quick chargers

[Gregg Feldstone]

Do quick chargers wear out batteries faster than 1hr or trickle chargers? I am only concerned with NiMh or NiCad batteries, no Lion yet.

[Gregg Feldstone]

any thoughts?

[Barry Vabeach]

Grigg, I am no expert, but understand that heat kills batteries. so long as they stay cool, I would guess that a quick charger is as good, or better than a longer charger. The manufacturers used to warn against leaving the battery plugged into the charger too long and said it would shorten the life of the battery. One other thing I read is that the lighter the charger, the better , the light charger apparently has a more sopdisticated charging system that is friendlier to the batteries that the heavy charger. IIRC, NIMH is supposed to survive more charging cycles than NICAD, all other things being equal, though the NIMH discharges on the shelf much quicker than NICAD, so you may end up charging it more frequently.

[Scott Conners]

NiCad and NiMH both suffer from the memory effect, but NiCad is much more effected. What this means is that if they are not fully discharged before they are recharged, they won't take quite as much of a charge, and will slowly lose capacity. Charging slower has two major benefits, with one being that the battery doesn't get as hot, which is better for the life of the battery, and it gives the cells in each pack a better chance to even out and each take a full charge. On some chargers, the voltage peak is not detected as precisely during a fast charge, which can stop the charge slightly before a true peak.

Because battery packs use multiple cells which use a chemical reaction, the cells won't necessarily drain evenly. It's a good practice to "balance" the cells in a pack every once in a while if you can - this involves fully discharging the battery before a nice slow 1/10 capacity (2000MaH batteries get charged at 200Ma, and will take 10 hrs to charge) charge, with a long period of trickle charging at the end. The trickle charge is small enough that a cell that is completely charged will bleed off the excess and stay peaked, but any cells that still need juice will slowly fill up, somewhat like filling an icetray from one end. This is what the chargers with "auto maintenance" modes do when left on overnight - they use a small trickle charge to help balance cells.

I typically "recondition" my packs when they seems to be losing capacity or function. This involves cycles of complete discharging and recharging at very slow rates, letting the cells balance and lose memory. Generally on a fully functional pack this can bring a lot of life back, especially if they'd been mistreated. If a cell has actually failed, the pack might act like it's not taking a full charge when in reality it's 1 cell that has stopped working, making the battery peak out 1.2V lower than normal, and often it will raise the resistance of the pack so the rest of the cells can't deliver full power either.

So the short answer is: Yes, they will wear out faster, because the chemical reaction is finite and the higher current of fast charging is less efficient. IS the difference significant? For me, the answer is no. I condition/slow charge when I can but, fast charging is really useful and sometimes necessary thing.

None of this applies to Lithium batteries, they work completely differently, with no memory to speak of and a full discharge would permanently damage a Lithium battery.

[Tom Veatch]

Gregg, the best, most trustworthy advice can probably be obtained from the battery manufacturer. But, as Barry said, the battery killer is heat. The old chargers were little more than a transformer and rectifier and charging was based on time, i.e., leave a discharged battery on charge for X minutes and remove it. The problem occurred when you put a partially discharged battery on charge for X minutes it would be fully charged in Y minutes and for X-Y minutes the battery was being cooked and damaged by the high charging current. That damaged a lot of batteries and gave rise to the "discharge the battery completely before charging or it'll develop a memory and won't take a full charge" idea came from. (Ref: http://www.repairfaq.org/ELE/F_NiCd_Memory.html )

That's not a problem with the newer generation chargers since their sensing circuity determines when the battery is fully charged and reduces the current to a trickle or maintenance level to limit heating the battery. As long as the battery is taking the charge, there's little heat developed. It's when the battery stops taking a charge with no reduction in current that the heat begins to build up and commences to destroy the battery. It's more damaging to the battery to leave it in the summer sun than it is to put it on a modern "quick" charger.

[Gregg Feldstone]

Thanks for your replies....they were very helpful. Does anyone know if the Bosch chargers work as trickle chargers after a battery has a full charge?

[Karl Brogger]

Most of the chargers switch to a trickle charge once the battery is full.





I love Port A. Went sailing down there a couple of years ago. I will never camp on a beach again though. I'm still digging sand outta misc places:D