Since a car's electrical system varies from 12V up to about 14.4 when running, is it safe to use a charger when the vehicle is running. For instance, my field is a considerable drive from my house. Would it be ok to start charging a battery and continue the charging while driving to the field? Will the different input voltages cause any problems with any particular chargers or batteries?

Brian

it only depends on the charger, if it is rated up to 14 volts or more. I use my triton all the time while driving, and the only problem is occassionally it will error out when starting the car (from the voltage drop)

You didn't specify if you're using the "timer type" charger that comes with a park flyer, the simple cigarette chargers or, a field charger, such as a Hobbico. If you're using the simple chargers, don't do it. If you're using a field charger, it should be okay. By no means, should you be charging a Li-Po on the way to the field.

Why is that? Sorry for the lack of info given; it would be a charger such as a triton or accucycle elite, something along those lines. If I can't charge on the way to the field then it would be beneficial to be able to charge two batteries at once, right? How do you experienced electric fliers deal with that. If it takes 1-1.5 hrs to charge a LiPo, wouldn't I be better off with a charger that will charge more than one at a time?

Also, I have noticed that a lot of chargers like the Smart chargers, Kokam and Celectra don't have variable charge rates. You have to pick a 1000 Mah rate for a 1200 or 1320 Mah battery, for example. Is this a problem? How much longer should I expect to have to charge a 1300 battery on a 1000 setting than if I could just select a 1300 setting as on a Triton or Accucycle?

As you can see I have lots of questions since I am new to electrics so please bear with me.\

Thanks,
Brian

I'm guessing he said that because of the tendency of lipos to burst into flames. personally i do NOT charge lipos in my vehicle, and they are stored in a ceramic mug while charging at home. (i do field charge, they just aren't in the vehicle)

Just to reinforce when NOT to charge Li-pos... They "vent with flames" when they burst.
Would you care to have this occur in your car?

Brian,

I suspect they sacrificed some input voltage regulation on my Celectra, to keep the cost down. It certainly was a bargain for all it's capability.

I understand your desire to charge on the way to the field. Safety is the big issue here, so I'd limit my charging to home (in a fire proof container), or the field, as others have stated.

I'm also new to E-flight (Yard Stick still in the box), and I'm very thankful that I have a strong electronics background, or I would be totally lost. [sm=drowning.gif]

The Celectra is a very capable charger, and you can easily determine the charge time by timing a charge cycle at home. Charge time between flights should be pretty consistent if you fly to voltage cutoff every flight, or finish discharging on the ground.

Good luck. I know I'm going to need it myself.

Bill

fireman7875, with a screen name like that, you might want to educate yourself on the special handling required for LiPoly batteries, and the risks involved with their mistreatment.

If you need to charge multiple batteries, buy additional chargers. That's how we do it. Why don't they make dual-output chargers? Expense. A dual output version of the chargers currently on the market would cost nearly twice as much as the single-output version. Would you really pay $250 for a dual-output Astro 109? Not many people would, and the point is to sell large quantities of chargers to make money. If you're not going to sell large quantities of chargers, why make them?

The Accucycle Elite is a dual output charger with Li-Po capabilities.

1) In 12 years of fire service experience I can't say that I have ever seen a fire traced back to a lithium battery. I am aware that a lithium battery will catch fire if it ruptures since lithium is pyrophoric. However, just because you charge a battery in your car doesn't mean that it will rupture. I have seen several recommendations (outside of this forum) to use a fireproof container for charging. A fireproof container will be fireproof weather it's in your house or car. I don't want to burn up anything, but if I had to choose, I would rather burn up my car than my house anyway.

2) As I &amp stated, there are dual output chargers available. I wouldn't pay $250 for a dual output Astro 109 nor would I pay $130 for a single output Astro 109. I don't need to charge that many cells for for a little 36" span park flyer. If I want the power that 8 LiPo cells put out I switch back to my glow planes. I just want to charge up to three cells and be able to go to the park near my house and fly for an hour or so.

Thanks,
Brian

I have seen video of a lipoly burst......TRUST ME....you dont want that to happen in your car......ESPECIALLY while you are driving.

This being said, If you do choose to do this, it would be in your VERY best interests to use a fireproof container to store the lipo in while charging. Not only while charging in the car, but also while charging at home.

Most of us use a simple metal ammo can, as these are cheap, and will effectively contain the flaming lithium if it does burst.

You guys are missing the point of my original question. If I use a fireproof container for charging at home, I certainly would also in my truck. Make no mistake, I don't want my Lipo's to burst into flame regardless of where I am charging.

Let me clarify my question. I am referring to the safety of the charger and the battery. In other words, when a vehicle is not running its battery has a nominal voltage of 12V. When you start the vehicle that voltage jumps to approximately 14.4V. I am asking whether this change in voltage will damage either the charger or the battery. I have heard from one source that it may damage the charger but this person is not someone I would consider to be an expert, or even knowledgeable on the subject so I thought it would be a good idea to ask those who know.

Thanks for your input,

Brian

At:
http://www.rcgroups.com/forums/showthread.php?t=209187
Reported Li-po incidents.
FIRE DURING CHARGING:
Operator Error-
9s pack catches fire while being charged at 10s setting. (9)
2s pack catches fire being charged as 3s (10)
2s pack catches fire when charged at 3s setting (13)
2s pack catches fire in plane while charging at 3s setting. (22)
3s pack charged at 4s voltage ignites (27)
2s pack catches fire charged at 3s (30)
2s pack ignites when charged at 10.2V (31)
Overcharged battery (34)
2s pack charged at 11.1V catches fire. (36)
2s pack charged at 3s setting (40)
2s pack charges at 11.1V burns – (44)
2s charged at 11.2V goes off in garage – (47)
2s charged at 3s voltage ignites in garage – (49)
2s charged at 3s ignites in workshop – (52)
Another count problem – Heli burns (57)
Cell count error caused fire – (61, 62)
Pack charged on NiCd setting - (66)
Run Down pack catches fire during charge – (71)
LiPo Burns during charge on 109 charger after mode mis-set (82)
Charging slightly swelled pack causes fire (86)
Li-Ion cells catch fire from charger setting error (88)

Undetermined Cause While Charging
Fire damages garage while charging pack. (7)
1500 3s pack catches fire during 1A , 11.1V initial charge. (1)
2 cell pack ignites while being charged with 2 cell charger. (11)
Car burns when pack being charged in car catches fire. (24)
2s2p pack catches fire in helicopter – possible that charger misread # of cells. (25)
2s pack ignites while on charger set for 2s. (28)
$30,000 damage to house when pack ignites during charging. (no details) (43)
3s pack burns in garage – (35)
3s pack burns at correct settings- (41)
3s pack burns at correct charger settings – (46)
3s 8000mah pack catches fire after 15min – correct settings – (53)
Helicopter and pack burns after 15min charge – (54)
Automatic cell count charger – pack catches fire (55)
Automatic cell count charger – pack catches fire (56)
Lipo rockets across room (58)
Automatic cell count charger – Lipos burn in garage (59)
Battery ignites in car seat during charging (63)
Damaged battery ignites during charge (67)
Pack balloons during charge, burns while under water (68)
11s3p pack burns during charging at correct parameters (70)
Another charging fire – (72)
Helicopter burns when LiPo ignites during charge (73)
Undetermined cause to LiPo fire during charge – (74)
Chopper burns from charging LiPo fire (76)
House fire (81)
3s Pack Ignites burning front of car during charge at correct settings. (83)

FIRE FROM PACK DAMAGE:
Cell poked with exacto knife catches fire- (2)
Dog bites pack, pack catches fire (4)
Lexus burns after pack from crashed plane put in car. (8)
Ballooned pack ignites when punctured. (20)
Repaired pack catches fire when connected to plane. (29)
Pack catches fire after plane crashes. (37)
Pack cut while shrink wrapping (39)
Pack punctured during crash burns. (64)
Plane crashes, pack removed and 10 minutes later burns (65)
Battery pack at 1V ignites while charging (71)
Puffed pack ignites during charging – (77)
Puffed Pack smokes when punctured (79)
Nicked pack catches fire (87)

BATTERY SHORTED FIRES:
Shorted pack catches fire (26)
Pack burns after shorting (15)
Possible Short (38)
Shorted when moved on table – (42)
Pack Shorted putting connector on and burns – (45)
Shorted pack burns hole in BMW seat – (48)
Crash causes 3s pack to short and burn – (50)
Pack ignites sometime after connector shorted for a short time (85)


NO CAUSE DETERMINED:
Multi cell pack catches fire in flight (5)
Possible over discharge (33)
Lipo pack catches fire in car (60)
2s pack starts house fire (84)

OTHER
2s pack connected in series with 3s pack ignites in fireball (78)

Paul,

Great info in your post!

I didn't graph the known versus unknown causes of LiPo damage, but considering a (hopefully small) percentage of contributors would be too embarrassed to admit a mistake, I'd say the vast majority of damage was caused by the operators.

The instructions on my E=flite Celectra state that it charges at a selected constant current up to the max voltage for the number of cells being charged (voltage detection by the charger), and current then tapers off to some minimum level where the charge is terminated.

That leads me to believe that a partially discharged pack would simply charge for a shorter period of time, but the accuracy might depend on the quality of the charger input voltage regulation, and output voltage detection/regulation. Makes me wonder what kind of precision can be built into a $40 charger?

I suppose it's possible that it's simply a constant current, voltage limited charger with a timed charge, but that wouldn't make sense with the limited range of charge currents selectable. I.e. charging a 1500 mah pack at 1 amp (the closest setting) would leave it a bit short of power.

Bill

Brian,

Being that you want to charge lipo's that have no more than 3 cells, the Hobbico Accu-Cycle Elite would be perfect for you. It has dual outputs.

I got a little 12v battery that I hook up to it to charge my batts on the way to the field or at the field.. No problems......

But, here's what I do. I fly a mix of Lipo's and NiMh's. I'll charge the Lipo's at home the night before I go flying. They don't lose a charge over a 24 hour period. Then either in the morning before I leave the house or on the way to the field, I'll charge the Nimh in my car...............Then field charge both at the field when they run out of power.

Lwien,

That's a good tip. I had never really thought about using different batteries. How much does the performance of the plane suffer when you switch to the NiMH batteries due to the excess weight? That's my only concern. I appreciate the advice on the charger. I hate to pay $160 for a charger but it certainly seems that is my best option. Thanks again.

Brian

Depends on the plane and the wind conditions.

Example:

I have both 2s and 3s TP1320 Lipo's along with about 10 various Nimh's and Nicads ranging anywhere between 6 and 8 cells and from 300 to 750 mahs. When a little breeze picks up, say between 2 to 5mph, my Slow Stick likes the extra weight of the Nimh's. The E-Starter is a lot more aerobatic and a lot faster on the Lipo's but if I feel like slowing things down and just putt around the sky, I'll use the Nimh's in her. The formosa likes both the 750NimH and the 2s lipo's.

But please understand that I had these Nimh and Nicads before I ever got into Lipo's. If I were going to do it all from scratch, I would have all Lipo's and if I wanted a little extra weight, I'd just go from a 1320 lipo to say a 2100.

Hope this helps.....

Oh, and the Accucycle is a great charger. It will charge Nicads, Nimh and Lipos. And on it's two outputs you can charge two batteries of totally different chemistries at the same time. Plus it is ac/dc...............Plus it will charge all the way down to 50mah so you can do a slow 10c conditioning charge on smaller packs. Plus, it was 10 memory slots.

The ONLY downside to the Accucycle is that it will not charge large battery pack of Lipo's 4 cells and above, and Nimh/Nicads that are 10 cells and above. I plan on sticking with parkfliers only, so for me, the inability to charge larger packs was not an issue.

Bill, I would expect most charging problems to be "operator error".. but with Li-polys the chance for a catastrophic result isn't emphasized sufficiently.
These are not batteries for a less than rigorous approach, they can and do cause extensive damage when -abused-.
Like any substance with this potential, the problems should be known to the user.
Then it's the user's fault when he does it wrong.
A friend that works on military UAVs says Li-polys when tested in combat conditions demonstrate an "explosive" response to bullets..
I've vented a few ni-cads but no Ni-mhs.. yet.
I charge everything outside on the concrete patio, just to be safe.

I just picked up a Multiplex LN-2000 charger.. it will handle 1-10 cells Nicads-Nimhs, and 1-4 cell Li-polys, adjustable rate up to .1A to 2A rate.
It trickles the Nicads and Nimhs when they are fully charged, and cuts off the Li-polys at full charge.
$90 at the LHS.
Instructions are printed in Lilliputian font.. had to run them thru a copy program to get something large enough to read.

Paul,

Very good points, and I agree completely. There are far too many people who don't read or heed instructions, but there is no way to protect that type from themselves.

The simplicity and price of the Celectra really appealed to me, because I have four ACE chargers left over from my glow flying days. I didn't really need another NiCad or Nimh charger.

I spent a few months at Palmdale and Edwards AFB, with the Boeing company on the B-1B program. Had good friends living in Palmdale, but lost track of them years ago.

Bill

Brian,

In response to your actual question. When I used Nicads I would often charge while driving. It has been my experience in most cars that there is a voltage drop and surge when you turn the ignition to start the car. It is possible that this could damage a charger but it is not a high risk IMHO. The real problem is that the charger will normally reset during the ignition from the drop in voltage. Thus you must start the charge cycle after the car is running. Also if the car does not maintain a relative stable supply voltage you may get false peaks or other problems. The higher voltage while the engine is running will not hurt the charger. In fact it is required in chargers that have a voltage bosting circuit to allow charging batteries over 12V. The case that is most likely to damage a charger is when the car battery voltage falls to low and the charger get damaged from low voltage. However most modern chargers have a reasonable low cut off voltage programed in that protects the charger.

Why don't you get a cheap PC power supply (~$15) to power your charger and charge you batteries at home? Take a look at the instructions on the bottom left hand side at this site, http://www.rcbatteryclinic.com/ or search for instructions at this site.

I use the battery for my glow-motor starter to charge Nicads in receivers, transmitters and motor batteries while in transit.
The one I use is for the riding lawn mower type of vehicle, and fits insida a standard 6-pack cooler.. the handle on the cooler makes for easy movement into and out of the car.

Brian,

A lot of people turn into chicken little(the sky is falling, the sky is falling!!!) at the mention of lithium battery safety, so that's my opinion of why you're not getting a straight answer. It's obvious you're aware of the issues and risks. The short answer is, almost all hobby DC chargers I've seen can take from 12-15VDC input. If you've already got a charger, just check the specs and make sure it can take 15V input. If you're looking for an inexpensive charger, I would suggest the Hobbico Field Charger MKII. I don't own one, but a close friend does, and I've used it when I left my Triton at home. It is a no-frills charger with no computer features, and it may not eke out the last milliampere hour of capacity from the battery, but the important thing is, it is easy to use and charges reliably, as long as you follow the directions. Hope my input helps.

-Matt

I agree. Thanks for your suggestions.

GWH- that computer power supply is sound better all the time!

Thanks, guys!

Brian

Ive done something similar to this . while charging many time I became concerned about starting the car. starting the car will draw amps from the battery, causing a flux in the charger &it very well may simply drop off line.(astroflight)