Need to charge a 7.4v 2000mAh Li-Polymer Battery

Seve OB

As the title says I need to charge a 7.4v 2000mAh Li-Polymer Battery. I actually have 2 batteries for the same product, but the second one has no "Li". The second one is not the battery that came with the product.

It is a handwarmer, but the problem is when I was given it, I got no charger. It came from the good old U S of A. I think I can buy a charger for it online, but it is about €50 by hte time they have added up all the charges and then I'll probably be hit with a customs bill when it gets here!

Anyway, I've gone to Maplins where figured I would probably walk in and pick a charger up handy enough but they had nothing.

Now I have a charger that fits, but that kind of reminds me of when one of the kids got electricuted in the snapper and Jimmy asks them why they put their fingers in the socket to be answered "cause it fit"

Anyway, the charger is input 100-240v 50-60hz, and output 5v
I'm guessing the output is really all that matters. is it safe to charge a 7.4 v battery with a 5v charger?

by the way, there are no lights on either to let me know if charging is taking place or completed

Bruthal

A proper lipo charger is needed for charging lipo batteries. It can be dangerous to charge them without the proper charger.

A 5v charger can not charge a 7.4v battery. 7.4v is the nominal voltage. Fully charged it will be 8.4v

Seve OB

Bruthal wrote: »

A proper lipo charger is needed for charging lipo batteries. It can be dangerous to charge them without the proper charger.

A 5v charger can not charge a 7.4v battery. 7.4v is the nominal voltage. Fully charged it will be 8.4v

cheers.

these are the batteries
as you can see, the charger plugs into the batteries, the warmer itself then plugs into the same socket

Seve OB

This is the charger, $20 plus another $25 to ship it.

https://www.gtechapparel.com/collections/products-g-tech-apparel/products/g-tech-7-4v-dual-head-wall-charger#content



Would this work do you think? I'm just not sure if the connections will work
https://www.amazon.co.uk/gp/product/B01EAAAPEG/ref=ox_sc_act_title_4?smid=A29EZVB447EKA7&psc=1

eeguy

You can't use any old plug adapter to charge a lipo battery. You need one that's correct for the voltage.

Read this before you damage something
http://www.dronetrest.com/t/everything-you-need-to-know-about-lipo-battery-chargers/1326

Seve OB

eeguy wrote: »

You can't use any old plug adapter to charge a lipo battery. You need one that's correct for the voltage.

Read this before you damage something
http://www.dronetrest.com/t/everything-you-need-to-know-about-lipo-battery-chargers/1326

thanks, will look through that link
i was thinking along those lines alright, i don't need to be starting any fires
looks like spending €50 to get the chargers from USA might actually be worth it

eeguy

Those chargers are less than a tenner on Amazon. If you can find one with the right plug you're golden, if not cut the plug off the 5v charger and crimp it onto the lipo charger.

Seve OB

eeguy wrote: »

Those chargers are less than a tenner on Amazon. If you can find one with the right plug you're golden, if not cut the plug off the 5v charger and crimp it onto the lipo charger.

Good idea, thanks for that

Tuco88

Why 2000mAh and not just 2Ah? Is this a marketing thing i have noticed a few people get caught out buying the likes of drills and stuff...same with sorta thing with broadband speeds.

ED E

Tuco88 wrote: »

Why 2000mAh and not just 2Ah? Is this a marketing thing i have noticed a few people get caught out buying the likes of drills and stuff...same with sorta thing with broadband speeds.

When things like RC and Airsoft started these packs were 800mAh which is easier than. 8, I suspect its just continued from there.

Seve OB

http://www.ebay.com/itm/7-4V-Lipo-Battery-Charger-AC-100-240V-1A-Power-Adapter-for-Fatshark-HD2-V3-FPV-G-/182418352110?hash=item2a78fb27ee:g:Th4AAOSwZQRYdmfg

might be the job

says output 1A though. I'm not sure what that means and do i need 2Ah?

Tow

Seve OB wrote: »

http://www.ebay.com/itm/7-4V-Lipo-Battery-Charger-AC-100-240V-1A-Power-Adapter-for-Fatshark-HD2-V3-FPV-G-/182418352110?hash=item2a78fb27ee:g:Th4AAOSwZQRYdmfg

might be the job

says output 1A though. I'm not sure what that means and do i need 2Ah?

Might, but I would look for one with a proper BS1363 plug.

They look like cheap charges/PSUs, even the proper one. The assumption is the charge/protection controller circuitry is in the battery. You need to think of Lithium batteries as incendiary devices, ready to burn your house down or a hole in your pocket/leg.

The 1A rating of the charger means it will take 2 hours (at 100% efficiency, which is impossible) to change the battery (.5C) fully. The charge rate will be governed by the 'assumed' controller on the battery. It may well want to draw more than 1A, which the charger may not like.

How long the is it supposed to take to change the battery?

Lithium batteries are not toys, so care most always be taken with them.

Bruthal

Tuco88 wrote: »

Why 2000mAh and not just 2Ah? Is this a marketing thing i have noticed a few people get caught out buying the likes of drills and stuff...same with sorta thing with broadband speeds.

Yea on RC aircraft we would be closely monitoring charge and more so, discharge levels in mA rather than amps, often during the actual flight.

Seve OB

Tow wrote: »

Might, but I would look for one with a proper BS1363 plug.

They look like cheap charges/PSUs, even the proper one. The assumption is the charge/protection controller circuitry is in the battery. You need to think of Lithium batteries as incendiary devices, ready to burn your house down or a hole in your pocket/leg.

The 1A rating of the charger means it will take 2 hours (at 100% efficiency, which is impossible) to change the battery (.5C) fully. The charge rate will be governed by the 'assumed' controller on the battery. It may well want to draw more than 1A, which the charger may not like.

How long the is it supposed to take to change the battery?

Lithium batteries are not toys, so care most always be taken with them.

Yea the yoke I have is an american product hence the american plug. I've emailed the company to see if they have a european supplied but no reply yet.

I've already decided, if i do indeed get a charger, it will be charged at my desk while i'm sitting here beside the fire extinguisher ready to pounce at the first sign of smoke. well actually, maybe i'll sit a bit away from it incase an explosion comes before the smooke :eek:

Here you go. This charges everything. You need to make your own leads and tail in a switched mode power supply.



Using mAh where Ah is more appropriate is a simple case of marketing w@nk. The number looks bigger.

Bruthal

Sir Liamalot wrote: »

Using mAh where Ah is more appropriate is a simple case of marketing w@nk. The number looks bigger.

Meters per litre for cars is next i guess.

They usually quote battery capacity not device operational reserve after quiesent losses and the discharge cut off varies. Most manufacturers drive the cells too hard to get better out of the box performance at the expense of serviceable life.

eeguy

Sir Liamalot wrote: »

Using mAh where Ah is more appropriate is a simple case of marketing w@nk. The number looks bigger.

Most batteries are still sub 1Ah, so it makes more sense to stick with the one scale.

760mAh sounds better than 0.76.
Also if you're calculating charged/discharge you'll usually do it in mA, so it saves calculation errors.

A lot of cells I think. Batteries will be larger by nature.

I agree but I move the decimal after the first whole number or follow the convention of the calculation.

I'd a friend send me a link to one of these thuther day.

"39600mAH 146WH lithium battery"

eeguy

Sir Liamalot wrote: »

A lot of cells I think. Batteries will be larger by nature.

I agree but I move the decimal after the first whole number or follow the convention of the calculation.

I'd a friend send me a link to one of these thuther day.

"39600mAH 146WH lithium battery"

Hah, there comes a point where you just say 40A