li ion,ni-mh,ni cad?

[neilyweely]

I have got a few drills in the back room, there is a makita 8434 with nimh batteries, a couple of ryobi's with nicads, a couple of cheaper drills that are nicad, and a 32v macallister with nicads that I have to say is really quite good, it is a bit of a lump, but on closer inspection I found the batts are 2.6ah, and in practical use the drill will put a LONG screw in anything, at least as well as my impact driver, which is rated as 135nm.
Then I have a new li ion hilti.

Anyway, my question is kinda twofold; the different types of batteries, as I understand it, are all about lifespan; nicad having memory so not so good, and tempremental. The nimh have no memory, but experience a drop off in power as they get towards the end of their charge, and li ion, which with no memory and maintaining their power till end of charge, plus longer life, are mustard.

Bearing in mind the difference in price, which is fairly noticeable, does anyone think that it is really worth it. With companies now offering a 'battery for life' deal , and my 32v for 50quid still running strong on both the first gen nicads I am not convinced at all. I have heard people bragging about their de walt/makita from 1960 still on its first set of batts!

Also then is the question of the price of the bare drill; I have the hilti, which is lovely (well engineered and so on) but do i use it - NO. I always take the Ryobi set, and the drill has never let me down. I don't expect it to drill holes in walls for extractors, so it does ok. The 32v does my framework.

I think a lot of chippies/builders have these mad expensive drills etc for a bit of a status competition first and foremost - the amount of times I have heard someone say ' yeah, and this one was 5 hundred quid....'

Am I missing something?

Neil

 

[Rich]

Hi Neil, from what I understand, with the Li on you can charge it when ever you like, I understand with the other types if you keep charging the battery when they are not fully empty the "bottom" cells die and so the unit can never be fully charged and you only get say, 1/2 hours usage, anyway that's what the sparky at work told me.
regards,
Rich.

 

[neilyweely]

(edited) sorry mate - hello Rich, how are you?


yeah, he's right, but i have 5 ryobi batts, so.....

3 hundred quid for the hilti, as opposed to 50 for the ryobi, well I paid a ton for the drill, jigsaw, circ saw, hoover, angle drill and sander, with 2 big bags and 3 batts, all new, and a charger, which still had the plastic binder on the cable, and cover on the plug pins.

My point being I see bargains on Ryobi and the like all the time, but not on Hilti or whatever. I dunno, maybe this should be telling me something!
Still feel like I know something the rest of the world is missing, or vice versa.

It just is NOT that much better.

 

[Slim]

The main advantage with li-ion for me is the huge battery life. Simply because I always forget to stick the other one on charge. I can get hours out of my bosch impact driver, and when the battery does die, it is fully recharged in 15 mins.

 

[Nailer]

Am I missing something?l

Personally,i don't think so.....the power to weight ratio alone compared to the same voltage nimh should have you sold and if used on a daily basis,even more so.
Also the quick charge times are a big bonus.
I'm very impressed with the Makita range of Li tools atm and can't fault their drill/drivers and saw.

Hilti on the other hand are nice tools but i'm not prepared to pay their premium prices :shock: .....a bit like Festool i suppose :lol:

Cheers

 

[neilyweely]

I have the makita li ion recip saw, and yeah its great, i just don't think they are THAT much better.

The Makita nimh drill, is it better than the nicad?

And the Ryobi impact driver runs all day on one charge too. It keeps snappin screws though.

Do you have the mak li ion jigsaw? I think the jigsaw drains batts quicker than any other power tool. Or maybe it's just me, but I have real trouble with mine, how about yours?

 

[johnbs]

The NiCd "memory effect" is an urban myth: it is possible to demonstrate under laboratory conditions (discharging cells to precisely the same point many times before each re-charge), but once you stop this artificial regime they fully recover.

NiCd, NiMH and Lead-acid cells will all have their lives shortened by running deep discharge cycles: in other words, don't let any of them regularly go flat before re-charge. Especially true of lead-acid.

I'm not sure if this applies to Lithium cells, but many people have observed that no matter how they are treated, LiIon batteries loose capacity after about 3 years use (lap-tops, PDA's, Iplayers etc).


NiCd's and NiMh can give very long service life if correctly charged; (and correctly made!): NiCd's tend to suffer from dendrite formation if regularly charged with a unipolar source (constant current) , whereupon they go short-circuit and refuse to re-charge. It is possible to "blow" the dendrite away with a massive pulse of charge current, but usually this is a short-term fix: they seem to re-grow.

 

[neilyweely]

holy moley, thats what i call an answer!

Johnbs, bloody marvellous stuff, so are you telling me to stop running the nicads down to empty on the radio before re-charging?

I thought I was being SO clever too! I must admit the li ions on my laptop are suffering, so maybe you're right.

Can you tell me the best way to look after my nicad batts then please?
And the NimH, and for that matter the li ions?

Thankyou VERY much![/list]

 

[mailee]

I have the Makita 9.6V drill driver and have had it for around fifteen years and it is still on the same batteries! I always use them until it won't turn the screw with any power and then recharge. I am wondering if it is the quality of the batteries more than the type that determines it's life? JMO. :wink:

 

[neilyweely]

ok mailee, that is what I used to do, until recently when I read about someone draining their batts with a torch, and I started doing the same with a drill or radio.

So i guess I shall revert back to my old way of using batt til it loses power, and then charging. Trouble is, with the Ryobi stuff the batts seem to give up quite quickly, maybe I shall start taking the makita with the nimh batts with me.

Have already had the charger from my li ion makita set nicked, along with a batt, so that has rendered the tools useless, and my attitude towards taking tools on site jaded.

In fact, if anyone has an extra li ion charger they wanna sell......

Thanks folks, Happy Sunday!!!!

neil

 

[wizer]

I treated my Makita Ni-Cads the same as mailee. They lasted 3yrs.

 

[johnbs]

I thought I was being SO clever too! I must admit the li ions on my laptop are suffering, so maybe you're right.

Can you tell me the best way to look after my nicad batts then please?
And the NimH, and for that matter the li ions?

Oh dear: this is such a complex topic!!!!

If you've got a bit of time & energy you can pick up some general tips from a bit of Googling (cf http://www.motorola.com/testservices/article1.htm), but here's a quick summary of what I believe may be generally "cosher" (but there will always be exceptions!!)

1. As someone has just hinted, the intrinsic quality of any technology will be a major determinant of life: in other words, you tend to get what you pay for!

2. Setting aside the above, there are some general "rules" for maximising life:
- don't allow batteries to get too hot >40C? (for whatever reason), generally accelerates ageing and/or dries them out.
- don't charge cells/batteries at low or high temperatures; normal room temp is optimum (15-25C)
- don't fully-discharge any battery if you can avoid it: lead-acids will fail very quickly, Li Ion / NiMh next, and according to this site http://www.buchmann.ca/Chap5-page2.asp (which is actually a book-review with useful extracts) well-designed NiCds can last for 2000 cycles under lab conditions. However, there is an interesting fragment of text at the bottom of this page which quotes cycle-life v depth-of-discharge, but annoyingly not the specific technology.
This book also states that NiCd's cells go s/c if reverse-charged. Now this is a real risk in a battery pack when one cell becomes slightly "weaker" than the rest, and discharges first. The more cells in the battery, the more likely one will become weaker during use, and the less you are likely to notice the loss of 1.2v. As you continue to use your tool (!!), this cell may go s/c. Your intelligent (or not) charger will probably not detect this at commencement of charge, but towards the end may think the battery is "not quite there" and overcharge all the other cells (big caveat; some chargers terminate on more sophisticated criteria). Over-charging dries out cells.
- store batteries at the lowest temperature possible (exp. Lithium)
3. If the probability of an individual cell "failing" is p, then your V volt battery has a failure probability of p x V/1.2 (Nickel-based cells).
i.e I'd prefer a 12 or 14.4V system over the higher-voltage offerings available nowadays
4. As I said before, I'm less familiar with Lithium technology, but this comment confirms what I've experienced/ heard from others: http://www.buchmann.ca/Article9-Page1.asp
Unless you keep your lap-top battery in the 'fridge, it's unlikely to last much more than 3 years!!

Finally, remember that continuous advances in technology mean that what was true yesterday may not be true today!

 

[ivan]

My oldest 9.6V Makita stick battery is marked 1997, so 11 yrs old. The low power may mean a change in battery performance is easier to spot?

NiCd life depends a lot on the charger, which as someone said above has to work on a 2 steps forward one back basis, the small amount of regular discharge (50 x sec)makes the electrode reform with a smooth surface (electroplaters use this to get a smooth coating). Without this whiskers of metal can develop internally which grow and eventually short out the cell.

Some chargers work on a time basis and may overcharge the cell if it is still holding a fair bit of charge. NiCd anf MH cells gas internally when overcharged and have a venting arrangement for safety. Regular overcharge gradually reduces battery capacity (chemicals turned to gas and vented)

Whilst you should completely flatten a single cell, don't do this with a battery (several cells in series). The weakest cell will get a reverse charge as the stongest still give current. Interestingly, my Festool drill (12VNiCd) cuts out and tells me to change batteries well before I notice any fall off in performance. A better charger and an intelligent tool maybe one reason for the higher price!

LI batteries can be recharged at a very high rate and topped up whenever you like, but this flexibility costs you!

 

[andyavast]

I bought a Panasonic 15.6v driver with 3.0Ah Ni-MH batteries just over two years ago. The driver functions well for a while then the power just drops right off, it continues to run at high speed with no-load for ages, but that's just useless to me. I really don't think two years is a long enough lifespan... but I guess I do use it pretty heavily. I reckon I'll go for a Festool 12v driver next and use a Hilti 110v SR16 for all my heavy drilling and driving tasks in future.

 

[neilyweely]

oh my days gents, what the hell do you expect me to do?


I am going to use the batts till they need re-charging then re-charge 'em.
Hows that sound? Keep em warm-ish, but not the li-ions, which I keep in the fridge.(mrs'll love that). So I definitely don't empty the nicads, or the nimh, or for that matter the li ions. Is that right? Just use 'em till they need charging.

Thanks a lot guys.I gottsa have a think about this one!!!

 

[superunknown]

I have a Bosch gsr 9.6, that was new in 1995. The batteries have been completely flattened every time before charging. The 2 original batteries are still going strong.

I also have a Bosch 14.4 I guess I got it in about 2003 and that only got charged when needed, not run 'till completely flat. That needs two new batteries.

Did anybody see the video of the chap giving a new lease of life to his re-chargeable NiCd batteries with a welder?

http://www.instructables.com/id/Revive-Nicad-Batteries-by-Zapping-with-a-Welder/

 

[neilyweely]

oh dear oh dear, don't know if I can cope with this.

I am gonna do both, the black ones I will drain totally, and the yellow not. how's that? Ivan? Johnbs? Comments?

Thanks a lot guys, where else would you get this sort of info/opinion?

 

[johnbs]

I'm sorry Nola, and many others who've recounted their own (perfectly valid but one-off) experiences. We can't draw conclusions from information such as this when there are so many unknowns. I suspect your 9.6v batteries were NiCds and the 14.4v NiMh? And the chargers completely different? (oh, and I bet the 9.6v charger took longer than the 14.4??) And probably the internal cells were sourced by Bosch from different companies? So, which factor do you chose to be the one which explains your observation?

I'm sorry Neil: I've tried to give you the best advice I can. I'd stick to using common sense and charging (at room temperature!) a little before either battery shows signs of distress!

 

[neilyweely]

johnbs

No need to apologise my friend, education is NEVER a waste.

I really appreciate all the advice and help, you obviously really know your stuff, and I have learnt from your entries on the forum, as I suspect, have others.

Thanks very much John, I will do as you said. Best go with the main flow. eh?

Cheers again, and don't be a stranger on the forum, your sort of expertise is valuable, if only to me.

Neil

 

[Anonymous]

nicad having memory so not so good, and Neil

Not they don't!! And haven't for a great many years 10+. This is an old wives tale, urban legend whatever you want to call it - it is simply not true.

The memory effect in Nicads should have left people's memory years ago