I have a light that runs on a 6v lantern battery. Can I substitute 4 AA batteries (mounted in a spring clip battery box)? The battery is powering a 6v lantern flashlight. Thanks.
AAs will work fine power wise but obviously don't offer the run time you get with the 4D or 4F cells that you find in a 6V lantern battery. The simplest method would be to use a 4D to 6V adapter with D to AA adapters or the AAs fixed in the 6V adapter another way. Dorcy still offers a 4D to 6V adapter and D to AA adapters are readily available online.
The majority of 6V lanterns are negative polarity where common in-line battery lights are positive. Like Lynx Arc posted it doesn't matter with an incan bulb but if your lantern is LED or you are using an LED drop in it must be the correct polarity. Finding LED drop-ins for old incan 6V and Railroad lanterns has been an obsession of mine and it takes some searching but there are dual-polarity drop-ins available that will work.If you are powering a light that is LED from the manufacturer then it is most likely not dual polarity and may not have polarity protection. In short having the wrong polarity will ruin the LED unless it has polarity protection.
You can use NiMH but they are only 1.2V compared to 1.5V in a fresh alkaline. NiMH is generally superior to alkaline IMO but output could be reduced in a light designed to run on alkalines. Lithium Energizers,also far superior to alkaline, are the reverse and usually have a slightly higher voltage than alkalines. It probably will be fine for most LED applications but will "overdrive" an incan bulb since you are using four in a series. "Overdriving" a bulb often produces better light but shortens bulb life and can "instaflash" a bulb sometimes. Not a big deal since most bulbs are easy to replace but if it has a specific bulb you want to keep it should be avoided.
Lastly if a light is safety rated that rating is based on using only the recommended batteries,usually alkalines.
Sorry for the long answer but not knowing the specific light or use I just kept thinking of more things to cover.
i have been building lights for about 2 decades, i can't count how many times i accidentally reversed polarity, not a single led was ruined due to it, they just do not light up until you reverse polarity again.
Rayovac sells a really nice 4C lantern with two output levels. Has all of the functionality of most 6v lanterns,just slightly smaller.Typically unless it is a "loved" 6V lantern the cost of the 6V adapter plus AA > D adapters would push the price rather close (or possibly more) than buying a lantern that can accept AAs like this one https://www.dorcy.com/6v-led-lantern that can take 4AA or a 6V lantern battery.
Here is a native 4AA LED lantern also https://www.amazon.com/dp/B009JCA2DK/?tag=cpf0b6-20
The cheapest way to adapt would be a soldering iron wired to a 4AA battery holder. My advice to increase runtime is to use multiple 4AA adapters wired in parallel so you can use 4,8,12, etc batteries to increase runtime.
I ruined a Dorcy drop-in some years back when I had the polarity wrong. Perhaps it is the way the LED is driven or the amount of time the reverse polarity current is on? I am not a builder or modder and won't pretend to have the best range of knowledge but I know others have had issues as well. If it is not a problem then why so much discussion on CPF about reverse polarity protection?
Without knowing the type, rated voltage and rated bulb life, it's hard to answer but if original battery is alkaline or even zinc, then better to replace 6 volt bulb instead of 4.8 volt.Will the standard bulb in a 6V incan hold up under the increased power delivery from a 6V lead acid rechargeable? Also what available bulb would work best with a lead acid 6V?
Without knowing the type, rated voltage and rated bulb life, it's hard to answer but if original battery is alkaline or even zinc, then better to replace 6 volt bulb instead of 4.8 volt.
If original bulb is PR based similar to older M*g "C" or "D" then PR base 5 cell bulb will work safer with 6 volt lead acid battery.
For brighter option, two pin M*gCharger bulb in socket will serve better.
BTW, lead acid battery likes to be fully charged all the time. This means, recharge them immediately after usage.
you burned driver circuit inside the dropin, not the let itself. i understand now why the confusion.