Forums

Using an AA battery charger to charge D cells

Started by Unknown April 7, 2018
I have a battery charger which only fits AA and AAA batteries. I
recently bought a Maglight flashlight, which uses three D cells. I want
to put rechargable batteries in it, but I have no way of charging them,
unless I buy another (expensive) charger. It seems that almost all
battery chargers these days are only for the AA and AAA batteries. There
are only a few that charge the C and D cells, and they are 4 or 5 times
the price of the AA/AAA ones.

I'm wondering if I can charge the D cells using my AA charger. I have
several D sized battery holders on hand. I'm thinking of attaching some
wires to the battery holders and just using some alligator clips to clip
to the AA charger contacts. (Making sure the polarity is correct). 

Physically this is easy. But I wonder if the battery charger will work
properly on the D cells. Both the D and AA batteries are 1.5 volts, but
the D cells have a higher current capability.

The higher current makes me think that the charging time will be longer,
which is no problem. But I am posting this to inquire whether there are
other reasons to NOT do this? For example, will it damage the charger?

Comments, anyone????

On 4/7/2018 11:42 AM, oldschool@tubes.com wrote:
> I have a battery charger which only fits AA and AAA batteries. I > recently bought a Maglight flashlight, which uses three D cells. I want > to put rechargable batteries in it, but I have no way of charging them, > unless I buy another (expensive) charger. It seems that almost all > battery chargers these days are only for the AA and AAA batteries. There > are only a few that charge the C and D cells, and they are 4 or 5 times > the price of the AA/AAA ones. > > I'm wondering if I can charge the D cells using my AA charger. I have > several D sized battery holders on hand. I'm thinking of attaching some > wires to the battery holders and just using some alligator clips to clip > to the AA charger contacts. (Making sure the polarity is correct). > > Physically this is easy. But I wonder if the battery charger will work > properly on the D cells. Both the D and AA batteries are 1.5 volts, but > the D cells have a higher current capability. > > The higher current makes me think that the charging time will be longer, > which is no problem. But I am posting this to inquire whether there are > other reasons to NOT do this? For example, will it damage the charger? > > Comments, anyone???? >
This question has many dimensions. Firstly, most of the rechargeable D cells you buy are just AA cells inside a bigger shell. A 'real' NiMH D cell will be expensive and heavy. You can buy the shells and recharge the AA's. How much current does your flashlight need? Easily available D-size may not have the run-time capacity you desire. How does your charger work? If it's a slow charger, rated something like 16 hours, it just keeps stuffing current into the cell forever. NiMH don't like that. If it's a fast charger the much higher capacity cell will not reliably terminate the charge and the battery will get hot and degrade quickly. You probably won't hurt the charger either way. But you can damage the cells. The solution is NOT to buy flashlights using D cells if you want rechargeable. Get a light that uses rechargeable lithium cells and use a compatible charger. That ship has sailed. So, the answer to your question is, "it depends." If you buy a charger, make sure it can charge odd numbers of cells. Many of the cheaper ones charge two cells in series. That's a problem when your light has three cells.
On Saturday, April 7, 2018 at 2:43:16 PM UTC-4, olds...@tubes.com wrote:
> I have a battery charger which only fits AA and AAA batteries. I > recently bought a Maglight flashlight, which uses three D cells. I want > to put rechargable batteries in it, but I have no way of charging them, > > > Comments, anyone????
Without knowing which battery charger you have, it is a little hard to say. And if you did provide the battery changer model, I would still in the dark. But I think you could make your kludge to connect to the D sized batteries with a resister to reduce the charging current. Look on your charger and see if it has any verbiage which tells what the current is. Dan
On Sat, 07 Apr 2018 13:42:20 -0500, oldschool@tubes.com wrote:

>I have a battery charger which only fits AA and AAA batteries. I >recently bought a Maglight flashlight, which uses three D cells. I want >to put rechargable batteries in it, but I have no way of charging them, >unless I buy another (expensive) charger. It seems that almost all >battery chargers these days are only for the AA and AAA batteries. There >are only a few that charge the C and D cells, and they are 4 or 5 times >the price of the AA/AAA ones. > >I'm wondering if I can charge the D cells using my AA charger. I have >several D sized battery holders on hand. I'm thinking of attaching some >wires to the battery holders and just using some alligator clips to clip >to the AA charger contacts. (Making sure the polarity is correct). > >Physically this is easy. But I wonder if the battery charger will work >properly on the D cells. Both the D and AA batteries are 1.5 volts, but >the D cells have a higher current capability. > >The higher current makes me think that the charging time will be longer, >which is no problem. But I am posting this to inquire whether there are >other reasons to NOT do this? For example, will it damage the charger? > >Comments, anyone????
Amazon has universal aaa...d chargers under $15. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Sat, 07 Apr 2018 12:34:15 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

>On Sat, 07 Apr 2018 13:42:20 -0500, oldschool@tubes.com wrote: > >>I have a battery charger which only fits AA and AAA batteries. I >>recently bought a Maglight flashlight, which uses three D cells. I want >>to put rechargable batteries in it, but I have no way of charging them, >>unless I buy another (expensive) charger. It seems that almost all >>battery chargers these days are only for the AA and AAA batteries. There >>are only a few that charge the C and D cells, and they are 4 or 5 times >>the price of the AA/AAA ones. >> >>I'm wondering if I can charge the D cells using my AA charger. I have >>several D sized battery holders on hand. I'm thinking of attaching some >>wires to the battery holders and just using some alligator clips to clip >>to the AA charger contacts. (Making sure the polarity is correct). >> >>Physically this is easy. But I wonder if the battery charger will work >>properly on the D cells. Both the D and AA batteries are 1.5 volts, but >>the D cells have a higher current capability. >> >>The higher current makes me think that the charging time will be longer, >>which is no problem. But I am posting this to inquire whether there are >>other reasons to NOT do this? For example, will it damage the charger? >> >>Comments, anyone???? > >Amazon has universal aaa...d chargers under $15.
Ah, yes, Amazon, from which all good things come ;-) Just had to order a new shower back brush... mine started shedding bristles like crazy... the info tab said this was my 72nd order in the past six months >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | To those of us in my age bracket... GREEN means inexperienced and/or incompetent.
On Sat, 07 Apr 2018 13:42:20 -0500, oldschool@tubes.com wrote:

>I have a battery charger which only fits AA and AAA batteries. I >recently bought a Maglight flashlight, which uses three D cells.
D cells are too expensive to waste in a flashlight. Get an adapter that allows you to cram AA cells into your flashlight: <https://www.ebay.com/sch/i.html?_nkw=aa+to+D+battery+adapter> I mostly use the adapters that come with Eneloop (Panasonic) NiMH cells sold by Costco: <https://www.ebay.com/itm/2-AA-to-D-D-Adaptor-Sanyo-Eneloop-Battery-Converter/392013317267> You might also consider switching your Maglite to Lithium Ion batteries. "Battery Alternatives for Maglite" <https://www.youtube.com/watch?v=fsyo_GUQMm4> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On 2018-04-07, oldschool@tubes.com <oldschool@tubes.com> wrote:
> I have a battery charger which only fits AA and AAA batteries. I > recently bought a Maglight flashlight, which uses three D cells. I want > to put rechargable batteries in it, but I have no way of charging them, > unless I buy another (expensive) charger. It seems that almost all > battery chargers these days are only for the AA and AAA batteries. There > are only a few that charge the C and D cells, and they are 4 or 5 times > the price of the AA/AAA ones. > > I'm wondering if I can charge the D cells using my AA charger. I have > several D sized battery holders on hand. I'm thinking of attaching some > wires to the battery holders and just using some alligator clips to clip > to the AA charger contacts. (Making sure the polarity is correct). > > Physically this is easy. But I wonder if the battery charger will work > properly on the D cells. Both the D and AA batteries are 1.5 volts, but > the D cells have a higher current capability. > > The higher current makes me think that the charging time will be longer, > which is no problem. But I am posting this to inquire whether there are > other reasons to NOT do this? For example, will it damage the charger?
It's unlikely to damage the charger.
> Comments, anyone????
NiMh charging is tricky. Many chargers look for the dip in terminal voltage that happens when the cell is full and starts heating up A D cell has like 3 times the surface area and 6 times the volume of an AA *, so the slopes will be shallower. And if the charger uses an actual temperature sensor it's not going to work at all. (both numbers rough guesses) -- This email has not been checked by half-arsed antivirus software
On Saturday, 7 April 2018 22:26:31 UTC+1, Jim Thompson  wrote:
> On Sat, 07 Apr 2018 12:34:15 -0700, John Larkin
> >Amazon has universal aaa...d chargers under $15. > > Ah, yes, Amazon, from which all good things come ;-) > > Just had to order a new shower back brush... mine started shedding > bristles like crazy... the info tab said this was my 72nd order in the > past six months >:-} > > ...Jim Thompson
not all for back brushes I hope! I do get good things from Amazon/Ebay, but also ungoodly things. It's hard to tell which will be which. NT
On Saturday, 7 April 2018 19:43:16 UTC+1, olds...@tubes.com  wrote:
> I have a battery charger which only fits AA and AAA batteries. I > recently bought a Maglight flashlight, which uses three D cells. I want > to put rechargable batteries in it, but I have no way of charging them, > unless I buy another (expensive) charger. It seems that almost all > battery chargers these days are only for the AA and AAA batteries. There > are only a few that charge the C and D cells, and they are 4 or 5 times > the price of the AA/AAA ones. > > I'm wondering if I can charge the D cells using my AA charger. I have > several D sized battery holders on hand. I'm thinking of attaching some > wires to the battery holders and just using some alligator clips to clip > to the AA charger contacts. (Making sure the polarity is correct). > > Physically this is easy. But I wonder if the battery charger will work > properly on the D cells. Both the D and AA batteries are 1.5 volts, but > the D cells have a higher current capability. > > The higher current makes me think that the charging time will be longer, > which is no problem. But I am posting this to inquire whether there are > other reasons to NOT do this? For example, will it damage the charger? > > Comments, anyone????
The short version is it'll be fine. But if the cpacity is high it'll take longer. Don't recommend leaving them charging indefinitely. Yes one could get a lot more into it, but no need. If it is a fast charger with small capacity Ds it'll work as usual, and a fast charger with large Ds will work as a slow charger. A slow charger with large cells could take a long long time to charge, but it will. NT
buy  a new LED flashlight that runs in 18650 cells.

they usually come with a charger.

mark