Rechargable Batteries, Help!

[PowerSlapper]

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I have a little problem that I hope someone can help me with. I am always running out of "D" and "C" cells for various gadgets which I keep onboard "Jules' Quest". This usually happens at the most inconvenient times and leaves me rather frustrated. I am afraid the duracell bunny is not doing it for me so I thought of buying some rechargable batteries and a charger but I cannot find a 12v operated charger for "D" and "C" cells. There are plenty of 240v operated chargers but I really need a 12v one. Any suggestions as to where I could look?

Unfortunately none of my gadgets run on 12v so I cannot connect them directly to the boat's batteries.

Also what type of rechargable is recommended? NiMH or Li-ion? The batteries will probably be flattened and recharged many times and will need to be suited to fast discharge and fast recharge.

xxx Jules

 

[jwilson]

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I have a little problem that I hope someone can help me with. I am always running out of "D" and "C" cells for various gadgets which I keep onboard "Jules' Quest". This usually happens at the most inconvenient times and leaves me rather frustrated. I am afraid the duracell bunny is not doing it for me so I thought of buying some rechargable batteries and a charger but I cannot find a 12v operated charger for "D" and "C" cells. There are plenty of 240v operated chargers but I really need a 12v one. Any suggestions as to where I could look?

Unfortunately none of my gadgets run on 12v so I cannot connect them directly to the boat's batteries.

Also what type of rechargable is recommended? NiMH or Li-ion? The batteries will probably be flattened and recharged many times and will need to be suited to fast discharge and fast recharge.

xxx Jules

If you look at the specs for NiMh rechargeables there are very few sold in D and C sizes, and the capacities of some of the available D and C cells are little more (and sometimes less) than good quality AA cells.

You can get adaptors that will put AAs into D and C sized plastic cases.

I do know that you can get very high capacity NiMh D cells, but thay are relatively uncommon - and expensive.

I have not found any standard battery size Li-ions.

 

[Matata]

I know there are a few model plane flyers on the forum and most of us use Sanyo eneloop batteries. good capacity and brilliant shelf life with very little self discharge. I turned on my radio gear after six months and the cells were still fully charged. Talk to the man at overlander and tell him your problem. Regards Nik

 

[ctva]

Agree with jwilson above. Get the AA adapters and use high capacity AA NiMH (higher capacity) or better still Hybrid type (slightly less capacity but very low self discharge) batteries as it is easy and cheap to get a AA / AAA 12v charger.

Cheapest place to get them from is ebay. The seller I use most is QualityDiscounts, and these are the ones I buy... http://www.ebay.co.uk/itm/4-x-AA-RE...rElectronics_Batteries_SM&hash=item43b0099dd5
No relationship, just a satisfied customer.

 

[greenalien]

The problem with rechargables, eco-friendly as they are, is that they are only 1.2 volts per cell, compared to 1.5 volts for non rechargables. This means that some equipment won't work properly with rechargables, and that which does will not work as long. They also self-discharge and need to be topped up every month, whether or not they are used.
It's a lot less hassle just to buy good-quality alkaline batteries in bulk, they don't have to be Duracell, I've found that GP are very good and much cheaper.

 

[noelex]

The problem with rechargables, eco-friendly as they are, is that they are only 1.2 volts per cell, compared to 1.5 volts for non rechargables. This means that some equipment won't work properly with rechargables, and that which does will not work as long. They also self-discharge and need to be topped up every month, whether or not they are used.
It's a lot less hassle just to buy good-quality alkaline batteries in bulk, they don't have to be Duracell, I've found that GP are very good and much cheaper.

In practice the slightly lower 1.2v of rechargables is rarely a problem. They hold their voltage better than alkaline with both high discharge currents and low capacities. This means that their voltage in use is often higher than alkaline batteries even though the nominal voltage is lower.
The capacity of good rechargables is better than alkaline batteries so in anything other than very low discharge devices ( such as remote controls) they will last longer.
The low self discharge models (Eneloop are the best by far) will last more than a year in storage and still have greater capacity than alkaline.

As has already been said using Eneloop AA and a battery holder is the easiest solution to C and D cells. If you have a specialist application higher capacity C or D cells are available, but they have more self discharge, and a shorter life.

 

[PCUK]

Latest rechargeables have very little self discharge and certainly don't need topping every month.

 

[greenalien]

In practice the slightly lower 1.2v of rechargables is rarely a problem.

This is very dependent on the voltage sensitivity of particular equipment - torches, for example, are rarely a problem; however, radios, CD players etc may have a problem - you need to try them out to be sure they're OK, and if they don't work properly then you've wasted your money.

They hold their voltage better than alkaline

I have found that some NiMH cells self-discharge quite quickly - after they've been through a few charge/discharge cycles, leave them on the shelf for 6 months, and they're dead.

 

[rogerthebodger]

I am moving over to grandcell rechargeable Alkaline battery's

They are 1.5 volt not 1.2 so work better in equipment designed for 1.5 and they do have a 12 vdc charger available for use on your boat.

Only available in AA and AAA but as said use an adaptor for C and D cells.

http://www.grandcell.com.au/index.php?option=com_content&task=view&id=17&Itemid=30

 

[noelex]

This is very dependent on the voltage sensitivity of particular equipment - torches, for example, are rarely a problem; however, radios, CD players etc may have a problem - you need to try them out to be sure they're OK, and if they don't work properly then you've wasted your money.

.

The point is if you put rechargable batteries in devices like cd players, the rechargable voltage will be higher than the voltage of an alkaline battery, so it's very unlikely not to work.
I have not never come across a device that does not work fine with rechargable batteries although often the battery life display will be inaccurate.
I am not saying it will never happen, but it's very rare and of course you have not wasted your money because the batteries will still power all your other devices.
There are also some devices like that do not work as well with alkaline batteries as they do with rechargable. Camera flash and high power LED torches often fall into this category.
Finally alkaline batteries are very good at leaking and ruining devices.

"Friends don't let friends use alkaline batteries" is sometimes quoted

I have found that some NiMH cells self-discharge quite quickly - after they've been through a few charge/discharge cycles, leave them on the shelf for 6 months, and they're dead.

Use Eneloop batteries with a good quality charger and I guarantee you won't have these problems.

 

[theoldsalt]

It is true that some devices are (were?) sensitive to voltage.

A few years ago I had a couple of hand held radios that ran off AA batteries. They needed 10 if using rechargables and 8 if using no-rechargables (+ 2 dummies to fill the empty spaces). But luckily they would run off an external 12v supply.

 

[Elemental]

The point is if you put rechargable batteries in devices like cd players, the rechargable voltage will be higher than the voltage of an alkaline battery, so it's very unlikely not to work.

Is that correct? I thought rechargeables had a nominal voltage of 1.2V and alkalines 1.5V, so it's the other way round surely - the rechargeable voltage will be lower than alkaline. And I believe that's why some devices don't work well as they falsely detect a discharged battery (and/or they require 1.5V to operate). Tungsten torches don't burn as brightly on rechargeables.

 

[theoldsalt]

Sea Spray,

I think the reasoning is that the voltage drop with current drawn may be greater using non-rechargables especially when motors (heavy current users) are in the device (eg cd player).

Rechargables may be better able to support high current users.

 

[Elemental]

Sea Spray,

I think the reasoning is that the voltage drop with current drawn may be greater using non-rechargables especially when motors (heavy current users) are in the device (eg cd player).

Rechargables may be better able to support high current users.

Ah, that makes more sense. I thought noelex was unlikely to have made an error - but I hadn't considered heavier current loads causing voltage drops in alkalines...

 

[noelex]

The voltage of all batteries drops under load and with discharge. This drop is much less for for rechargable batteries than alkalines.
So the alkaline battery has a higher voltage, but as soon as the device is turned or the battery is no longer new the voltage will sag more than the rechargable battery. This means that with a medium discharge and half empty battery the voltage of the rechargable will be higher than an alkaline battery, when in use.
With high discharge items like camera flashes for example the recycle time will be less with rechargable batteries because the voltage is higher.
With very low powered devices the voltage will be higher with a new alkaline, but even then when the alkaline battery is getting close to empty an almost empty rechargable battery will have a higher voltage. For this reason it's very rare to find even a low powered device that will not run on rechargable.
There are rarely, some devices that warn not to use rechargable batteries. This is because
1. They have been through licence testing and the manufacturer does not want the expense of testing the device with different batteries.
2. The battery scale is inaccurate with rechargable batteries
3. The device is not protected. Rechargable batteries can deliver more energy with a short circuit
4. The device is very low drain ( like a multimeter) and uses the battery voltage as a reference.


With 1 and 2 it is usually still safe to use rechargable batteries, but 3 can be more risky. 4 is the only category that will not work.

These warnings are rare anyway.

A final note is that rechargable 9v batteries are often not very satisfactory, because of the high number of small cells. As these are often used in very low drain devices rechargable batteries are not a good choice anyway.

 

[greenalien]

I am moving over to grandcell rechargeable Alkaline battery's

I have used - and still use - 'Pure Energy' rechargable alkaline batteries - however, it's important to not run them even close to flat, and they can leak, especially if they are left in a partly discharged state. They are quoted as being rechargable up to 25 times, which is a lot less than other rechargable technologies. I would be interested to know how the Grandcells compare.

rechargable 9v batteries are often not very satisfactory

I've just built a headphone amp that uses a pair of rechargable (NiMH) 9v batteries - and they work very well indeed.

 

[ctva]

...There are rarely, some devices that warn not to use rechargable batteries. This is because
1. They have been through licence testing and the manufacturer does not want the expense of testing the device with different batteries.
2. The battery scale is inaccurate with rechargable batteries
3. The device is not protected. Rechargable batteries can deliver more energy with a short circuit
4. The device is very low drain ( like a multimeter) and uses the battery voltage as a reference.


With 1 and 2 it is usually still safe to use rechargable batteries, but 3 can be more risky. 4 is the only category that will not work....

Apart from the multimeter above (useful info which I did not know), I've never found a device that will not run on rechargeables. Has anyone got an example of one that they have found or is it all just hearsay put about by the alkaline battery producers?

 

[noelex]

I've just built a headphone amp that uses a pair of rechargable (NiMH) 9v batteries - and they work very well indeed.

Those electronic projects are great fun. If It uses the batteries in parallel and you build another one consider using 7 AA batteries. They would not be much bigger than 2x 9v ( usually 8.4v) . The energy density is much better 7AA batteries will last almost 10x longer than 2x9v. The AA batteries are more durable and would be cheaper.
Even in series 14 AA batteries would be a similar cost, the case would be larger however.
You can also use low self discharge batteries which are usually much more practical.
If you have some knowlege of electronics the Lithium rechargable batteres are often even better. The cells are about 4v so not many are needed, they have very little self discharge and much better energy density.

 

[rogerthebodger]

I have used - and still use - 'Pure Energy' rechargable alkaline batteries - however, it's important to not run them even close to flat, and they can leak, especially if they are left in a partly discharged state. They are quoted as being rechargable up to 25 times, which is a lot less than other rechargable technologies. I would be interested to know how the Grandcells compare.

Have a look at my local grandcell supplier web site

http://www.grandsolar.co.za/techtalk

We have used 3 of there solar lights on our boat for the last 2 years with no problem with the battery's and they have twin LED's and last all night with no dimming. Only had one set leak after the 2 years.

SWMBO has lots in her garden for the last 5 years and are just starting to replace some of the batteries.

 

[TQA]

These guys are battery suppliers to the model rc world and really know their stuff.

http://www.overlander.co.uk/batteries-chargers.html

Get some Nimh cells and a 12 volt charger plus some plugs to fit the charger..

Get some battery holders, Maplins do them if Overlander can't help.

http://www.maplin.co.uk/search?criteria=C+Size+Battery+Holders

I use 8 cell holders and wire it up so that one side charges two at a time, the other four. N.B. you can not charge 4 + 2 at the same time the way I wire it.

Works for me.