Large Scale Central

Battery and Track Power

Electronics Power and Sound
#41
John Bouck said:
I'm still on the fence on this one. I started out with Nicads. They worked fine for about three years, and started to fail this year, with only 10 or 15 re-charges. Now I'm experimenting with Nihm's, but on my first year, with excellent results. I have three sets of Liths (or whatever they are called) and can't report on them, either, other than they run a train for a long time. But take a reeeely long time to re-charge.
All battery chemistries have pluses and minuses. Lion has a very high energy density but is finicky about charging. NiCads can be prone to shallow charging if incorrectly charged, etc. NiMHs are not without problems however they have a very nice flat discharge curve, are very easy to charge and can be trickle charged almost forever if properly current limited. The big down side I see to NiHMs is the slow charge time ( 14 hours at 0.1C) and a fairly high self discharge rate.

We selected the NiHM chemistry as our battery for TrainUPS because of the flat discharge curve and the charging characteristics. Since a TrainUPS battery pack rarely discharges fully (we’re using track power maybe 80% of the time) a slow recharge overnight is fine and since we recommend that people leave the loco on powered track at all times self discharge isn’t an issue because we’re always trickle charging (floating).

We’re using the battery for supplementary power, not prime power. Since the battery comes up essentially instantaneously when track power drops off due to crud on the rails (Schottky diodes are fast) you never see a glitch or a dropout on dirty track but you’re still mostly using track power. I’ve been doing this personally since 2004 and as part of our business since we started it back in 2008. We get about 2 years out of a NiHM battery pack before the pack gets ‘shallow’. That’s with 24x7 charging and daily operations. At about $30 per pack that’s pretty cost effective in my book. And the battery pack small enough to get into to road units without using a trail car. We put one under the short hood of an RS3, two of them into an SD45, etc.

I guess what I’m really saying is that I’m a track power guy who hates the hassles of track power, like track cleaning and reverse loop wiring, so I developed a system to get around them.

As to facts about the batteries, I agree, we need to keep the discussion fact based. Our battery data sheet is here http://www.iptrains.org/mediawiki/images/c/c2/2300mah.pdf and I believe it bears out what I claim for the battery.

#42

I use an expensive balancer/discharger/charger on all my applications.
I have two of them.
I let it discharge the Nicads with a low rate, and then recharge them at around 1 Amp.
Everything worked fine until this year when two Sub C 14.4 2100 mah 12 cell just came apart and oozed crap all over them during the re-charge.
I also have one that stopped taking a charge altogether.
Like I said, so far I treat my Nihams the same, without the discharge cycle.
I also now have one Lith that is now dead and won’t charge. I have a special charger for those.

#43

John, with a proper charger, discharging before recharging is never necessary.

The ongoing wives tales about discharging completely first is a result of facts and the incorrect interpretation of them.

You have to go back when there were just trickle chargers and fast chargers. Most trickle chargers actually put out more current than the battery can tolerate “forever” but just enough more that the charging did not take forever and so that it took a while to overcharge. The “regular” chargers would overheat and damage the batteries quickly.

When a nicad is “mistreated”, it develops “memory” which is can be several things that reduces it’s ability to store a charge. Overheating damages the electrolyte and impairs it’s ability to hold a charge, this is not reversable.

But, the source of the “discharge fully” myth is another thing that happens, the battery can develop internal shorts, small paths of conductive crystalline growths, normally called “dendrites”…

You can sometimes eliminate them by vaporizing them, and this is done with high current. The best way to “focus” charging current on the dendrites is to fully discharge the battery, into a very low impedence state. Then the charger will dump a lot of current into the battery at first.

Since current always follows the path of least resistance, it “selects” these minor “shorts”, most of the current goes through them and they often vaporize. The outward appearance is you have “fixed” the battery. If you have a situation that “encourages” these shorts, then discharging fully and then recharging can keep them at bay.

Of course, an intelligent charger, proper use of your batteries will make it so this never happens, especially with modern chargers that use pulses, high initial current and an intelligent shutoff.

So, there’s sort of “truth” to the myth, but unless you have a really stupid charger or bad usage (shallow discharge, long times sitting with no use and storage in a low charge state), you never need to “believe” in the myth.

There’s the explanation, which to this day, many accomplished engineers still do not know. It’s really funny when this myth is extended to NiMih and Liion batteries which do not have this particular failure mode.

Regards, Greg

#44

When digital camera makers first started using AA NiMh batteries to power their products they quickly discovered the fact that when sitting on the shelf, NiMh batteries self discharged. Rapidly. It was not uncommon for a camera to be put away fully charged and the batteries be flat within 3 weeks.
Sanyo, and then Panasonic, solved the problem with a mixture of NiMh and Alkaline chemistries and now have the hybrid cells in both AAA & AA size batteries.
These are guaranteed to hold 85% of a charge for at least one year.
They work really well but have one main drawback when used for our purposes. You MUST NOT draw any more than about 1 amp continuously from them, or their life span, in terms of the number of cycles, will be severely reduced. They were designed for digital cameras to provide a smallish current for a long time. Rather than a lot of current for a short time.
BTW. You can only get them in AAA or AA sizes.

#45

Tony,
You must be talking about the Eneloop.
I plan to use those in my controllers.
I put a set of non-rechargeable Lithium’s in both my Airwire and Revo controllers and when they run down, I’ll switch to Eneloops.

#46

ENELOOP is the Sanyo brand and I have been using them since they first came out 4 -5 years ago.
I use them in the 2.4 GHz stock radios.
Panasonic have their own brand.

#47

Well, I’ve been manufacturing battery-packs for DeWalt in 17 states for the past 8 years, and two-way radio battery-packs for W & W manufacturing for the past 15 years. When testing, I have never seen a NiCd cell that would reach the 500 cycle plato, but I have tested many 4/3A, 4/3AF, SC, AA, AAA, A, 4/5AF & D Nimh cells that have repeatly reached over 700 cycles. You can read many websites that will say something different, just like this forum; but I have purchased and tested hundred of thousands of cells per year from 9 different suppliers, and I have never tested or used a NiCd cell that has ever reach the 500 cycle mark.

Thank you for your time,
Rick Isard
Cordless Renovations, LLC

#48

So the NiCd - v - NiMh cycle comparisons on the Sanyo website cannot be trusted eh???

#49

No Sanyo makes the best cells, period. It’s where you buy those cells from. Lime green shrink wrap is a knock off brand from China, you want to purchase the dark green shrink that has markings that is say; “Japan OC.” “OC” is the date code markings.

Rick Isard
Cordless Renovations

#50

Tony, if your buying the CP2500SCR cells, there are shrink wrapped in yellow wrap with the same markings.

Rick Isard
Cordless Renovations

#51

I only buy Sanyo cells and they are wrapped in yellow.

You can only fairly compare good NiCd cells with good NiMh cells.
Or;
Crap NiCd cells with crap NiMh cells.
So I stick by what I say.
In GENERAL, NiCd cells last twice as long as NiMh cells.

#52

I’ve got some nicad packs that are over 25 years old.

I’ve seen 1,000 cycles, and I’ve been using rechargeable batteries seriously in multiple applications since about 1970.

Regards, Greg

#53

I keep changing battery technology to better fit the space available, so the 1200 mAh sub-Cs I used to use in the late 80s and 90s are as antiquated to me as black and white televisions, even if they would still hold a charge. The fact that I can get 7 hours run time out of a battery that’s 3" x 3" x 2" is light-years ahead of what we started out using. I’ll sacrifice overall longevity for space and per-charge run time. I love the batteries I’m using now, just as I loved the NiCads over the Gel-Cells and lead acid batteries I had used previously. (Never “loved” them…) I’d quite imagine in another 5 to 10 years, I’ll look at what I’m using now as equally antiquated, and I’ll probably adopt it at some point. Charge the battery once and it lasts all season? I’d be game for that.

Later,

K

#54

Kevin -

Since you came into this hobby as a child, and are still lots younger than most of us (Rooster and Shawn are exempt), no doubt you will see many more advances of technology in your lifetime. You can probably look forward to the day that both the power and the control signals can be transmitted by RF :smiley:

#55

Jon,

I’m sure some high power Ham Radio guys will figure out how…

How about a 3 meter diameter receiving dish on flat cars (DOFC)?

How about running under a Broadcast FM tower - hijack a muzak sub-carrier signal?

Joe Satnik