Whats the life span of nimh battery??

[longboardnj]

Whats the life span of nimh battery?? how many years are they worth keeping?? i have some old race packs that im debating on junking.. if i cycle them they seem to work ok..sometimes i even charge my new nimh for about 45 and then they only last 3 min in a traxxas vxl.. then i charge them again i get good runtime... is there any way i can test my bats to find out if they are good??

[Charlie don't surf]

You can cycle them a few times to try to get then back- depending on what NiMh packs they are (3300/4200/4600sho/worlds) some will come back better than others but these packs had a prime output and storage for weeks in the later packs.

Go get some cheap (30 bucks) Turnigy lipos and don't bother wasting time trying to bring them to a 1/4 of what they once were-

[longboardnj]

i feel the lipo stuff is too dangerous.. i store all my rc stuff in my studio apartment...the 3300 race packs i have are over 6 years old..i know age plays a factor with bats . i really just want to be reassured its a wase of time trying to get life out of them before i junk them.. the fastest thing i run is a vxl rustler ,i was thinking of just getting 2 or 3, 3000 duratrax packs for $20 each and calling it a day... the other hand i dont want to junk the packs if they are still good...

[AYKBOBCAT]

i feel the lipo stuff is too dangerous.. i store all my rc stuff in my studio apartment...the 3300 race packs i have are over 6 years old..i know age plays a factor with bats . i really just want to be reassured its a wase of time trying to get life out of them before i junk them.. the fastest thing i run is a vxl rustler ,i was thinking of just getting 2 or 3, 3000 duratrax packs for $20 each and calling it a day... the other hand i dont want to junk the packs if they are still good...

I'm with you on this... I also have 3 old nimh and I didn't touch them for more than a year now. I think I'll try to cycle them a few times.... I also don't like the safty issue with Lipos...

[SRTracer121]

lipos are not dangerous. if you abuse them by over-discharging them, overcharging them at a different setting (as nimhs for example) and then yeah it can bite you on the keaster but overall they are fine. ive had packs that were trashed and i went to blow them up for funnsies and i couldnt. you really have to abuse the packs to get the to fail catastrophically. most of the time if you run them too hard (run a low "c" pack in an 8th scale for example) then they puff and you can them (though a little puffing is fine) ive got 10 packs sitting right next to me in my bedroom of my dads house and i dont give them a second thought.

anyway if you are stuck on the idea that you rather run nimhs id just buy new packs. the promatch enerG 4600 matched packs are probably the best bang for your buck. probbly the best on the market overall too. i had a few matched/zapped enerG's from spc when he still sold them and they were the bees knees. better then EP cells atleast and miles ahead of the old GP 3300's

http://www.promatchracing.com/products.php?cat=6

[Jay Dub]

The safety issue with Lipos, is really overarated. I have never seen (in person) any real problem. Recycle the old packs (they really are no good), and invest in some cheaper LiPo's like charlie said. You will be happy you did. -Jeff

[SRTracer121]

ive seen a fair number of lipo fires but they were user induced, the one set failed because a screw came up through the bottom of the guys battery box (1/8th buggy) and he kept wrecking packs till he caught on. the other (from the same guy) did the same thing i had done a month earlier, he charged the packs as nimhs and they puffed then caught fire (lipos dont explode fyi, its an intense chemical fire) i was lucky and it happened to (in my case, 2 packs at the same time )me outside, his were in his garage. ruined his beloved hitec aggressor and his one charger that the pack was sitting on. luckily his work area has tile backsplash so nothing else went.



now, for the sake of conversation, the way you put out a lipo fire is with sand. you smother it and deny it oxygen to burn. thats why ROAR requires a bucket of sand be within so many feet of the pit area.

[longboardnj]

thanks for the info guys but i just want to stick with nimh for now.. i love the new 2.4 radios and brushless systems but this oldschool guy wants to stay away from lipo for now.. besides i had fun with brushed motors and 1700nicads.. im sure runing brushless motors and 3000nimh stick pack will be fun...

now back to my problem... i have 8 nimh packs and 5 nicads (i had 9 nicads but got rid of 4)... the reason i am asking for advice is cause ive had 7 year old race packs take a better charge then my new traxxas 7 cell 3000nimh .. i know that pack is good and i just need to charge and use it a few times and it will be fine.. i have five 7 year old race packs that i know dont have 400-600 charge cycles (thats "nimhs life span").. the problem is the packs are 7 years old and i know if a bat in an atv/motorcycle was 7 years old i would junk it.. if i could hook up my old packs to a machine and i found out the bat only had 50% life left id just junk them.. the point of all this is i dont want to spend $60 on 3 duratrax 3000 nimh stick packs just to find out i get the same kind of performance out of the old packs i have now

[Charlie don't surf]

As they went higher in the mah ratings and discharge rates the NiMh cells became less stable. The older ones were more consistent than the later ones. I would bet money that after 50 cycles anything over a 3000 pack lost 30% of its output and capcity. The need traxxas packs are still newer unstable chemistry. NiCads however seem to be good for almost ever.

[SRTracer121]

do you need a discharge rack or bulbs? i might have some id get rid of for a little nitro fuel money (10-15 bucks i guess) ive got a trinity "real time" rack and a bulb discharger set.

[longboardnj]

As they went higher in the mah ratings and discharge rates the NiMh cells became less stable. The older ones were more consistent than the later ones. I would bet money that after 50 cycles anything over a 3000 pack lost 30% of its output and capcity. The need traxxas packs are still newer unstable chemistry. NiCads however seem to be good for almost ever.

yea it stinks how some new products are worse then older products..

[longboardnj]

do you need a discharge rack or bulbs? i might have some id get rid of for a little nitro fuel money (10-15 bucks i guess) ive got a trinity "real time" rack and a bulb discharger set.

i think i have something but thanks if i need it ill let you know.. i was thinking of making something like a electric heater to discharge.. my place gets kinda cold this time of year..

[Jay Dub]

Well, if you have your heart set on NiMh batteries, then what you really need to do is rather complicated. First, figure out what type of cell you have, and then find out what care regimine is prescribed (most manufacturers had this available at one time). It really does vary for every type of cell. There are some general guidelines, but to get the best from your packs you need to do some research.

Basics: Never discharge your cells past .9 volts per cell (very difficult to do with pre assembled packs) -it will ruin the cells (you spoke of inconsistency in run time and perfiormance ). After every run (remember you can't run your packs all the way down), tray your packs with a discharge tray (Rayspeed made an excellent one).

Then you need to charge them before storage (if you don't they will be damaged). They need to be stored with a 1000 Mah per week of storage. 3 weeks = 3000 Mah of charge. If they are 3800 Mah packs, then they can't sit for 4 weeks without damaging the packs (providing they were in perfect shape to begin with). Then they need to be discharged before they are charged for a run.

To charge them' you need to find a charger than has the peak detection fcn adjustable, and it need to be adjusted for each type of cell, and pack configuration (eg. 4 cell, 6 cell, 7cell etc.) -Ip cells, Ib cells, Powers, GP etc.

Next you really can't run them more than once a week, or you will damage the cells. Some cells can go 4 days, but you should find out which ones (research). And, if you do everything correctly, you should get 20 or so runs in tip top form. If you missed anything, then you can count on reduced performance -Yaaaayyy! Now you know the basics of caring for NiMh cells! -Jeff

[SRTracer121]

im not sure i believe the whole part about running packs more then once a week. ive been told by 2 different mfg's that as long as they are allowed to cool to ambient temperature between a charge or discharge you can charge and run them as much as you want.

[Jay Dub]

Of course they will tell you that, they sell more batteries. Plus once a week sounds shitty to tell customers. So their batteries sound better if they tell you that you can run them as much as you want. But, I can tell you as a national champion, 100% sponsored factory racer for nearly 20 years, including up and through the NiMh craze that what I wrote is what they tell the factory drivers about the batteries -NOT the general public. Believe what you want, I have noting to gain by giving out this information. This is simply what my sponsors told me during the NiMh heyday. The guy asked how to best take care of his NiMh batteries. I am giving him the best info available.