[Rhodes22-list] Batteries

Tue Jan 31 23:03:44 EST 2006

Bob,

Yes, this makes perfect sense, and it is easy to understand why it would 
drain the batteries. 

I don't have an autopilot installed yet (I bought it 2 or 3 years ago, 
but haven't gotten around to installing...) but I would guess that it is 
the big factor. 

The notion of "Amp Hours" works fine if you're not really using your 
batteries all that much, but it's a distortion in your case.  I'll try 
to find something on it, but the underlying information is this:

Let's say your batteries each are rated at 125 amp hours, for a total 
(you would think) of 250 amp hours of use.  If all you attached to the 
batteries was one of my LED lights, which I will say has a rating of one 
amp-hour, you would expect that light to burn for 250 hours before the 
batteries were both "dead" as you used that term in your original posting.

In fact, that light might actually burn continuously for over 1000 
hours, and after the batteries seemed "dead" they might subsequently be 
able to light the light some more without ever being externally recharged.

On the other hand, if you put your 2 batteries into your car on a cold 
day and cranked your starter motor which we will say has a draw of 25 
amps per hour, you would expect that starter motor to be able to crank 
for 10 solid hours before the batteries were "dead".  But it won't.  
Chances are the batteries will be really "dead" in less than an hour.

The available power in the battery varies with the speed it is pulled 
out of the battery bank, and so is the ability of the batteries to 
regenerate.

The e-meters will tell you how much time you have left in the battery at 
varying rates of discharge which it learns over time as you charge and 
discharge the batteries, and as they age.

You may initially set it for 250 amp hours, and over time it will tell 
you that even fully charged, those batteries have less power that they 
did when new, and exactly how much power remains available at all times.

It is interesting stuff to learn, and, in your case, probably would have 
told you to replace your batteries after 3 years, whereas mine, which 
withstood only a gradual draw, were perfectly adequate for 6 years.

With regard to identical batteries, in your case I would surely 
recommend it, while in mine it makes little difference.  I doubt the 
super sizing will make much difference at all.  They will still need 
replacement after 3 years, and during that 3 year period they will 
probably never flat line, even with the standard batteries.

The meter is the trick.  If you know what's happening inside those 
batteries you'll never be surprised, and you won't have to oversize in 
the hope it will make a difference.  What you will save in more 
expensive batteries and peace of mind will offset the (high) cost of the 
meter.  It is easy to set up.

Bill Effros

Bob Keller wrote:

> The batteries are 4 years old so they have to be replaced. They are 
> standard Interstate group 27 batteries which I will super-size to a 29 
> or 31 when I replace them in March.  An important point with batteries 
> connected in parallel as mine are is that I make sure the batteries 
> are identical in size and replace them at the same time.
>
> Mine are not actually dead now, but they don't hold a charge and will 
> run out after several hours of sailing using autopilot, stereo, depth 
> finder, knotmeter & wind instrument.  Can you believe that would drain 
> the batteries?
> Bob K
>
>
>> From: Bill Effros <bill at effros.com>
>> Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>> To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>> Subject: [Rhodes22-list] Batteries
>> Date: Mon, 30 Jan 2006 21:32:36 -0500
>>
>> Bob,
>>
>> How did you manage to do this?  Was one of the batteries damaged?  
>> Did you fail to add water to wet cells?  Wet cells?  Gel?  AGM?
>>
>> Link 10. -- Now Xantrex e-meter and this will never happen.  No 
>> excuse for it.
>>
>> I have 2 batteries connected, no switch, solar, elec start motor -- I 
>> have never, ever, needed a shore power charge, my batteries last for 
>> 6 years, I leave them in the boat summer and winter...been down this 
>> road before.
>>
>> KISS with a meter -- the meter tells you of a problem coming 6 months 
>> before it happens --BTW, just to add fuel to another fire, I don't 
>> replace both batteries at the same time, I mix types, (one is AGM, 
>> one is Wet) I prefer wet cells all round -- I know what the magazines 
>> and west adviser say, I know the science behind it, but I'm a curious 
>> guy so I try it out in my boat when it's not critical and what I find 
>> is that on our boats with their minimal power needs it's really tough 
>> to drain well maintained batteries.
>>
>> How did you do it?
>>
>> Bill Effros
>>
>> Bob Keller wrote:
>>
>>> I paid (overpaid?) someone to run cables from my electric start 
>>> motor to the battery under the port settee.  Then we connected both 
>>> batteries together and so now I charge both batteries with the 
>>> motor, and two solar panels and even have an electric charger on 
>>> board if needed.  Guess what?  My batteries are currently dead...
>>>
>>> Anyway, I vote with Chris who used jumper cables.  The cables in my 
>>> boat are big-but I don't know the size.  Lots of useful information 
>>> here, isn't there?
>>> Bob K
>>>
>>>
>>>> From: Michel Meltzer <mjm at michaelmeltzer.com>
>>>> Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>>>> To: 'The Rhodes 22 mail list' <rhodes22-list at rhodes22.org>
>>>> Subject: RE: [Rhodes22-list] 12 volt wire gauge from OB to Cabin 
>>>> (10'maxassumed)
>>>> Date: Sun, 29 Jan 2006 13:33:35 -0500
>>>>
>>>> Been their before on the sizing, IIRC my run from the front(under the
>>>> step) to the mount lungs was 16 feet each way(32 total) and the motor
>>>> had #8 wire leads for 8 feet each way(meant to go on the battery) for
>>>> another 16 feet worth, it a good trip,, because the batty is far away
>>>> the voltage regulator also gets effected on charging(i.e. the voltage
>>>> drop), after everything was said and done, #4 came out right and I 
>>>> used
>>>> #2 just to improve performance and all but handle a dead short. NOW #2
>>>> could be a PITA for getting it passed the bulkhead but I did not have
>>>> that issue. Using the breaker is just cheap insurance.
>>>>
>>>> -MJM
>>>>
>>>> > -----Original Message-----
>>>> > From: rhodes22-list-bounces at rhodes22.org [mailto:rhodes22-list-
>>>> > bounces at rhodes22.org] On Behalf Of R22RumRunner at aol.com
>>>> > Sent: Sunday, January 29, 2006 12:47 PM
>>>> > To: rhodes22-list at rhodes22.org
>>>> > Subject: Re: [Rhodes22-list] 12 volt wire gauge from OB to Cabin 
>>>> (10'
>>>> > maxassumed)
>>>> >
>>>> > Bill,
>>>> > Not necessarily true. Having to large a wire makes for difficult
>>>> handling,
>>>> > but also is a waste of money. Sizing the wire to the required 
>>>> project
>>>> is
>>>> > always
>>>> >  the best way to go.
>>>> >
>>>> > Rummy
>>>> > __________________________________________________
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>>>
>>>
>>>
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