Silly question about charging marine batteries

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sleepnosleep
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Silly question about charging marine batteries

Post by sleepnosleep » Wed Jul 29, 2015 10:53 pm

Sorry for the silly post... I'm planning to run four marine batteries with decent AH, one for a box cooler, and three for LEDS (shade structure, kitchen, yurt). We're bringing a couple Honda 2000s, so I have charging capabilities, but have no clue how to do this. Can someone point me in the right right direction? I know I could just run stuff off the generators, but would prefer to be a good neighbor. Any help would be much appreciated!

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Popeye
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Re: Silly question about charging marine batteries

Post by Popeye » Thu Jul 30, 2015 2:45 am

Four batteries are probably overkill but I'll assume you know what your load is and figure on depleting a charged battery in 24 hours. If this is the case buy two inexpensive name brand battery chargers from Sears, NAPA, etc. Make sure they have an "automatic" setting. Every morning, when you get up put two on charge by connecting the alligator clips on the charger to the battery terminal, Red to + (Positive) and Black - (negative). When you come back for lunch put the other two on charge.
You might want to charge the battery for the bucket cooler at lunch time :wink:
Whatever you do, do NOT try to charge the batterys from the unregulated DC output on the generators. You will overheat and damage the battery.

Unless you have an awful lot of lights two batterys and one charger is probably enough.
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Token
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Re: Silly question about charging marine batteries

Post by Token » Thu Jul 30, 2015 7:51 am

Ulisse wrote:
Unless you have an awful lot of lights two batterys and one charger is probably enough.
Here at BM Playa we don't leave anything to chance. We double up on everything.

Ignore the good intentioned Ulisse and bring everything ;)

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Re: Silly question about charging marine batteries

Post by FIGJAM » Thu Jul 30, 2015 8:16 am

Are you going to be moving these batteries around or will they stay put once you unload?

Will the batteries be all together or scattered?

If they are together, you can easily create a battery bank by connecting all the positives with one wire, and all the negatives with another wire.

This will keep the batteries "balanced" discharging equally.

When charging, put the positive clamp from the charger on the first battery and the negative clamp on the last battery.

This will balance the charge to ALL the batteries at the same time. 8)
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Re: Silly question about charging marine batteries

Post by Popeye » Thu Jul 30, 2015 8:20 am

:D :D :D
Image
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Token
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Re: Silly question about charging marine batteries

Post by Token » Thu Jul 30, 2015 11:23 am

Now if only we can take all the sound reduction stuff off it and slap in an afterburner!

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Re: Silly question about charging marine batteries

Post by maladroit » Thu Jul 30, 2015 11:36 am

It'll win the land speed record for a generator.

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Re: Silly question about charging marine batteries

Post by Just_Joe » Thu Jul 30, 2015 12:15 pm

FIGJAM wrote: When charging, put the positive clamp from the charger on the first battery and the negative clamp on the last battery.

This will balance the charge to ALL the batteries at the same time. 8)
And just to keep it silly, assuming we're using a smart charger, can we DOUBLE (or triple, quadruple) the initial amount of charge current?

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Re: Silly question about charging marine batteries

Post by Molotov » Thu Jul 30, 2015 12:51 pm

maladroit wrote:It'll win the land speed record for a generator.
Until somebody pitches one of those nasty-ass Harbor Freight gensets from an airplane at 1000 feet.

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Re: Silly question about charging marine batteries

Post by maladroit » Thu Jul 30, 2015 12:58 pm

The_Sheik wrote:
maladroit wrote:It'll win the land speed record for a generator.
Until somebody pitches one of those nasty-ass Harbor Freight gensets from an airplane at 1000 feet.
New prank: buy cheap generator. Place in victim's camp, start it up and run away laughing.

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Re: Silly question about charging marine batteries

Post by FIGJAM » Thu Jul 30, 2015 3:04 pm

Just_Joe wrote:
FIGJAM wrote: When charging, put the positive clamp from the charger on the first battery and the negative clamp on the last battery.

This will balance the charge to ALL the batteries at the same time. 8)
And just to keep it silly, assuming we're using a smart charger, can we DOUBLE (or triple, quadruple) the initial amount of charge current?
Not sure what you mean by silly?

Research showed that RV battery banks with the charging system hooked to just the first battery was causing the system to detect when the first was fully charged, leaving the last in a slight undercharged state.

This caused the batteries to "go bad" one at a time and with a shorter life span.

The way I described keeps them balanced and with a longer life span as the healthiest state for the battery is fully charged. 8)
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Re: Silly question about charging marine batteries

Post by maladroit » Thu Jul 30, 2015 3:09 pm

FIGJAM is referring to the slight voltage drops caused by wire and connections between the batteries. If you wire from opposing ends of a parallel array, then every battery should see the same voltage.

Incidentally, this also works for LED strips. If you find that there's a visible dropoff in brightness along the length of a strip, you can apply the positive to one end of the strip and the negative to the other. This will even out the voltage drop in the wiring across the whole system (every LED has the same total amount of wire in between it and the power source).

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Re: Silly question about charging marine batteries

Post by FIGJAM » Thu Jul 30, 2015 3:21 pm

Hard to believe there would be a drop with the batteries that close together.

People were confused why the batteries were failing at different rates when they were bought and installed at the same time.

That must be it. 8)
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Re: Silly question about charging marine batteries

Post by sleepnosleep » Thu Jul 30, 2015 4:47 pm

Ulisse wrote:Four batteries are probably overkill but I'll assume you know what your load is and figure on depleting a charged battery in 24 hours. If this is the case buy two inexpensive name brand battery chargers from Sears, NAPA, etc. Make sure they have an "automatic" setting. Every morning, when you get up put two on charge by connecting the alligator clips on the charger to the battery terminal, Red to + (Positive) and Black - (negative). When you come back for lunch put the other two on charge.
You might want to charge the battery for the bucket cooler at lunch time :wink:
Whatever you do, do NOT try to charge the batterys from the unregulated DC output on the generators. You will overheat and damage the battery.

Unless you have an awful lot of lights two batterys and one charger is probably enough.
To be clear, do I need a separate charger? All I have are the Honda generators... Do I connect straight to those? If something separate, any recommendations?

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Re: Silly question about charging marine batteries

Post by maladroit » Thu Jul 30, 2015 5:10 pm

FIGJAM wrote:Hard to believe there would be a drop with the batteries that close together.

People were confused why the batteries were failing at different rates when they were bought and installed at the same time.

That must be it. 8)
Most people don't realize just how high the currents can be to their inverters, and they don't realize how big the voltage drop can be at high amperages with thick (yet still undersized) cables.

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Re: Silly question about charging marine batteries

Post by mooserider » Thu Jul 30, 2015 5:27 pm

maladroit wrote:
FIGJAM wrote:Hard to believe there would be a drop with the batteries that close together.

People were confused why the batteries were failing at different rates when they were bought and installed at the same time.

That must be it. 8)
Most people don't realize just how high the currents can be to their inverters, and they don't realize how big the voltage drop can be at high amperages with thick (yet still undersized) cables.
Especially if the cable terminals are corroded to any extent. I was really complaining to my RV manufacturer about why the generator wouldn't start or run unless the main engine was running. It turned out that the coach battery cable terminals were so corroded, trying to start the generator dropped the voltage at the generator starter solenoid to only 9 volts (from a 12 volt system), and that wasn't enough to run the starter. A hour with a wrench and a wire brush solved the problem.

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Re: Silly question about charging marine batteries

Post by FIGJAM » Thu Jul 30, 2015 5:30 pm

Use the sealer on them once they're clean and reconnected.

Air is what promotes corrosion.
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Re: Silly question about charging marine batteries

Post by Popeye » Thu Jul 30, 2015 10:59 pm

sleepnosleep wrote:
Ulisse wrote:Four batteries are probably overkill but I'll assume you know what your load is and figure on depleting a charged battery in 24 hours. If this is the case buy two inexpensive name brand battery chargers from Sears, NAPA, etc. Make sure they have an "automatic" setting. Every morning, when you get up put two on charge by connecting the alligator clips on the charger to the battery terminal, Red to + (Positive) and Black - (negative). When you come back for lunch put the other two on charge.
You might want to charge the battery for the bucket cooler at lunch time :wink:
Whatever you do, do NOT try to charge the batterys from the unregulated DC output on the generators. You will overheat and damage the battery.

Unless you have an awful lot of lights two batterys and one charger is probably enough.
To be clear, do I need a separate charger? All I have are the Honda generators... Do I connect straight to those? If something separate, any recommendations?
Yes, you need a separate charger. The DC output from the generator is unregulated (and weak) and will overheat and kill the batterys. You need a regulated output battery charger that will decrease the current to the battery as it charges. There is a lot of Chinese junk out there, go to Sears or NAPA or someone else that sells automotive equipment.
Something like this will work although I think I paid about $30.00 for mine.
http://www.napaonline.com/Catalog/Catal ... 0006389653
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Re: Silly question about charging marine batteries

Post by SageV » Fri Jul 31, 2015 3:01 pm

Just to throw another twist on the recommendations, I do tend to bring twice the battery I need because I only deplete the batteries half-way, I have a cutoff switch that cuts power when they get to 50%. Not depleting them below 50% greatly increases the life of the battery. Also, I sometimes do pairs of 6V batteries in a series to make a 12V and then wire those together in parallel. That gives you more capacity and allows you to use golf cart batteries, which tend to be readily available and tolerate more deep cycles than an average lead acid or marine battery. Don't let anyone tell you that golf cart batteries or certain marine batteries are magic though, I've actually found forklift batteries have more cycles in them. It's just a matter of your budget, if you don't draw out the amps from a lead acid too fast or past 50%, they will last a long time too.

I have MILSPEC solar panels to keep them topped off, there's a lot of solar radiation in black rock, it works pretty good. The defense department specs insist that the panels still produce 90% power when occluded by dust, so they are pretty good for the playa since you can never get panels completely clean. Still, solar charging is slow so I usually come on the playa with the capacity I'll need for the week.

Cabelas has some excellent "smart" charge regulators intended for boat use that can be often found in the discount cave...not sure why just that people tend to return charge regulators I guess. I usually have one of those on my rig because I can often steal a charge from someone else's generator with an smile, a pretty please, and an extension cord.
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Re: Silly question about charging marine batteries

Post by NoAngel » Sat Aug 01, 2015 8:21 pm

You don't need separate chargers but the rule of thumb is that the charger needs to be around 1/3 of the amperage rating of the total size of the battery bank. Assuming you have 4 group 27 batteries run parallel you're looking at a bank size around 320 amps. That means that the charger needs to be somewhere around 100 amps. You might want to break that up into two banks to keep the wire sizing and charger sizing to something reasonable. There are several companies that make good chargers or RV converters. Progressive Dynamics makes a relatively inexpensive RV converter that might work well for this.

If you are going to build a battery bank there are a couple very important rules to follow: The batteries all must be the same size, same brand, same age, and bought on the same day. Never mix different batteries. Differing resistances and differing plate sulfation will create problems in both the charging and storage.

The output on the 12V side of your EU2000i is probably only around 8 amps. Completely insufficient.

Blue Sea Systems has a great wire sizing calculator. You can go cheep on wire by using welder wire. Use a catastrophe fuse on the negative terminals. Blue Sea makes a terminal fuse that goes right on the battery.

A EU2000is is so quiet that you can barely hear it on the playa by the way. You might do well so save your cash on the batteries and just be considerate about it's placement.
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Re: Silly question about charging marine batteries

Post by rmc50 » Sun Aug 23, 2015 12:48 pm

I know I am commenting on this really late, but perhaps it might save you some grief.

I have a fair amount of experience at using 12 volts to run refrigeration. The bottom line: it doesn't work well for extended periods. Or it requires a lot of expense to make it work well.

A typical 12 electric cooler will draw about 4 amps. A high quality unit, one that uses Freon with a compressor and so forth, will operate intermittently, but in the heat of the playa I would expect about 50%. The cheaper units use "themro-electric" coolers, which are no where near as efficient and I would expect them to be drawing 100% of the time (and probably not keeping the food as cold as you would want).

The typical marine deep cycle batteries come in two common sizes: 100 (series 27) and 80 amp-hour (series 24). An 100 amp-hours means that it is rated to deliver 1 amp for 100 hours. If this were a perfect world, it would also be able to deliver 100 amps for 1 hour, but this world is far from perfect so the higher the current draw, the less you actually get. You should not draw more then 80% from the battery, so assume you have 80 amp-hours. Thus, a four amp draw would deplete the battery in 20 hours.

So now you need to charge it. Figure that the cooler will still be drawing 4 amps while you are charging, so if you connected a 4 amp charger there would be nothing going to the battery. Ideally, you would charge at a rate of 20% capacity of the battery, which would be 20 amps. Or 24, to compensate for the draw of the cooler. In a perfect world that would recharge the battery in 4 hours (20 amps x 4 hours = 80 amp-hours). As I mentioned above, we don't live in a perfect world, and the efficiency loss at higher currents applies to charging as well as discharging, so figure it will take 5 hours.

Okay, one more issue: I mentioned above that you don't want to pull the battery down below 20%. Likewise, on a charge, the effective rate of charge really drops off when the battery goes above 80%. People who live off battery systems will generally operate between 20% and 80% capacity, as it takes a lot more fuel to charge that last 20 %. So figure you have 60 amp-hours to play with, or 15 hours of run time, and then 4 hours of charge time if you have a 20 amp charger.

So, what I really recommend, is to plan on running that little generator most of the day, and then running off battery alone during the "quiet time" of the night.

Rod

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Re: Silly question about charging marine batteries

Post by Zubeneschamali » Tue Aug 25, 2015 3:57 pm

Silly answers about charging marine batteries.

Step 1: Make sure you charge your batteries.

Step 2: Don't forget #1

Step 3: You might want to go out right now and check your batteries. Cause I did and found out that I failed on both Step 1 and Step 2.

Step 4: Go buy another fucking set of batteries because you didn't do #3 until they were completely drained and now won't hold a charge.

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Re: Silly question about charging marine batteries

Post by rideincircles » Tue Aug 25, 2015 4:17 pm

What should we be looking for on battery charges using a multimeter? Will that tell us the level of charge?

Also, should I just leave it hooked up to the HF trickle charger until I leave, or do I need to pull it off there so it doesn't overcharge. The only thing mine has been used for is about 15 minutes of testing the pump on my swamp cooler.

I guess I will google this also.

Edit:
I found this.

Digital Voltmeter Open Circuit Voltage Approximate State-of-Charge
12.65 100% 1.265
12.45 75% 1.225
12.24 50% 1.190
12.06 25% 1.155 -
11.89 Discharged 1.120

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Re: Silly question about charging marine batteries

Post by FIGJAM » Tue Aug 25, 2015 5:39 pm

Zubeneschamali wrote:Silly answers about charging marine batteries.

Step 1: Make sure you charge your batteries.

Step 2: Don't forget #1

Step 3: You might want to go out right now and check your batteries. Cause I did and found out that I failed on both Step 1 and Step 2.

Step 4: Go buy another fucking set of batteries because you didn't do #3 until they were completely drained and now won't hold a charge.
They may not be ruined yet.

Some chargers won't charge If the batteries are zeroed.

Hook a good battery to one of the bad ones and let it sit for an hour.

Then put the charger on.

I've recovered many a battery this way.
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Re: Silly question about charging marine batteries

Post by GreyCoyote » Tue Aug 25, 2015 6:17 pm

Your charge table shows 12.6 volts as being 100% charged. That isn't correct.

The target float voltage for a 12v wet cell is 13.2 volts with current limited to 2-3% of the total AH rating of the battery. Under these conditions, the battery is considered completely charged. This is the holding voltage for all modern chargers plus or minus a tenth of a volt. Any higher in voltage and you get outgassing. Any lower and the battery doesn't remain fully charged. This 13.2 volt number is changed only slightly by temperature, and many "smart chargers" carry temperature compensation formulas in their programming. Virtually all high-end alternative energy chargers make a serious effort to compensate.

With a small wall-wart-based charger, you should see 13.2 volts when the battery is full. Note this is for a single battery. A multi-battery system may not ever reach full charge on a very small float charger.
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Re: Silly question about charging marine batteries

Post by Zubeneschamali » Tue Aug 25, 2015 6:41 pm

Thanks FJ for the tip. My charger worked and after 48 hours on a 2AMP charge it read 12.5V. It lost 60% after 12 hours on a minimal draw. Luckily still under a 12 month full replacement warranty, so a short trip to Costco and got a fresh one.

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