Batteries

[Aaron.l]

Hi guys,

Complete noob talking here.

Got myself a basic smart charger. One that allows you to select voltage etc to charge at, battery type etc.

Also got a 9.6v 1600 nimh and not sure what to charge it at, volts, time and so forth. Also wanted to know if I have to discharge it before I store the battery and again, what volts or whatever I need to discharge it at and again, times and so on.

I'd appreciate any help.

Cheers

 

[Shamal]

Hi fella

Has your smart charger got a display? If it has then that should give you the info you need.  Plug batt in and select voltage and select batt type ie nimh and select start. You may be asked to select  amps if so maybe go safe and select 0.5 amps. The charger will let you know when it's finished. Just dont leave it unattended and keep checking to make sure batt and charger are not getting too hot.

Not quite sure how nimh work 

But your charger may have a storage charge setting for if the batt is not gonna be used for some time. If you are using it regularly then charge it after game and then check before next game.

Stand to be corrected on above as not to familiar with nimh but smart charger will let you know if something is wrong.

Regards 

 

[EDcase]

NiMh is a bit old tech.  Have a read here.

Li-Po (Lithium Polymer) are more common now as they do not have any memory effect and can store more power in a smaller package (Higher power density)

 

[Rogerborg]

Got myself a basic smart charger. One that allows you to select voltage etc to charge at, battery type etc.

How smart are we talking?  SkyRC or similar, with a display?

Also got a 9.6v 1600 nimh and not sure what to charge it at, volts, time and so forth.

NiMH is a bit of an issue for chargers.  With lithium (or lead) batteries, you can tell a charger what voltage the battery is, and it will know what voltage to limit itself to, as well as limiting the charging current.

With NiMH, the charger doesn't actually know the voltage, or at least I've not seen one that does.  It just charges until it sees the battery resistance spike / charging current drop, which indicates that it's (probably) full.  You generally want to charge batteries at a low current, as heat damages them, but that makes it harder for a charger to spot the current drop when a NiMH is full.  They can do it, but it's a slight risk factor, and some "smart" chargers - I'm looking at you Nuprol - are fit only for throwing in the bin, before they burn your house down.

A 1600 mAh, i.e. 1.6 ampere-hour battery charged at 1 amp will take at most 1.6 hours to charge from completely empty to full, plus a bit more for heat losses.  At 1.6A it should take an hour, At 2A, it will take 0.8 hours or 48 minutes, and so on.  But batteries rarely get that empty, so those are upper limits.  Keep an eye, or rather a hand, on the battery while it's charging, and if it gets uncomfortably warm, stop charging rather than pushing it too hard.

Or skip all that and get yourself some lithium-polymer or lithium-ion batteries.  

 

[Aaron.l]

Hi guys,

Complete noob talking here.

Got myself a basic smart charger. One that allows you to select voltage etc to charge at, battery type etc.

Also got a 9.6v 1600 nimh and not sure what to charge it at, volts, time and so forth. Also wanted to know if I have to discharge it before I store the battery and again, what volts or whatever I need to discharge it at and again, times and so on.

I'd appreciate any help.

Cheers

That's great thanks.

What would be the settings I'd need to use to charge a 7.4 lipo? The charger I have has a display so I can enter certain parameters, I just want to make sure I'm charging safely and properly.

Do I use the discharge program for lipo's after a game day if there's still charge left in the battery or before storage? And what amp or voltage do I discharge a 7.4 lipo to?

Cheers again for any advice you can offer.

 

[Cannonfodder]

I wouldn't fully discharge lipos as this fucks up the cells

 

[Rogerborg]

What would be the settings I'd need to use to charge a 7.4 lipo?

It depends on the charger.  If you tell us, I'm sure someone here will have some experience with it.

If it's using the SkyRC firmware it'll have a specific lithium balance mode, good for lipo or li-ion, and a "2S" i.e. 2... er... cell, or 7.4V settings.  This actually means charging the cells up to about 4.2V each, or 8.4V for a "7.4V" battery.

You should be able to set the maximum charging current.  If I'm not in a hurry, I use 1C, i.e. the current that will charge the battery in an hour.  For a 1600 mAh / 1.6Ah battery, I'd charge at 1.6A - you'll see the current drop as the battery gets full.

Do I use the discharge program for lipo's after a game day if there's still charge left in the battery or before storage?

Opinions vary, but you never want to over-discharge lithiums.  I used to to leave mine alone unless they were very discharged, in which case I'd charge them fully.

However, I've recently been convinced that keeping them at a storage charge level is kindest to them.  A decent charger will have a storage setting, which will charge (or discharge) lithium battery cells to whatever it thinks (or you tell it) is an appropriate level.  My iMax B6, for example, takes them to 3.8V per cell, which represents about a 40% charge.

Some owners prefer higher, say 60-80%.  Depending on your charger, this might represent about 4.0V per cell.  What I wouldn't do any more is leave them at the full 4.2V per cell for any length of time, although I expect most of us charge to that level the night before a game.

They're cheap enough now, especially in the overall context of airsoft costs, that it's not something that bothers me that much.

 

[EDcase]

Depending how often you play, I would suggest the 'storage' option if there is one or leave them as they are until the next game.

From info I've seen, its best to leave LiPo's about 70% charged for storing.

Give them a full charge the day before a game.

 

[Rogerborg]

Its best to leave LiPo's about 70% charged for storing.

So I've heard, but my B6 stores at 3.8V per cell which is (somewhat surprisingly) just 40% based on https://blog.ampow.com/lipo-voltage-chart/

70% would be about 3.95V per cell.

I have no firm opinion on what's actually best. The most I'd really venture to suggest that storing at anywhere between 3.6V and 4V is probably better than at under or over that range.

 

[Speedbird_666]

So I've heard, but my B6 stores at 3.8V per cell

That's normal for most chargers.

I have about 50-60 LiPo packs at the moment for my RC hobbies as well as Airsoft, they all get stored at 3.8v per cell with no noticeable ill effects.