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Old 19-07-2012, 09:19   #16
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Re: Golf cart batteries

BatteriesPlus carrys the Trojan 105 and they have several store in MA. I picked them up on sale for 127.00 and they are normally 137.00
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Old 19-07-2012, 09:38   #17
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Re: Golf cart batteries

FWIW, whether you buy the batteries in "tropical" locations also makes a difference. Apparently they are filled with a different electrolyte when intended for use in hot climates.
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Old 19-07-2012, 13:28   #18
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Re: Golf cart batteries

Quote:
Originally Posted by hellosailor View Post
FWIW, whether you buy the batteries in "tropical" locations also makes a difference. Apparently they are filled with a different electrolyte when intended for use in hot climates.
I had not heard that before. So, google being my sometimes friend, I did some searching. There is not a bunch out there, but found this site which advises:
In the past it was believed that, when batteries were to be used in the tropics, the specific gravity of the electrolyte should be reduced to approximately 1.225.
The battery industry no longer recommends such action. Any advantages which can be related to reducing the specific gravity are more than offset by the problems of
  • (1) electrolyte adjustment,
  • (2) identifying such reduction to all battery service personnel so the batteries are properly charged,
  • (3) greater internal resistance,
  • (4) reduced cell capacity and
  • (5) assuring that the higher gravities are again restored if batteries are reshipped to a cold climate where freezing could be a problem


Do you have any contrary information? It sounds that either way, one needs to keep the issue in mind.
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Old 19-07-2012, 13:36   #19
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Re: Golf cart batteries

"Do you have any contrary information?"
Yes. The contrary information comes form the owner of a battery distributor/exporter in the SE US, who was talking tech with me earlier this year. He may be wrong--but he's got a major distributorship, not just a retail store, and that's how he swears that manufacturer still makes their batteries.
Don't ask me if he's right or wrong, you'd have to ask the battery makers directly.
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Old 19-07-2012, 13:39   #20
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Re: Golf cart batteries

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Originally Posted by Maine Sail View Post
You can buy that same battery at Sam's Club for $88.00 sold under the Duracell label. It is called the EGC2 and is 230 Ah. They also have the GC2 which is 215 Ah's......

Curious battery characteristics
Specifications
  • 20 amp hour rate:230
  • 5 amp hour rate:174
  • 6 amp hour rate:178
  • BCI Group Size:GC2
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Old 19-07-2012, 13:44   #21
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Re: Golf cart batteries

One other suggestion. Try the construction equipment rental places for used batteries. The electric scissor lifts use 6-volt golf cart batteries, and if they have a good maintenance program, they replace them yearly.

I got 4 "Napa 8146" batteries - similar to Trojan T125's. One year old, all cells tested good, and best of all FREE. Even if I only get a few years out of them, I'll gladly take the price!

Be careful to check the batteries well before taking them, they do get used - and abused - in these pieces of equipment, so you want to be sure they still have life in them.
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Old 19-07-2012, 14:59   #22
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Re: Golf cart batteries

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Originally Posted by cuthbert View Post
Curious battery characteristics
Specifications
  • 20 amp hour rate:230
  • 5 amp hour rate:174
  • 6 amp hour rate:178
  • BCI Group Size:GC2

where did you find this as I would like to read it more
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Old 19-07-2012, 15:18   #23
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Re: Golf cart batteries

Sams Club website

Sam's Club
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Old 19-07-2012, 15:43   #24
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Re: Golf cart batteries

Quote:
Originally Posted by cuthbert View Post
Sams Club website

Sam's Club

OK, I wonder where they got it then as it doesn't make much sense to me. Is it true that you get more amp-hours out of a battery at a bigger load?
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Old 19-07-2012, 16:32   #25
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Re: Golf cart batteries

Quote:
Originally Posted by Don Lucas View Post
Is it true that you get more amp-hours out of a battery at a bigger load?
Bigger load (as in, draw more current) = less amp hours

For the numbers posted by Sam's Club (20 hrs = 230A/H) means that if you started at 100% and put a load on it that would run the battery flat in 20 hrs, the current flowing would be 230/20 = 11.5A

And then for the 5 hour rate it is 174/5 = 34.8A

6 hour rate is 178/6 = 29.9A

Just from the curves I'm guesstimating that the definition of battery flat may be changed with discharge rate, a bit like this graph I found out on the internet somewhere (not this specific battery).



It would be nice (for marine purposes) if rather than the industry standard 20Hr rate or 5 or 6Hr traction battery rate, they posted the rates for 50% (12.1-12.6V) discharge over 24hrs and 12hrs.

That 24hr current is the number I'm constantly calculating in my head and switching things off or starting the engine or generator to stay within.
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Old 19-07-2012, 16:36   #26
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Re: Golf cart batteries

cuthbert is correct. The less the load the more amps you'll get in a single discharge cycle. The higher the load the less amps you'll get in a discharge cycle.

The fact that drawing more load faster lessens the total amp output of a battery discharge was first discovered/described by Mr. Peukert. Batteries come with a Peukert number that describes the relation of the battery's rate of discharge to the amount of power it takes to recharge it, or said another way, how the rate of discharge effects what you'll get out of it.

SmartGauge Electronics - Peukert's Equation - what it means to you
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Old 19-07-2012, 16:38   #27
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Re: Golf cart batteries

As a side note for those not overly curious about these sorts of things... Its industry standard to rate the battery by its 20hour amp hour rating. A 220ah battery is a 220ah battery at 20hours. Sometimes shady dealers will try to use a 25hour rate or something beyond 20hour rate to make their batteries look better than they really are.
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Old 19-07-2012, 16:41   #28
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Re: Golf cart batteries

Quote:
Originally Posted by Target9000 View Post
cuthbert is correct. The less the load the more amps you'll get in a single discharge cycle. The higher the load the less amps you'll get in a discharge cycle.
which what I have always thought and why I asked, I think the Cosco chart is trying to confuse us/me ................. which worked!


is it just me or do others get tired of having to think about this stuff?
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Old 19-07-2012, 16:44   #29
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Re: Golf cart batteries

The industry standard for a fully depleted flooded battery is 10.5 volts. This does not vary with load.

The 20-hour rate is the generally used rate for deep-cycle batteries. As noted above, it is measured by applying a resistive load which is 1/20th the rated AH capacity to a fully charged battery. At the end of this period, a healthy battery should show 10.5 volts.

If you reach 10.5 volts in less than 20 hours, the battery's capacity has been reduced. Batteries begin to lose capacity when they leave the factory. If you reach 10.5 volts in, say, 5 hours, your batteries have reached the end of their useful life.

Statements like, "I got seven years out of my batteries" are virtually meaningless because they say nothing about the real residual capacity of the batteries...only that they're not performing as well as the owner thinks they should. Your car battery is "good" -- even with 90% reduced capacity -- right up to that morning when it won't start your car.

It really isn't rocket science! Resting voltages (i.e., no charge or discharge overnite) for flooded batteries will indicate the state-of-charge (SOC) of the battery as follows:

12.6 is 100% charged
12.4 is 75% charged
12.2 is 50% charged
12.0 is 25% charged

AGMs and gels will show slightly higher voltages at each SOC.

If you know your boat well, an accurate digital voltmeter will give you a good enough indication of SOC (e.g., on my boat during the day with the frig running and the VHF and instruments on, I'll see about 0.1V less than the above).

When you see 12.2 volts or less, it's time to charge!

Put as much in as you comfortably can, because ALL batteries -- flooded, AGM, and gel -- will sulfate if not fully charged frequently at voltages above about 14.2.

And, be sure to keep in mind that SOC does not indicate capacity of the battery! After years of use and abuse, a fully charged battery may only have a tiny portion of its original capacity left.

Bill
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Old 19-07-2012, 17:18   #30
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Re: Golf cart batteries

The resting voltage thing just seems worthless overall. I need to believe the SOC while using my systems and before leaving the boat.

My 1 year old 460 AH batteries can start at 12.5 resting voltage and low 90% SOC of charge on my monitor and after 45 AH out at 5-6 amps and with the monitor now saying 80-85% SOC, the voltage with be reading 12V. And it reads the same on the panel volt meter and with a hand held.

So near as I can tell my voltage reading goes down a lot more than0.1 amps under 6 amps load.!

And yes the monitor has been syn'd recently and at the time the charge current had dropped to 2 amps.

PS - I acturally have my monitor programed for a 400 AH bank instead of the 460 AH
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