I have a couple questions about rechargeable batteries for emergency LED lanterns

RobinS

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I have a couple LED lanterns for emergency power outages that take D cell batteries and I'm thinking about investing in rechargeables and a high-quality charger. Before doing so I have a couple questions:


Chargers I'm looking at include the Maha POWEREX MH-C808M Charger (currently around $100 on Amazon) and the EBL 906 Smart Charger (currently around $30 on Amazon).


Batteries I'm considering are the Powerex 10,000mAh Low Self-Discharge NiMH Batteries, (MHRDP2) which are $26 for 2 and the EBL 10,000mAh batteries at half the price, $26 for 4.


Now I can understand why the Maha charger is more expensive than the EBL, most obvious is the size, however, what makes the Powerex batteries twice as expensive as the EBL? Do they have a slower internal discharge rate?


Secondly, I have a question about battery maintenance and storage. In my house, I have a home automation hub and the ability to turn on and off devices on a scheduled event. My line of thinking is this, can I leave the batteries in the charger after being fully charged and control when the batteries get charged at the outlet? I was thinking after the batteries are fully charged, cycling on the charger for a couple hours every two weeks to keep the batteries as fully charged as possible. Both chargers are supposed to be "smart chargers" so I wouldn't think overcharging them would be a possibility. The only thing I can think of is would keeping the batteries in an unpowered charger cause the batteries to discharge faster by completing a circuit through the charger between charging times?


Any thoughts?
 

WalkIntoTheLight

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Since this is for emergency use only, it seems like kind of a waste to buy rechargeable D cell batteries that you would probably seldom use.

Have you considered using AA Eneloops, and some D-cell spacers so that they can fit your lantern? The advantage is you likely have plenty of other uses for rechargeable AA cells, and Eneloops will hold a charge for years. You might only top them up every couple of years, just to be sure they're fully charged. If you're using them for other devices, you'll be topping them up anyway as you cycle through your supply.
 

Timothybil

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How emergency are these emergency lights. If they are the just gotta have no matter what, then some lithium primaries and the AA to D adapter would be the way to go, IMO. No worries about how much charge is left in the cell, no charger to have to buy, and no leaks! If you do want to use rechargeables go ahead and get some, but for guaranteed full power first use use the lithium primaries, then switch to the rechargeables once the first need is over if the emergency is going to last longer than the primary cells.

As far as the automated recharge goes, DON"T! Good chargers are reliable but can still fail, and all the current rechargeable cells of any chemistry are not reliable enough to be recharged unattended.
 

ChrisGarrett

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I'm in Miami and faced this dilemma some 6 years back and decided to just buy alkaleaks. I have chargers that can work with NiMH D batteries, but it just wasn't worth the scratch for me.

I went 84 hours without power during Irma last year and really didn't need the lanterns, although I had them out. I have some 20 year old Duracell/Energizer Ds that still put out some juice and never needed the newer stuff.

Go to Costco, or Walmart and buy a couple of dozen Ds and go from there.

Of course, if you just want NiMH rechargeable D/Cs, then fine.

Chris
 

xxo

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I have been having good luck with Tenergy Centura NiMH D's, I also recently got some Shoshines that seem to be good, so far. I have not used EBLs but I have seen some mixed reviews on these. Powerex is supposed to be good, but more than I was willing to spend. I would not recommend leaving these cells on a charger, it is better just to top them off on a smart charger every 6 mo. or 1 year.

AA Eneloops in adapters will work also and are cheaper than investing in a NiMH D's and a D cell charger.

Unless you are going through several sets of D batteries in you lanterns over the course of a year, it might cost less to just stock up on some alkaline D's - just don't store them in the lanterns as they may leak! If you want to keep the lanterns ready to go, I would take Timothybil's advice and use Energizer lithium AA's in adapters for storage. If you do go with alkalines keep them in their packages until you need them and check them for signs of leaking every so often; they should have a shelf life/expiration date of about 10 years. The Energizer lithiums have a self life of 20+ years and don't leak so there is no worries with these.
 

john1230

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D cell rechargeable are only worth it if you use the light a lot but seeing as you said emergency, I'm assuming you'll want to use it as such.

As everyone said already get 3AA parallel to D adapter and some Energizer L91 Ultimate Lithium AA.

20 years of shelf life with the Energizer L91 Lithium for emergency. You can load the batteries in the AA adapter then store and forget about it. When you need to use the light, just load the adapter into the lantern and away you go.

For the occasional lantern usage Amazon basic AA made in japan cells are good value.

If you want a tried and tested rechargeable, eneloops are currently $4 more than the Amazon basic

Charger wise I'll get the MH-C800S as the default charge rate is 1A (which people say is easier on the cells) rather than the MH-C801D which is 2A. But if you want a fast 2A charger I would get the MH-C808M (they are both about the same price) as it's basically the same as the MH-C801D but it can handle C and D cells too.

Some links to the stuff on Amazon. You can check your local retailer as they sometimes have better prices.

Hope this helps you.

https://www.amazon.com/dp/B00OUM1BGQ/?tag=cpf0b6-20

https://www.amazon.com/dp/B01C4PP8FK/?tag=cpf0b6-20

https://www.amazon.com/dp/B00CWNMV4G/?tag=cpf0b6-20

https://www.amazon.com/dp/B00JHKSN5I/?tag=cpf0b6-20

https://www.amazon.com/gp/product/B000LQMKDS/?tag=cpf0b6-20
 
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PartyPete

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We had a nasty storm knock power out here for 48 hours back in September. Thankfully, temperature-wise it came at a good time; not too hot or cold yet.

However, the saving grace here in terms of lighting for me was just having a variety of lights, many with good moonlight modes. Keep your batteries topped off every so often, have lithium primaries on hand etc.
 

StarHalo

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Eneloop Power Pack, includes charger and two AA-to-D adapters, ~$35; available anywhere online and most box stores.

epKq8X3.jpg
 

RobinS

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Thank you ALL for the replies and especially the product links.


I didn't even know the three cell parallel AA to D cell adapters even existed. It does make a lot more sense to buy AA cell batteries. I live in Tampa and the LED lanterns are part of my hurricane preparedness supplies.


Thanks again!
 

ChrisGarrett

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Thank you ALL for the replies and especially the product links.


I didn't even know the three cell parallel AA to D cell adapters even existed. It does make a lot more sense to buy AA cell batteries. I live in Tampa and the LED lanterns are part of my hurricane preparedness supplies.


Thanks again!

Don't forget to order from WalMart, your 02 Cool 10" AC/DC two speed fans. While Eneloop D adapters work in these 9v/12v fans, they can be tricky to insert properly. That's really what I bought my D alkaleaks for, not the lanterns. I already have plenty of lights.

You'll need those as much as a lantern.

Chris
 

ChrisGarrett

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I love my 5" model, perfect for just one person and it only needs two D cells.

Yeah, being in Miami with no power during the hot months, fans are a necessity. They make living viable and with a 12vdc AGM/SLA battery, they run a long time, even on good alkaleaks.

My first was a 12vdc Ozark Trails rebrand for $15 and then the latter 9vdc model, which still runs well on 12vdc.

Fans are a must, IMO. I even got my GF to buy two for $30. Her power just went out a few hours ago when the 'KONE elevator guys' blew out her condo's power circuits, while inspecting the three elevators, earlier in the day, lol!

She has no power, but the weather is cooler today. Sucks to be her right now, but I left her flashlights, lanterns and a Xiaomi power bank, so it she doesn't brain fart, she should 'survive.'

Chris
 

Timothybil

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I've got my little fan that I can just plug into my charge controller (2 USB outlets) or one of my power banks if I want to move around.

I'm like you - gotta have a fan. Way back in my mis-spent you I and a couple of friends rented a house off campus in Nebraska while going to college. No A/C of course. I rigged up a cooling fan from a broken filmstrip projector and had it blow on me every night. Since them I have a hard time getting to sleep if I don't have some air moving. We all have our little kinks.
 

john1230

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I forgot to say that the AA parallel adapters will put out 1.5v no matter how many cells you have in there, so you can use 1,2 or 3 cell in each adapter and it'll still work but the run time will be much shorter due to it being on lesser cells in each adapter. The more AA cells you have in each adapter the better the run time you'll get.

You're not going to get the run time of a proper D cell battery but it's not a million miles apart either. Until they come out with a proper lithium D cell battery, the AA adapter with lithium primary L91 is the best choice currently for long term storage.
 

ChrisGarrett

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I forgot to say that the AA parallel adapters will put out 1.5v no matter how many cells you have in there, so you can use 1,2 or 3 cell in each adapter and it'll still work but the run time will be much shorter due to it being on lesser cells in each adapter. The more AA cells you have in each adapter the better the run time you'll get.

You're not going to get the run time of a proper D cell battery but it's not a million miles apart either. Until they come out with a proper lithium D cell battery, the AA adapter with lithium primary L91 is the best choice currently for long term storage.

Well, if you're shooting for something that takes more than a few D/C size batteries in series, then getting those 2-3 AA adapters is going to add up and unless you have a huge stash of Eneloops, the more economical play might just be the Tenergy Premiums at about $7-$8 per battery.

When you start using large numbers of AAs, you want to match them, so they remain uniform from battery to battery over the long haul. For emergencies, who cares, but that's something to consider.

Chris
 

thermal guy

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I forgot to say that the AA parallel adapters will put out 1.5v no matter how many cells you have in there, so you can use 1,2 or 3 cell in each adapter and it'll still work but the run time will be much shorter due to it being on lesser cells in each adapter. The more AA cells you have in each adapter the better the run time you'll get.

You're not going to get the run time of a proper D cell battery but it's not a million miles apart either. Until they come out with a proper lithium D cell battery, the AA adapter with lithium primary L91 is the best choice currently for long term storage.

Would 3 lithium primary L91 not give you more capacity then 1D cell? I think they are like 2500 mah each.
 

Lynx_Arc

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Would 3 lithium primary L91 not give you more capacity then 1D cell? I think they are like 2500 mah each.

It depends on the current you are drawing from the batteries as an alkaline D cell has 10-16,000mah capacity at lower power levels so it would take 4 or more AAs to match that.
 
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