Throttle Batteries NiMH; What a difference in mAh!

[gmpullman]

Hello all

I've been a Digitrax user for about four years now and one of the first realizations I came to was that I was going to need rechargeable NiMH 9V. batteries for my four throttles. So off I went to find the batteries and a charger. Around here Eveready Energizers were available and I thought... what the heck, Big name brand, must be the best.

Well, after many operating sessions I figured that I was averaging about three or four hours of throttle time and the useable range seems to be dropping off more quickly lately... as any battery will do. Time to get a few more batteries.

I did a little digging around Amazon and e-bay figuring to buy another couple of Eveready's. I didn't bother to research the milliamp-hour rating until reading some of the reviews posted on Amazon's site.

Turns out that the Energizers are only 150 mAh batteries. I bought a few from Bulldog Battery and these were a Varta brand and rated a bit higher at 170 mAh. The most recent ones I bought are a Powerex brand name and they are rated at 230 mAh!

What a difference! As anybody knows with a Digitrax throttle- it is a minor hassle to get the battery out for recharging but with these 230's I have been running almost six hours on one charge and the battery voltage when I unplug the throttle still shows 8.8 V.

Anyway, I just wanted to pass on to anyone looking to buy rechargeable 9V batteries that they should seek out a brand that has a higher mAh rating and spend a little less time changing out batteries. I thought one 9V NiMH was the same as any other... wrong!

On my Digitrax wish list would be a throttle holder that would have battery contacts like a cordless phone to recharge the battery without removal. I had a Radio Shack scanner like that, you could recharge "on the fly."

Thanks, ED

[jeffrey-wimberly]

 I found out the same thing with rechargable AA's for my cameras. My Olympus and Nikon are fairly easy on them so I use Duracell 2000 mAh batteries in them. The Vivitar however has a hearty appetite so I use Duracell 2650 mAh batteries in it. Something else I learned. Don't recharge batteries of different mAh ratings together in the same charger. Not a good idea.

[mfm37]

 Ed,

 How well do they fit in the throttle? Can the cover be used?

Martin Myers

[CSX Robert]

Something else that can make a big difference is some "9 volt" rechrageable batteries are 8.4 volts, and some are 9.6 volts.

[gmpullman]

Martin,

The outside form factor of the battery is identical to any other 9V battery. The difference is in the internal cells used.

My Eveready weighs a bit over 35 grams and the Powerex 9.6V weighs closer to 55 grams.

Yes the cover fits and the external dimensions of the battery are the same.

Thanks, ED

[rrinker]

 Ah, all '9V' batteries are not created equal - there is no real standard for the dimensions. Glad those brnads you tried fit. There are some that don't, the DT400 battery space is a bit on the small side.

 Also true on the voltage, NiMH 'cells' are 1.2V each. 7 of them makes an 8.4V "9V' battery, 8 cells makes a 9.6V '9V' battery. Wit few cells they can be larger in the same package, generating a higher mah capacity. The difference can be summed up by using the mah rating - With a 10ma draw, a 170mah battery can supply power for 17 hours. The same 10ma draw on a 230mah battery will last 23 hours. Or 100ma draw, 1.7 hrs vs 2.3hrs.

                                   --Randy