Ultrax Battery Rapid Voltage Drop

[Phaedrus]

The best batteries I’ve ever used were made by MaxAmps, but the cost for the performance is quite high. Where such performance is necessary that cost is justified.

If we were to consider how most multirotor operators treat their batteries we might find some justification in using lower cost, lower performance batteries as many would unwittingly damage them in the first few cycles and never be able to make full use of a battery regardless of the quality.

There's a lot to be said for that approach. I did some measurements/calculations after several flight on my H+ and I was very surprised at how light the load really is, and when you spread it across 6 motors none of the ESCs/motors are working overly hard. 20C-25C cells would be more than adequate for this type of use.

Users are far harder on their packs than the aircraft is. Improper use by over discharging and poor charging and storage practices are doing far more damage to the packs.

 

[Satdiver]

What is the date of manufacture on the UltraX batteries? The IR values are high for supposedly new stock.

Under the latching tab on the back of both batteries are the numbers "180727" so I'm guessing that may mean a manufacture date of July 27, 2018. There is also a QR code under the tab that I scanned and did an internet search for but nothing came up.

The only other numbers on the batteries is a bar code on the side- 8 89551 00249 3

I'm giving them a second chance and have another set of 2 new Ultra X batteries that I should be receiving today and will IR test them as soon as they arrive as well.....I hope they work out better than the last set!

Todd

 

[DoomMeister]

The barcode on the side is definitely the UPC for the UltaX 6300mAh for the Typhoon H.

I believe you are probably correct about the numbers under the latch. I am truly baffled by the high IR readings. I also think you will find they are in milliohms and not ohms.

 

[Fred Garvin]

I checked the 2 Ultrax batteries I have....same 180727 under the latch.

 

[PatR]

IR is usually a measure of milliohms with our batteries.

 

[DoomMeister]

IR is usually a measure of milliohms with our batteries.

Thanks PatR! Your post made me recheck mine above. I edited millions to milliohms as I originally intended. Siri’s autocorrect is dumb as a rock or thick as a brick as Jethro Tull would say.

 

[Satdiver]

The barcode on the side is definitely the UPC for the UltaX 6300mAh for the Typhoon H.

I believe you are probably correct about the numbers under the latch. I am truly baffled by the high IR readings. I also think you will find they are in milliohms and not ohms.

IR is usually a measure of milliohms with our batteries.

@DoomMeister and @PatR - You are correct as my Tenergy battery checker reads out in milliohms (ie .010 ohms) but I mistakenly failed to type it in in decimal format.

Well, my two new replacement Ultra X batteries arrived this evening at a storage voltage of 15.21v and 15.28v with what appears to be a manufacturer date of November 04, 2018 (181104). These two were also purchased from Amazon but the seller was GensAce/Tattu.

When checked for IR, they were .010, .002, .004 and .010 ohms for one and .011, .002, .004 and .009 ohms for the second. Quite a bit less than the original two that gave me issues at first but still, they're already at double digits in some cells.

I'm planning to charge them up and try and fly them tomorrow (very low to the ground!) to see how they react. If they act anything like the last two, they'll be returned and I'll be looking for a different brand.

I'll give an update tomorrow.

Todd

 

[PatR]

Each battery has a cell reading much too high for a new assembly. I’m starting to wonder if the high count cell is not in some way being influenced by a wire and connector.

I’d like to see Phaedrus step in and share his thoughts with us.

 

[Phaedrus]

Here's a good general guide to IR readings for lipos:

a) Packs that are as good as new: between 0 and 5 milliOhm/cell
b) Packs that have been used dozens of times, but still feeling fairly good: between 5 and 10 milliOhm/cell
c) Packs that have been used even more, and start to feel weak: between 10 and 20 milliOhm/cell
d) Packs that almost won't hold your model in the air anymore: over 20-25 milliOhm/cell

But don't get super hung up on them. Due to variability of the instruments used to measure and the conditions (mostly temperature) under which it is measured there is some slop in the above numbers. FWIW on the first dozen or so cycles on my four H+ packs I am seeing an average of around 6 milliohms per cell. What is important is to establish a baseline for each of your packs and to track it over time. I keep a spreadsheet that tracks how many milliamps capacity was put into the pack, IR for each cell, and % of pack that had been used (based on recharge data). I use a charger that allows me to track these values.

The numbers above are worrisome not so much for the absolute values, but for the difference between the cells in a pack. My packs normally are showing around 1 milliohm per cell max variation across all four cells. A spread of .002 to .011 is a big deal. I agree that some funky wiring or connector issue could be the issue. This is one of the rare cases where I would recommend cycling the packs. I would use around a 5C load to drop the voltage down to around 3.2 volts per cell. Then let the pack sit for a time and charge it normally. This can sometimes even out the IR of the cells. This assumes no other physical issues are present.

Keep in mind that lower temperatures tend to increase IR and warmer temps lower it. So don't discount that effect either.

Finally, I see no reason not to do a few low slow flights watching the battery voltage and then charge again.

 

[Satdiver]

Each battery has a cell reading much too high for a new assembly. I’m starting to wonder if the high count cell is not in some way being influenced by a wire and connector.

I’d like to see Phaedrus step in and share his thoughts with us.

@PatR - with my charger set-up, I have four seperate charging/balancing leads and have used different leads with different batteries during testing. I still end up with the IR readings I posted earlier.



Todd

 

[Satdiver]

Here's a good general guide to IR readings for lipos:

a) Packs that are as good as new: between 0 and 5 milliOhm/cell
b) Packs that have been used dozens of times, but still feeling fairly good: between 5 and 10 milliOhm/cell
c) Packs that have been used even more, and start to feel weak: between 10 and 20 milliOhm/cell
d) Packs that almost won't hold your model in the air anymore: over 20-25 milliOhm/cell

But don't get super hung up on them. Due to variability of the instruments used to measure and the conditions (mostly temperature) under which it is measured there is some slop in the above numbers. FWIW on the first dozen or so cycles on my four H+ packs I am seeing an average of around 6 milliohms per cell. What is important is to establish a baseline for each of your packs and to track it over time. I keep a spreadsheet that tracks how many milliamps capacity was put into the pack, IR for each cell, and % of pack that had been used (based on recharge data). I use a charger that allows me to track these values.

The numbers above are worrisome not so much for the absolute values, but for the difference between the cells in a pack. My packs normally are showing around 1 milliohm per cell max variation across all four cells. A spread of .002 to .011 is a big deal. I agree that some funky wiring or connector issue could be the issue. This is one of the rare cases where I would recommend cycling the packs. I would use around a 5C load to drop the voltage down to around 3.2 volts per cell. Then let the pack sit for a time and charge it normally. This can sometimes even out the IR of the cells. This assumes no other physical issues are present.

Keep in mind that lower temperatures tend to increase IR and warmer temps lower it. So don't discount that effect either.

Finally, I see no reason not to do a few low slow flights watching the battery voltage and then charge again.

Thanks for the insight. I'll recheck them tomorrow after test flights and cooling to room temperature to see what IR readings they end up at.

Todd

 

[Phaedrus]

It loos like you eliminated any external issues regarding the charging leads, etc. There may still be something in the packs themselves. Let us know how the flying goes and if a couple of cycles on the packs changes anything.

 

[Vegasrobbi]

Sorry I have not read this entire thread but wanted to add something. I have 4 of these batteries and overall they work well IMO. Recently with the cold I had the low voltage alarm come on shortly after take off so I did a little experiment. I fully charged two batteries, one I warmed in the car to about 80*f, the other I did not warm and ambient was about 41*f. As you can imagine the cold battery went into low voltage cutoff just after takeoff, the warm battery flew 15 minutes. After warming the cold battery it too flew as expected.

 

[Mrgs1]

Take a leaf out of Formula One, the tyres have their jackets on til tyre change, keep batteries in a jacket, coat, bag or similar to keep warm too.

 

[Phaedrus]

When I was racing fast electric RC boats we learned that we got max performance by warming the packs to 110 degrees F.

Most of used either heating pads or one of those heated camping deals that look like a cooler, except they have a heater in them.

Cold pack bad, very bad!!!

 

[PatR]

When I was racing fast electric RC boats we learned that we got max performance by warming the packs to 110 degrees F.

Most of used either heating pads or one of those heated camping deals that look like a cooler, except they have a heater in them.

Cold pack bad, very bad!!!

Aerospace outfits use something similar. It didn’t take them very long performing thermal extremes testing to definitively establish what happens to a battery at -20C. Funny thing is, they did that in 2008 but hobbyists are still trying to figure it out.

 

[JizzyGillespie]

Under the latching tab on the back of both batteries are the numbers "180727" so I'm guessing that may mean a manufacture date of July 27, 2018. There is also a QR code under the tab that I scanned and did an internet search for but nothing came up.

The only other numbers on the batteries is a bar code on the side- 8 89551 00249 3

I'm giving them a second chance and have another set of 2 new Ultra X batteries that I should be receiving today and will IR test them as soon as they arrive as well.....I hope they work out better than the last set!

Todd

Uggggghhhhh! I purchased the same batteries Ultrax 180727 lot late last week. I'll charge them and test tomorrow morning and report back. This is like flying my plane to Mexico and constantly worrying about contaminated fuel all over again

 

[Satdiver]

I charged up both of the new "181104" Ultra X batteries and flew them earlier today... After set-up and checklist completion, I took off and hovered low, watching the battery voltage. The voltage was stable and I kept the H close and didn't take it up very high. I'm usually on the ground by 14.7v but I wanted to see how much flight time I could get out of these batteries. I just hovered low and landed on the first low voltage warning. I ended up with right around 11 mins flight time each. The ambient temp was approx. 40*F.




After they cooled off I checked the IR again and got 9,3,3,8 & 7,2,2,7. I'm going to continue to cycle them and hopefully will get more flight time.

I plan on warming them up as @Vegasrobbi suggested and see if I can squeeze a few more minutes out of them.

 

[JizzyGillespie]

I charged up both of the new "181104" Ultra X batteries and flew them earlier today... After set-up and checklist completion, I took off and hovered low, watching the battery voltage. The voltage was stable and I kept the H close and didn't take it up very high. I'm usually on the ground by 14.7v but I wanted to see how much flight time I could get out of these batteries. I just hovered low and landed on the first low voltage warning. I ended up with right around 11 mins flight time each. The ambient temp was approx. 40*F.

View attachment 13997
View attachment 13998

After they cooled off I checked the IR again and got 9,3,3,8 & 7,2,2,7. I'm going to continue to cycle them and hopefully will get more flight time.

I plan on warming them up as @Vegasrobbi suggested and see if I can squeeze a few more minutes out of them.

I tested my new to me, Ultrax lot 180727 batteries just now. I fully charged them and flight tested, hover only, right off the charger, real sense off in angle mode. Voltage dropped rapidly to 15v then gradually to 14.3 volts, 12 minutes each battery.