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Help Needed!😞

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Hi guys

Last week I bought a new HPI plazma 3300 nimh battery for my hotshot and all was well until last nights garden bash. 😞(Let me explain)

I,ve been charging my battery at 3.5amps as advised by modelsport when I bought my battery and running the car till it looses its punch then stopping it and recharging it the following night prior to use again.

Right here we go after lasts bash the battery lost its punch after a very short time(10 mins approx) and the car just stopped dead. (Was getting a good 25 minutes after first few cycles and the car would start to slow down)No forwards or backwards movement only the steering would function.

After letting the battery cool down(1 hour) I put it back on charge and was surprised to see the fully charged light on after only 20 minutes.

I gave it another bash and the car lasted about 5 minutes before stopping completely again!😞

Ok this morning I charged it again this time on only 2 amps and again the fully charged light came on after only 30 minutes plus the battery was very hot!

This time the car would not move backwards or forwards but again the steering worked!😳

So now I'm thinking the battery has died after only 7 good cycles??

Now the weird bit😁

I charged up my 2700 hump battery out off my unbuilt buggy champ which again seemed to charge very fast(20 minutes) and when I tried it same as no power to the drive only steering is working.

This battery worked fine last week.😳

So I'm thinking I'm I unlucky to have 2 batteries die or is there a problem with my motor or ESC both have had very little use from new and only run on very short grass.

Could my charger be destroying my batteries as the charge time seems to have gone too fast???

Do I need to send my new battery back too modelsport??

Sorry for the long tx but I had to give you all the details.

Cheers Karl

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Sounds like the charger is cutting the charge cycle short.

Does the battery get warm when charging?

Have you tried putting the battery back on charge as soon as it cuts out?

What voltage is the battery / charger showing at the point it cuts off ??

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Hi percymon

Yeah the new battery was very hot after this mornings charge. It was hot to hold for long!

I haven't tried putting it back on charge once the green fully charged light came on as it was very hot.

I don't have a volt meter or my charger does not tell you the voltage.

If I could get a volt meter how do you check the battery voltage and should it be 7.2 volts if fully charged?

I take it you just touch the 2 wires in the correct order?

Electrics are not my strong point!

Cheers karl

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Hi mate

Yes it is!

I,ve just posted in another thread about them.

If my charger is not working correctly can it damage batteries permanently?

Cheers karl

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My Fusion Vector did the same thing to two of my very expensive 4700mah NiMhs. Started off working well but after a few cycles the charging time became less and less (I was doing the same procedure as you). It recently gave up after no more than 50 charging cycles in total (probably less).

I actually switched to LiPo a while back and it's the best thing I've done in terms of the hobby, much easier to manage the batteries!

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My Fusion Vector did the same thing to two of my very expensive 4700mah NiMhs. Started off working well but after a few cycles the charging time became less and less (I was doing the same procedure as you). It recently gave up after no more than 50 charging cycles in total (probably less).

I actually switched to LiPo a while back and it's the best thing I've done in terms of the hobby, much easier to manage the batteries!

Hi steveU30

Did the charger ruin your batteries or was they ok if you used a different charger to charge them?

Is there any way of testing the charger?

Although its a few years old its had very little usage.

Looks like I'm gonna convert to lipo although I need to find a stick pack size with a tamiya connector as my ESC has tamiya plugs.

Also I will need a lipo to fit in my buggy champ if I change.

Cheers karl

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It's hard to say as it was gradual, I think what confirmed it for me was when I got my LiPo charger which tells you how much charge a battery is taking. My 4700 NiMhs were only taking around 1000ma which is well short of what they should be taking.

Short of being an electrical genius I don't know what can be done to test the charger sorry.

If you're going to switch to LiPo you should get the following batteries which are one of the only ones guaranteed to fit 99% of all Tamiya battery bays, yes they are a little dear but they are the correct shape, length and have the wires exiting the pack in the correct place:

http://www.modelsport.co.uk/core-rc-4000mahr-7.4v-20c-lipo/rc-car-products/366384

Charger wise, my Overlander is excellent, not exactly the same as this one but this one gets good reviews too:

http://www.modelsport.co.uk/overlander-rc6-vsp-80watt-7a-output-ac-dc-charger-with-fan/rc-car-products/379060

If you do go LiPo you should seriously consider switching your Tamiya connectors over to Deans or similar as the old Tamiya connectors aren't rated to carry a very high current and act as a bottleneck in the power line (a potentially dangerous one too).

Lastly, see here for LiPos for your Buggy Champ:

http://www.tamiyaclub.com/showroom_model.asp?cid=122994&id=29487

Hope this info helps!

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Hi mate

The only thing working with my "fully charged batteries" is the steering.

Is this because the steering takes less voltage?

Do you think the batteries will be knackered now?

Re lipo

The wires on my ESC are short already so cutting the plug and replacing with deans might be tricky.

94EG! Said with my set up

BZ motor should be fine with tamiya connectors and he seems a very clued up guy as far as R/C goes.

I'm interested as to what he makes of my problem although he,s advised me to go lipo as you have.

For somebody like me who only has a part time interest in the hobby cutting plugs and wires and then resoldering them is a bit tricky or I buy 2 new ESC,s to replace already new ones with TAMIYA connectors.

Thanks for all your help and advise though.

Cheers karl

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If your NiMhs have been drained too low the cells will have been irreparably damaged which could well be what's happened. If you're only getting steering then yes this could be because the voltage in the battery is too low (servos will turn at a much lower voltage than the low voltage cutoff of some ESCs).

I appreciate what 94EG! is saying about Tamiya connectors on a BZ motor, yes he knows his stuff and yes you'll 'probably' be OK but there's no escaping the fact that it's a very poor connector, rated at a very low amperage and isn't to be trusted, certainly not where LiPo is concerned.

Don't want to scare you off LiPo as it's a fantastic technology but you need to be fully armed with the facts to you can make your own informed decision if/when you take the plunge.

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Hi steveU30

Yeah he said he recommends deans but I,ll probably be ok like you said as well as he runs his hotshot with a RZ motor and the ESC thermaled before the plug caused a problem.

Would it be possible to extend the ESC wires if I go to deans if required?

ESC is a Mtroniks tio 19 storm!

Are deans connectors smaller than the tamiya type as that would help if I have to trim the wires?

Cheers karl

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Yep extending the wires is fine, just stick to a similar gauge and solder the extension on then protect with some heat shrink for a neat job.

Deans plugs are much smaller and compact than Tamiya plugs, another benefit of switching to them!

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Hi guys

After contacting modelsport they suggested I send the battery back to them for testing.

So I did and two days later I received a brand new battery. πŸ‘Great service as alwaysπŸ‘

I,ve not tried charging it yet as I'm still thinking the charger could be damaging the batteries or was I just very unlucky to have two batteries fail at the same time??

Would you risk trying to charge the new one or shall I buy a new charger which does lipo and nimh?

Cheers karl

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I would personally go a new charger, preferably a combination one and something that can cycle your battery's for you. I use both NIMH and lipo battery's. Lipo for racing NIMH for bashing. I cycle my NIMH battery's about every 4 runs to keep them in good condition. I would consider the deans or similar style plugs. The biggest problem with Tamiya plugs is when they get hot the metal stretches out of shape and looses contact between male and female which causes arcing which causes more heat which...... You get the picture.

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hi, if the battery is getting hot and not just warm then there is a good chance that one or more of the cells has died , this causes huge internal resistance spike and thus the charger pushes harder and you get heat and lots of it , given how cheap modern digital chargers are it is a false economy to get these prehistoric chargers , http://www.hobbyking.com/hobbyking/store/__216__408__Chargers_Accessories-Battery_Chargers.html

even with having to buy a DC supply for some of them they are still cheap and will pay for themselves in the long run by not killing battery packs , the x100 touch screen is such a clever device , it even gives real time graph to let you know if your battery has issues . ;)

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