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Li-ion batteries from Hong kong


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I'm in need of a new battery to power my magnet. Like most I have to carry enough kit and my normal 12v 17ah battery doesn't lend itself to the weight saving side of things. Browsing the auction site there are these lithium ion batteries available which are blue in colour from Hong kong. Does anyone on here use them to good effect with there magnets?

 

Cheers

Ben

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I've talked about lithium batteries in a few threads and can throw quite a bit of info into this. I use them in my job on a day to day basis and they are INCREDIBLY dangerous in the wrong hands.

 

These batteries offer the highest Ah per square inch than just about any other form of battery power, but with this comes great risk and danger.

 

The first thing is to divert you away from 'cheap' lithium batteries. Never ever buy cheap Lipo/Li-ion batteries. These things are dangerous and need to go through stringent quality control - when you buy cheap ones from no-name brands, you're going to be putting you, your family and home at great risk.

 

Most problems actually occur when charging the batteries. If you've scrimped on cheap batteries, you'll inevitably scrimp on the charger, which ends up putting you in a double failure situation. A 'good' lithium battery for a magnet (3S, 8000mah) should cost you £90-120 and the balance charger £100-250 depending on how many you want it to charge and the wattage.

 

A good charger will balance the cells and keep it in good health. When you use one on a magnet you also need a battery alarm, or it'll be over discharged and put the cells out of balance, again, putting a risk of fire into the recharging process.

 

It's not all doom and gloom with these batteries, but as I'm sure you'll see from the reloading threads, if you try and do it on the cheap it won't go well. If you invest properly in the right equipment and learning, you'll be much safer.

 

Any questions, let me know!

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In addition most of those blue packs are sold as suitable for CCTV systems, that is low current draw over a long period. Your magnet will want much higher power than they would deliver.

 

I'm not entirely sure you're right there. Lipos are renowned for being able to dump a very high current in a short space of time and useless at long slow discharges (plus they're very susceptible to the cold). That's why they're used in car booster packs, whereas lead acid are great at slow trickle of current over a long period of time.

 

The C rating of a Lipo denotes the amount of current it can deliver, multiplied by the mAh rating. So a 10C 5000mah lipo can safely discharge 50amps. I haven't seen many packs under 10C and your average wiper motor draws between 4-15 amps.

 

If OP has a link, I'm happy to shed some light on the quality of lipo, for the interest of science.

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I've been buying the black plastic lithium packs such as http://www.dx.com/p/rechargeable-dc-12680-12v-6000mah-battery-w-switch-led-lamp-black-424486#.Vvwgvsvmpaw and they've proved ideal for flappers and small geared magnet motors (with a speed controller to stop them tripping on start up). Apart from charging them in a safe place I don't see the problem. Let's face it no-one is going to pay £3-400 just for a battery and charger to shoot a few pigeons.

 

Are they really that bad?

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http://www.ebay.co.uk/itm/Convenient-12V-Li-po-Super-Rechargeable-Battery-Pack-DC-for-CCTV-Camera-8000mAh-/311468596135 as an example.

 

The wiring used for these is very very fine and they apparently have a 1 amp cut out according to what I read somewhere, I can't recall where.

 

Notice none of the ebay vendors are willing to put a discharge current rating on them.

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