Thread: Getting the best from NiCad batteries

Don't ever flatten them on purpose, and try to avoid it in use.

Read this about memory effect. Basically, memory effect is a salesman's excuse as to why the battery pack failed.

TL;DR version - Flattening pack causes the weakest cell in the pack to take a reverse charge. Good packs have cell capacities matched to minimise the chance of this, but as this takes time and charge/discharge mapping for each individual cell, it is an easy step to miss to keep the price down, and 'memory effect' is simple 'no, it is user error' explanation to get away with selling crap.

Thanks for that. Very nice explanation (yes, I read the whole thing

So basically; just use the battery/tool as you would normally and recharge as required.

It is what it is.

Originally Posted by Master Splinter

Flattening pack causes the weakest cell in the pack to take a reverse charge.

Is that why the occasionally a battery in my daughter;s toys will have a + and - a.r.$.e about?

Tools

We had AEG battery drills at a job where I was some years ago, and I considered them the best of the battery drills that I had used at that time. After five years of industrial use witha variety of users, the batteries were still viable, and probably retained about 80% of their original work capacity. The big difference at that time was they were one of the very few manufacturers that bothered to use matched cells and intelligent chargers to avoid overcharging batteries. I don't know if this remains true with AEG gear as I have moved to lithium gear of late

The two issues to avoid with Nicads are overdischarging individual cells in the pack (as per MS's explaination), and cooking the pack by overcharging it or charging at an extreme rate to achieve rapid recharge.

If possible, swap batteries as soon as they are obviously struggling to cope with the load, rater than taking them to the point where the tool stalls.

If your unit is a positive evolution of the units I used some years ago, the manufactureres should have done a reasonable job of avoiding ovoiding overcharging or excessive charge currents. If it's not a positive evolution, who knows.

With regard to memory effect, the best insurance against this is regular long slow charging which allows each cell to fully charge without cooking other cells by overchargiing. Not sure if your unit can provide this.

Originally Posted by malb

With regard to memory effect, the best insurance against this is regular long slow charging which allows each cell to fully charge without cooking other cells by overchargiing. Not sure if your unit can provide this.

Nah. Just a fast-charger with my tool. But I will be sure to avoid over-discharging. It's interesting: I have seen a few other forums that suggest "discharging completely" the first few times, but based on the advice here that would appear to be faulty advice.

I'll stick with what you guys have told me, as it seems to be based more on science than a 'vibe'.

Very, very happy with my new drill so far (just done a few repairs around home at this stage, but it has handled driving 100mm screws into treated pine (garden box) and 20mm galvanised self-tappers into a very, very hard mountain ash tool cupboard, both without pre-drilling.

I even had a crack at drilling a hole in an old brick (just for fun), and managed a 10mm hole without too much effort.

Batteries will be tested this week on the job, but mainly driving self-tappers into pine, so I think it'll be okay.