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Author Topic: Weird Batteries  (Read 1745 times)

SJG001

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Weird Batteries
« on: June 04, 2021, 10:00:39 am »

Due to working from home and COVID - modelling has taken a back seat - however I am doing repairs on RC tanks at the moment

The current batteries are LiPO - but are temperamental and the onboard PCB goes to sleep randomly so the tanks become paperweights. The batteries can be woken by charging them as NICAD's on a fast charger for 10-15 minutes - but this is a short-term fix and to be honest scares me.

I am trying to find replacements and would rather replace the batteries with something safe, easily used along with a better quality (safe) charger - any suggestions on a supplier for unusual batteries

(I have tried local and online model stores - the standard RC packs are either the wrong shape or size)
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Tug Fanatic

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Re: Weird Batteries
« Reply #1 on: June 04, 2021, 10:52:08 am »

Are you saying that the LiPO packs have a PCB built into them?
A photo with dimensions would make life much easier. What is the voltage & MaH rating of the packs.
Are your tanks a recognized brand?
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SteamboatPhil

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Re: Weird Batteries
« Reply #2 on: June 04, 2021, 10:55:26 am »

Component shop has a huge variety of normal and weird batteries
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SJG001

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Re: Weird Batteries
« Reply #3 on: June 04, 2021, 11:41:10 am »

They are  65 by 35 by 18mm  - 7.4V 1800mAh - with a Tamiya fitting - They have a onboard LiPO charger

Thanks - The Component shop - that was the name I forgot
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chas

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Re: Weird Batteries
« Reply #4 on: June 04, 2021, 12:38:41 pm »

I'd be suspicious of the Tamiya connector, a poor or intermittent connection can do strange things to electronics. To say that they aren't my favourite would be a huge understatement.
Charles

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SJG001

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Re: Weird Batteries
« Reply #5 on: June 04, 2021, 01:19:25 pm »

Might switch out the connectors - but at the moment getting a safe battery and charger option is the priority.


The onboard charger with the lipos is something I have seen before - but hate
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tsenecal

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Re: Weird Batteries
« Reply #6 on: June 04, 2021, 04:18:11 pm »

the size and power of the battery is going to make this difficult...  what are the actual dimensions of the space that the batteries fit in?  can a bigger battery fit?

hobbyking has a nice system where you can actually use dimensions as a filter when searching for replacement batteries.
they have a 2100mah lipo battery that is 62x34x28mm, and several batteries that are 14mm to 16mm thick, but those are 100+ mm long.

any current lipo charger should work fine.

I agree with the others that almost anything would be better than the tamiya connectors.
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SJG001

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Re: Weird Batteries
« Reply #7 on: June 04, 2021, 04:30:13 pm »

I am guessing they are designed so that  you have to use their fittings.


The Sherman could accept a bigger battery - The T90 the battery box is 50*75*35 - I just emailed the component shop.


Did manage to get one working today - lasted 30 seconds before the PCB put itself back to sleep
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SJG001

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Re: Weird Batteries
« Reply #8 on: June 04, 2021, 05:00:07 pm »

Added some photos
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RST

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Re: Weird Batteries
« Reply #9 on: June 04, 2021, 06:40:49 pm »

Hi,


Have you ever watched bigclive.com on YouTube?  For a while he was stripping lots of batteries and showing how they worked.  Not saying he's right or wrong, but perhaps it's possible to re-use the original Li-Po but stripped of the PCB for charging with a separate Li-Po charger and balance leads etc.  I'm not saying it's right or safe but if the battery itself is good it might be an option if space is an issue?  Saves binning both parts if you have a separate Li-Po charger to use?


Rich
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SJG001

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Re: Weird Batteries
« Reply #10 on: June 04, 2021, 07:20:44 pm »

Did have a look at removing the PCB - but the one I stripped down had so much expoxy - i don't think it could be done safely - Will pop over to Dingwall tomorrow and see if our FLMS has any ideas.

These packs are popular in China so have encountered them before. You can trick the PCB LiPO charger by charging as Nicads first - but its not safe and having to do it every time you run the tank is a pain

I could repurpose a RC Car battery for the Sherman - but the T90 - the battery bay is too small.

The importer was about as much use as a paper fireguard
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RST

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Re: Weird Batteries
« Reply #11 on: June 04, 2021, 10:48:31 pm »

I don't know what FLMS is but yes the Sports and Model shop have a few batteries, mostly from Radient I think.  Sure you know but most of the packs are in the glass case.  They've got a few smaller ones hanging up in packets up in the back left corner with aeroplane props etc.  But I'm not a Li-Po user so tend to glaze over them!  I think if you have a separate charger then surely it must open up more options.  One pic you didn't add is of the batteries themselves.  Andy always seems to have a rummage under the counter for me if it's a bit of an obscure request.  One or three 40mhz receivers have not been unknown to appear in his hands over the last few years which were snapped up immediately!
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SJG001

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Re: Weird Batteries
« Reply #12 on: June 05, 2021, 02:31:14 am »

Friendly Local Model Shop


Tried to upload a photot of the battery - but it kept failing
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Martin (Admin)

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Re: Weird Batteries
« Reply #13 on: June 05, 2021, 05:25:09 am »

Friendly Local Model Shop


Tried to upload a photot of the battery - but it kept failing

Email me a photo , I'll post if for you.   :-)) 
 martin@modelboatmayhem.co.uk
 

 
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grendel

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Re: Weird Batteries
« Reply #14 on: June 05, 2021, 05:38:23 am »

in my experience the pcb part of the battery pack is designed as a safety feature to cut the power if the pack falls below a certain voltage, thus if the output voltage drops for any reason,below this it cuts out, it seems to me that either the load on the battery is pulling the voltage below the cutoff, or the batteries are not taking enough charge to keep the voltage high for long.
in such a small space you will find it difficult to get much better than lipo, for capacity vs weight and size. you can get the lipo packs in all shapes and sizes, just get a suitably sized pack with a connector and balance lead and a charger and you should be good. it might be worth trying to measure the current draw when operational, or check the voltage when various components are run, to get an idea of the reason the battery trips out. I tend to make up a lot of my own battery packs from 18650 cells, and add the balance leads, if you do this without the pcb you do have to keep an eye on the voltage so I use a plug in battery monitor that connects to the balance lead and gives an audible warning when the cutoff voltage is reached, but that would lose you space in your battery compartment, its not huge about 25mm square and 6mm thick.
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SJG001

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Re: Weird Batteries
« Reply #15 on: June 07, 2021, 03:59:11 pm »

So an update -  I managed to get the Sherman running with a stick battery for a RC CAR as the battery bay is larger.- The solution dimension wise is not ideal but it works so I will be buying a slightly smaller pack

The Component Shop have suggested a solution which may work for the T90 as the batteries may have have a lower than badged amperage of 1300mAh rather than 1800mAh.

Sorry about the quailty of the photo - SMH
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