2013, 08:27 PM
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an acr between the house and engine battery would allow the house battery to charge both from the engine while running, and off your current charger. both of which you want. no need for another charger (unless it's on the small side)

the blue sea off / on / combine switch would be recommanded for the house and engine bank. and a seperate off / on switch for hte trolling batteries.
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Old 03-03-2013, 01:31 PM
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Originally Posted by smac999 View Post
an acr between the house and engine battery would allow the house battery to charge both from the engine while running, and off your current charger. both of which you want. no need for another charger (unless it's on the small side)
He still needs a 24V charger (or a dual-bank 12V charger with fully "stackable" outputs to form 24V overall) for the Trolling Motor bank, which will NOT be getting recharged via the ACR/VSR, or the other charger.


the blue sea off / on / combine switch would be recommanded for the house and engine bank. and a seperate off / on switch for hte trolling batteries.
Agreed.



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Old 03-03-2013, 01:40 PM
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I'm about to be in the same situation with a new flats boat Friday. Why wouldn't you want the alternator to charge the trolling bank also? Do they make a 3 bank ACR?
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Old 03-03-2013, 01:42 PM
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Originally Posted by Itteldoo View Post
He still needs a 24V charger (or a dual-bank 12V charger with fully "stackable" outputs to form 24V overall) for the Trolling Motor bank, which will NOT be getting recharged via the ACR/VSR, or the other charger.



sounds like he already has a 3 bank though with 2 used to charge the trolling bank, and then 3rd would charge eng and house with acr. as long as it's isolated outputs should be fine. though maybe it's not and he currenlty dissconnects the bank every time at home to charge as 3 12v batteries.
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Old 03-03-2013, 03:11 PM
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Originally Posted by Ricci View Post
I'm about to be in the same situation with a new flats boat Friday. Why wouldn't you want the alternator to charge the trolling bank also?
Because (at least usually) the trolling motor bank is 24V or 36V; while the Starting and House banks are 12V, as is the output from the alternator. There are ways to "kludge" this to feed at least some alternator output to at least part of the trolling motor bank; but they tend to resemble the collected works of Rube Goldberg, and at least most of them are never all that successful.


Do they make a 3 bank ACR?
No; and in this context, it wouldn't help anyway, due to the voltage difference.

However, on twin-engine installations, it is S.O.P. to use two ACRs to feed charge current from both engine alternators to th House bank.



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