Arduino Forum

Using Arduino => General Electronics => Topic started by: Boardburner2 on Oct 10, 2016, 11:12 pm

Title: New batteries.
Post by: Boardburner2 on Oct 10, 2016, 11:12 pm
I needed a 4 cell flight pack for a model and purchaced 4 x NIMH cells from maplins.
Getting them home i measured 1.25V per cell.

Went back to check the packaging which i had discarded.

The advertise the advantages of alkaline and NIMH ??

Also had some other rechargeable cells (Nickel Zinc) with a 1.6V potential.
Thy also say that they retain their charge well for a long time.

This does not coincide with my recollection of nickel zinc cells.
Also have a good power rating, but need another dedicated charger.

What am i missing ?.
Title: Re: New batteries.
Post by: outsider on Oct 11, 2016, 12:42 am
Well, the NIMH cells I use (RayOvac & Energizer) are rated nominal 1.2V and full charged up near 1.4, alkalines are usually around 1.6 when new, I'm not familiar with nickel/zinc.
Title: Re: New batteries.
Post by: MarkT on Oct 11, 2016, 12:52 pm
NiMH are about 1.3V during operation (a little higher than the NiCd they replaced, but drop
noticeably during discharge).  NiZn are 1.7V or so and need different charger (or a modern smart
charger that can automatically figure it out).

NiCd  1.2
NiMH 1.3
zinc-carbon 1.5
alkaline 1.5
NiZn 1.7
Pb/PbO2 2.0
non-rechargable lithium 3.0
LiFePO4 3.2
other Li-ion and LiPo 3.7

New rechargables are usually sold without much charge, so the first thing you do is charge them.
Title: Re: New batteries.
Post by: Boardburner2 on Oct 11, 2016, 01:32 pm
New rechargables are usually sold without much charge, so the first thing you do is charge them.
Sigh.
I deliberately went for a NiMh knowing i have a charger.
Sadly it does not like whatever these things are.
Title: Re: New batteries.
Post by: Noobian on Oct 11, 2016, 01:35 pm
eneloops are sold pre-charged they have a lower self discharge compared to ordinary NiMH.
Title: Re: New batteries.
Post by: Boardburner2 on Oct 11, 2016, 01:45 pm
These would appear to be an own brand version of eneloop but say on the side charge before use.
Title: Re: New batteries.
Post by: gpsmikey on Oct 11, 2016, 04:58 pm
The chargers I have (Maha etc.) all take both NiCd and NiMH batteries, but they do recognize the difference in them and charge accordingly.  I have both a Maha Powerex MH-C204W Rapid Battery Charger  and La Crosse Technology BC-700 Alpha Power Battery Charger that handle both NiCd (which I don't have many of any more) as well as the NiMH very well.  If you are looking for a charger and you tend to be mobile at all, look for one that comes with a 12v adapter - often they come with not only a car adapter, but a 12v universal wall-wart that can be used world wide.  I have not played with the eneloop batteries at all although I notice that Costco carries them with a charger last time I looked (at least here in the US)
Title: Re: New batteries.
Post by: INTP on Oct 11, 2016, 05:18 pm
Eneloops are what I've stocked up on. Low self discharge is great, not prone to leaking and corroding and ruining devices like alkalines do is great.
I think nowadays most rechargeables will come ready to use out of the package as the tech has improved for low self discharge. They are not charged to 100% iirc at the factory. Maybe shipping/warehouse/store shelf sitting stability is the reasoning.
Title: Re: New batteries.
Post by: gpsmikey on Oct 11, 2016, 05:50 pm
I remember reading somewhere that LiPO do best stored partially charged.  As for the other technologies, the big danger with not charging them before use is (especially in higher current applications) is if they are in series and one is very low while another is fully charged, you run the risk of reverse charging the very low one which is bad for the cell.  Better to start with them all in the same state (and use ones with the same mah capacity).  Batteries can do bad things when abused - I just saw on the news that Samsung has halted their Note 7 after several of the replacements for the ones with battery fires also had battery problems on an airplane which really gets people excited !!  :o
Title: Re: New batteries.
Post by: Boardburner2 on Oct 11, 2016, 08:16 pm
I remember reading somewhere that LiPO do best stored partially charged.
 Batteries can do bad things when abused - I just saw on the news that Samsung has halted their Note 7 after several of the replacements for the ones with battery fires also had battery problems on an airplane which really gets people excited !!  :o
38 or 40 % are often quoted as optimal storage for lipo and lion batteries.

Lipo are scary though lion less so.

Puncturing a naked lipo is easy and the results are scary.

Excited-.
Seems even the experts get it wrong in the world of smaller is best.

The chargers I have (Maha etc.) all take both NiCd and NiMH batteries, but they do recognize the difference in them
I have an expensive clever charger which charges anything.
Too clever by half.

Could not afford the prophecy version though so this new battery does not work.

Keeps telling me i have a damaged lipo , charger is only designed for 2 cells upwards so not sure why it does that.
Title: Re: New batteries.
Post by: Boardburner2 on Oct 14, 2016, 01:04 pm
Finally got them charged.

Terminal voltage is 1.43 V so i am still not sure what i have.
Title: Re: New batteries.
Post by: MarkT on Oct 14, 2016, 01:22 pm
Are they hybrid NiMH then?  They are supposed to hold charge much longer than 'standard' NiMH
(which discharge in a month or two).  The problem with NiMH is it covers many slightly different
chemistries, such as the metal M (often but not always lanthanum) can vary, the electrolyte might
be formulated differently, and all these have some effect on the charge/voltage profile.  An old
charger might be too fussy for newer versions.
Title: Re: New batteries.
Post by: Boardburner2 on Oct 14, 2016, 02:06 pm
Not sure Maplins do theit own brand version of Eneloop which is hybrid , 1.6 V.

This is something else, again own brand but its only in the shops not on the website so i cannot post a link.

I am going there later and will have a closer look at the packets.
Title: Re: New batteries.
Post by: Boardburner2 on Oct 14, 2016, 03:01 pm
OK its these.

http://www.maplin.co.uk/p/maplin-nimh-extra-high-capacity-rechargeable-2400mah-aa-batteries-4-pack-n05bw (http://www.maplin.co.uk/p/maplin-nimh-extra-high-capacity-rechargeable-2400mah-aa-batteries-4-pack-n05bw)

My older NiMh charger (maplins) did not like them.

Q and A indicates 1.2 V.
My newish digital battery gauge is confused and 24 hr off charge i measure 1.4V.

Considering they have had some load i suspect they may be hybrid wrongly labelled as NiMh
Title: Re: New batteries.
Post by: MarkT on Oct 14, 2016, 07:21 pm
This seems relevant: https://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery#Low_self-discharge (https://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery#Low_self-discharge)