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Oct 25, 2008, 09:22 AM
7000mw of raw power!
rich smith's Avatar
Thread OP
Mini-HowTo

2 batteries at once w/$5 charger


Here's a way to charge couple 2s batteries at once with a low cost Turnigy/Esky charger. Just cut out a small piece of plastic over pin 3 on the 4 pin (3s) connector so it will accept 2 cell. Same as connecting two batteries in parallel but no wiring changes or cables to build. Safer than building "Y" adapter. They don't have to be same brand, capacity, or charge state. Still safely polarized for charging a 3s.

Also note that this is a good way to solve the "low mah battery, high current charger" problem. Milliamps are split between the two batteries. Personally I have no problem charging my lipos at 2-3C so don't even bother.

It's also possible to charge 1 cell batteries with this unit by putting two of them in series. It will be necessary to build a cable in this case. Again, because it's a true balancing charger, they don't have to be same type.
Last edited by rich smith; Feb 02, 2009 at 03:38 PM. Reason: 4 pin not 3 pin
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Oct 25, 2008, 10:59 AM
characters welcome!
Mark Wood's Avatar
Quote:
Originally Posted by rich smith
This saves having to switch out batteries so often. I like to load up a couple chargers before going to bed so I'll have four batteries to fly in the morn.
Where do you charge your batteries and what are you using for a risk management device? (LipoSack, Battery Bunker, clay pot, etc.)

Rule #1:
Do NOT charge unattended.

mw
Oct 25, 2008, 11:34 AM
7000mw of raw power!
rich smith's Avatar
Thread OP
I have no problem charging unattended. Sometimes in a $3 Walmart glass pie plate if it's one of my "untested" charger designs or some other experiment. Did use a glass aquarium once to try the famous 110vac lipo trick. Worked as EE for over half century specializing in battery technology and power system design so I understand the risks. IMO lipophobia runs rampant in this hobby.

I have limits. Wouldn't do something dumb like storing lipos in ammo case, use non-polarized connectors (deans), or put one in salt water. Other battery types can be far more dangerous. Ever accidently drop wrench across a car battery? As a kid tried to charge a D cell with house current. Lucky to be here to talk about it. Far worse than any lipo. I'm grown up now.

People can accomplish any disaster if really determined. Risk vs benefit. It's just that I don't put lipos near the top of the list.

Rule #1: know what the true risks are

-Rich

P.S. Everyone makes their own decisions in life and I try to base mine on critical thought rather than fear and superstition.



Quote:
Originally Posted by Mark Wood
Where do you charge your batteries and what are you using for a risk management device? (LipoSack, Battery Bunker, clay pot, etc.)

Rule #1:
Do NOT charge unattended.

mw
Oct 25, 2008, 11:56 AM
WAA-08 THANK FRANK!
JimNM's Avatar
Rich - you have just helped me find extacly what I've been wanting - a 7$ method to burn my house down and endanger my family at the same time!

IMHO - there is no excuse or reason to rely on a very affordable (or is it cheap?) charger to hurry up and charge a lipo. Lipo batteries do not suffer the voltage sag that Nicd and Nihm do - Lipos will hold a charge for well over a week.

"I like to load up a couple chargers before going to bed so I'll have four batteries to fly in the morn. Also a neat trick is to parallel two cells which would not charge alone because they are too small. Both batts should be similarly discharged but don't have to be the same size. I've use it for 250mah and 2200mah." -

I am NOT an EE - but I am a professional risk taker. This statement is negligent and I'm happy that I would not have to defend it in the courtroom, should somebody attempt to replicate your method and fail.

JMHO -
JimNM

My advice would be to get another 7$ charger and use them in parallel, to charge 2 batteries at the same time.
Last edited by JimNM; Oct 25, 2008 at 12:27 PM.
Oct 25, 2008, 12:24 PM
Registered User
Rich is correct in that the risk of fire or other catastrophe is negligible with dedicated lipoly chargers that charge cells individually through the balance tap. 100% of the lipoly failure reports that I've read involved either a) improper setting on a multichemistry charger, b) poorly designed charger that charges through the discharge lead and sets cell count incorrectly (Astro 109), c) severely imbalanced lipoly charged through main discharge lead resulting in cell overcharge, d) attempting to charge a severely damaged or puffed lipoly.

That said, I personally would use a liposack or other containment device as Mark suggested just to sleep better even though the risk of issue with Rich's method is exceedingly small. Basically the same risk of charging a cell phone, iPod or other device that uses rechargeable lithium chemistry and employs very reliable charge termination circuitry.

Mark
Oct 25, 2008, 01:03 PM
7000mw of raw power!
rich smith's Avatar
Thread OP
Quote:
Originally Posted by JimNM
Rich - you have just helped me find extacly what I've been wanting - a 7$ method to burn my house down and endanger my family at the same time!
Glad I could help!

Seriously, I appreciate your concern, you seem to mean well. Your problem appears to stem from paralleling rather than charging environment like MW. This has been argued endlessly and those with willingness to learn accept it as safe practice. You'd be well advised to get up to date by reading a recent thread:

https://www.rcgroups.com/forums/showthread.php?t=943455

I've half dozen of these chargers from various makers because I reverse engineer all new products as part of my business. Not inclined to clutter up the desk with them all though and trying to help those who may only have one.

-Rich

P.S. Your thread was VERY creative use of color!


Quote:
Originally Posted by JimNM
IMHO - there is no excuse or reason to rely on a very affordable (or is it cheap?) charger to hurry up and charge a lipo. Lipo batteries do not suffer the voltage sag that Nicd and Nihm do - Lipos will hold a charge for well over a week.

I am NOT an EE - but I am a professional risk taker. This statement is negligent and I'm happy that I would not have to defend it in the courtroom, should somebody attempt to replicate your method and fail.

JMHO -
JimNM

My advice would be to get another 7$ charger and use them in parallel, to charge 2 batteries at the same time.
Oct 25, 2008, 01:07 PM
7000mw of raw power!
rich smith's Avatar
Thread OP
I HATE it when people agree with me. You're no fun at all!

Bolsters my theory that biggest risk to lipos and wooden structures is fancy-schmancy chargers.



Quote:
Originally Posted by mrforsyth
Rich is correct in that the risk of fire or other catastrophe is negligible with dedicated lipoly chargers that charge cells individually through the balance tap. 100% of the lipoly failure reports that I've read involved either a) improper setting on a multichemistry charger, b) poorly designed charger that charges through the discharge lead and sets cell count incorrectly (Astro 109), c) severely imbalanced lipoly charged through main discharge lead resulting in cell overcharge, d) attempting to charge a severely damaged or puffed lipoly.

That said, I personally would use a liposack or other containment device as Mark suggested just to sleep better even though the risk of issue with Rich's method is exceedingly small. Basically the same risk of charging a cell phone, iPod or other device that uses rechargeable lithium chemistry and employs very reliable charge termination circuitry.

Mark
Oct 25, 2008, 01:11 PM
WAA-08 THANK FRANK!
JimNM's Avatar
Rich - I'm glad that you approve of my use of colors - that makes my day complete!

Have a great time with your charger(s) and batteries(s).... Sleep well, but lightly.
Oct 25, 2008, 01:23 PM
7000mw of raw power!
rich smith's Avatar
Thread OP
Wouldn't it be funny if I woke up tommorrow morn to the smell of smoke and that "sweet" characteristic odor? There's a grain of truth to what everyone here says and energy storage devices of all types should be treated with respect. It certainly don't hurt to have a cheep 'ol flower pot sitting around. Doubles as an ashtray too.
Oct 26, 2008, 01:49 AM
Registered User
SteveM732's Avatar
I have been woken up in the middle of the night by the sound of an AA rechargeable alkaline cell popping and spewing its electrolyte. In this case the manufacturer claimed the batteries could be left on the charger indefinitely so I assumed bad cell and shrugged it off. A few weeks later I was charging again and had forgotten to check the progress for several hours when I was startled with a loud "POP" of another cell bursting. So I figured bad charger and bought a new one, any guesses what happened the next time I tried to charge overnight?

Moral of the story is that devices fail and what works 1 night or 100 nights may not work as planned tonight. The OP is hidden so I cannot read it and can only guess the content from subsequent posts. But I think it safe to say that it is not wise to hand out advice contrary to the warning labels put on by manufacturers in such a public place where someone less experienced might think it a safe idea (even though your experience and attention to detail may make it reasonably safe for you).

It is also not fair to compare to cell phones as these have a very specific battery and built in charger tailored to that battery.
Oct 26, 2008, 09:28 AM
7000mw of raw power!
rich smith's Avatar
Thread OP
Well, I feel privileged to finally be initiated into the Galileo Club by members of the Flat Earth Society. The post recieved warning for "designed to annoy others" which is puzzling because contained no personal attacks etc. but simply showed how to do parallel charging with esky charger. This is consider safe practice by knowledgeable battery users:

https://www.rcgroups.com/forums/showthread.php?t=943455

There are certainly no "warning labels" on the Esky charger forbiding this other than part number, DC input 11.5-13.5v, and list of LED functions.

My guess is someone felt threatened by comments made in other posts and this was their only way of striking back or simple ignorance of technology. I think I know who. In any case I am honored to join the ranks with tic et al.


Quote:
Originally Posted by SteveM732
The OP is hidden so I cannot read it and can only guess the content from subsequent posts. But I think it safe to say that it is not wise to hand out advice contrary to the warning labels put on by manufacturers in such a public place where someone less experienced might think it a safe idea (even though your experience and attention to detail may make it reasonably safe for you).

It is also not fair to compare to cell phones as these have a very specific battery and built in charger tailored to that battery.
Oct 26, 2008, 10:30 AM
characters welcome!
Mark Wood's Avatar
Rich:

You're an EE and I've been a civilian maintenance electrician for the Navy for going on 35 years so we both have background in the area of electrical energy. My concern stems not from a lack of knowlege but a distinct history with the " happens" syndrome. Due to my side job (LipoSack.com) I also am terribly aware that in fact still happens with lipo chemistry on a regular basis. We continue to this day to receive notes of lipo failures and not from beginners. Almost all of the ones we hear about these days are from people who one would think would have known better. The seven instances in our Survivor's Gallery are the tip of the iceberg and are just the few that have allowed us to publish their experience in the hope of alerting others that the hazards still exist.

Good luck but be careful as always.

mw (not the reporter)
Oct 26, 2008, 11:24 AM
WAA-08 THANK FRANK!
JimNM's Avatar
I think I know who?

Ummm - not me, either.

Sleep well...**
Oct 26, 2008, 11:29 AM
7000mw of raw power!
rich smith's Avatar
Thread OP
Mark,

I've been following your posts for years and find you to be not only technically knowledgeable but a gentleman. Never suspected for a minute. I have great respect for the product you developed and although more inclined toward el cheapo solutions myself I believe it's been a boon to the safety of this hobby. The forums are mainly populated by people who want to learn. There are also a few at the bottom with insecure personalities and a few at the top with true knowledge and willingness to help. I count you in the latter group and aspire to get there myself.

My suspicion was toward someone who lacks true techincal knowledge and had tendency to find fault where there was none. Not one of the "regular gang". One clue was other posts in this thread that might be considered objectionable were not warned. When I challenged the warning a moderator removed it but thought it better to delete content anyway. Possible the only part that might be considered worthy of a warning in that post was my statement that "I like to charge batteries overnight". Subsequent posts were far more "annoying" but not hit. I'm sure you and the others here notice I DO enjoy a good technical argument.

Thanks to you and the others for helping me learn much over the past few years about how motors and batteries are used in this hobby.

Regards,
-Rich

PS As an engineer I appreciate what you're saying. Can never predict all possible consequences and happen often as a result (best laid men of mice and plans etc.).



Quote:
Originally Posted by Mark Wood
Rich:

You're an EE and I've been a civilian maintenance electrician for the Navy for going on 35 years so we both have background in the area of electrical energy. My concern stems not from a lack of knowlege but a distinct history with the " happens" syndrome. Due to my side job (LipoSack.com) I also am terribly aware that in fact still happens with lipo chemistry on a regular basis. We continue to this day to receive notes of lipo failures and not from beginners. Almost all of the ones we hear about these days are from people who one would think would have known better. The seven instances in our Survivor's Gallery are the tip of the iceberg and are just the few that have allowed us to publish their experience in the hope of alerting others that the hazards still exist.

Good luck but be careful as always.

mw (not the reporter)
Oct 26, 2008, 11:31 AM
7000mw of raw power!
rich smith's Avatar
Thread OP
Quote:
Originally Posted by JimNM
I think I know who?

Ummm - not me, either.

Sleep well...**

Yeah, BIG mistake for me to blurt that out. I don't think it was one of my beloved argue buds.

Gawd, I love those colors. Who needs drugs?


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