Battery trouble - again!

[skip asay]

Jonathan -

The simple answer is

[color=#000000]Jonathan -

The simple answer is that NiMH batteries have far greater energy density than NiCads, size for size.
Example]

[petn7]

what good is double the

what good is double the capacity when it can't hold a charge for 8 months? exactly, it is no good.

that's my reasoning for never using my nimh tx pack. yeah, i bought it...but never used it.

main battery packs for actual vehicles is another story...

[JWLaRue]

what good is double the

what good is double the capacity when it can't hold a charge for 8 months? exactly, it is no good.

Well, from my perspective, I'm not sure that I see this as a problem.....here's why]never[/i] assume that a battery pack is fully charged before I go to the local pond to run my subs. I always top off my batteries the night before. It's simply part of my "pre-flight" checklist...which is a good practice that everyone should do.

The possibly minor annoyance of having to charge my batteries beforehand is well worth being able to run on a single charge for extended periods of time. I'm there to run my boats, not swap out batteries!

-Jeff

[petn7]

well i only work on

well i only work on my subs every once in a while; more often every few (or more) months. i just like the fact that when i test my servos or esc after even a year (even if it's not for a sub) i know my tx will have some juice at least for a few hours.

[jdbostrom]

Well seeing everyone's personal opinions

Well seeing everyone's personal opinions has convinced me that they are just that; personal preferances for whatever purpose that person has, and there isn't really a right or wrong choice. I think in my situation, NiMhs will be the best choice.

Now that raises a question. Can I get a NiMh pack for my radio (a Hitec Laser 4)? Conversely, could I buy individual cells and put them in the old pack? I would really prefer the latter if possible. I am also assuming I can use the same old wall charger for NiMhs.

Thank you,
Jonathan

[JWLaRue]

Jonathan,

Yes and yes.

I've gotten prebuilt

Jonathan,

Yes and yes.

I've gotten prebuilt battery packs from Batteries America, just charge and drop into your transmitter. You can also get individual cells from them as well. I'd recommend getting them with "solder tabs" to make it easier to join them together. I get the individual cells for building the battery packs for my various U-boats.

-Jeff

[skip asay]

Petn7 wrote -

"what good is

Petn7 wrote -

"what good is double the capacity when it can't hold a charge for 8 months? exactly, it is no good."

"that's my reasoning for never using my nimh tx pack. yeah, i bought it...but never used it."

Curious. How is it that you know your NiMH pack won't hold a charge for 8 months.....if you never used it? And are you aware that NiMHs don't have full capacity until after 3 - 4 charge/discharge cycles? And what NiCads are you using that hold a charge for that long? None that I've ever seen. Some charge, possibly, but then, NiMHs hold some charge for a long time. Mine do.

"main battery packs for actual vehicles is another story..."

Why is this another story? Don't you drive the vehicle with the TX?

Skip Asay

[petn7]

well you make a good

well you make a good point. technically i don't know that the tx nimh i bought won't hold a charge for 8 months, but i used AAA nimhs for my micro heli (Piccolo) a little while back and i can remember after a few weeks, those little suckers just didn't have the voltage or flight time they would normally have fresh off the charger. with micro helis, every little extra volt and mah in your battery was easily noticed.

i'm assuming the tx battery pack is similar and i don't have the patience to test if it can last 8 months idle in my tx.

main battery packs for vehicles ia nother story since, with micro vehicles (especially micro helis) size/weight is a premium, so you want the highest capacity battery you can buy for the given space/weight. with micro helis where i was getting 4min of run time off a AAA nicad battery pack...yeah using AAA nimhs was worth it. also, i'd end up recharging it after every flight (7 min or so) so the batteries didn't get as much of a chance to sit idle. with subs, when you make a 1/200 scale alfa submarine, weight isn't the problem ,but space is. again, it pays off to use small high capacity batteries such as nimh. lithium polymers would be even better, but i get enough run time with nimh and i don't wanna get into lithium battery technology just yet.

[jdbostrom]

Ok, I'm looking at buying

Ok, I'm looking at buying a prebuilt pack and then just keeping the faulty NiCd pack as is, or maybe finding the bad cell and replacing it. I cannot decide which of these I want though]http://www.batteriesamerica.com/newpag28.gif[/img]

9.6v 1650mAh
Ni-MH Reg. 35.00 ea.
SALE $29.95 BUY

9.6v 2100mAh
Ni-MH $39.00 ea.

9.6v 2300mAh
Ni-MH $42.00 ea.

All of these are from the Batteries America site. Basically I just need some idea of how long charging should take and how much running time I should plan on, but I don't know how to figure this out myself.

Jonathan

[jsl]

Basically I just need some

[color=#000000]

Basically I just need some idea of how long charging should take...

Easy math Jonathan.

I think I mentioned it somewhere else.

You mention three packs of different capacity. To make up for energy lost as heat, charge the pack with 1.4 times the capacity.

Let's take the 2300 mAh pack as an example.

This pack needs 1.4 x 2300 mAh = 3220 mAh to be fully charged.

Your wall-charger has a small figure somewhere, where it reads]

[Guest]

Jonathan,
I hate to confuse you

Jonathan,
I hate to confuse you further, but if you go to Best Buy or Micro Center, or any discount store, you can get 4 AA NiMH button cells, with charger, and a refill of 4 additional cells. Put the 8 cells in a battery holder from Radio Shack, cut off the leads from your bad pack, connect the wires cut off from the bad pack to a 9V battery lead from Radio Shack, and snap that on to your battery case. If you get quick charge cells and charger, you can take the cells out, and charge 4 at a time. You're good to go again in 30 minutes.

[jdbostrom]

Jacob,
I knew it must

Jacob,
I knew it must be easy math. It's just that no one has ever explained it to me before. Thank you.

Dr. Broder,
Do you know how much money I would save doing that? We don't have a Best Buy or anything like that around here and Radio Shack doesn't seem to have what I need. I just want to make sure it is not more trouble than what it is worth.
You said that they were AA button cells? I thought button cells were the little flat ones though. I'm a little confused. Thank you very much for all the help.

Jonathan

[jdbostrom]

Maybe this will work]http://www.bestbuy.com/site....0621751

http://www.subcommittee.com/forum/icon_question.gif

Maybe this will work]http://www.bestbuy.com/site....0621751[/url]

[jsl]

That should work just fine.

But

That should work just fine.

But go with Art's idea with the battery rack. It will save you the trouble of soldering up the cells. You'll only have to solder two wires then.

Only one problem with the link you posted. No charger. You could use your wall charger, but I think it would take forever.

Personally and thinking of my student economy, I would go with two of these.

Energizer overnight charger

or a charger with 4 NiMh AA and a pack of four extra AA cells.

Duracell fast charger with 4 AA
4 spare AA cells

In the end there is only a $4 difference anyway.

Jacob

[Guest]

Jonathan,
Correct, not button cells. They

Jonathan,
Correct, not button cells. They are standard cylinder AA cells like those used in flashlights. Available with charger and four AA NiMH batteries for $12.95 from Microcenter. Home > Product Information
Specific Specs & Info

UltraLast AA/AAA Fast Charger

Mfg. Ultralast

Mfg. Part No. ULAAVSC

SKU 517888

UPC 076097108271

Shipping Usually ships in 1-3 business days.

Price $12.99
How many?

BUY NOW!



Save a bundle on batteries with this Nickel-Metal Hydride rechargeable battery kit that comes with 4 AA 2300 mAh batteries. Our charger can fully charge the 4 AA 2300 mAh batteries in 90 minutes. If you are traveling in your car, it comes with convenient DC car adapter.






View all items in this category General Purpose Battery Chargers / Accessories




Product Specifications Battery Type
Nickel Metal Hydride Technology

Battery Size
AA, AAA

Charge Capacity
Charges up to 4 Batteries

Included Batteries/Accessories
Includes 4 AA NiMH 2300mAh batteries with Car Charger

Voltage Required
12 V

Manufacturer Warranty
Limited lifetime warranty