9000 mAh Batteries.... Why not?

[SR5Dave]

I found these on Froogle.

http://www.amondotech.com/index.asp?...ROD&ProdID=402

THATS A BIG... uhh, battery. Is there anyting against me getting this and making some packs out of them? They are NiMh so I'd imagine charging them would be easier? Sure they're D cells and a bit bigger.... but I really dont care, my batteries are mounted SUPER low, so it would help my COG if anything, and its already WAY light at just over 8 pounds.

So? Whaddaya guys think?

Dave

[kevinlongisland]

those batts would work just fine. build them just like all the other packs, in series to add the voltage of each cell.

i would recomend that once the pack is built, charge it at a low rate for 12 hours. a c/10 rate is good, which would be 9000/10, or 900mA (milliamps). this will equilize all the cells to the same full charge state. and a c/10 rate will not harm the cells.

[SR5Dave]

Originally Posted by kevinlongisland

those batts would work just fine. build them just like all the other packs, in series to add the voltage of each cell.

i would recomend that once the pack is built, charge it at a low rate for 12 hours. a c/10 rate is good, which would be 9000/10, or 900mA (milliamps). this will equilize all the cells to the same full charge state. and a c/10 rate will not harm the cells.

My charger has three settings. On, off and discharge. Whats a good charger? Also for anyone else interested they sell TONS of batteries, including smaller D cells
http://www.amondotech.com/index.asp?...ROD&ProdID=291
CHEAP 3,000 mAh packs
http://www.amondotech.com/index.asp?...ROD&ProdID=407
up to 8 cell packs even... for cheap! Check it out, seems like a great find.

[RcRock-Guru]

Sounds like a good idea. They shoudl work fine. Let us know how they work out if you end up getting some.

[SR5Dave]

Originally Posted by RcRock-Guru

Sounds like a good idea. They shoudl work fine. Let us know how they work out if you end up getting some.

My only problem, I run a EVX, 14.4 Volts, two batteries. I could make room for one D cell pack (A D cell pack will be about 7.5"x3"x1.5") but probably not two packs. They would also run about 55$ a pop for all the stuff plus shipping, which is a REALLY cheap pack, but still a lot up front. More likely I'll buy 4 3,000 mAh packs instead..

They have slightly cheaper D cells, and some full size C cells, maybe a pack outta those wouldn't be too bad.

[kevinlongisland]

Originally Posted by SR5Dave

My charger has three settings. On, off and discharge. Whats a good charger? .

i recomend the triton charger.

http://www2.towerhobbies.com/cgi-bin...?&I=LXCJG7&P=7

it has tons of options and you can charge any type of battery, nimh, nicd, lead acid, li poly. if you want to use your charger, i would recomend charging each individual cell before you build the pack so you know that each cell is in about the same state of charge.

[SR5Dave]

Originally Posted by kevinlongisland

i recomend the triton charger.

http://www2.towerhobbies.com/cgi-bin...?&I=LXCJG7&P=7

it has tons of options and you can charge any type of battery, nimh, nicd, lead acid, li poly. if you want to use your charger, i would recomend charging each individual cell before you build the pack so you know that each cell is in about the same state of charge.

Wow, thats one hell of a charger.. might have to wait a paycheck though. I'm thinking I might go with Full size C packs.. a bit cheaper, 4300 mAh, like 25$ per

[MudCow]

I have tried this before. I have experimented with 9000mAh D cells and 4,500 mAh C cells. There are a few of problems:

They don't like high rates of discharge or getting too hot. (Despite what the marketing guff states)
They are HEAVY.
They have no punch.
They can be a PITA to charge properly with normal RC battery chargers.

Unless you are getting them for a price that can't be refused... stick with 2,400 NiCds.

[SR5Dave]

Originally Posted by MudCow

I have tried this before. I have experimented with 9000mAh D cells and 4,500 mAh C cells. There are a few of problems:

They don't like high rates of discharge or getting too hot. (Despite what the marketing guff states)
They are HEAVY.
They have no punch.
They can be a PITA to charge properly with normal RC battery chargers.

Unless you are getting them for a price that can't be refused... stick with 2,400 NiCds.

Whats the cheapest pack you would reccomend that performs well? Is there anything wrong with the packs they sell? (The price is right..)

[MudCow]

There is more tech in RC batts than meets the eye. They are designed for extremely high rates of discharge unlike commercially available cells that are designed for other applications like emergency lighting etc.

By all mean, give them a go and tell us if they are worth the $$$.

Personally I would only buy an RC specific battery in NiCd 2,400mAh that cost more than US$40 ea and only Sanyo cells.

I learnt the lesson long ago that with batts you really get what you pay for.

[kevinlongisland]

definitely, there is more than meets the eye with batteries. the design of the internals determines if they can handle high current discharge well. the most detrimental affect being the build up of heat which deteriorates the internals of the cell decreasing the effective life of the cell. but you also never know until you try. if you experiment with any type of cells, always check how hot they get when in use in the vehicle and also during charging. if they ever become extremely hot, then they are probably not well suited for your application. some info:

http://www.rcgroups.com/links/index.php?id=3554

http://www.rcbatteryclinic.com/

[SR5Dave]

Well, I picked up some 3000 mAh batteries from Http://www.amondotech.com for 15$ a piece I couldn't say no! I am absolutely DELIGHTED with the service I got. Three confirmation emails, ordered on thursday here on monday We will see how they do, they speak the world of their batteries so I imagine they'll do OK...

[Phantez]

Originally Posted by MudCow

I have tried this before. I have experimented with 9000mAh D cells and 4,500 mAh C cells. There are a few of problems:

They don't like high rates of discharge or getting too hot. (Despite what the marketing guff states)
They are HEAVY.
They have no punch.
They can be a PITA to charge properly with normal RC battery chargers.

Unless you are getting them for a price that can't be refused... stick with 2,400 NiCds.

just curius, wut run times did u get with those batteries?

[SR5Dave]

As an update for my batteries.... I could not be happier with them!! For the price, run time (30-45 minutes, EVX, 12T puller motors, 14.4V), and also pop, they do pretty good!

I could ask for a LITTLE more power on start, but its still enough to lift the wheels up They give out 30A, which is standard AFAIK

[jeep_boy02]

which ones did you get? the 7.2V stick pack? what is good for a TXT 7.2, 8.4? is it just preference?

[SR5Dave]

Originally Posted by jeep_boy02

which ones did you get? the 7.2V stick pack? what is good for a TXT 7.2, 8.4? is it just preference?

Prefrence I suppose, I am going w/ my EVX so 7.2Vx2 is plenty! So yes, I am running the 7.2V packs

[kevinlongisland]

jeep_boy02, what esc do you have in your txt and what motors?

[jeep_boy02]

stock motors and a super rooster

[kevinlongisland]

yeh, preference. 8.4v will give you a little more punch, but then you have the longer pack or the hump.

[jeep_boy02]

punch - do we really need punch with crawlers?