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HomeTurbineAircraftHelicopterTurbine Helicopters › Battery Charging.
03-09-2008 03:09 PM  10 years agoPost 1
G-SWSMrrApprentice - Midlands, UK - My Posts: All  Forum  Topic

Hi Gang.

I have been talking with the people from Overlander who make the Tornado range of batteries.

I have three of their products, and have just recently bought a Bantam BC6 charging unit, which as I'm sure you are all aware is very popular, and does a lot more than just charge batteries.

I am however stuck, and would welcome some help if anyone knows what the problem is.

I emailed Overlander to ask what the cycling rates should be, with the emphasis on the requirements for discharging and recharging, and got this reply.

Hi Steve.
Please find the details as requested.

Cycling.

2500 X 8 TX Discharge Current / Final Voltage = 1 Amp / 6.8V

4100 X 4 (4.8v) Receiver Discharge Current / Final Voltage = 2.00 Amp / 3.4V

4300 X 6 (7.2v) ECU Discharge Current / Final Voltage = 2.0 Amp / 5.1V

Charging.

2500 X 8 TX Upper Limit = 1 Amp manual

4100 X 4 (4.8v) Receiver Upper Limit = 4.10 Amp manual

4300 X 6 (7.2v) ECU / Kerosene unit Upper Limit = 4.10 Amp manual

The point where I am now stuck is when it comes to the charging side of things.

I charged the Transmitter battery this morning, and it charged far too quickly for my liking, then shut itself off as it said "completed charging" and yet when I connected the battery to the transmitter it showed up as 8.6v.

Can anyone please tell me where I'm going wrong, as good as this charger is, and after reading the manual several times I can't help but feel that the manufacturers must practise vague at the weekends.

Thanks.

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03-09-2008 03:46 PM  10 years agoPost 2
FCM

rrElite Veteran

Surrey, England

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I am not familier with the charger you have but those charging rates look high to me. I assume these are NiMh cells?

I would not want to put a 1 amp charge rate into an 8 cell 2500 mah TX pack. I have similar 'sounding' 2500mah NiMh TX packs and these cells are very fragile and will only take a trickle charge of 150ma or up to a maximum of 1 amp with 'temperature control' otherwise overheating will occur and they will vent. It sounds as though you got false peaks when you charged. This is good as it should have prevented overheating.

I do not peak charge my TX batteries. I will only trickle them. The other flight pack and turbine cells should peak okay but unless you are in a hurry, I would cut back the charge rate on them too.

My batteries came from Hangtime Hobbies in the USA. The amount of information on their website makes it well worth a visit even if you just read the free advice they give.

Paul.

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03-09-2008 09:47 PM  10 years agoPost 3
Dave Wallace

rrApprentice

Devon UK

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Nimhs
I use 4100mah nimhs and I regularly fast charge them at 3 amps with no problem and no overheating. Obviously fast charging will shorten the life of the battery but it pays to cycle them at least three times from new. I have been told to charge them on cycle at 10% of their capacity so a 4100mah pack will be 410mah for ten to twelve hours and I discharge them at 500mah. You will then get better performance from them. it's also good to do this every so often as well.

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03-10-2008 02:44 AM  10 years agoPost 4
FCM

rrElite Veteran

Surrey, England

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Yes, all should be 'condition charged' before being fast charging.

Not all NiMh are the same and have different max charging rates. Those 2500mah NiMh TX cell have a high internal resistance hence the low rated max charge.

The others should have a far lowe resistance and should be good for fast charging.

Paul.

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