Peculiar issue with a battery powered lantern

Thread Starter

Edgecrusherr

Joined Aug 3, 2022
16
Hi, just found this site while trying to figure out this issue I'm having, I hope I'm in the right place. I'm not an engineer, just computer enthusiast with a graphic design degree, and now working in IT...so thank you in advance!

So, I have a battery powered lantern, made by Rayovac, that seems to no longer power a light bulb. It uses 4x AA batteries, and a standard little flashlight bulb. Product photo attached below from Google Images.

81f4005499cb78a034e35b5dbe4b1017_large.png

My daughter has been using it to pretend camp at home for a few years. We're going real camping this weekend, so I grabbed it from her room to put fresh batteries in it, and discovered it doesn't turn on anymore.

I confirmed the new batteries are good, via my multimeter. So I ran to Home Depot last night and got the only flashlight bulb they had: https://www.homedepot.com/p/Nite-Ize-C-D-Cell-LED-Flashlight-Upgrade-Kit-LRB2-07-PR/204787538.

When I installed the bulb, the lantern still didn't not turn on. So I opened up the lantern and grabbed my multimeter.

There's no corrosion at all, looks like it's still new. I tested the voltage before and after the on/off switch, get's 7.06v. I tested right up to the copper contacts / bulb socket, all reading 7.06v. I pulled out the wiring with the copper contacts, and touched the to be bulb to make sure it wasn't a seating issue where the bulb connects, but it still didn't light the bulb. I then installed the bulb into a 2x AA battery flashlight and it turned on just fine. I tested the bulb from the AA flashlight in the lantern, and it didn't power on either. I used the multimeter in place of the bulb to be sure power was getting to the contact, and it read 7.06v. I even measured the voltage right off the bulb's side and bottom, while it was installed in the lantern, to make sure it was getting power. It read 7.06v. I tested the original lantern bulb in the flashlight, it did not work. So I assume it blew.

At this point I took the 4 AA batteries, and taped them together with some wire to make make a circuit, to make sure it wasn't an issue with the bulbs not supporting 7.06v. Both the new bulb and the bulb from the flashlight lit right up. I then put the batteries back into the lantern, and ran wire right from the positive and negative end of the battery chain, and ran them to the bulbs, they lit right up.

At this point I realized I was assuming the 4 batteries together were giving the same 7.06v that I measured inside the lanterns wiring. I decided to confirm this, and measured 6.88v directly from the batteries. I took the batteries out of the lantern, taped all 4 of them together, and measure them, and got 6.88v. I'm not sure if the difference from 7.06v inside the lantern vs the 4 AA batteries' 6.88v is meaningful or not. I looked up the new bulb's specs, it supports 3v-9v. So either way it should work fine. There I'm using is pretty thick (forget what I bought that wire for, maybe something to a computer repair I did). It's nothing crazy though, maybe slightly thicker than traditional car stereo wire. I'm not sure if that affects the voltage not, vs the thinner wire used inside the lantern.

So here's where I'm at:
  1. I have a lantern that I can read 7.06v all the way up to the terminals / bulb socket (the on/off switch works just fine too).
  2. The bulb seems to support the voltage range I'm working with, but there is some variation in voltage when I test the 4xAA batteries directly, vs what I'm reading in the lantern.
  3. Bulb seems to be making contact with the terminals/socket, and I can read 7.06v off the bulb.
  4. The batteries work, and the bulb works in a 2xAA flashlight, and when I run wires right from the 4xAA batteries.
  5. There's no physical damage or corrosion in the lantern.
  6. The lantern's original bulb does appear to be blown.

I have to imagine I'm missing something or misunderstanding something with how the circuit works. I'm not an engineer. I did buy another lantern off Amazon for the camping trip, so I'm mostly just trying to save this from being waste, and am also really wanting to solve this mystery, even it's its for my own future knowledge.

Thank you for coming on this journey with me!
 

LesJones

Joined Jan 8, 2017
3,773
Although the link you provided does not work part of the URL says "flashlight upgrade kit". I am wondering if your new bulb is a LED type bulb. If it is it is probably polarity conscious (A filament type bulb works with either polarity.) If it is then the polarity to the bulb holder in the lantern may be the reverse of the correct polarity for a LED type bulb. Can you confirm if it is a normal filament type bulb ?

Les.
 

MisterBill2

Joined Jan 23, 2018
12,697
OK, welcome to this site. And the link provided the answer. It worked for me but does not link to a light bulb at all. If the thing is an actual incandescent bulb, use the ohm meter function of your multimeter to verify continuity of the filament.
Is that LED item what you purchased??
That replacement shows to be an LED device, which, if that is actually what you have, is polarity sensitive. With a reversed polarity it will not light, and may possibly become damaged. Read the package and see what it tells you about polarity. ON LED devices polarity maters a great deal.
 

BobTPH

Joined Jun 5, 2013
5,467
Link works for me. Les is right, it is an LED replacement for old flashlight bulbs.

An old style flashlight would have the + to the bottom contact of the bulb. Use your multimeter to see if yours is reversed.
 

Audioguru again

Joined Oct 21, 2019
4,930
I think the flashlight wiring has the opposite polarity than the replacement LED.
The lantern is not sold anymore so maybe it used an old incandescent bulb with a filament that burned out and its polarity did not matter.
 

Thread Starter

Edgecrusherr

Joined Aug 3, 2022
16
Hey everyone, thanks so much for getting back to me on this!

The new bulb is indeed an LED, and the old one was incandescent.

I have images of the packaging attached. It's pretty much are marketing hype, no specs. The back of the package says "important information inside", but I tore it all out and son't see anything. There was nothing indeed with the bulb either.

I was assuming the bottom was positive, so when I made the circuit for testing, I used positive on the bottom and and negative on the sides, and the build did light up. When I tested the lantern, I used the multimeter assuming positive was the bottom terminal. Not sure if that accounts for anything. The bottom terminal also came from a black wire, and the side was a red wire (granted, the wires may not really mean anything).

When get home in an hour or so, I'll get you all photos what the side looks like, and test the ohms. If I reverse the polarity of the wires to test, will it blow the LED bulb?

The build I used from the flashlight was also an incandescent and didn't work.

If it is a polarity issue, I can switch the wires around to make it work with the LED.

nite-ize-flashlight-bulbs-lrb2-07-pr-64_1000.jpgnite-ize-flashlight-bulbs-lrb2-07-pr-44_1000.jpgIMG_9154.jpg
 

Thread Starter

Edgecrusherr

Joined Aug 3, 2022
16
If you put the red probe of your meter on the bottom contact, the meter will show a negative voltage if it is wrong.
Thanks! I just got home and tested it. The polarity is correct, read/side is negative, black/bottom is positive. That is exactly what the bulb is as well. Now I'm ally stumped. Going to check the Ohms now.
 

Thread Starter

Edgecrusherr

Joined Aug 3, 2022
16
Here's what the inside of this looks like. I have the terminals pulled out, but they go inside the white cylinder with a divider in the middle (divider not pictured).
IMG_9156.jpg
 

Thread Starter

Edgecrusherr

Joined Aug 3, 2022
16
I'm looking at the original bulbs. I'm not sure which one came out of the flashlight and which one was in the lantern, but one is 2.4v .7a, the other is 2.8v .75a. Does this make much of a difference? Also, if I getting a reading of 7.06v off the terminals, does that mean something isn't working right, and that's why the original bulb blew? Maybe there's something inside the switch houses that steps it down to 2.4 or 2.8? (I haven't figured out how to get inside there, I don't see screws, may be sonically wielded). Sorry, I don't really know how this stuff works, just trying to find my way through.
 

Audioguru again

Joined Oct 21, 2019
4,930
An LED works from a minimum voltage but has a maximum allowed current.
The LED bulb says it works with 2 cells (maybe 1.8V when the cells have low life remaining) to 6 cells which might 9.6V when new.

A white LED needs at least 2.8V to 3.6V to be bright and will explode of given more voltage so the LED bulb must have a current regulator in it. The current regulator might even stepup the battery voltage if it is low like my solar garden lights do.
We do not know if the current regulator protects the LED against getting a reversed voltage.
 

LesJones

Joined Jan 8, 2017
3,773
A few points. As both bulbs are rated at about 2.5 volts they are both designed to work in a device using two cells (1.5 volt cells.) connected in series which will provide about 3 volts when the cells are new. The lantern seems to use 4 cells connected in series so that would normally be fitted with a normal filament bulb rated at about 4.8 volts. Neither of the two bulbs you mention are suitable for the lantern. I am surprised the two bulbs survived more than twice their rated voltage even just for a short time.
It is VERY unlikely that there is anything inside the switch to reduce voltage.
Are the two brass strips in the picture in post #11 the connections to the bulb ?
If so is the one with the right angle end the one that connects to the tip of the bulb ?
It seems odd that the black wire connects to the tip of the bulb as black would normally be negative.
Can you post good closeup pictures of the three bulbs so we can see which are LED and which are filament bulbs.

Les.
 

LesJones

Joined Jan 8, 2017
3,773
From the picture in post #7 the card states that the bulb that you bought is suitable for use with 4 cells.
I think the problem may be due to the metal strips not making good contact with the bulb. (The original bulb may well be OK.)

Les.
 

Thread Starter

Edgecrusherr

Joined Aug 3, 2022
16
Thanks so much for all your help, you guys are great!

A few points. As both bulbs are rated at about 2.5 volts they are both designed to work in a device using two cells (1.5 volt cells.) connected in series which will provide about 3 volts when the cells are new. The lantern seems to use 4 cells connected in series so that would normally be fitted with a normal filament bulb rated at about 4.8 volts. Neither of the two bulbs you mention are suitable for the lantern. I am surprised the two bulbs survived more than twice their rated voltage even just for a short time.
It is VERY unlikely that there is anything inside the switch to reduce voltage.
Are the two brass strips in the picture in post #11 the connections to the bulb ?
If so is the one with the right angle end the one that connects to the tip of the bulb ?
It seems odd that the black wire connects to the tip of the bulb as black would normally be negative.
Can you post good closeup pictures of the three bulbs so we can see which are LED and which are filament bulbs.

Les.
Thanks Les, that's what's really confusing to me is that I'm getting 7.06v from the lantern, yet the original bulb is way less. My daughter's 7 now, so I want to save I've had this thing for at least 4 years, BUT I may have bought it before she was born, I really can't remember. We've used it many times too, enough times that I've replaced the battery at least 10 times.

Are the two brass strips in the picture in post #11 the connections to the bulb ?
> Yep, they are.
If so is the one with the right angle end the one that connects to the tip of the bulb ?
>Yep, the right angle does to the bottom of the bulb.
It seems odd that the black wire connects to the tip of the bulb as black would normally be negative.
>Oh man, you know what? I have my multimeter mislabeled then. I look it up, I have the colors backwards. That changes a lot. So this could mean the terminal ARE reverse polarity on the lantern. With negative at the bottom, positive on the side. That would solve a lot! I knew I had to be missing something! What a mistake on my part!
Can you post good closeup pictures of the three bulbs so we can see which are LED and which are filament bulbs.
>I tired to get some photos, but they're really hard to make out. I'll get some a little later today and label them in photoshop, so you know what's what. As of right now, this is what I believe I have:
  • Krypton 4.4v / 0.7A bulb that I think was in the flashlight.
  • Krypton 4.8v / 0.75A bulb that I think was the one in the lantern.
  • LED 3ish volt to 9ish volt bulb that I bought at Home Depot.

Also, I remembered I had an old rechargeable flashlight with a bad battery, so I pulled the bulb out if that to see what happens. It was a 2.3v .27a. I put it in the lantern and it lit for a sec and blew spectacularly lol. So, I guess that tells us the lantern does work, it's just a matter of a compatible bulb.

So, given that I have my multimeter backwards, do we think a 4.8v / 0.75A bulb will do the job, maybe this one? https://amzn.to/3JqUIZQ
 

Reloadron

Joined Jan 15, 2015
6,822
A little late. When we measure the voltage of AA, AAA or D cell common alkaline batteries we use the word "about" when referring to their voltage. The voltages you are seeing for four AA batteries in series is about right. Brand new I am seeing numbers like 1.6 to 1.7 volts on Eveready Energizer and Duracell batteries. While 7 volts is a little high I doubt it's a gamebreaker.

In your images, nice job with the pictures, if the two brass rods or copper rods are part of the socket I see a red and black wire which I would expect. The red wire does look a little flimsy at the connection point but as to polarity they look to be correct. OK, I see you just posted and yes, they are the lamp socket. :)

I tend here to agree with Les in that something is making poor contact be it socket or switch based on all the data you have posted. If you can connect batteries to lamp and it lights there is not much else other than a poor contact point.

Ron
 

LesJones

Joined Jan 8, 2017
3,773
Just swap the red and black wires over. (You may have to use longer pieces of wire.) The LED bulb should work with the wires swapped over. (As you seem to know which bulbs a re filament types you do not need to photograph them.)

Les.
 
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