Batteries

Are most of you as confused as I am about batteries ?

There are several sorts of non-rechargable batteries but all claim to be longer lasting and higher power so it's hard to tell which to choose. For example, what sort would I need for an alarm clock or a room thermostat. Would it be "Alkaline power, 50% longer lasting" (even short circuited !) or "plus, 100% extra life". And perhaps, judging by the size, for something a little heavier duty, "Pro power, advanced, long lasting energy". Because most of us, unfairly, apply common sense we need to know whether it's long life at low power or short life at high power and it's difficult to tell which from the labelling.

Rechargeable batteries are a much larger minefield. IIRC there are 7 types of rechargeable battey commonly available at the last viewing each with its own energy storage, discharge and recharging characteristics. Although I conscientiously read through the paperwork on purchase of a new device (drill, lawn mower, hedge trimmer, vacuum cleaner, etc.) I'm usually not clear about how I should react to the information. In any case, it would be wonderfull if I could remember it all when it comes to the next recharge. Some need to be totally discharged before recharge for maximum life, others are damaged if allowed to discharge below 50% charge (how do I tell ?), yet others are ruined if left on charge beyond the full charge point, etc.. I'm not into electronics but would it be beyond the current state of technology to provide batteries and chargers with inbuilt provisions for correctly charging these products ?

I'm not expecting solutions but would be interested in comments, particularly from those with the knowledge to deal with my last point.

1. get a battery tester

2. If an item conks out with 2 duracell batteries then test them, often only one is a dud

Nowadays I mix my batteries, one duracell and the rest rechargeable,

This setup isn't so long lived but most of the time it's a rechargeable which needs changed and so only costs pennies after the purchase (Lidl gear mainly)

The best basic stuff is duracell rechargeables + fast charger but they aint cheep

For very low batteries which struggle to recharge I use a hiking portable solar recharger box to get a bit of power into them, these use a very low trickle charge, just stick it on a window sill for a day or two and If the battery still won't charge up after that then in my house its a dud

I recall something concerning freezers/fridges... but a long time ago now

Edited By Ady1 on 01/02/2023 16:38:57

You should NEVER mix alkalines (primaryvcells) and rechargables (secondary cells). The problem is when the first rechargables cellis discharged the alkaline(s) charge it in reverse and permanently damage it.
Ideally you shoul keep even cells of the same make and capacity in sets that are used and charged together.
for primary cells I tend to buy Energiser alaklines these days. They seem to have a better chemistry than Duracell for combating the leakage issues that developed with alkalines when mercury was banned in them.

Robeert G8RPI.

There was a recent Which? review of AA/AAA batteries which is worth looking up. Overall Aldi were much the best value for money!

There was a programme on the BBC recently about some tests of basic cheap AA against expensive makes and none of the premium ones gave more than about 1.5 times life let alone their extra cost factor.

The programme was "Sliced Bread" - they do somewhat informal but interesting comparisons of this kind of thing. The title comes from, "Better than Sliced Bread or just BS?"

One issue seems to be that, say, cheap batteries are fine for low-consumption items but expensive batteries better for high-power loads. Or maybe it's the other way round!

I use a fair number of AA batteries in wireless radiator thermostats which last around 18 months. I use mid-price cells from a supermarket which seem ok, but few of us are in a position to really test these things scientifically. It's all a bit like car fuel consumption - "real world" is all very well but whose world are we talking about?

Chris,

If you can’t remember about the discharge/recharge details, write it down - on a sticker stuck to the item in question.

Next, most Joe Public call single cells a battery - which they are not. I doubt you've ever seen a WWII anti-aircraft battery with one single gun? Only when more than a one cell is it a battery.

Rechargeables.

Lead/acid - best to never discharge below 50% (for most types) and recharging immediately, or soon, after using is an important factor for longevity. Automotive batteries should not even be allowed to discharge to 50%, these days - they are designed for minimum discharge but very high current output (the starter motor on a cold morning start). Recharged by constant voltage (due to gassing off if charged at a too high voltage - again for most types). Voltage is a good measure of state of charge for these cells.

Lithium Ion - Best used between 80% down to 20% for longevity, but can be charged to 100% (but definitely not above) and can be discharged to quite low levels (but never fully discharged). In both extremes, damage to the cell(s) will likely occur - particularly that of catching fire, for some chemistries). Discharge and recharge currents can be high, but generally constant current chargers are the order of the day. Think here electric car batteries - older types were limited to lower charging rates - and cars need high current discharge for rapid acceleration.

Most good batteries will have an electronic battery management system (BMS) to maintain the battery parameters to the safe usage limits (maximum and minimum voltage, maximum current drain, temperature control, frost protection, cell voltage balance across the battery and probably etc).

Nickel metal hydride (NMH) - Longish charge times (8h?), reasonable discharge rates, but cannot be completely discharged without damage or destruction. Serious over-charging will damage the cells (usually swell and can split).

NiCad - No longer available due to the Cadmium content. Used to be important to discharge fully before fully recharging - to avoid dendrite formation which kills them.

Nickel/Iron (NiFe) - can be very long-lived. Good for short term storage but self-discharge quite quickly. Not so efficient over the recharge/discharge cycle. But can last almost forever!

There are lots of other chemistries being developed. Lithium ion variants, I expect, are among your group of seven? Remind me of the others.🙂

Non-rechargeables

Lithium ion button cells - potential long life, lowish powers,

General button cells - various choices of chemistry, different capacities and life spans. A whole range of sizes for driving things like toys, digital calipers, LED torches, etc. The most common cells that are swallowed by infants and small children!

Alkaline cells - good for high power uses. Some can be carefully ‘recharged’ a limited amount, but not recommended. Recharging can cause them to over-heat, leak and even set on fire!

Zinc/Carbon - cheapest and oldest disposable cells. Use and discard. Lower power uses and special types for low current with long life are available (clock cells)

Air cells - typically as used in hearing aids. Safe, use once and discard without special concerns.

____

They all have marketing hype which can be addressed by looking up the cell specifications (capacity, output, life expectancy, storage before use, etc. Not worth too much trouble as ‘you pays your money and….’.

With some typical Lithium workshop power tools the BMS can be onboard the battery or within the dedicated charger for that type of battery.

Separate cells, used in series, are best recharged separately

Got to stop, here, as my wife needs some milk for her breakfast.

Another point worth noting is that alkaline cells are 1.5v per cell as opposed to only 1.2v for rechargables. This difference can cause some devices to become problematic. Then there is lithium cells at 3.7v. All a bit of a mine field if you don't understand. Noel.

Edited By noel shelley on 02/02/2023 10:43:26

which is why some devices show flat batts but are technically not as the device requires to see a certain voltage which a rechargeable seems to drop below even when it still has plenty of power below that voltage. Apple keyboards and mouse are susceptible to this.

Edited By bernard towers on 02/02/2023 10:41:04

There are Energiser lithium non rechargable cells in AA and AAA available in two grades which have the advantage of 1.7V. Costly, but I had no choice with my Pentax K100D camera which had a poorly adjusted voltage requirement which was greater than any rechargable or alkaline cell.

Edited By old mart on 03/02/2023 20:36:45

Edited By old mart on 03/02/2023 20:37:09

To clarify, my choice of primary cell is based on their ability to not leak in an expensive piece of equipment. I'm not bothered by a few mAh per penny cost advantage.

Robert.

Same here Robert, batteries are cheap compared to the equipment they power. I used to use Duracell industrial batteries but since watching this video <Edit and suffering some leakages> I have switched to Amazon basics low self-discharge NiMH cells, charged in their own overnight USB powered charger.

Brian G

Edited By Brian G on 04/02/2023 22:38:44

Not really my area of expertise but another difference between regular alkaline and NiCd/NiMh rechargeables is that the latter have quite a low internal resistance. In certain circuits this can cause excessive current flow.

The internal resistance is more important for efficiency of the battery. A low internal resistance can mean much less wasted heat produced from the cell. All to do with current (squared) x resistance losses.

Taking high currents from high internal resistance cells will clearly reduce the voltage available for the circuit.

It is short circuit situations where the low internal resistance cells can provide very high currents - and overheat or even cause a battery fire.. An operator problem, not a battery one, I would suggest?

The current drawn in any circuit will depend, to a great extent to the cell emf and the effective resistance of the circuit.

In some cases a direct short circuit where the resistance is low enough will cause the cell/cells to discharge explosively ! Noel.

A/k/a Ohm's law!

.

I couldn’t agree more, Robert

… and in my personal experience with Alkaline AA cells [going back to the mid 70s] Duracell has given me more problems than any other manufacturer.

It’s a clever brand-name, and their advertising is obviously effective, but I no longer trust the product.

MichaelG.

two comments

Canon camera manuals uswed to specifically forbid use of Ni cads presumably because mof the ability nto supply damaging high cuttents.

(They work very well in Metz CT45 flashes. (The mdry cell carrier uses a mdifferent connection npoint for the 9 volt supply mfrom the 7.2 volt NiCad. )

I smear both ends of alkaline cells with petroleum jelly before installation. This sems to prevent the corrosion / crystals that seem to seep out of the negative end, whether exhausted or not.

Howard

Similarly, it was very noticeable to me that rechargeables gave a much quicker flashgun recharge cycle rate.

....& Minolta photographers seem to have be the worst culprits for leaving batteries unused in situ for extended periods judging by the examples i've seen.

And whilst on the subject of leakage - what is the best method to neutralise the spillage from these batteries ?

Bob