Typhon Battery and Charger Advice/Questions

[MZA-4x4]

Hello All,


I have a 3 Typhon Mega V3s that I'm slowly upgrading (me and my sons just got these for xmas). I purchased a couple of 2s, 5200mAh, 50C LiPos to use with the stock setup to have more batteries/more power & Capacity. I have a few questions/concerns about LiPos and wanted to get your guys input:

1 - How do I know what the actually capacity is so that I can charge at 1C (or is it safe for me to just assume that these are 5200mAh, and use 5.2A charge)?

2 - if these are all the same specs, should they balance or charge from used (after a run) at about the same rate (with about the same mAh used to get to those points)?

3 - the stock ESC has "Low Voltage Cut-Off (LVC) = 3.2V per cell", is that too low?

4 - Can I safely store these (like overnight/for a few days) somewhere when balanced charged and not worry about them burning up, or should I always have them somewhere fireproof?

5 - Can I expect that the my brand new balance charger is calibrated correctly and that when it ways it's charged to 4.2v per cell that it's actually correct (or really close and within accepted tolerances)? Also, can I trust the IR (Internal Resistance Number)? Also, how close should the IR of each cell be (or what numbers should they be within)?




Here is the Batteries and Charger that I got:

Zeee 5200mAh, 50C, 2S

ISDT D2 Mark II Charger

Sorry about so many question/concerns, but I've just had a hard time finding good information about my question. Any links to good documents or information is greatly appreciated, as well as any advice.



Thank you,
MZA

 

[pug]

I'll try to answer what I can.

1. Whatever capacity is written on your LiPo is the capacity, so it it says 4000mAh, charge it at 4.0A, 5200mAh, charge it at 5.2A.

2. Charge them at the same rate, never leave a LiPo fully discharged or fully charged, if you won't be using it for more than 24 hours and it's dead/charged, storage charge it.

3. 3.2v/c isn't too low, the lowest a LiPo should go is 3.0v/c. If you want, you could get a LiPo voltage alarm and set it to whatever you want.

4. Don't leave them fully charged for more than 24 hours, don't balance charge it to put it away, storage charge it instead. To be safe, get a Bat-Safe.

5. The LiPo charger should be calibrated from the factory unless it's defective. You can trust the IR meter to check the health of your LiPo, for example, if the cells are 4, 7, 3, it should be fine. If it's way off like 4, 15, you will know one cell is degrading quicker than the other. I would keep note of the IRs before you charge and keep the notes safe so that you can see how quickly it's wearing out. Also check the voltages of each cell and take note of it.

 

[Adiabatic]

1. The capacity rating is usually determined by a controlled discharge test at low current from a fully charged cell voltage of 4.2V to an empty cell voltage of somewhere around 3.2V. The only way to know for sure if the rating is accurate - it usually is, though many people misunderstand what it means and expect the battery to output the full rated capacity during a run - is to do the test yourself. Discharge the battery from full to empty at a low continuous current and measure the energy output. But it's probably safe to just assume the rating is in the ballpark if it's a reputable battery brand. For my 5200mAh batteries I usually just set the charger to 5.0A.

2. You should use the same current for charging from storage to full, empty to storage, or empty to full. The charge curve of a lithium ion/polymer battery is non-linear so it will take less energy and time to charge from storage to full than empty to storage, and more than double the energy and time to go from empty to full than storage to full.

3. The 3.2V/cell cutoff is fine. This is generally considered the lowest voltage you should allow cells of this type to reach. Keep in mind that the ESC can only measure the total input voltage and not the individual cell voltage, so it will cut off if the input voltage drops below 3.2x where x is the number of cells in the battery. In theory this could allow some of the cells to drop below their recommended minimum voltage but in practice it seems to be fine. The voltage drops under load so you'll only momentarily be hitting the LVC target anyway, and the voltage you measure at rest after a cut off event will be hundreds of millivolts higher, 3.5-3.7V.

4. These batteries are at their highest risk of thermal runaway during charging and when fully charged, so I wouldn't consider this practice safe. You should always keep them storage charged except for when you're heading out for a run, and it's best to always store them in something fireproof or fire resistant. Bat-Safe at home, LiPo bag for transport to the field is what I prefer.

5. Chargers are usually calibrated okay but it's better to have something else to measure the voltage so you can check the readings against each other. IR is much more finicky to measure as you'll get different numbers depending on the charge state of the battery and the current used to measure it. I wouldn't trust the numbers your charger outputs as being an accurate measure of resistance, but they can be useful to track increases in resistance over time ie. if all the cells measure 3-4mΩ new and then increase to 7-8mΩ over time you can reasonably assume IR has about doubled. Those numbers should always be close to each other, within a few mΩ when the pack is near fully charged. If one is much higher than the others it suggests there may be a fault with that cell.

This post turned out to be mostly a longer form explanation of what pug already said so TL;DR read and follow his post.

 

[MZA-4x4]

1. The capacity rating is usually determined by a controlled discharge test at low current from a fully charged cell voltage of 4.2V to an empty cell voltage of somewhere around 3.2V. The only way to know for sure if the rating is accurate - it usually is, though many people misunderstand what it means and expect the battery to output the full rated capacity during a run - is to do the test yourself. Discharge the battery from full to empty at a low continuous current and measure the energy output. But it's probably safe to just assume the rating is in the ballpark if it's a reputable battery brand. For my 5200mAh batteries I usually just set the charger to 5.0A.

2. You should use the same current for charging from storage to full, empty to storage, or empty to full. The charge curve of a lithium ion/polymer battery is non-linear so it will take less energy and time to charge from storage to full than empty to storage, and more than double the energy and time to go from empty to full than storage to full.

3. The 3.2V/cell cutoff is fine. This is generally considered the lowest voltage you should allow cells of this type to reach. Keep in mind that the ESC can only measure the total input voltage and not the individual cell voltage, so it will cut off if the input voltage drops below 3.2x where x is the number of cells in the battery. In theory this could allow some of the cells to drop below their recommended minimum voltage but in practice it seems to be fine. The voltage drops under load so you'll only momentarily be hitting the LVC target anyway, and the voltage you measure at rest after a cut off event will be hundreds of millivolts higher, 3.5-3.7V.

4. These batteries are at their highest risk of thermal runaway during charging and when fully charged, so I wouldn't consider this practice safe. You should always keep them storage charged except for when you're heading out for a run, and it's best to always store them in something fireproof or fire resistant. Bat-Safe at home, LiPo bag for transport to the field is what I prefer.

5. Chargers are usually calibrated okay but it's better to have something else to measure the voltage so you can check the readings against each other. IR is much more finicky to measure as you'll get different numbers depending on the charge state of the battery and the current used to measure it. I wouldn't trust the numbers your charger outputs as being an accurate measure of resistance, but they can be useful to track increases in resistance over time ie. if all the cells measure 3-4mΩ new and then increase to 7-8mΩ over time you can reasonably assume IR has about doubled. Those numbers should always be close to each other, within a few mΩ when the pack is near fully charged. If one is much higher than the others it suggests there may be a fault with that cell.

This post turned out to be mostly a longer form explanation of what pug already said so TL;DR read and follow his post.

Thanks for the reply, and I am reading all of this and any other info you guys send my way! I guess I need a Bat-Safe ASAP for at home!!

As for my second question, I might have worded it poorly, but I was basically asking that iff I have 2 identical batteries and I charge from empty (at the same time, one on each charging port), shouldn't they charge relatively equally (same amount of mAh into them, same amount of time, give or take).

and as far as question 5, I was asking this because my IR numbers seemed to be kina all over the place. Here is a list of what two of these are showing today from a storage charge to fully charged:

Thanks for the replies!!!

 

[Adiabatic]

For question two, yes you would expect them to charge about equally. Not necessarily exactly equally because there will be slight variance in construction from the factory.

For question five, those numbers look about right. It's normal to see a large disparity when the cells are near storage and have just begun charging. The last two rows of numbers in your table are the most accurate and meaningful.

 

[MZA-4x4]

For question two, yes you would expect them to charge about equally. Not necessarily exactly equally because there will be slight variance in construction from the factory.

For question five, those numbers look about right. It's normal to see a large disparity when the cells are near storage and have just begun charging. The last two rows of numbers in your table are the most accurate and meaningful.

Awesome! I really appreciate the help. Thank you again!

 

[SrC]

Thanks for the reply, and I am reading all of this and any other info you guys send my way! I guess I need a Bat-Safe ASAP for at home!!

As for my second question, I might have worded it poorly, but I was basically asking that iff I have 2 identical batteries and I charge from empty (at the same time, one on each charging port), shouldn't they charge relatively equally (same amount of mAh into them, same amount of time, give or take).

and as far as question 5, I was asking this because my IR numbers seemed to be kina all over the place. Here is a list of what two of these are showing today from a storage charge to fully charged:


View attachment 194753


Thanks for the replies!!!

IR's are best evaluated when the lipo is at Full Charge. How the Lipo industry evaluates them.
When new out the box, usually should be around 5 miliOhms. From my experience, give or take. And all cells should be fairly close. The better lipos that are matched better will be closest. With age and more cycles, normally the IR's may drift apart from each other. One cell that is like 3 times more than the rest is a sign of a short lived, well used lipo. Proceed with caution at this point. Keeping them balanced and at 3.8v/ cell when stored for long periods helps in this regard.
I don't let my lipos sit for more than 24 hours in a full charged state. If I can help it. They are most volitile and dangerous in this state. Lipos like to be discharged right after a charge. Last longer. Won't degrade as fast. Leaving them charged for long periods of non use creates high IR's needlessy.
3.2v/cell is rather low for LVC. 3.4 is my target. Hard to control however unless using a Lipo alarm with a selectable voltage to remind when you hit your target cutoff.. Or with an ESC that has accurate enough LVC parameters that can be selected.
Always good to have a Cell Checker in hand when out bashing. Checking the lipo right after a full run.

 

[The Bean]

To be safe, get a Bat-Safe.

Or an ammo box. Those are way cheaper
Before/after running/charging I always check it with a LiPo checker, just to see how full, balanced etc they are.
The capacity the charger and checker show are always ±3% of each other.

 

[pug]

Or an ammo box. Those are way cheaper

Yep, just remove the rubber gasket.

 

[The Bean]

And put something in it to keep it open enough. If you remove that rubber seal, it creates a wider opening, causing the latch to not hook.

 

[MZA-4x4]

two other related question:

1 - I started charging a battery after a run and it was at 3.60v/3.61v, when the battery finished charging it showed 4186mAh. It that about what you expect a 5200mAh battery charged from that voltage?

2 - On the stock Typhon Mega system (ESC and Brushed motor). Does a runtime of 15-20 minutes (usually closer to 15 minutes) for on of these 5200mAh, 2S, 50C seem right?

 

[pug]

two other related question:

1 - I started charging a battery after a run and it was at 3.60v/3.61v, when the battery finished charging it showed 4186mAh. It that about what you expect a 5200mAh battery charged from that voltage?

2 - On the stock Typhon Mega system (ESC and Brushed motor). Does a runtime of 15-20 minutes (usually closer to 15 minutes) for on of these 5200mAh, 2S, 50C seem right?

1. That's normal, they count the total capacity from 3.2v/c usually.

2. 15-20 minutes is an above-average amount of runtime from that capacity.

 

[MZA-4x4]

1. That's normal, they count the total capacity from 3.2v/c usually.

2. 15-20 minutes is an above-average amount of runtime from that capacity.

OK, Awesome. All of this info has bee really helpful and reassuring.

Now the question is, how can I get longer runtime (or is just having more batteries the answer)?

 

[pug]

OK, Awesome. All of this info has bee really helpful and reassuring.

Now the question is, how can I get longer runtime (or is just having more batteries the answer)?

You can get a larger capacity LiPo or more LiPos, but you don't want too much runtime as you can burn out the motor.