Watts Help Needed.

[Community Alumni]

I am trying to figure out how long a battery will last. I have Googled it and read a few sites but I still have a few questions.

I have a small TV that I plugged into my Kill a Watt meter. That shows 22 watts. I plan on using a 1000w inverter hooked to one 12v battery. I havn't purchased a battery yet so i'm not sure how many AH I will have to work with.

At 12v that would be 1.8 amps.
at 124v that would be .18 amps.

Which amp usage would I use, the 1.8 amps or .18 amps?

Thank You
Jim

[pianotuna]

Nice post Mr Wizard.

310 watts / 0.7 power factor gives about 443 watts.

[MrWizard]

your charge WON'T USE 25 amps, it might charge at 25 amps at 14v = 310 watts

25 amps 'use' times 120v would be 3000 watts

amps will 'ALWAYS' taper down

a charger doing 30amps at 14v will still taper to 1amp at 14v when the battery is near full

battery capacity & ability to accept the charge determines the amps at 'ANY' voltage

a partially used battery has a lower internal resistance than a charged battery
as the battery charges, the resistance to accept charge also increases
the battery controls the amount of charge it accepts, not the charger

automatic 'car' battery chargers, turn OFF, when the battery acceptance slows down
they shut off before the battery is fully charged

i know this is a lot to learn,
BUT learning to understand the 'terms' correctly, and correctly charging your battery, will save you money and future problems and expenses

[pianotuna]

Jim,

I think DB levels are taken at a distance of 7 meters (22.9659 feet). I may be wrong about this.

A larger generator with an eco switch may be more fuel efficient than a smaller one. It may also be quieter.

When the time comes that you have an RV with a microwave the 1800 watt will power it--and the 1000 may not.

[BFL13]

You might have missed this earlier. This one is quiet, runs on propane, same as your BBQ/camping stove, and will run a 25 amp charger. Perfect for your beach scenario!

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29853063/gotomsg/29890403.cfm#29890403

[Community Alumni]

pianotuna wrote:
Hi,

I would spend the extra 100 dollars for the 1800 watt unit. It is much more capable than the 1000 watt.

Consider this manual charger instead of the automatic:

https://www.harborfreight.com/10250-amp-12v-manual-charger-with-engine-start-60581.html

Do use a coupon to reduce the price.

The Megawatt may be a better choice. Have a look here:

https://www.amazon.com/MegaWatt-S-350-12-9-5-15-Adjustable-Supply/dp/B00JZBE97U

As of now I am going to use the generator for charging the battery. I'm guessing I will get a charger that uses about 25 amps. Wouldn't the 1,000 watt generator be plenty? My thinking is if I get the bigger one it will be a little heavier(not much), little more fuel and a tad bit louder.

How acurate is published db levels?
Are most published levels rated at 1/4 load?
I never see published at what distance the db levels were taken.

We will be tent camping on the beach so the next person may be closer than would be in a campground so I would like to keep the generator noise to the lowest level I can. If could afford it I would get a Honda. I know there are other brands just as quite as a Honda but still a bit more than I can afford right now.

Jim

[BFL13]

"automatic" means it shuts off and does not go into float mode.

"manual" means it does not shut off and you have to unplug it before the battery voltage goes too high.

"regular charger" means it just brings the battery up in voltage and then shuts off (if automatic type)

"RV converter/charger" most have "three-stage charging" ( three different voltages ) and stays on to do the float charge. it is "automatic" for changing its stages, but it stays on.

"adjustable voltage charger" -you pick a voltage and it stays at that until you change it. so it is "manual" for that. Charger stays on. It is not "automatic" --you have to change the voltage from charging at say 14.5v then when the battery is full you can drop it to a float voltage, say 13.5.

The Megawatt is like that last one. The PowerMax LK model of converters has three-stage automatic or you can set it to adjustable voltage. If you have the adjustable voltage set to 14.5, say, then you need to change that when the the battery is full to a float voltage, OR you can use Mex's timer to just turn the thing off, guessing how long to leave it on for.

My suggestion is to pick the car type automatic charger and when it shuts itself off, then you can turn on the Tender to do the float , which you can leave on as long as you like. No timer, no complications.

[Community Alumni]

I really appreciate all the advice.

I thought it was better for the charge to start off high then as it charges the amps slowly starts to drop then when full the charger goes into trcikle cahrge?

So it's better to charge a battery a full amps during the whole charge time? Like you said, going this way with the Megawatt I would need to put on a timer. Now the question is how long to set the timer for?

From what I have seen and somewhat understand there is two types of automatic chargers. Regular and one for RV batteries.

The car charger - depending the level of charge in the battery the charger starts at x amount of amps then slowly drops in amps then at a preset voltage the charger goes into trickle mode and the charging is done.

RV battery charger - basically does the same but goes through these 6 or 7 different stages to charge and condition the battery.

I have gone to different sites and talked to people that have RV's. Some say the one type, some say no get this type. I don't know which is the best so it is hard to make my mind up. I have looked at all types of chargers on Amazon and most have a lot of good reviews with a smaller amout of bad reviews. I really want to to what is best. I would rather have a charrger that gooes into trickle when done. With the Megawatt there is a chance to over charge or under charge if I don't get the timer on for the correct amount of time.

Decisions decisions decisions

Thanks guys
Jim

[pianotuna]

Do yourself a favor and get a Megawatt.

[MEXICOWANDERER]

Just fine. Smart chargers fill the battery to 80% which allows them to start sulfating right off the starting blocks. They end up ruined maybe 3 or 4 months after the warranty ends. Always wanted a SMART charger that turns a 100 amp hour battery into an 80 amp hour battery. You can thank the Socialist State of Californiagrad for outlawing the importation of ANY manual charger. Companies like Harbor Fright REFUSE to ship manual chargers to zip codes in Californiastan. A place where failed lawyers in Sacramento think for you. Even manual chargers with timers to shut off automatically are outright BANNED. Soon, don't laugh, they will be playing the part of doctors and electrical engineers and dieticians. Without a shred of proof they damned near got to the first stage of banning coffee (enforcing the law of putting a cancer warning label on packaging). Instead of insisting on a right out way of thirty feet clearance around power lines, when it's windy they are going to shut the grid down. Remember, you cannot cure STUPID

The MEGAWATT or converters like what BFL 13 likes are the SOLE sources of battery chargers that do not murder batteries in California.

Don Pianotuna, here are the SPECIFICS I have found in repairs to Harbor Freight chargers.

Button diodes that release their bond to cheap aluminum heatsinks. They will then instantly overheat and burn up.

Cheap 19 gauge POWER WIRES inside that attempt to pass 20 amps of current. BRASS fast-on terminals that overheat, then anneal, get soft as butter then the terminal burns up. Selector buttons that burn out, and their function means trying to switch six terminals at once. A DO NOT BUY even at a 90% discount recommendation from me. They are total 100% garbage.

Down here in Mexico, wheeled Schumaker manual chargers are sold in COSTCO for $107 dollars + 8% tax. Mexican batteries are not worth their cost.

Cut out the fan cutout atop a MEGAWATT then place s correct WIRE fan guard using GOOP and this will drastically increase cooling airflow through the unit. Credit where credit is due to LANDYACHT for finding this. For the last year MEGAWATT switched to a higher airflow ball bearing cooling fan that quadruples fan life.

Always use a reliable timer on the AC of a manual battery charger. Unlike a Failed lawyer you can THINK to resolve a problem.

Yeah CALIFORNIA. The home of Ocasio Cortes who wants to ban RV's and air travel. "Take the midnight train to Tashkent and Tokyo?" Because I am a battery engineer I despise the double-digit IQ in Sacramento. Sue me.

Either charge a battery right or spend $500 by destroying them regularly by boondocking with a SMART charger.

[MEXICOWANDERER]

Just fine. Smart chargers fill the battery to 80% which allows them to start sulfating right off the starting blocks. They end up ruined maybe 3 or 4 months after the warranty ends. Always wanted a SMART charger that turns a 100 amp hour battery into an 80 amp hour battery. You can thank the Socialist State of Californiagrad for outlawing the importation of ANY manual charger. Companies like Harbor Fright REFUSE to ship manual chargers to zip codes in Californiastan. A place where failed lawyers in Sacramento think for you. Even manual chargers with timers to shut off automatically are outright BANNED. Soon, don't laugh, they will be playing the part of doctors and electrical engineers and dieticians. Without a shred of proof they damned near got to the first stage of banning coffee (enforcing the law of putting a cancer warning label on packaging). Instead of insisting on a right out way of thirty feet clearance around power lines, when it's windy they are going to shut the grid down.

The MEGAWATT or converters like what BFL 13 likes are the SOLE sources of battery chargers that do not murder batteries in California.

Don Pianotuna, here are the SPECIFICS I have found in repairs to Harbor Freight chargers.

Button diodes that release their bond to cheap aluminum heatsinks. They will then instantly overheat and burn up.

Cheap 19 gauge POWER WIRES inside that attempt to pass 20 amps of current. BRASS fast-on terminals that overheat, then anneal, get soft as butter then the terminal burns up. Selector buttons that burn out, and their function means trying to switch six terminals at once. A DO NOT BUY even at a 90% discount recommendation from me. They are total 100% garbage.

Down here in Mexico, wheeled Schumaker manual chargers are sold in COSTCO for $107 dollars + 8% tax. Mexican batteries are not worth their cost.

Cut out the fan cutout atop a MEGAWATT then place s correct WIRE fan guard using GOOP and this will drastically increase cooling airflow through the unit. Credit where credit is due to LANDYACHT for finding this. For the last year MEGAWATT switched to a higher airflow ball bearing cooling fan that quadruples fan life.

Always use a reliable timer on the AC of a manual battery charger. Unlike a Failed lawyer you can THINK to resolve a problem.

Yeah CALIFORNIA. The home of Ocasio Cortes who wants to ban RV's and air travel. "Take the midnight train to Tashkent and Tokyo?" Because I am a battery engineer I despise the double-digit IQ in Sacramento. Sue me.

Either charge a battery right or spend $500 by destroying them regularly by boondocking with a SMART charger.

[BFL13]

Maybe the way to go for the OP is to get the auto charger to bring the battery up till it shuts off BUT also get one of these (on sale!) for doing the Float charge/maintain afterwards.

https://www.walmart.com/ip/BATTERY-TENDER-BAT0210123M-Battery-12-Volt-Battery-Tender-Junior/41162133

Also get an hydrometer ( $5 ) so you can tell if the SG gets up where it belongs doing that.

[MrWizard]

You still don't understand

Automotive battery chargers are not designed to do a full charge

They bring the battery to about 90% charge,
They charge enough for you to start the vehicle the battery came out of and to be used intermittently as needed

Power supplies are designed to supply the rated voltage and amps continually, for as long as needed

Most battery chargers will never reach full saturation voltage that will insure the battery electrolyte was returned to correct specfic gravity density
Aka all sulfur from the acid returns to the acid and not left on the battery plates to harden

The mega watt with cables and clamps attached will exceed the performance of any car/vehicle battery charger NOW available

The megawatt will out preform your chosen battery charger
It does require the user to pay attention, it's not idiot proof

Maybe on your case the battery charger is the safer option
And you can upgrade to a megawatt when you have more experience

[Community Alumni]

The one looks odd to be a charger and the one from Harbor Freight has a ton of bad reviews. The reviews are even worse on Amazon. I could not find a manual charger in the amp range I want that had decent reviews. So far I'm going to get the one in my list above. I won't be ording for about a week so I have time to change my mind.

Jim

[Community Alumni]

The one looks odd to be a charger and the one from Harbor Freight has a ton of bad reviews. The reviews are even worse on Amazon. I could not find a manual charger in the amp range I want that had decent reviews. So far I'm going to get the one in my list above. I won't be ording for about a week so I have time to change my mind.

Jim