MTH Locomotive batteries

Vin Sharkey posted:

I recently acquired several MTH O gauge locomotives made in the 1990's.  As far as I can tell, they have never been run, and were taken out of their original boxes only for display.  A local dealer/repair technician has advised me to remove the batteries, ostensibly because the batteries may reverse polarity and damage the electronics in the locomotives when they are run.  Is he right?

Absolutely he is right!

 Can someone tell me more about this?

The original rechargeable (Nickel Metal Hydride?) batteries will no longer take & hold a charge, thus remove them, throw them in the recycle battery depositary near you, and replace them with fully charged batteries.

 Should I remove and replace the batteries in all of the locomotives?

Absolutely YES!!!!

Thank you, Hot Water.  I suspect that you have saved me a lot of disappointment, and expense!

Those old locomotives all have NiCad batteries that have long since passed their sell-by date.  By all means do NOT even power them up before replacing the batteries.  You can use most 7-cell NiMh batteries with a nominal voltage of 8.4 volts.

I have recently been changing the batteries in my older MTH engines, 5v as well as 3V. For the 5V in particular, I'm replacing the older batteries with the newer MTH Ni-MH replacement, see attached. Is there any reason I can not use the 9Volt battery charger, second attachment & link (from Amazon), to charge the batteries first?

https://www.amazon.com/Tenergy...y%2Bcharger&th=1

Thanks,

Joe

Not a reason in the world that you shouldn't charge them first, AAMOF that's a good idea.

Thought so. Thanks again!

If they truly reversed polarity they may cause some damage, but I have not really seen that.  The bigger issue with early PS-1 (pre 97) is software conflict which disables the PS-1 board until it is reset with Tech chip.   They also can gas out at times.  So replace battery and inspect battery harness for corrosion of the terminal or wires.  Most unplug, so it is an easy replacement.  Only early engines had battery wires soldered to board.  G

Vin, Thank you for your initial question.  Joe's comment about charging the new battery with the little charger he has from Amazon brought a question to mind.

I have charged new batteries with track power before turning the engine on.  I don't see any reason that either method would be better or safer.  Does anyone have an electronics reason to prefer one method over the other?

Mark Boyce posted:

Vin, Thank you for your initial question.  Joe's comment about charging the new battery with the little charger he has from Amazon brought a question to mind.

I have charged new batteries with track power before turning the engine on.  I don't see any reason that either method would be better or safer.  Does anyone have an electronics reason to prefer one method over the other?

Not really an "electronics reason", but remember that with track power applied to a model, i.e. sitting on the powered track, the "clock is then running" inside the DCS memory. Thus, I prefer to charge the batteries prior to installing them. I use the MTH charging set. If the model already has a newer battery installed, I then charge the model via the battery charging port/plug, using the MTH charging set.

Hot Water,

Excellent point about the running clock!!  It didn't even occur to me.  I was thinking about older engines that don't have the charging recepticle.  Thank you!

One issue with charging a new battery in the engine that I don't like, is, how does one know they fully charged it?  Using a charger like the Tenergy first is nice because it tells you when it's finished and drop the battery to a trickle charge if you forget about it. 

About 15 hours in general, is normally suggested on other rechargeable devices to ensure a 100% topped charge first time. There is obviously internal regulation or you'd have a warning on how long they could sit on powered rails too.

I'm guessing the PS/2 internal charger does regulate the charging current when the battery approaches full charge.  At least I sure hope that's how it works.

If you want to charge the battery with engine, do it for 15 to 20mins to get a surface charge to work.  Once it works, run the engine for a good period to finish the charging.  Letting an engine sit powered over night is not a good thing in my mind.  G

I believe the green MTH batteries are pre-charged from the manufacture. I'm sure they loose some of that charge from shelf life, but I never purchased one that had less then 8 volts in it. I must agree with G on charging with track power overnight. I sleep better knowing everything is powered down in the basement before I go to bed. Also, using a small wall charger to top off a new battery before installing it, will use less household current and not add any wear to our layout equipment. Or if the engine has the plug on the bottom to just use the MTH charger. John, I also wonder if the charge circuit shuts down when a battery in the train is fully charged and if the plug on the bottom of the engine goes through that charging circuit or directly to the battery. If it's direct, does the MTH charger contain a circuit to stop charging when full?

The separate charger is just a cheap wall-wart, no automatic shutdown.  If you use that, you have to remember to unplug it after 12 hours or so.  I believe the engine has a charge management circuit.

GGG posted:

If you want to charge the battery with engine, do it for 15 to 20mins to get a surface charge to work.  Once it works, run the engine for a good period to finish the charging.  Letting an engine sit powered over night is not a good thing in my mind.  G

I'll see the overnight point and raise you an "unattended".

An amp push/draw test on one would be interesting.