Battery dead?
 

Hi all,

So 1 of my 7 cell Tenergy NIMH batteries do not take a charge, hold a charge, and only let my MM power up then die out. My other identical 7 cell Tenergy I bought at the same time works just fine. Im using a Super Brain charger.

Im assuming a cell went bad on me and the pack is toast?

If so I think its time to switch to LIPO.

Please advise. Thanks.

Probably a bad cell... but check it with a voltmeter, pull out the bad cell and run it as a 6 cell...

and order a lipo... :)

I bought two 7 cell 4000mah, Emaxx pacs of these cells and they frankly are my worst pacs and I've been real disappointed in them. New, they would only charge to a little over 3000mah and now after 15 or so cycles have improved to 3200-3400mah.

I have other 4000mah pacs (Maxxamps) and when they were new that would reoutinely charge to 4400+mah. Now that they have 50-70cycles (don't know exact number, lost track) they still are charging to 3600+mah. I won't be buying any more Tenergy cells. I guess there's a reason they're cheaper than everybody elses cells.

I have had good luck with the tenergy 3500 cells.

In any case they are still nimh cells and unless you run alot of them in parallel they just do not work well with higher power brushless systems. I still use mine in a SV27 boat, 14 cells in series, but 26 dollar 3600 12c lipos will post better numbers than my tenergy cells, and get better runtimes and stay cooler.

Lets face it, nimhs are just no good enough!

Before I knew better, I bought 10 of the Tenergy packs. I don't remember what capacity they were, but I wound up throwing the away soon after I got them.

Wow, I'm glad I only bought a pair! I used them to build two 8cell pacs to run the 8xl I'm trying to finish up on. I def wouldn't buy from them again. Mine behaved as if they had been sitting on a shelf way to long somewhere.

I want to start with nimh and once I get more comfy with what I'm doing, then pop for some expensive lipos.

Tenergy is good enough for running a roto start or bump box for your nitro... Thats about it though. I had a couple packs of the 3300's back in the day and they were utter crap. Fried the thin metal strip they used between the cells the first time I ran them.

I wound up breaking the packs down and building a proper pack from them and now use them in my roto-start and glow ingitor . They are fine for that.

A little off-topic here, but just because your charger says it's putting more than the battery capacity back in does not mean it is actually doing that. When the battery starts to get warm towards the end of the charge, that heat is wasted power. So, the last few hundred mAh is probably gone as heat and you are actually getting close to the battery capacity put back in...

RMA denied
 

Thought I would share the reply from all-battery.com when my warranty repair request was denied. I was 12 days over according to my calculation of the 6 mo warranty on their packs.

I liked the "sorry" hahaha.

Looks like Ill be forced to buy a nice lipo now :gasp:

----------------------

Dear customer:

The order was placed on 3/13/2007. It is out of warranty, so we cannot set up the replacement for you.
Sorry.

Regards,

Customer Service
All-Battery.com

Well, you can have the last laugh, write them back and tell them you won't be spending another dollar with them and that thousands will read of your experience on the various rc forums you belong too. End your letter with the same I'm sorry, lol!

I know I'll never buy anything from them again. Their 4200s were a rip, just a joke. If I hadn't assembled them into a pac, they would have gone back immediately, but its way too late now for mine. At least I've gotten a few runs out of them.