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Old 26-02-2012, 02:40   #1
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440AH Not Enough ?

We bought a 40ft Challenger not long ago and I replaced the two house batteries with two12v 220AH VRLA Batteries thinking that should be plenty of power. We have about 200W of solar and in the marina a 30A smart charger is keeping the batteries full. We have 2 fridges running most at the time.
First time we went out over night the batteries went down to about 50% capacity and down to about 12.6 Volt.
I really thought 440AH should be plenty of power but maybe not?
What setup do most of you have reg batteries and solars?

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Old 26-02-2012, 03:48   #2
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Re: 440AH Not Enough?

660AH with 370 watts of solar and 12V refrigeration. With full sun I can go a week or more until I'm down to 50%.
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Old 26-02-2012, 05:30   #3
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Re: 440AH Not Enough?

Since 12.6 V is what a fully charged battery should indicate after resting for several hours, I doubt that you were down to 50%.

David
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Old 26-02-2012, 05:39   #4
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Re: 440AH Not Enough?

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Originally Posted by djmarchand View Post
Since 12.6 V is what a fully charged battery should indicate after resting for several hours, I doubt that you were down to 50%.

David
I got a battery monitor and he was showing 50% capacity left in batteries.
So I assume that was what I had left in the batteries. Batteries full show 13.7volt.

Reiner
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Old 26-02-2012, 05:49   #5
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Re: 440AH Not Enough?

Re-set the battery monitor and try again, but as David pointed out I doubt that you used 50%, that's more like 12-12.2V. The 13.7v reading was probably a surface charge from the battery charger which lingers on the batteries for short while after they have been disconnected.



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Old 26-02-2012, 05:57   #6
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Re: 440AH Not Enough?

Hi Reiner,

When your batteries are full, they should read 12.6-12.8V. The 13.7V you see is when the battery is on the charger and the charger is keeping it in float charge mode (although that is a tad high for float). If you take them off the charger and let them rest for a few hours without any loads, they will read ~12.7V.

Battery monitors can be very inaccurate. Even the best of them drift over time and need to be recalibrated periodically. The worst of them are next to useless. If you have not calibrated yours recently, it may not be reading correctly - particularly if your batteries are kept on a charger all the time.

440Ahr should be plenty for a boat that is used for occasional cruising, and even for one that cruises full time. Certainly enough for overnight trips. It all depends on how much power you use and how much you can put back in.

Mark
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Old 26-02-2012, 06:03   #7
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Re: 440AH Not Enough?

Quote:
Originally Posted by reiner View Post
... We have 2 fridges running most at the time ...
Although I agree with the previous posters, I'd note that 2 fridges can be very "spendy" on electricity.
ie: 5 or 6 Amps each x 2 fridges x 16 hours = 160 - 192 Amp/Hrs.
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Old 26-02-2012, 06:08   #8
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Re: 440AH Not Enough?

11 something is low. Report back when you see less than 12V. When the fridge stops that is your clue that you've reached the limit. Battery monitors are a waste of money.
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Old 26-02-2012, 06:09   #9
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Re: 440AH Not Enough?

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Originally Posted by colemj View Post
Hi Reiner,

When your batteries are full, they should read 12.6-12.8V. The 13.7V you see is when the battery is on the charger and the charger is keeping it in float charge mode (although that is a tad high for float). If you take them off the charger and let them rest for a few hours without any loads, they will read ~12.7V.

Battery monitors can be very inaccurate. Even the best of them drift over time and need to be recalibrated periodically. The worst of them are next to useless. If you have not calibrated yours recently, it may not be reading correctly - particularly if your batteries are kept on a charger all the time.

440Ahr should be plenty for a boat that is used for occasional cruising, and even for one that cruises full time. Certainly enough for overnight trips. It all depends on how much power you use and how much you can put back in.

Mark
I got the old batteries still at home and after being disconnected for nearly two weeks now they still show over 13 V.

Reiner
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Old 26-02-2012, 06:35   #10
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Re: 440AH Not Enough?

Then the voltmeter is stuffed, try another one.

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Old 26-02-2012, 16:27   #11
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Re: 440AH Not Enough?

Quote:
Originally Posted by reiner View Post
We bought a 40ft Challenger not long ago and I replaced the two house batteries with two12v 220AH VRLA Batteries thinking that should be plenty of power. We have about 200W of solar and in the marina a 30A smart charger is keeping the batteries full. We have 2 fridges running most at the time.
First time we went out over night the batteries went down to about 50% capacity and down to about 12.6 Volt.
I really thought 440AH should be plenty of power but maybe not?
What setup do most of you have reg batteries and solars?

Thanks
Reiner
I assume these are 8D batteries? They would have to be to have 220 AH each I think.

Was your battery monitor properly set-up so it knows the size of the battery bank?
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Old 26-02-2012, 20:02   #12
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Re: 440AH Not Enough?

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Originally Posted by reiner View Post
I got the old batteries still at home and after being disconnected for nearly two weeks now they still show over 13 V.

Reiner
G'Day Reiner,

I have to agree with Pete7... if those old batteries are showing over 13V on your voltmeter, the voltmeter is incorrect.

FWIW, Insatiable II has about the same AH capacity (4x Trojan T-105's) and 240 watts solar. Has done well by us for many years... we get several days of no sun before we get down to ~ 12.0 which is where I will start thinking about running the engine.

You should check to determine how much each of your fridges draw whilst running, and get some idea of their duty cycle. Armed with this data you can start working out what your daily usage is, and hence, how long your batteries should keep you going without charging. I agree that the battery monitor is most likely not properly calibrated re percentage charge, and quite possibly for voltage measurements as well. Hope that you got the manual for it with the boat!

Good luck,

Jim
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Old 26-02-2012, 20:15   #13
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Re: 440AH Not Enough?

Hey Buddy shut off that second fridge, you are supposed to be roughing it. Unless that is your keggerator, in which case I fully understand.

12.8 to 12.6 is should be your resting voltage ie the voltage you achieve after the batteries come to rest after accepting a charge. Battery monitors can take some messing with.

Don't forget that you upped your battery capacity so your monitor will need to be re calibrated for the larger bank. It thinks it is attached to a 220 Ah battery bank right now.
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Old 27-02-2012, 05:51   #14
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Re: 440AH Not Enough?

Quote:
Originally Posted by Jim Cate View Post
G'Day Reiner,

I have to agree with Pete7... if those old batteries are showing over 13V on your voltmeter, the voltmeter is incorrect.

FWIW, Insatiable II has about the same AH capacity (4x Trojan T-105's) and 240 watts solar. Has done well by us for many years... we get several days of no sun before we get down to ~ 12.0 which is where I will start thinking about running the engine.

You should check to determine how much each of your fridges draw whilst running, and get some idea of their duty cycle. Armed with this data you can start working out what your daily usage is, and hence, how long your batteries should keep you going without charging. I agree that the battery monitor is most likely not properly calibrated re percentage charge, and quite possibly for voltage measurements as well. Hope that you got the manual for it with the boat!

Good luck,

Jim
Thanks Jim, I will buy another multimeter and see what is going on.
I read too that new batteries need too "run in" to hold charge better.
The new ones only had one charge.
By the way I see you down there in Hobart. If you go into the Huon River up to Cygnet you might come across our old H28 Kakahi.
Please say Hi to Ann and take care
Cheers
Reiner
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Old 27-02-2012, 06:28   #15
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Re: 440AH Not Enough?

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Hey Buddy shut off that second fridge, you are supposed to be roughing it. Unless that is your keggerator, in which case I fully understand.

12.8 to 12.6 is should be your resting voltage ie the voltage you achieve after the batteries come to rest after accepting a charge. Battery monitors can take some messing with.

Don't forget that you upped your battery capacity so your monitor will need to be re calibrated for the larger bank. It thinks it is attached to a 220 Ah battery bank right now.
Shut off the second fridge? and where do I keep my ice-cream please?
Yes I did that already . We run both fridges while on shore power but turn one off when we depend on the solar panels.
A friend suggested to see if I got diodes in the solar panels. He seems to think they could help discharging the batteries at night.
The panels are quiet old, maybe that is where the problem is.

Reiner
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