Charging NiMh batteries

[ge_rik]

I'm just wondering if I can re-start the discussion on NiMh batteries which wandered off topic and then cropped up on another thread. So, to pose a couple of questions to which I'd still like some answers:

1. A General question - what are people's experiences in using NiMh batteries either as a loco power source or to power other equipment? Are they reliable

2. More specifically - has anyone experienced problems when recharging NiMh batteries? I've heard of cases where Low Self Discharge (LSD), Eneloops or ready-charged batteries are giving confusing readings to smart chargers which prevent them from charging up fully.

The reason I'm asking is that I've only recently invested in a quite few of these and although I personally have not experienced problems so far, I have only been using them a short while and wonder what the pitfalls might be.

Please feel free to reiterate what you've already posted elsewhere as I think it might be useful to bring together these thoughts into a single, focused thread.

Thanks

Rik

 

[Keith RhB]

To answer your questions first Rik,

1) My experience with NiMH batteries has been mixed. Non-Eneloops were absolutely terrible at holding a charge, meaning if I wanted my batteries in my navigator to last a few hours during an open house I would have to charge them the day of or night before, and have spares on hand. Since switching to Eneloops (mine are Sanyo, 2000mAh's) it has completely changed things: now I never have to worry about not making it through, or having to charge them the night before. For example this winter my navigators won't get used much and by Spring they will still have most of their charge. So in summary, since changing to the Eneloops life has been as good as it can be dealing with batteries.

2) Never had a problem charging the Eneloops but in general batteries don't like to be fast-charged. I can't remember how long they take to charge but it's a few hours for sure. Before I had the Eneloops I tried never to use the fast charger unless I absolutely had to--I preferred the trickle charge which usually took overnight.

I should say that my navigator is wireless, radio for N/A --nothing exotic or high output etc.

Keith

 

[ge_rik]

I've taken the liberty of copying and pasting the relevant posts from the other thread about this topic. My apologies if this offends or repeats what's already been said - but i felt there were some useful contributions on there. Let me know if you'd prefer me to remove any of your parallel contributions from this post.

Rik

I think you may be referring to the discussion that recommended using Sanyo Eneloop rechargeables. These have now been replaced by Panasonic - probably due to a company buyout. Anyway, on the strength of the discussion, I went out and bought 4 AAs with a charger and 4 spare AAs. All brand new Panasonic Eneloops 2100maH, with a rapid charger. These were for use in my Dimax Navigator. I duly loaded 3 of the batteries from the charger, straight out of the packaging, into the Navigator and proceeded to program it with some track routes. I had probably only used it for 10-15 minutes and the thing switched off! I think the so-called pre-charged batteries were exhausted. This somewhat surprised me. Anyway, I loaded 3 of the batteries from the spare package and completed my programming task. Less than an hour later, the charger had apparently fully recharged the first set of batteries.

This was of some concern as well - as it should have taken at least 2 hours, according to the manual, if the batteries were really discharged. I will reserve judgement on these batteries until they have done a few charge cycles, but the initial indications are not good. To be continued...

I also find rechargeable batteries in a Navigator a bit unreliable. I was told some while ago that the voltage on a rechargeable is less than a standard battery and this can effect some electronics. I understand that rechargeables are 1.2V as opposed to 1.5V from standards.
I now use standard non chargeables in the Navvy and only use a few sets a year despite frequent use for hours on end.

Your comment about the 1.2V rechargeables is correct. I am not sure this is the whole story though. I also have a set of COMBO instant power rechargeable NiMH batteries that I have been using in the Navigator for a while. These are also rated at 2100maH and are only 1.2V and have a rapid recharger. They were made in China. These seemed to have a reasonable life, although I tend to recharge them after each day's use - mainly as I wanted to be sure they were fully charged at the start of each session.

I went for the new batteries because of the recommendations and because I have just upgraded my Navigator with the higher power R/C board, to improve its range. The range is now excellent for my needs, but I figured the drain on the batteries would now be greater. Anyway, the jury is still out, for me, on which batteries last longer, but the idea of going back to 1.5V non-rechargeables is not out of the picture. Maybe the more expensive lithium ones? So long as a rechargeable lasts for one full days use, it would still seem to be the most economical, if it really can be recharged 2000 times. However 15 minutes is not on!!

As regards 1.5 volt cells, I found that the Ever Ready ultra lithiums were perfect for Navigator type cabs. From memory on one set I got nearly two years usage. They are not cheap but are reliable (around $20.00 for a pack of four).

Rik

 

[GAP]

My experience with NiMh cells, has been very good touch wood, but I use tagged cells from an electronics trade supplier to build my loco batteries, my motto buy quality and it should last.

In my transmitters I use Hobby King LSD cells and have had no problem with them at all, I found that they hold the charge better then non LSD when on the shelf but when the transmitter is getting a flogging then they are the same as non LSD in performance.

I did find that removing batteries if possible from the device they are powering and storing them in a cool dark place helped reduce discharge of non LSD batteries/cells.

In my time in the services we used to store our cells for refurbishing portable radio batteries in a fridge till they were installed, the batteries were then discharged via a load (light bulb) then charged before being put on the serviceable rack. When they were required a top up was done prior to issue.

In 1:1 aircraft world the batteries are cycled through a discharge / charge cycle using chargers designed for the purpose but then they are required to perform at all times.

My charger at home is similar and instead of applying a constant charge to the batteries it produces a charge voltage/current cycle then a rest cycle. The cycles happen about once every 5 seconds and I can set the charge current. This is the beasty https://www.master-instruments.com.au/products/57859/MW7168.html

Now if we are talking the cheap and nasty things from evil bay then that is a whole different story.

The other thing I have noticed is that most people focus on the voltage of their batteries when the capacity has more effect over usage time eg a 2000mA/Hr battery can supply 2000mA (2A) for one hour (or 1ma for 2000Hours) conversely a 4000mA/Hr battery will in theory last twice as long.

Now the variables kick in when comparing battery life, what is the battery driving a transmitter maybe?
Then power consumption will be greater than if powering a receiver, likewise a string of incandescent globes will drain a battery quicker than a string of LEDs.

Another thing is to keep in mind is that even though the controllers etc are the same externally they will all have different power consumptions. This is mostly due to the differences in electronic components (It is known as production spread by chip manufactures.)

Any way enough of my foaming/frothing and back to the debate.

 

[beavercreek]

I think this site could be useful...if only for non-rechargeables

http://www.batteryshowdown.com/results-lo.html

 

[spoz]

Most of what I would want to contribute has been said, I think (although I have no idea what a "navigator" is, other than the officer who navigates a ship), except to repeat the comment that eneloops seem great to me although before I came across those I also had good outcomes from standard NiMHs in locos. But it is important not to try to charge them too fast, that seriously reduces the battery life of almost any type of battery; one should not exceed 0.5 C where C is the capacity of the battery (not the voltage). So a 2000 mAH battery should not be charged at over 1 amp, a 950 mAH at no more than 450 mA. Indeed, I usually charge my 2000 mAHs at 500 mA. I monitor how much I put into each battery when I charge and record that against the battery capacity and I have yet to see any significant fall off in the capacity of the eneloops; although to be fair I haven't had too many problems with normal NiMHs in that line either. They do leak charge in storage more though.

However, as I reported somewhere else (and I can't find it) I did have an NiMH battery group stop taking charge, and on inspection had leaked badly. I think it may have been a duff battery but I don't know; it was about 3 years old at the time and hadn't been through all that many cycles. That remains my only problem with them.

 

[GAP]

For the record, a Navigator, in this case, is a handheld controller from Massoth that can be used, in wireless or tethered mode, to supply DCC commands to the track, via a DIMAX 1200Z command station. It requires 3 AA batteries.

My thoughts after watching this thread.

Not having any experience with the Navigator but from the description I would hazard a guess that in wireless mode the power demand will be far higher than in tethered mode.

The main reason that in wireless mode the unit would be driving a power amplifier (a high current draw component generally) to achieve the required connection while in tethered possibly only a data transfer component will be required with lower power demands.
If the system has constant 2 way communication then the transmitter on time will generally be long thus increasing power consumption.

My suggestion is to increase time between charges is to use the highest capacity AA's ( Biggest MA/Hr number) that you can get. Also as previously mentioned removing the battery after use will prevent any leakage through the device.

 

[stockers]

Several Navigators at a garden meet.

 

[KeithT]

Oh joy. NOT!

My wife organised a Christmas tree festival at her church over the last two days. She took along 10 donated trees which were to be sold . In addition, she took our prized artificial tree which is about 3ft tall and has small crystal "lozenges" arranged along silver branches. Very attractive. It was fitted with two sets of LED lights and to ensure that it performed over the two days I fitted 6 of my Best performing 2800MaH rechargeables.

What did she do?


Sold it for a fiver!!

Bb#%%#y H#%%!!!!!!!!
I don't begrudge giving for charity but that lot for a fiver...............? I need a lie down and many large whiskies. :-(. :-(