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Old 15-04-2017, 03:40   #1
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New Inverter / Charger

I have 8 12v AGMs on order (total Ah wired in parallel is 900) but I have a concern about load balancing, so I plan to cut the Ah is half and wire in parallel 2 sets of 4 batteries wired in series. Thus having 24 volts mated to a 24v inverter / charger.

Question: if I am inverting 24v instead of 12v do I get the Ah cut out by going to 24v in some way? I suppose I just get more watts nut not more watt hours?
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Old 15-04-2017, 04:37   #2
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Re: New Inverter / Charger

I cannot answer question #1.
I don't understand question #2.
But may I add still some comments?

Maybe before you decide on the battery wiring and voltage, consider how you are going to charge the batteries. If your alternator is currently 12 Volt, then you need to change that alternator to one for one made voltage you decided on (if other than 12 Volt). Same for a windgenerator, a change required if go for a voltage other than 12. Yes, windgenerators are available for most voltages. Solarpanels can be arranged or re-arranged easily to a voltage you desire, and many solar controllers play that game too without any fuss.
If you have a genset that provides mains supply ie 110 or 220 Volt, then indeed the charger/inverter can charge the batteries.

Another aspect is that to my knowledge there is very few (?no) nautical equipment made for 48 Volt, only some older commercial equipment for 32 Volt is availble, quite a bit of stuff is made for 24 volt, and the majority is made to work on 12 Volt. So for any voltage higher than 24 Volt you need to get a converter (that transforms a higher DC voltage to a lower one), and that means another small loss of efficiency. And even for 24 Volt, you may need a converter for some stuff. Just think of USB chargers if nothing else.

I would say 24 Volt could be a good option if you have a large windlass, bow thruster, an engine with a 24 Volt system or other high electrical loads.
To me, a voltage of higher than 24 volt only makes sense if one has electric propulsion.

If your inverter/charger is still working, why change that? Maybe if that unit dies, then consider alternatives.

BTW, I have similar setup as you have: 8x120 Amp hr batteries and 3000 Watt inverter/charger on 12 volt.
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Old 15-04-2017, 04:43   #3
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Re: New Inverter / Charger

I just noticed that you have changed that first post, and deleted one question and re-worded the other one. So my post above may not make sense.
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Old 15-04-2017, 04:47   #4
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New Inverter / Charger

Quote:
Originally Posted by HankOnthewater View Post
I just noticed that you have changed that first post, and deleted one question and re-worded the other one. So my post above may not make sense.


Yes. I did change the question but to answer yours I have 24v 1000 watts of solar. Are your batteries parallel, series or combination?
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Old 15-04-2017, 05:55   #5
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Re: New Inverter / Charger

If your inverter is providing 1200W to a 120VAC load, the supply current on the DC side will be approximately 100A at 12VDC or 50A at 24VDC. Total energy stored and delivered will be broadly similar, but amp-hours consumed will obviously be different.
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Old 15-04-2017, 05:58   #6
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Re: New Inverter / Charger

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If your inverter is providing 1200W to a 120VAC load, the supply current on the DC side will be approximately 100A at 12VDC or 50A at 24VDC. Total energy stored and delivered will be broadly similar, but amp-hours consumed will obviously be different.


Precisely!
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Old 15-04-2017, 06:04   #7
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Re: New Inverter / Charger

> I have a concern about load balancing

Care to explain what you understand by "load balancing" and what your concern is?

>
wire in parallel 2 sets of 4 batteries wired in series. Thus having 24 volt

That will give you 48 Volts, not 24 Volts.


> if I am inverting 24v instead of 12v do I get the Ah cut out by going to 24v in some way?

The answer to that question is yes, you get less Ah drawn by the inverter but at higher voltage, so the total power (Watt hours) drawn doesn't change.

>
I suppose I just get more watts nut not more watt hours?

That statement is not just incorrect, it reveal a major lack of understanding of what Watts, Volts and Amps are. It just doesn't make sense at all.

If you have to ask these questions, you need to learn a lot more about DC electrical systems before doing anything with your current setup.


> I have 24v 1000 watts of solar

I assume that you have several nominal "24Volt solar panels", presumably wired in parallel. What sort of charge controller do you have?

Note that "24 Volt solar panels" do not put out 24 Volts. They will generally have a rated/operating voltage of around 36 Volts with an open circuit Voltage of around 45 Volts.

For your information, I have 1000 Ah of 12V AGM batteries in my house bank (plus separate starter batteries for each engine) and 800W of solar, have no problems with "load balancing" and wouldn't consider switching to a 24V system.
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Old 15-04-2017, 06:17   #8
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Re: New Inverter / Charger

Yes, please clarify your reasons for wanting to pay so much more for a 24V system.

How large is your boat?

What do you mean by load balancing? Perhaps some links?
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Old 15-04-2017, 06:19   #9
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Re: New Inverter / Charger

Quote:
Originally Posted by StuM View Post
> I have a concern about load balancing

Care to explain what you understand by "load balancing" and what your concern is?

>
wire in parallel 2 sets of 4 batteries wired in series. Thus having 24 volt

That will give you 48 Volts, not 24 Volts.


> if I am inverting 24v instead of 12v do I get the Ah cut out by going to 24v in some way?

The answer to that question is yes, you get less Ah drawn by the inverter but at higher voltage, so the total power (Watt hours) drawn doesn't change.

>
I suppose I just get more watts nut not more watt hours?

That statement is not just incorrect, it reveal a major lack of understanding of what Watts, Volts and Amps are. It just doesn't make sense at all.

If you have to ask these questions, you need to learn a lot more about DC electrical systems before doing anything with your current setup.


> I have 24v 1000 watts of solar

I assume that you have several nominal "24Volt solar panels", presumably wired in parallel. What sort of charge controller do you have?

Note that "24 Volt solar panels" do not put out 24 Volts. They will generally have a rated/operating voltage of around 36 Volts with an open circuit Voltage of around 45 Volts.

For your information, I have 1000 Ah of 12V AGM batteries in my house bank (plus separate starter batteries for each engine) and 800W of solar, have no problems with "load balancing" and wouldn't consider switching to a 24V system.


I forgot stu, this forum is for !intelligent!questions only. I'll be sure to take some classes before asking next time.
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Old 15-04-2017, 06:45   #10
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Re: New Inverter / Charger

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Originally Posted by john61ct View Post
Yes, please clarify your reasons for wanting to pay so much more for a 24V system.

How large is your boat?

What do you mean by load balancing? Perhaps some links?
https://www.victronenergy.com/upload...alancer-EN.pdf

60'

From the link:

The problem: the service life of an expensive battery bank can be substantially shortened due to state of charge unbalance. One battery with a slightly higher internal leakage current in a 24V or 48V bank of several series/parallel connected batteries will cause
undercharge of that battery and parallel connected batteries, and overcharge of the series connected batteries. Moreover, when new cells or batteries are connected in series, they should all have the same initial state of charge. Small differences will be ironed out during absorption or equalize charging, but large differences will result in damage due to excessive gassing (caused by overcharging) of the batteries with the higher initial state of charge and sulphation (caused by undercharging) of the batteries with the lower initial state of charge.
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Old 15-04-2017, 06:53   #11
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Re: New Inverter / Charger

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Originally Posted by rwells36 View Post
I forgot stu, this forum is for !intelligent!questions only. I'll be sure to take some classes before asking next time.
Don't think he is trying to be insulting, it's just that electrical questions with mixed-up units pop up a lot, and they invite confusing answers as different people will read the question differently.

"If I add a second faucet to the master bath, will it change the number of gallons I use, the rate of water flow, or just the gallons/hour?"

Again, no insult intended, it's just confusing.

W = V * A (unit of power (energy per time))

Whr = W * hrs .. OR .. Ahr * V (unit of energy)

Ahr = A * hrs (not really a "complete" unit, a convenient representation of energy when all voltages are equal)
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Old 15-04-2017, 10:20   #12
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Re: New Inverter / Charger

I have to say guys that I thought the forum idea was for contributors to help each other with advice not insult each other because the level of knowledge varies and hence the logic of a forum for all not just the smart a....s.
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Old 15-04-2017, 10:33   #13
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Re: New Inverter / Charger

Am I wrong or are 4 X 6 volt batteries = 24 volts?
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Old 15-04-2017, 10:44   #14
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Re: New Inverter / Charger

Quote:
Originally Posted by rwells36 View Post
I have 8 12v AGMs on order (total Ah wired in parallel is 900) but I have a concern about load balancing, so I plan to cut the Ah is half and wire in parallel 2 sets of 4 batteries wired in series. Thus having 24 volts mated to a 24v inverter / charger.

Question: if I am inverting 24v instead of 12v do I get the Ah cut out by going to 24v in some way? I suppose I just get more watts nut not more watt hours?
I converted both my house and starter banks to 24V. I went with (2) 8D 12V AGM's in series for the house and (2) group 31 lead acid for the starter. I had to change my alternator, AC/DC inverter, wind generator and starter to 24V. I installed a DC-DC converter so that I have a 12V system for all the electronics, etc.

My bow thruster is 12V so I installed a seperate 12V 8D agm in the sail locker with it's own charger.

Like most systems on your boat, there is no solution that is perfect for everyone, so you need to weight the pluses and minuses and make a decision that works best for you.

Good luck,

Jeff
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Old 15-04-2017, 12:00   #15
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Re: New Inverter / Charger

Quote:
Originally Posted by robbievardon View Post
Am I wrong or are 4 X 6 volt batteries = 24 volts?
Yes if all 4 wired in series.
6V if all 4 in parallel.
12V if 2S2P


Quote:
Originally Posted by rwells36 View Post
That may be a great add-on gadget if you had other strong reasons to go to 24V.

But the problem that "solution" is addressing is IMO not itself such a reason.

This stuff is complex and expensive enough, it is very important also for safety and reliability to stick to the KISS principle.

Especially for beginners.
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