Adding a Third Battery for Ice Maker ?

[SirenSong]

Hello,
I have a 92 Bayliner Sunbridge 2255, 4.3L V6 Alpha One, stock 65A alternator, that currently has 2 batteries, Start & Run. The Run is a new Deep Cycle Exide NG-31, 115Ah, 205rc . This year I added an Ice Maker, Magic Chef MCIM22TW, draws about 4 amps, 200 watts steady, 300 watts when dumping ice, and a stand alone inverter, Whistler Pro 1200W. At full charge the ice maker would run for 1 hour and then the inverter would beep and then stop, indicating low charge, and shut off. I am thinking of adding another deep cycle battery in parallel to keep the unit running longer but have read that the alternator will not be able to charge this bank of 2 parallel batteries. My existing wiring when i had it hooked up was 12 gauge and i planned on getting 4 or 6 gauge for permanent wiring but might have to scrap the whole thing if it's too much of a hastle, the last thing i want is to have to start the engine every half hour just to have ice. Any Advice?
Rob

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

You are going to be drawing close to 20A off a battery to run this thing assuming 200W. No battery is going to last very long doing this.

Your numbers also don't make sense. 4A at 110V is way more than 200 watts. If it really draws 4A at 110V, that's 440 watts.

Its no wonder your inverter is squaking. You are discharging the battery by more than half over an hour's use!

 

[UncleWillie]

Re: Adding a Third Battery for Ice Maker ?

Agree with Bruce!

You have 2 batteries Run/Start, and a House Battery.

I would recommend only running the Ice Maker when the engine is running.
Two batteries in parallel will be just fine as far as the charging goes.

The problem is, after an hour or so, the batteries are going to need 4 to 6 hours of the alternators attention to recharge them, Unless recharging them on shore power is your intention.
In which case the alternator is a minor consideration.

Using battery power for heating or cooling is seldom practical.

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

the last thing i want is to have to start the engine every half hour just to have ice. Any Advice?

Way cheaper to buy ice!

 

[SirenSong]

Re: Adding a Third Battery for Ice Maker ?

OK, i can't be the only guy who wants an onboard ice maker, how does anyone else do this?

I am looking for a solution not anecdotal quips.

I am out for 7-10 days at a time, no shore power, no ice store.

 

[Bondo]

Re: Adding a Third Battery for Ice Maker ?

OK, i can't be the only guy who wants an onboard ice maker, how does anyone else do this?

I am looking for a solution not anecdotal quips.

I am out for 7-10 days at a time, no shore power, no ice store.

Ayuh,.... Welcome Aboard,... Make yer ice, while the motor's runnin',.....

 

[Silvertip]

Re: Adding a Third Battery for Ice Maker ?

Install a 120V alternator on the engine. Make ice underway.

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

OK, i can't be the only guy who wants an onboard ice maker, how does anyone else do this?

Generator that runs when ever the ice maker runs or bring enough ice for 7 days.

Its not going to happen with the way you want to do it with a battery and an inverter.

 

[pikefisherman]

Re: Adding a Third Battery for Ice Maker ?

Thought about a Yeti brand cooler?

 

[sam am I]

Re: Adding a Third Battery for Ice Maker ?

Best to use a 24VDC to 120VAC inverter.

Sry for the math here but it's in my blood......... Example 120VAC 300 Watt(output) @ 12VDC at say 80% efficiency (typical)

Ohms law states V=I*R and P=I*V

where

Resistance(R)
Power(P)
Voltage(V)
Current(I)
Efficiency(e)

So if.......P out = P In and the device is 80% power efficient(e) , nobody is perfect!!

then we have to say P out = P in * .8

and you say your output is using/needing around 300 watts, then

P out/.8 = P in or 300/.8 = 375 watts.

Since we're using 12VDC inverter and needing 375 input watts to create 300 output watts and

P = I*V then P/V = I or 375/12 = 31.25 Amps DC.

We know we have/use certain Amps/hr batts. i.e. 500 Amp/hr (50/60% of Vout full)batt. then 500amp/hr/31.25amps, amps cancel and we have approx. 16 hrs of run time (approx. down to 7.2VDC w motor off). (500/31.25 = 16)

For a 24VDC inverter, same output requirements, same efficiency, same amp hr batt (two in series), same math, BUT.......

375/24 = 15.625 amp and

500/15.625 = 32 hrs of approx. run time (twice the hrs)........just love living the lies in the linear world.

I think the one I have is 92% efficient @ 24VDC type. Cost more but do the math, it is worth it depending on situations of course....Oh btw, efficiency typically will go down as the input voltage goes down........damn engineers anyway!!

I added/mounted a belt driven 24VDC truck alternator (diesel big rig), maybe was 50/60 amps, not sure, to my motor. Bought/had two 12VDC Deep cycle batts, put them in series, ran the remote sense from the alt. (3rd wire typically) down the the batts pos. lug (had like 4ft of wire and didn't want any wire loss, sorta critical for proper charging eh?)

As a bonus and when designed properly...you won't exceed the alt's amp output max. value (15/16 amp lets say), your alt voltage won't be sagging and will stay above the batt. cell voltage.......i.e., when you need to charge up, it will be fully charging (30 amps initial charging let says) properly at the same time you're running the ice maker........JOY!!

Oh and, your system/boat ground will be at the most negative post of the two batteries, you can use the pos. term of THAT batt. for anything 12VDC on the boat AND/OR if the device is isolated (say a plug in phone charger etc) you can use the other battery (center tap the two series batteries) for more even more 12VDC needs.......the options abound!!!

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

We know we have/use certain Amps/hr batts. i.e. 500 Amp/hr (50/60% of Vout full)batt. then 500amp/hr/31.25amps, amps cancel and we have approx. 16 hrs of run time (approx. down to 7.2VDC w motor off). (500/31.25 = 16)

Show me a 500 Amp hour 12V battery please!!

You also never run a deep discharge battery down past 12.0V which is 50% unless you want to damage your battery.

By the way, 2 12V batteries in series or 2 12V batteries in parallel will have approximately the same amount of runtime. It would be a little less because of efficiency but it won't be double.

 

[sam am I]

Re: Adding a Third Battery for Ice Maker ?

Just approx. examples for concept man, just examples. and okay......5 12VDC 100amp/hr batts in parallel is a 12 VDC 500amp/hr batt.


And no, two 12 batts. in parallel will provide twice the run time with the same fixed discharge rate as opposed to two of the same batts. in series. You double the capacity in parallel or double the voltage in series........the power always stays fixed, .

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

And no, two 12 batts. in parallel will provide twice the run time with the same fixed discharge rate as opposed to two of the same batts. in series. You double the capacity in parallel or double the voltage in series........the power always stays fixed, .

Yep...power will stay fixed. That is why run time remains same.

You are really recommending him to go with 5 batteries? You do realize that your example of 24V 500 Amp hour would require 10 100 AH 12V batteries right? :facepalm:

 

[sam am I]

Re: Adding a Third Battery for Ice Maker ?

It was an example dude, he can use 200amp/hr, 100amp/hr IDK, its up to him.


Here, be enlightened

Connecting Batteries in Series or Parallel

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

I am an electrical engineer. I think I understand.

 

[sam am I]

Re: Adding a Third Battery for Ice Maker ?

Hmmmm

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

If the OP wants to go with a 130 AH 12V battery, this is what he will need to get, although he already has one 115 AH battery.

Trojan SCS225 12V 130Ah Flooded Battery

Around $240/ea including shipping.

One of these will run the icemaker around 1 1/2 hours before it gets down to 50% using his 4A 110V number.

 

[dingbat]

Re: Adding a Third Battery for Ice Maker ?

An Icy-tek cooler and dry ice would be easier and more cost effective

 

[sam am I]

Re: Adding a Third Battery for Ice Maker ?

Orrrrrrrrrr,



As OP KNOWS, he can increase his run time by paralleling batteries.......

At any rate, another design comes to mind where a delay/s can be used to limit the inrush/s (help reduce the initial load currents your alt see by delaying time) of things coming online by sequence them in over time. A second or third or....... battery can be connected in parallel each having it's own time delay. Each has adjustable time delays that upon starting the engine will sequence subsequent batteries into the parallel circuit.

If you were to view a inrush graph/plot of a discharged battery charging, the current (inrush) spikes high in the beginning where the voltage from the alternated exceeds the given lowered cell voltages, over time (say as an EXAMPLE), the battery will initially draws say 100 amps for like a few minutes then begin to taper down to say (for EXAMPLE) 10 amps and slowly over time tapers down to 1 or 2 amps.

Your alt can do approx. 65 amps, so say after (for example) 5 minutes of a set delay of allowing the firsr batt's inrush current to subside, switch in the second batt in parallel, then a third after 5 aditional mins, etc, etc.

Basically this is what you do when you use a Off, Batt 1, Batt 2, Both Switch. If after you start your boat, you switch from say Batt 1 to Both, you,ve just paralleled the batt 2 with the batt 1.

This mearly automates the process with time delay contractors that you can set from say (for EXAMPLE) 2 sec - 2 hrs.

 

[bruceb58]

Re: Adding a Third Battery for Ice Maker ?

Orrrrrrrr,

the OP can install a nuclear reactor. He can heat his coffee that way too! :faint2: