Author Topic: Batteries in a Harris style mobile bank  (Read 6598 times)

Offline jeepster

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Batteries in a Harris style mobile bank
« on: December 03, 2016, 10:44:34 AM »
OK I would like opinions and actual real life experiances.

I am buying the parts to finally build my Harris battery bank. The problem is the cost for GC2 batteries.

What are the advantages/disadvantages of using marine batteries in a mobile application?

Yes I have listened to the shows and bought the videos from Mr. Harris.

Offline jerseyboy

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Re: Batteries in a Harris style mobile bank
« Reply #1 on: December 03, 2016, 05:06:15 PM »
The GC2 batteries are deep cycle batteries and are 6 volt 210 amp-hour batteries and weigh almost 70lbs a piece. Two of them make 210 amp-hours at 12 volts. That is ~140 pounds of lead and sulfuric acid.  I was able to get a 125 amp-hour 12 volt AGM battery that was about $125 dollars on sale at batteries plus because they couldn't sell them. Two of these would be around 250 amp-hours and they weigh about 80lbs a piece. Either way you are set back between $250-370 dollars. My deal was after chatting up the manager. He said they keep some in back for solar installations and was not on the shelf.

Deep cycle batteries have less damage during discharge due to thicker lead plates. Do not buy car batteries add they have more plates which are thinner for higher amps during start up.

Jerseyboy

Offline fritz_monroe

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Re: Batteries in a Harris style mobile bank
« Reply #2 on: December 03, 2016, 06:16:52 PM »
Exactly right.  With the GC2, you are paying for the thick lead plates and the ability for deeper discharge without damage.

Offline Alan Georges

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Re: Batteries in a Harris style mobile bank
« Reply #3 on: December 03, 2016, 06:20:00 PM »
Deep cycle batteries have less damage during discharge due to thicker lead plates. Do not buy car batteries add they have more plates which are thinner for higher amps during start up.
This^^^, and watch out for the "dual use cranking/deep cycle" stuff.  A lot of marine batteries are dual-use (which you don't want), and some are pure deep cycle which is what you want.  It is not always clear from the labeling and packaging which is which, and the folks down at the big box store sure as hell haven't got a clue, so do your homework before you buy.

Group 24 12v batteries weigh in at about 45 lbs each but are only 65 amp-hours, so 2x = 130 AH but weigh in at 90 lbs.  Compare to 2x GC2 = 210 AH and 140 lbs.  The lighter weight may or may not be worth the lower capacity; your call.  Group 27 12v batteries more or less split the difference.

A pair of GC2's would be a beast to move around by hand, but they're going to generally be tougher, longer lasting, and more forgiving than a comparable bank of 12v batteries.

A pair of 6v GC2's must remain paired to give 12v, but a pair of 12v deep cycle batteries can be split into two power systems, should that need ever arise.

Or depending upon your needs, you may be able to get by with 1x 12v deep cycle battery.  If you're just running a few lights, a small TV, and recharging cell phones, that may be an option.

Offline CountryRootsCityJob

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Re: Batteries in a Harris style mobile bank
« Reply #4 on: December 04, 2016, 05:54:11 AM »
Good info!
 :popcorn:

Offline Carl

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Re: Batteries in a Harris style mobile bank
« Reply #5 on: December 04, 2016, 06:28:49 AM »
A better question is What do you plan to run with the battery bank?
People often buy big batteries that they don't use and when used or not they will die within a few years.
An average auto will run an inverter at 2000 watt surge with 500 watt continuous while the motor idles
for over 2 hours a gallon of fuel per hour for 4 cylinder and 1 & 1/2 gallon/hour for V8 ...often cheaper
on fuel than most generators.

The GC2 batteries are sturdier for more frequent use though I have found floor sweeper and polisher batteries
at lower cost and capable as they too are deep cycle.Batteries have a limited lifespan,it pays not to over buy.

Offline Montag 451

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Re: Batteries in a Harris style mobile bank
« Reply #6 on: December 04, 2016, 06:24:43 PM »
I went with golf cart batteries for my small setup.
The low maintenance of the AGM battery was attractive,
but also more $$  Also my bank is stationary, so I wasn't worried about portability.
My 2 GC-2's were about $100.00 ea.
If you are using in a mobile application, get a lifting strap,
is cheap,  and sure makes them easier/safer to move.
I have one something like this:
https://www.amazon.com/EZGO-609628-Battery-Lifting-Strap/dp/B00699WCUM
Going to use mine to run my exterior lighting at night, and timer charge
the batteries durring the daylight hours, if I ever get the spare time to rewire the lights..... :P

Offline Carl

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Re: Batteries in a Harris style mobile bank
« Reply #7 on: December 04, 2016, 06:51:25 PM »
So with 2 GC2 batteries you get about 100 watts per hour for lighting for a 10 to 12 hour night.
That is good for about 10 of the 60 watt equivalent LED or Compact fluorescent lights.
Good for a tennis court size area.That will be a nice setup.
Do your lights add up to more than 100 watts all together?

Offline Montag 451

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Re: Batteries in a Harris style mobile bank
« Reply #8 on: December 11, 2016, 11:51:47 AM »
I currently run 3 - 60 watt equivalent cfl's on dusk/dawn switches. Think that's 39 watts if I remember it right.
Will eventually go to LED, but have several extra floodlight cfl's sitting around.
Come to think of it, that's likely to last me many years, lol. Since converting all my bulbs to cfl/led,
I can't remember the last time I had to change a burned out bulb ;D
A few years ago it seemed like I was changing bad bulbs every week, lol.



Offline Carl

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Re: Batteries in a Harris style mobile bank
« Reply #9 on: December 11, 2016, 01:26:48 PM »
The power required is little different from CFL and LED for same light output so I am not in any rush to change just yet.

Offline alan123

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Re: Batteries in a Harris style mobile bank
« Reply #10 on: December 11, 2016, 04:22:20 PM »
When they are saying 210 Amp hours, is that until totally drained? What do you want to stay above for long life of battery? 50%? that would be 105x12v=1260 watts. So I can use 100 watts an hour for 12 hours? Will an inverter cut off drawing power before the battery gets too low?

Offline Alan Georges

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Re: Batteries in a Harris style mobile bank
« Reply #11 on: December 11, 2016, 04:33:25 PM »
When they are saying 210 Amp hours, is that until totally drained?
Yes.  With the small caveat that at higher current rates, this total AH number drops about ~20%.

Quote
What do you want to stay above for long life of battery? 50%? that would be 105x12v=1260 watts. So I can use 100 watts an hour for 12 hours?
Yes, largely.  You can get away with completely discharging a deep cycle battery a few times, and I would not hesitate to do so in an emergency.  OTOH, batteries are happiest when the don't go below 75% or so on a regular basis.

Quote
Will an inverter cut off drawing power before the battery gets too low?
Depends on the inverter, but probably not.  Most of the $20–$150 modified sine wave inverters out there don't have this feature.  If one does, it'll say so proudly in the advertising.

Offline Carl

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Re: Batteries in a Harris style mobile bank
« Reply #12 on: December 11, 2016, 06:05:08 PM »
I suggest getting an inverter at least 4 times larger than your planned load or it may automatically shut down when you need it most as inverters are often over-rated for output and we try not to let the smpke out.

Offline Alan Georges

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Re: Batteries in a Harris style mobile bank
« Reply #13 on: December 11, 2016, 06:28:06 PM »
I suggest getting an inverter at least 4 times larger than your planned load or ...
Good point to remind us of, Carl.  And in addition to inverters being over-rated, starting currents for refrigerator motors and such easily take this kind of excess capacity, and maybe even a bit more.

For example, in actual-real-world-testing with a a Kill-A-Watt meter on the Maytag in my kitchen, it draws a steady 240w.  However, a Cobra 800w inverter wouldn't get it to budge.  With a 1500w inverter, all is sunshine and roses – and once started, the meter on the front of the inverter drops back to reading 240w.

Offline BLACK SHIRT

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Re: Batteries in a Harris style mobile bank
« Reply #14 on: December 11, 2016, 06:40:36 PM »
So your saying you can't run a refrigerator with a 800 watt inverter?

Offline Carl

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Re: Batteries in a Harris style mobile bank
« Reply #15 on: December 11, 2016, 06:41:59 PM »
Even CFL lamps require a pretty good surge of power to start as the gas must have a filament to get the light started.

Offline Carl

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Re: Batteries in a Harris style mobile bank
« Reply #16 on: December 11, 2016, 06:45:09 PM »
So your saying you can't run a refrigerator with a 800 watt inverter?

Often not,a lot depends on the design of the fridge...my 140 watt running fridge refused to start with a 1350 generator...that actually only provides HALF the total output on one plug (675 watts would not start it) The compressor takes a good bit of power to start and then runs on much less.

Only way to be sure is to try it. Keep wire from inverter to battery HEAVY and SHORT.

Offline BLACK SHIRT

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Re: Batteries in a Harris style mobile bank
« Reply #17 on: December 11, 2016, 07:05:31 PM »
Often not,a lot depends on the design of the fridge...my 140 watt running fridge refused to start with a 1350 generator...that actually only provides HALF the total output on one plug (675 watts would not start it) The compressor takes a good bit of power to start and then runs on much less.

Only way to be sure is to try it. Keep wire from inverter to battery HEAVY and SHORT.

Great info, Thank You

Offline Carl

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Re: Batteries in a Harris style mobile bank
« Reply #18 on: December 11, 2016, 07:19:40 PM »
Great info, Thank You

You did show me something on the paranoia thread, too many people worry too much.


If you have an 800 watt,try it ,as some will work...it depends a lot on the extra surge capacitors built in...don't go cheap on a device you may depend on.
Bigger inverters do not cost you much extra $$$ for the benefit of internal design. I use XANTREX 1600 with 3200 start burst...this is overkill but I already had them and they use no more power than a smaller inverter that gets heat frustration while running long duration.

Offline Black November

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Re: Batteries in a Harris style mobile bank
« Reply #19 on: December 15, 2016, 03:27:48 PM »
I have real world experience using Trojan T105s. I am very happy with them, and have used them for over 2 years now.

https://youtu.be/zUhncTX38oA

I also use a 2500 watt inverter. Even that trips on rare occasion with large power tools.