going LIPO - is it worth my time?

[alvinlwh 5895]

20 minutes ago, Wooders28 said:

My dailys have been diesels for 20yrs, peak torque at 2200rpm is brilliant.

My diesel had been giving me nightmares about its DPF for the past 5 years, even it never had a problem so far. The thought of it going wrong just scares me. Turns out that the car does so little miles a year that a diesel unjustified and with the upcoming ban on diesel, it maybe time for a change. I got quite a few test drives lined up for my trip south next week.

[Wooders28 4723]

5 minutes ago, alvinlwh said:

My diesel had been giving me nightmares about its DPF for the past 5 years, even it never had a problem so far. The thought of it going wrong just scares me. Turns out that the car does so little miles a year that a diesel unjustified and with the upcoming ban on diesel, it maybe time for a change. I got quite a few test drives lined up for my trip south next week.

Only issues with the filter I've had, was when I surgery a while ago, and my wife was using my car for short journeys every day, when I wasn't allowed to drive.

Once I got back to work, and driving, with the oil warmed up on the commute, I could do a couple of 4k+ rpm pulls, and it cleared, unfortunately, that's what you need to do with them.....🙄😏

[alvinlwh 5895]

27 minutes ago, Wooders28 said:

Once I got back to work, and driving, with the oil warmed up on the commute, I could do a couple of 4k+ rpm pulls, and it cleared, unfortunately, that's what you need to do with them.....🙄😏

Typically, it will do about 15 miles, each way, on A roads single carriageway. I am worried it may not be long enough or fast rev enough for a carbon burning run cycle on such journeys. Once a year, it may get the chance to go down south to stretch it's legs properly. It does no more than 6k miles a year, which for a Mondeo is very little. In fact at 60k miles after 10 years, it was described at "just run in" recently.

I am torn between keeping (and maintaining) it or buying new. 

[MadInventor 3884]

Just to bring you all full circle, none of the above issues occur with electric cars ....

[BuggyDad 4480]

19 minutes ago, MadInventor said:

Just to bring you all full circle, none of the above issues occur with electric cars ....

True, but to really complete the circle I've spent the last 3 years sitting on a mattress of explosive Lipos! 😉 🤯

[MadInventor 3884]

1 hour ago, BuggyDad said:

True, but to really complete the circle I've spent the last 3 years sitting on a mattress of explosive Lipos! 😉 🤯

And you're still here  

[Wooders28 4723]

2 hours ago, alvinlwh said:

I am torn between keeping (and maintaining) it or buying new. 

I'd keep it, although, I buy a 2yr old low mileage car (let someone else, take the big financial hit), and run it until it falls to bits....

2 hours ago, MadInventor said:

Just to bring you all full circle, none of the above issues occur with electric cars ....

Not even sure that's been discussed on this platform? 

I'm still on the fence....🤔

[BuggyDad 4480]

7 minutes ago, Wooders28 said:

I'm still on the fence....

Electric fence? 

[Wooders28 4723]

1 hour ago, BuggyDad said:

Electric fence? 

Would certainly generate a bit of emotion! ⚡️😱

[Elbowloh 1130]

2 hours ago, Wooders28 said:

I'd keep it, although, I buy a 2yr old low mileage car (let someone else, take the big financial hit), and run it until it falls to bits....

Not even sure that's been discussed on this platform? 

I'm still on the fence....🤔

Yep, never personally bought a brand new car myself, (had 4 different company cars however) the money lost from just driving it away is eye watering!

Bought current car at two years old and 11000 miles 

[alvinlwh 5895]

1 minute ago, Elbowloh said:

the money lost from just driving it away is eye watering!

 

2 hours ago, Wooders28 said:

let someone else, take the big financial hit)

However at the moment, a used car costs more than a brand new car.

[SlideWRX 785]

On 1/17/2023 at 4:26 AM, Twinfan said:

I think that graph might be a bit misleading.  Shouldn't the area under the curve be the same if both batteries had the same capacity?  If so, the LiPo would deplete first if it's putting out more power for longer?  If all else were equal, according to that graph LiPo batteries would substantially outlast NiMh which I don't think is the case?

I don't dispute the voltage drop that NiMh has, but it seems very over-exaggerated in that mock up graph.

The mAh rating is for a low amperage discharge, like 0.1C or less.  For general running around we probably average 1-2C, but use it in bursts of 5C or more.  It really depends on how powerful your motor is. 

The graph doesn't mention what drain on what capacity battery, or from when it was made, but that looks like a constant high draw, likely similar to what an RC plane might see.  They don't really coast, hit the brakes (they'll fly right by), or reverse in most cases .  Different amounts of draw will have different voltages - there isn't one line on the graph.  That applies to both NiMH and Lipos, however the Lipo lines will be closer together - less voltage drop on higher current draw.

It isn't easy to find technical data on how many Lipos or NiMH actually perform, mostly just a lot of repetition and personal experience.  Both batteries are getting better Current Draw (C) or higher capacity (mAh) with newer manufacturing and technologies are figured out, so the answer is changing a bit all the time.  NiMH at 5000mAh are pretty common, with reputable places offering 6000+.  What is their performance versus the 3000mAh that was state of the art a decade or two ago? What about compared to the 1800 mAh a lot of cheap current ready-to-runs come with that people will upgrade from?

[Wooders28 4723]

On 1/21/2023 at 4:55 PM, SlideWRX said:

It really depends on how powerful your motor is. 

Absolutely, 

If you're running a silver can, you still get a noticeable punch increase (its get up and go), as a silver can still pulls a good few amps on start up, and the faster motor you're running, the bigger the noticeable difference.

The 6.5t motor in my race truck, runs a 3800mah 65/130C battery down in 6 mins ,with no noticeable drop in performance at the 5 min mark (race length) ,so would be averaging 38amps (if the full mah is used?).

 

On 1/21/2023 at 4:55 PM, SlideWRX said:

mostly just a lot of repetition and personal experience. 

Yep, when I dipped my toe in the lipo water, I swapped all my escs to deans/T plug, and figured I'd run Nimh for bashing (as if you crash with a lipo, they seemingly blowup ,killing you and your family...), and lipo for only racing.

Swapping back to nimh, is like watching old vintage CRT telly, when you're used to HD, so needless to say, my nimh sat on the shelf, and infact gave all the decent ones away...🤷‍♂️

[Falcon#5 594]

How many of us can honestly say that we don't leave lithium batteries on charge while unattended, charge them inside, or even sleep with them 2 feet from our heads while charging without a second thought?

- No one.

We all charge our phones this way, yet a lithium battery for an RC car is somehow a ticking time bomb that will explode, burn the house down & create a black hole that will suck the entire Milky Way inside it?

 

The hype doesn't align with reality. It seems to be the ones who have never run LiPo are the ones who are anti-LiPo.

I heard my mates, neighbours, cousin met a taxi driver once who heard about a LiPo explosion from a passenger whos mates, neighbours, cousin blew his face off...

 

I've had so many LiPo over the years & never had an issue. Had a few that had puffed, but that was all. (A couple of IP round edged & 1 Turnigy that was like 10 years old)

The battery technology that is available now has been the biggest game changer in RC since its inception.

 

All I can say to anyone is forget the 'horror stories' & enjoy the increased performance & run time, yes run time from 21st century technology.

You'll never look back.

[Twinfan 1254]

Nah, you're alright.  I'll stick with NiMH packs thanks...

[Kol__ 3377]

3 hours ago, Falcon#5 said:

How many of us can honestly say that we don't leave lithium batteries on charge while unattended, charge them inside, or even sleep with them 2 feet from our heads while charging without a second thought?

- No one.

We all charge our phones this way, yet a lithium battery for an RC car is somehow a ticking time bomb that will explode, burn the house down & create a black hole that will suck the entire Milky Way inside it?

 

Isn't there notable differences between lithium ion (in phones) and lithium polymer (RC) batteries. The former not being anywhere near as unstable or dangerous, if punctured for example.

[Fish Slice 35]

24 minutes ago, Kol__ said:

Isn't there notable differences between lithium ion (in phones) and lithium polymer (RC) batteries. The former not being anywhere near as unstable or dangerous, if punctured for example.

That's my understanding of most consumer batteries.

As for the practicalities of the difference, I've no Idea. I come for the cars, not the chemistry! 😄

[LongRat 616]

2 hours ago, Kol__ said:

Isn't there notable differences between lithium ion (in phones) and lithium polymer (RC) batteries. The former not being anywhere near as unstable or dangerous, if punctured for example.

The difference between RC batteries and all other consumer lithium batteries, including phones, laptops, scooters and everything else, is that RC batteries have no in-built protection circuit.  The protection comes from the users correctly setting the charger up.  On top of that, the current spikes and general mechanical abuse that the batteries endure are more severe in RC than any other application I can think of.  These two reasons are why battery fires are orders of magnitude more common in RC than in other applications.  Using the fact that thousands of tablets are charged daily in kids bedrooms to imply RC LiPos are perfectly safe is like saying top fuel dragsters are safe because you've never had a 300mph blowover in your commuter SUV.

RC LiPos are more dangerous than other batteries, but are safe enough for many peoples' tastes, including my own.  But if anyone doesn't feel comfortable using them, I can fully understand that too. 

[LongRat 616]

On 1/17/2023 at 9:26 AM, Twinfan said:

I think that graph might be a bit misleading.  Shouldn't the area under the curve be the same if both batteries had the same capacity?  If so, the LiPo would deplete first if it's putting out more power for longer?  If all else were equal, according to that graph LiPo batteries would substantially outlast NiMh which I don't think is the case?

I don't dispute the voltage drop that NiMh has, but it seems very over-exaggerated in that mock up graph.

Capacity is not energy.  So a 5000 NiMh will have less stored energy than a 5000 LiPo.  This is the main reason the LiPo will still outlast the NiMh on the same load.

Amp-hours (capacity) represents the total stored electric charge.

Watt-hours represents the total stored energy.  You need to consider the voltage at all points along the current discharge curve to measure total energy discharged.

[Twinfan 1254]

9 minutes ago, LongRat said:

Capacity is not energy.  So a 5000 NiMh will have less stored energy than a 5000 LiPo.  This is the main reason the LiPo will still outlast the NiMh on the same load.

Amp-hours (capacity) represents the total stored electric charge.

Watt-hours represents the total stored energy.  You need to consider the voltage at all points along the current discharge curve to measure total energy discharged.

You've lost me there.  Capacity of both is 5000 mAh (milliampere/hour).

Capacity (milliampere/hour) = discharge (milliampere) x discharging time (hour)

So if the LiPO is putting out more power (discharge) then time has to reduce does it not?

[LongRat 616]

2 minutes ago, Twinfan said:

You've lost me there.  Capacity of both is 5000 mAh (milliampere/hour).

Capacity (milliampere/hour) = discharge (milliampere) x discharging time (hour)

So if the LiPO is putting out more power (discharge) then time has to reduce does it not?

More current doesn't mean more power.  More current at a given voltage, yes.  In the NiMh case, because of the greater internal resistance of these packs, you need to pull more amps to get the same power because of the greater voltage sag.
A 30 amp discharge on a LiPo might give you 210 Watts (30A x 7V).

A 30 Amp discharge on a NiMh might give you 180 Watts (30A x 6V)

[Twinfan 1254]

Nope, still makes no sense to me!  Is the NiMH pulling more power out of the battery because it's inefficient or is the LiPO pulling more power out because it's providing more speed/punch/acceleration?

In laymans terms, if capacity is the same and the LiPO is putting out more energy (more punch/speed/acceleration) with less output drop over time then the run time can not also be longer can it?

 

[LongRat 616]

Capacity can be the same with both batteries and the lipo can put out more power and for the same or even longer time. There is more stored energy in every mAh of capacity in a lipo battery than in the same mAh in a NiMh, because the voltage during discharge is higher.

[Twinfan 1254]

Thanks for your posts, I clearly need to read up on electrics to get a handle on it.

I'll try and find an example with the maths online.

[alvinlwh 5895]

Amazing how some will insist that lipos are safe as they had used it for years without any problems. It is like saying 1:1 cars or planes are safe as they never had a crash in one.

I had the personal (myself, not a mate's uncle's taxi driver) experience of a 3.7v 800mah lipo blew up before and it was quite a bang, will be far worse with a 7.4v 5000mah battery.

Also, there are some claim that lipos are safe as long as they are not abused and/or charged incorrectly. Well, I don't think the batteries on UPS Flight 6 were being charged or abused when they went up.

I am not anti lipo, I use lipo too but just wish people will at least acknowledge the risks rather than brushing them under the carpet.