Need a better battery.

I have a project to decorate the family "Little Red Wagon" with Christmas lights. So I stated experimenting with LED light strings and battery combinations. I finally decided to use an Inverter and not cut up any light strings. The LED light set that I found has 80 lights and the specs state it uses 12 watts. So as a test I connected two 6v lantern batteries in series and ran the leads to the inverter (rated at 100watts), connected a lamp with 40 watt bulb.

The inverted started up and seemed to be working, but when I connected the lamp, the green led on the inverter turned to red and lamp glowed at 60% of what it should. The voltage from the battery dropped from

12.6 to 11.5v. I need a battery with less internal resistance.

What would make a better 12v source ? Most NiCad drill batteries are up around 18v+ What is the voltage of battery in APC backups ?

Reply to
sid
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Your family has one of these?

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Just run the inverter off of the truck's battery.

Reply to
DerbyDad03

Get a bigger battery? Like for a motorcycle or self-starting mower, or even one designed for a UPS.

Reply to
HeyBub

80 watts at 120 volts is the same as 960 watts at 12v. add in the losses in the inverter, and you're gonna need a large battery
Reply to
charlie

Nope !

80 watts is 80 watts ! P =3D I * E or I =3D P / E 80watts / 120volts =3D 0.66 amps 80watts / 12 volts =3D 6.6 amps

I never figured I would ever get more than 1.5 to 2 amps from dry-cell or alkaline batteries. But I didn't expect it to be that poor.

Its not only for a display, its a contest !

Reply to
sid

Nope !

80 watts is 80 watts ! P = I * E or I = P / E 80watts / 120volts = 0.66 amps 80watts / 12 volts = 6.6 amps

I never figured I would ever get more than 1.5 to 2 amps from dry-cell or alkaline batteries. But I didn't expect it to be that poor.

Its not only for a display, its a contest !

----- oops. i doubt you could get 6.6a out of a dry-cell battery for long. try a car battery.

they also make led xmas lights that work off a small battery pack. i recently saw a lady wearing some, that were hooked up to the ones she had on her baby's stroller running of a small c cell battery pack.

Reply to
charlie

The watts is the same for any voltage as you noted. Just add some for the loss in the inverter. Might as well think of it as 10 amps to allow for the loss in the inverter.

That means something the size of a lawn mower battery to run it for an hour or so. I have a rechargable to start a 5 KW generator. It is rated 15 amp hours. It is about 4 x 4 x6 inches. This would run your lights around an hour and a half, maybe slightly more.

Reply to
Ralph Mowery

That is a little big. My 1st string of LEDs is rated at 18w and the ones with color that blink are rated at 8 - 12w I was figuring before I stated that I could get a respectable display for under 25w and not have to invest in a marine battery ?

Reply to
sid

Uhm. You might have some numbers mistaken. 80 watts at 120 volts is also 80 watts at 12 volts. It's the amps that change.

Reply to
Stormin Mormon

A computer UPS battery could be 12 or 6 volts. What I'd reccomend is a battery jumper pack from Napa, or reputable auto parts company. That contains a small lead acid battery. Typically with a wall wart for recharging. Or, you can charge with a double ended lighter plug cord. After the display, you put the jumer pack in the car (read the instructions) and you are everyone's buddy when they have a dead battery.

Reply to
Stormin Mormon

If you don't want to invest in a jump pack. Buy two Energizer brand alkaline lantern batteries (6 volts each). Alkalines supply a LOT more power than heavy duty cells. My ceiling light in the van will barely glow on HD cells, but runs fine on alkalines. Actually, at the moment I run it off a battery booster pack. Practicing what I preach.

Reply to
Stormin Mormon

That would be the best solution... There are portable strings of lights that use AA cells for decorating wreaths and such. Should be much easier to work with.

Reply to
Me

The liitle crap is 12 volts - the bigger stuff 24 and up. Most use multiple 12 volt batteries. 12v8Ah batteries are common and can be easily recharged. 12V 5aH batteries are also readilly available. Often the cheapest way is to by a 12 volt "booster pack" when on sale at WallMart or wherever. Usually 18 Ah or better, often available for $49 or less. Come with 110 volt charger and a cord to charge them in the car from the "convenience outlet" (aka Cig lighter)

Reply to
clare

No, 80 watts at 120 volts is the same as 80 watts at 12 volts, give ot take the percentage of inefficiency.

80 watts at 120 volts is .67 amps. At 12 volts it is 6.7 amps, give or take according to efficiency. The lanmtern batteries are generally good for about 10 watts at 6 volts - or 20 watts at 12, more or less. Generally Alkaline batteries are good for about 2.5 to 2.9 amps MAXIMUM draw. The old Manganese Dioxide carbon-zinc batteries put out a bit more, but for significantly shorter time.
Reply to
clare

.

This is the results of my initial test using two Energizer 6v Alkaline Lantern batteries in series. Here is what I measured: voltage not connected =3D 12.5v voltage connected =3D 11.4v current connected =3D 1.3 amps So: R =3D E/I (12.5 - 11.4)v / 1.3a =3D .85 ohms of internal resistance. I need a source with a much lower resistance or more batteries in parallel.

I found an old "APC Smart UPS 650", Specs show it should have a 12v

650va battery. Tomorrow I will post what happened.
Reply to
sid

The SmartUps 650 I have sitting here takes 2 6 volt batteries of I believe 12 AH. They are no longer here - scrapped them but have not replaced them yet. The SmartUps 1000 is a 24 volt unit.

Reply to
clare

DerbyDad03 wrote in news:eacadd8d-ce48-4139-8ec7- snipped-for-privacy@p8g2000yqb.googlegroups.com:

Holy crap! That one always filled the park at National Speedway on Long Island in the 60's & 70's. Funny Cars, The Green Monster, Big Daddy Don Garlits, talk about popping memory bubbles.

Reply to
Red Green

Do you mean on Sunday Sunday Sunday at National Speedway?

I grew up in Queens during the 60's & 70's.

Well, "grew up" would be stretching things a bit.

Reply to
DerbyDad03

DerbyDad03 wrote in news: snipped-for-privacy@p30g2000vbt.googlegroups.com:

I would tell them "Cousin Brucie sent me" but still had to pay to get in.

Reply to
Red Green

I had one of those trucks but it only had a slant six engine, darn.

TDD

Reply to
The Daring Dufas

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