RC Tank Warfare community hobby forum

I saw some cheap Nimh batteries on Ebay so bought three thinking that they were a bargain. Advertised as 5300mah, so I thought they would be good for a days tank running. Charged them up and tried one. I was using an IBU2 and a tank with plastic tracks, gearboxes, no smoker...it lasted 30 minutes. I pulled the battery out and checked the remaining voltage and it was 7.2v?

I wondered whether it was the IBU2 low voltage detection causing the problem, so pulled out an old 3700mah battery that had been stored for 12 months without being charged. I charged it up, and ran the same tank. I even upped the Current Motor Threshold setting to 12, and shoved the right trim right up for maximum power. The tank ran for an hour flat out on carpet doing spins etc. It never even slowed down, and in the end I got bored with trying to run the battery down. it was still going strong.

Lesson learned...you get what you pay for. It makes more sense to pay extra for quality batteries with a lower mah than a cheap one with a big number, they will last longer as they will maintain a higher current for longer instead of suffering a current drop after a short period of load.

Contact the seller and let them know you may have got a bad battery.

jackalope wrote:Contact the seller and let them know you may have got a bad battery.

What jack said

I am guessing that all of their batteries are what we could describe as 'bad', they are probably cheap chinese items and may well not even be 5300mah, that is very difficult to prove. Their argument would possibly be that they are 7.2v 5300mah batteries, but as there is no graph on their description showing where the power drop off is, I basically got what I paid for. They will be put to use on models powered by RX18's as these have a very low power demand. I have since ordered two Vapextech batteries, more expensive, but a known high quality brand. Used them before and they last very well in tanks.

wibblywobbly wrote:I am guessing that all of their batteries are what we could describe as 'bad', they are probably cheap chinese items and may well not even be 5300mah, that is very difficult to prove. Their argument would possibly be that they are 7.2v 5300mah batteries, but as there is no graph on their description showing where the power drop off is, I basically got what I paid for. They will be put to use on models powered by RX18's as these have a very low power demand. I have since ordered two Vapextech batteries, more expensive, but a known high quality brand. Used them before and they last very well in tanks.

Good way is to put them on a smart charger. Whilst they only say what's gone in its a good indication of capacity.

Hi Rob have to agree with your findings ,when I started out bought cheap batteries ,but as time went by found out better to spend a few pounds extra and get a quality battery. Have you noticed that cheap batteries feel lighter than a quality one (could be me but they do to me )


regards pete

You're not the only one that has fallen prey to the off brand battery temptation, saving that $8 always turns out to be well worth it eh? Was yours colored blue y any chance? I got a 4000 MAmp and it wont even come close to lasting as long driving time, as my 3300 Mamp venom. i only buy venom, for the reasons you state...I read some info on the different types, Nicad vs Nimh vs lipo etc. NIMH seems the best compromise over all for tank batteries. Lipo are too finicky, charger costs a lot more, battery costs way more, plus you have to fit the tamiya connectors, no thanks...and if you are careless, as i occasionally am, you can start a small fire real easy...

I always have a volt meter lying around within reach, i try to charge them all at least a prtial charge once per month. Letting them run down all the way dead, which they will do if you ignore them a couple months, is a bad idea, they need about 2/3 charge in them all the time for max life. No matter what rating size you get, you may have noticed, the 7.2 V cap batteries we use, will take a max of 8.5V regardless of how long it's charged. The battery will be almost too hot to hold by then anyway. I check the voltage at about 10 min in, If its 8.25 V or over I just shut off the charger then. I use an outlet timer to plug the charger into and 15 minutes is usually all it takes. With the timer it leaves you some latitude to forget that you left your $35 battery plugged in too long... (Never trust the red light on the charger to blink out when it is supposed to, them "charging" lights are jimmy big fibbers, They often over charge when you don't want them to. Even worse some of the cheaper ones (that would be mine) will not only still glow "charging' when battery is way full but WILLL NOT cut the voltage a that point! And will just keep right on (over) charging which is why I do the checking meself.

Hi Rob,

Been there myself on got the t shirt. But I know I go on about LiPo batteries a lot but last battery I bought £16 deliveried from UK Turnigy soft skin 5000mah, it's just a no brainer for me now LiPo are cheaper if your want high capacity.

I try find the link later today and share.

Ian.

Is that a genuine one? I read quite allot on other RC forums about how Turnigy batteries from ebay are regularly re-branded Chinese knock offs.

I just wish you could get larger capacity Lipos in the UK for better prices. If you want over 6000mah it costs a fortune. I had to get a US company to send me some 9000mah 60c/120c2S lipos (SMC Factory Spec) to get a good price on good quality ones for my Yeti XL. $48 each though, so even with shipping and taxes it worked out cheaper than buying the same number of the large size 2S I could get in the UK. They did FedEx too so go them in 2 days from ordering. Going to order from them again to get some 3S and 4S versions for my Losi Ten SCTE 2.0 since they last for absolutely ages - 35 minutes in parallel 4S pushing around a 20lbs truck using a Neu-Castle 1515 2200kv 8th scale motor.

Hey guys, I get my turnigy batteries off ebay 5000mah 2s, 20c, for 20 quid with Tamiya connector, they have always held more capacity then stated, lasted ages and been reliable. But I know what you mean about anything over abit 5Ah billpe, seems to be alot more costly!