Replace NiCad with NiMH cells Makita [UPDATE]

Looks good - where did you get the cells, please?

NiMh are fine if you are using them regularly but have a much higher self discharge rate then NiCd how regularly do you use that drill ?

This used to be true, but I don't think its like that now as long as you do not buy the very highest capacity for the size types in my experience. Brian

PeterC pretended :

They took 25 days to be delivered from HK at a cost of 2x £8.42. I intend seeing how these pan out and probably order another set to rebuild a second pack. The tags were strip type, quite narrow, each sleaved with shrink sleaving and easy to solder. I had to fold some, so as to exit in the correct direction to match the build.

To reply to the other question - my drill gets used infrequently, but I usually make quite heavy use of it when I do. Maybe once a fortnight. The voltage has not dipped, since I initially charged them 3 days ago.

If they really are as good as you say, remarkable value.

Does the drill have as much torque as with the originals when they were good? This is often the giveaway with replacements - they can't deliver the same peak current.

Dave Plowman (News) brought next idea :

Difficult to be sure, but I would say yes. I cannot stop the drill with my hand, without risk of a friction burn when it runs at full speed.

Yes, I've found this also replacing Nicad with NiMH.

Looks good - if you'd let us know how they seem to hold up please, I'll order some if good.

On an 18v drill? I'd hope you couldn't stall that with your hand even with the old batteries.

For that price I suspect there is something fishy going on. I realise that shipping has some subsidy, but the price is too cheap. Additionally that package weighs about 400g which hits the pricey end of shipping from China (I think they would pay about $20 shipping)

UK suppliers are about 3-4 pounds per cell and most of the cells on the market are 3.3Ah or thereabouts, while these are 6Ah. A fun trick to making 'larger' batteries is to take an AA NiMH, put it in a C/D cell case and surround the outside with cement so that it weighs about right. A Sub-C NiMH should weigh about 55g - would be interesting to know how much yours weigh.

It may be they're production failures, which might be managed by having overstock and swapping in cells as they die. But I suspect they're flat lying about the capacity for starters.

Theo

Probably a little of all of them

You can get tagged sub Cs @ 5Ah for around £5 a cell...from overlander

Other places around £4 per cell for 4Ah...

Agreed. They simply seem to be too good to be true at the price. Hence my question about the drill performance - maximum current delivery is a very good test of a cell's quality.

Of course they may be adequate for light use of the drill, and better than knackered ones. But the other test is just how long they last in service. Batteries seem to be one thing makers get away with not providing any real warranty with. Making them a prime target for fraudulent selling.

The batch of 8 x (so called) 10Ah C NiMhs I bought on eBay from China all tested out at around 1.7Ah.

When I posted the results of my automatic / electronic tests of all 8 cells over 5 complete cycles they offered a full refund citing 'production batch issues' ... but when I asked if (therefore) that my purchase of a second batch of the same should give me a good chance of the 'good' cells, they suggested I buy them from elsewhere. ;-)

Before I purchased I had seen negative feedback citing similar observations but I was just interested to test them for myself.

Cheers, T i m

My 18V Mak couldn't be stopped, then the batteries died (both at about the same age - suspiscious?). Fully 'charged', I can't stop it but after a couple of goes I can.

I think there are several wheezes they're using:

One is that the real test of cells is their longevity. Top end laptops spec their batteries have 80% capacity at 1000 cycles, and they mean it. A lower quality battery might only get 250 cycles. You only get to find this out several years down the track, long past any 'buyer protection' has expired.

Then they rely on consumers buying in small quantities and not bothering to complain if the product is junk - because they're not buying again and it isn't worth it. Nobody is going to be sending faulty parts back to China.

And also 'buyer protection' turns out not to protect future buyers. I recently opened a case about an eBay listing where the seller said the item was in the UK but actually came from China and didn't turn up after two months. The seller just refunded me my 99p and it erased all history of the transaction - which meant I couldn't neg them for lying on their listing. So, while it lands up some black marks on their eBay record (which they can fix by just making a new identity and starting over), there isn't much comeback for buyers if they complain.

Theo

'Vaping' batteries are an interesting one. Usually Li-ion, they often come in a sealed housing with switch and overload protection etc, and shut down before totally flat. Normal sort of load on a single cell 1500mA.hr one is about 2 ohms. So quite heavy. And in plactice, you might be lucky to get

Luckily for extra cost you can get a so called MOD type. This is a case plus electronics with replaceable cell(s). And a 2500mA cell costs about 8 quid - under half that of the smaller sealed units. And hopefully will last more like the claimed 500 cycles or so - looking good at the moment.

Theo laid this down on his screen :

This is true of everything I get from China. They seem to have some special deal on shipping.

Most of what the UK sellers offer, is imported from Chinese suppliers anyway - they just double the price in the UK.

Certainly they are lying about the capacity. it is a given when buying batteries from China. I have been satisfied with all the batteries and cells I have previously bought direct from China, ignoring the wild capacity claims. It has had a bit of use this morning and the battery voltage is still close to 20v after its had a rest.

I suspect the shipping regulations insist they are sent out close to flat condition.

Dave Plowman (News) explained :

I now source all of my vaping needs direct from China, including the liquid. I have had zero issues in the two years I have been doing this. Hardware costs are around 60/70%, liquids around 20/30% of UK prices. My two batteries are now 24 months old and still good as new.