Battery Duration

[Jubalr]

I'm sure you did read that somewhere. But I can assure you whoever wrote it doesn't know what they're talking about. They're either repeating bad information they read somewhere. Or making up best practices that aren't grounded in reality.

I don't think I would word it quite that strongly as the person giving bad information or not knowing what they are talking about. It may not even had been Solo related. And it may have been a personal practice of someone writing an article saying that THEY like to recommend getting back at around 30% for a comfortable margin of error and nothing to do with LiPo battery specs. Kind of like me and not letting my gas tank get below a 1/4 in my truck. YMMV..

 

[Pedals2Paddles]

I like to keep my gas tank above 1/4 tank too. But I don't park it and walk to work if it gets down below 1/4 tank either

 

[Jubalr]

I like to keep my gas tank above 1/4 tank too. But I don't park it and walk to work if it gets down below 1/4 tank either

I agree. 1/4 is a reserve, not a dry tank. I figured that's why they put a screw on cap for the tank, and recharge plugs on the battery. Re-fill/recharge as needed.

 

[SteveReno]

They say, if you run you car/truck low of fuel, good chance of floating debris to clog up the filter.
They say that running our battery down to a low % can cause problems with the battery in the future. I haven't given any % cause I know of none. This may be hear say. But I hear it's a fact?

 

[PdxSteve]

Everything is a tradeoff. Yes you can charge faster, but it shortens the battery life a bit. Yes you can run them to a lower voltage/percent, but it shortens the battery life a bit. Most lipos can charge over well over 500 cycles. If it shortens the battery to something like 400 cycles, I'm ok with that. I've had my solo for almost a year and have 10 batteries. None of my batteries have over 50 cycles yet. I expect quite a bit more life out of these things. Faster charging and longer flights are more important to me than wearing the battery out slightly faster. At that point, I'll just slap some new lipos in the battery and reset the cycle counter in the battery, but I don't expect to hit that point for at least 2 years at my current rate.

 

[PdxSteve]

Solo also won't let you run your batteries down to a really dangerous level. 0% is not 0 Volts. It's closer to 14V. Solo won't quit spinning the motors and fall out of the sky at 0%. It has a small built in reserve.

 

[Jubalr]

Everything is a tradeoff. Yes you can charge faster, but it shortens the battery life a bit. Yes you can run them to a lower voltage/percent, but it shortens the battery life a bit. Most lipos can charge over 500 cycles. If it shortens the battery to something like 400 cycles, I'm ok with that. I've had my solo for almost a year and have 10 batteries. None of my batteries have over 50 cycles yet. I expect quite a bit more life out of these things. Faster charging and longer flights are more important to me than wearing the battery out slightly faster. At that point, I'll just slap some new lipos in the battery and reset the cycle counter in the battery, but I don't expect to hit that point for at least 2 years at my current rate.

Well said, and I have believed the same for some time. I guess it may depend on your financial ability to buy more as needed. I see the batteries as being a consumable and part of the cost of flying. You can be more aggressive and get longer flight times and faster charging but may have to buy batteries more often than someone that prefers to be conservative and baby the batteries along. For me, I prefer to push them a little. Someone else may prefer to leave 30% on the table. No big deal and up to each pilot to determine what is best for them.

 

[PdxSteve]

Well said, and I have believed the same for some time. I guess it may depend on your financial ability to buy more as needed. I see the batteries as being a consumable and part of the cost of flying. You can be more aggressive and get longer flight times and faster charging but may have to buy batteries more often than someone that prefers to be conservative and baby the batteries along. For me, I prefer to push them a little. Someone else may prefer to leave 30% on the table. No big deal and up to each pilot to determine what is best for them.

I think solo will be a distant memory by the time I have to buy new batteries due to fast charging/flying the battery down. And I meant just replace the lipos in the actual battery housing (pretty cheap) instead of buying a whole new 3dr battery at 4-5x the cost. I mean a decent 4s/5200MAh lipo pack is only like $30 compared to 3dr's $150. Just reuse the existing circuitry in the battery.

 

[SteveReno]

@ Amazon $133 shipped.

 

[PdxSteve]

I usually buy mine when 3dr has a 2 for 1 battery deal. Even at $75ea, they are still more 2-3x expensive than the equivalent regular lipos.

 

[SteveReno]

<---wishes he would have got on that 2 4 1 sale

 

[STM]

Just a word of caution on the battery %.

One of my batteries started to drop on % much quicker recently. Initially I thought it is about to die. A few days ago I used a standard LiPo charger to discharge the battery to storage level (15.2V). When the battery reached the 15.2V the last two LEDs on the battery were blinking. In other words the "smarts" in the battery thought it is already way below 50%. I discharged the battery further to see what capacity really was left. It turned out there was still more capacity left than what the LEDs were indicating (unfortunately I can't remember the exact value).

After fully recharging and then discharging the battery to storage level (15.2V) four LEDs on the battery were on as you would expect.

It turns out I used this battery quite a lot for testing and development in the lab, i.e. without the motors running. Therefore it had quite a few shallow discharge cycles. My guess is this confused the "smart" chip in the battery. Doing the complete discharge recalibrated the % the chip is reporting.

 

[PdxSteve]

That's a pretty common characteristic of lipos in general, including the one in your phone. Totally discharging and recharging periodically will prolong the battery life as well because it resets most things. Here's more than you ever wanted to know about prolonging lipo life: How to Prolong Lithium-based Batteries - Battery University

There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device. (See BU-603: How to Calibrate a “Smart” Battery)

Of special interest in terms of battery state-of-health (SoH) is full charge capacity (FCC), coulomb count that is hidden in the table among tons of other information. FCC can be used with reasonable accuracy to estimate battery SoH without applying a full discharge cycle to measure capacity. Best accuracies are achieved if the battery is being cycled with a full charge and an occasional deep discharge. If used sporadically, a deliberate calibration involving a full discharge/charge cycle will be needed from time-to-time to maintain accuracy.

 

[Pedals2Paddles]

The total discharge and recharge will also basically recalibrate what the smart battery believes it's MAH capacity is. Which should make your % remaining much more accurate.

 

[Joe Horn]

The Solo manual says (page 28), "If the battery is hot to the touch, wait for it to cool before using or charging." But it's "hot to the touch" after most flights, especially this time of year. Does recharging it right after flying harm it? Do we really have to wait for it to cool?

 

[Joe Horn]

The total discharge and recharge will also basically recalibrate what the smart battery believes it's MAH capacity is. Which should make your % remaining much more accurate.

So total discharge can be a Good Thing? But the Solo manual says it's a Bad Thing on page 63: "...if the battery level reaches 0% at any time, irreversible damage occurs and the battery should be recycled." Now I'm confoozed.

 

[Pedals2Paddles]

The manual is written for the lowest common denominator consumer that doesn't know what they're doing. It's probably the safest general advice for that clientele. But the reality behind it isn't that simple. The % remaining is a calculation based on what the smart battery thinks its capacity is vs what it has used in the flight. What the smart battery believes it's total capacity is could be a right on, or it could be a little off, or it could be a lot off. In such circumstances, the % remaining will be wrong.

Watch the voltage in flight, not just the % remaining. When it gets down to <13.8 volts, just hover a few feet up in your landing area to wear it down lower. Land and shut down at about 12.8 volts. Be ready to land, because it will begin dropping off very very quickly at that point. Then do a complete recharge.

 

[Pushjerk]

A few days ago I used a standard LiPo charger to discharge the battery to storage level (15.2V).

STM,

My i kindly ask you to describe how you did this? I come home with full batteries often, and discharging this way just seems way safer than hovering in my confined backyard for 10 minutes around tall trees, houses, and a super high 2.4 noise floor.

 

[STM]

1. Cut the cable of your 3DR charger (void your warranty in doing so! ;-).
2. Solder on connector that fits your standard charger (I use an XT60 connector).
3. Optionally solder on connector to 3DR charger. So you can continue to use it.

done (see photo attached)

Use the "storage charge" mode of your charger.

Advantages:
- More controlled way of discharging your batteries.
- You don't have to stand right next to it.
- Not weather dependant.
- Most importantly. You are not wearing out your Solo doing nothing exciting.

Of course you can recharge your Solo batteries with the standard charger as well. Just use "LiPo charge" mode (not "LiPo balance charge"!!!) for 4S batteries. Set the max. charging current to something below 6A (I'm not sure what the exact max. current is. I use 5.5A. 5.75A seems to work as well). The good thing is recharging at 5.5A is obviously quicker than with the 3DR charger. The other good thing is you can use your car battery for recharging in the field.

Obviously you can build a suitable cable for your charger using one of the various methods described in this forum for building a connector that fits the Solo battery (e.g. modify two pole US mains plug, 3d print a connector, buy one, etc). I just couldn't be bothered. I had the connectors. So this was a 1min job.

 

[Pushjerk]

1. Cut the cable of your 3DR charger...done

Thanks for the detailed write up, STM. Photos are always appreciated as well. I'll be doing this with my spare Solo charger.

So theres no fiddling with balance ports - I assume all of the cell balancing is taken care of within the inner circuitry of the "Smart" battery?

Yeah, running Storage cycles on the balance charger has been as much a part of this hobby for me as building and flying. Charge five packs, get a flight in, weather rolls in (Or wife calls and says get the hell home), then stuck with a handful of topped of lipos. Will be nice to do this with Solo batteries.

Regarding charging current, (not sure how much science is behind this), It has always been beaten to death that you charge your lipos at 1C, or 1 x the battery capacity. 5.2A in Solo's case, that is if your charger supports .1A increments. My first couple chargers only did .5A increments, but I'm sure nothing will blow up if you charge a battery a few tenths of an Amp above 1C.

Again, thanks for the write up.