Battery Capacity

[parcou]

Question on charging and battery capacity. I have Spektrum 3S 5000mha 11.1v smart batteries using a Spektrum charger. Does a 5000mha battery every charge to that amount. I assume no...but what amount should it realistic get to? I would assume over 3000mha in that range is what I am seeing but never in mid 4000mha or 4000mha.

 

[Rainger40]

What you’re seeing is the mah it put back into the battery not the total for the pack.

 

[Jackjax801]

Depends on when LVC kicks in. The rated capacity, if it's a true rating, should be around what the pack takes if going from empty to full. My Typhon's LVC seems higher than most so it doesn't show as much mAh when charging it. I also haven't charged from empty (LVC) to full but instead from LVC to storage and then storage to full when I'm ready to use it again.

 

[KevinC]

@jkflow chime in please.....
I regard him as the Willy Wonka of all things electronic...

cheers,
kev

 

[Jerry-rigged]

Note to get 100% MAH you need to take the pack down to 3.0v. Most LVC will leave the pack at 3.5 or 3.7. Lots of MAH left on the table.

Check the manual on your charger. See if there is a Cycle option. This should fully charge the pack, then discharge, then charge, repeat for a set number of cycles, and should save charge/discharge mah.

 

[jkflow]

@KevinC Willy Wonka? ?

Everybody summed it up already. You will never be able to charge the listed capacity. The listed capacity is the total capacity of the battery but not the 'usable' capacity. Rule of thumb, you can only use 80% capacity without damaging the actual chemistry inside the battery permanently. That is reached when you are ~ 3.7V per cell (resting). Typically we all run these to 3.5V under load. LVC on stock BLX kicks in at ~3.2V i.e. by default you are damaging lipos if you do that.

The hard thing for people to understand, the battery can still give 'capacity' even below 'empty' but at that point you are altering the chemistry inside the battery for good, that is what we all want to avoid. You can never recover this lost capacity, typically visible sign of stress if puffing (balloon style, not slight puffing).

Pending the chemistry types, the absolute 'zero capacity' is at ~3.2V per cell i.e. if you charge from here you should get the advertised capacity. Problem is, you already damaged the lipo and it will not reach that advertised capacity. How much damage really depends on how long it was in the damaged state, measured in hours.

Back to OP, you should be seeing a charge of ~ 4000mAh as the max at from the 'empty state', that would be a good lipo. That is when you are at ~ 3.6-3.7V prior charging.
Keep in mind, if you are charging from storage level (3.8V), as you should, you already have ~ 35%-40% and you only see ~3000mAh added capacity to get to full charge.

Use that as a gauge i.e. charge to storage level and you should be close to the 3000mAh (~60% of advertised capacity).
Give it +/-5%, as all our hobby stuff is not the most accurate to begin with.

Now let me hand out some golden tickets!

 

[parcou]

@jkflow @Jerry-rigged

Thx...great info. The Spectrum S2100 charger does not have a cycle option I see....however all the feedback was helpful and full of education to help me to understand what I am seeing from a 3.8 storage charge to 4.2v on 5000mha battery. LVC cutoff does not go down too low for the Infraction v1 & Granite v2....seems to me the new Felony and Big Rock do go a tad bit lower for LVC in the new Arrma but I need to reverify that.

Thx!

 

[arrmadillo]

@parcou Think of it this way, when you go to the gas station to fill up your car, you top off what has been burned off in the tank and not the total capacity of the tank. Same principle applies to your lipos!

 

[Jerry-rigged]

@jkflow @Jerry-rigged

Thx...great info. The Spectrum S2100 charger does not have a cycle option I see....however all the feedback was helpful and full of education to help me to understand what I am seeing from a 3.8 storage charge to 4.2v on 5000mha battery. LVC cutoff does not go down too low for the Infraction v1 & Granite v2....seems to me the new Felony and Big Rock do go a tad bit lower for LVC in the new Arrma but I need to reverify that.

Thx!

At 3.8v, your cells still have 40% capacity left.

As a side note, often, when I get done with a wrenching session, and want to test the truck, I will grab a battery off storage charge (3.85v) and run it test the build. After 5 minutes of running in the yard and up and down the street, the pack will often still be around 3.7v-3.6v.