Customizing LiPo Final Charge Voltage?

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Sep 11, 2014
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N. TX, USA
Is there a cheap, good LiPo (6s) charger that will allow you to customize ending charge voltage?

Say I want to charge to 4.0V per cell, instead of 4.1V ("LiIo") or 4.2V ("LiPo"), for my own purposes. Is that even possible? Preferably, I'd like to be able to balance charge to a safe per-cell voltage of my choosing, especially if I'm going to be dropping significant coin on very advanced, supposedly customizable chargers.

I've read the manuals for Imax B6 and Tenergy TB6B, which appear to be the best-regarded of the lower-cost chargers, and in the running for my first LiPo/Balance charger purchase. They let you specify exact voltage for NiMH and Pb, but not Lithium? I assume those programs might not be safe for Lithium chemistry, but if so, would like to know why. I do know that if you screw up your manual voltage setting with lipo (too high), you could end up with a fire. Even more reason I think they should offer a custom "final charge" setting (within a safe range) for Lithium chemistry.

The closest thing I could figure out was to use the 'discharge' or 'storage' voltages, but those are fairly low (highest=3.85V for LiPo).
 
iChargers allow you to customize Lipo charge voltage over fairly wide range. But they aren't exactly cheap. In the states I buy 'em from EP BUddy (Buddy RC) for fastest delivery and domestic warranty.
 
So is it dangerous to use a charger's "NiCd" or "Pb" program to manually set the voltage (assuming you set the voltage correctly)? Both the models I mentioned above have storable settings, so assuming you programmed it right the first time, getting it right again wouldn't be a risk. I would also charge in fire-safe place. I wonder how arbitrary or specific their 'chemistry' programs are. And of course there would be no Balance function on those programs. Not ideal, but maybe a way, if I ever wanted to?
 
SkyRC iMAX B6AC V2 has a little extra control:
TERMINAL VOLTAGE CONTROL: The voltage at which the charger cuts off the charge to each cell can be adjusted. LiPo 4.18V-4.25V (Default 4.20V) / LiIo 4.08V-4.20V (Default 4.10V) / LiFe 3.58V-3.70V (Default 3.60V)
So basically, you can control the voltage down to a hundredth of a volt from 4.18 to 4.25. Between 3.7V and 4.18V, you're on your own. At least it measures internal resistance, and has USB too. I can't find a 'V2' of the non-'AC' version. The newer, genuine B6's measure internal resistance, but I don't know if they have this terminal voltage control.
 
Good find digging into the system menu. IMO those built in IR functions suck so I just do it the old manual way:

http://endless-sphere.com/forums/viewtopic.php?f=14&t=48739&hilit=

From that thread - here's the video that inspired me to learn IR testing:

[youtube]usRE3gLFnOc[/youtube]
 
A popular charger is thunder 1220. From hobbypartz. It allows setting end voltage and you can bulk charge 12s. Plenty of threads on this one.
 
SprocketLocket said:
I do know that if you screw up your manual voltage setting with lipo (too high), you could end up with a fire. Even more reason I think they should offer a custom "final charge" setting (within a safe range) for Lithium chemistry.

you do not know that. the balance chargers will not allow you to overcharge a battery cell to an excess voltage. the risk of fire is not from overcharging but from shorts on the output of the battery.

there is no reason to not charge the battery to full charge if you use it right away. charging a lipo cell to 4.10V and leaving it charged to that level is more damaging to the cell than charging to full voltage and using the battery immediately after, and leaving it resting at the 3.8v level.
 
drew12345 said:
A popular charger is thunder 1220. From hobbypartz. It allows setting end voltage and you can bulk charge 12s. Plenty of threads on this one.
Thanks, I tried, but couldn't find it in stock anywhere--new or used. It seems to me like this is a custom model just sold by HobbyPartz. Plus, the price used to be reflected in the 70s of dollars, now it's listed close to 100 IIRC, though still out of stock. As a 2nd charger in the 70-ish range, I still would consider it. Could you charge two 6s packs in series, and still have the balance connectors work their magic?

I ended up going with a newer B6AC clone as my first charger. Seemed like the best deal for a beginner charger. Has some fancy features I may or may not end up using, but the most important seemed like measuring internal resistance. The cheapest charger that supposedly measures IR was a few dollars less ("50W X-Charger"), but did not include a power supply, plus had reports of overheating on 6s.

Ykick, I watched the video, thank you. What is the problem with cheaper chargers' IR measurements? Could you elaborate? It seems like a fairly simple calculation. Could you recommend a strategy for creating a super-simple resistive load for a 6s 10Ah pack? I have no idea, myself. I saw the same question in the thread you referenced, with no answer.

dnmun said:
you do not know that. the balance chargers will not allow you to overcharge a battery cell to an excess voltage. the risk of fire is not from overcharging but from shorts on the output of the battery.
Well hi, dnmun. Nice to finally meet you in person, kind of.
I didn't mean charging on LiPo setting. I meant like if someone put a massively wrong voltage setting on a lipo pack. Like putting a 38V brick charger on a 24V lipo pack, or using a manual NiMH setting on a multi-charger with a voltage that was signifcantly too high. In other words, not using balance chargers or even a proper lipo charger. It is possible to set lipos on fire with massive overcharges, though in most cases people who try this on purpose seem to have to really try. Although, I've read at least one thread here (with pics) where a guy had a cell or pack burn up in normal charging (I don't remember the charging technique).

You don't know that I have no reason to not charge a pack to full voltage. And if I just wanted to ask informationally if some chargers allow a custom final charge voltage, giving an example to clarify what I'm asking, it's a perfectly valid question, with a valid answer provided by Drew12345. I was trying to prevent being flamed in the opposite direction, where people might think I had no idea of the potential safety risks of lipo.

Still no answer if it's okay to use a customized NiCd or Pb setting on one of these chargers, if you're sure the voltage is right? (I assume in that case, the balance connectors would be disconnected?) I don't really want to do this latter question, but I am curious for informational purposes, learning the finer points on how multi-chemistry chargers function, and the secret life of lithium polymer batteres.
 
yes, i am of the opinion that the fire that floont had was caused by buk charging of his new lipo pack with a series of meanwell chargers he used to get up to 35S as i recall. i was gonna sell him one of my 36V meanwells but he got some other ones. he did not use any cell monitoring and no BMS from what i knew and he has never reported what happened. that was devastating, but there have been other charging fires too. the guy silverheels who gave me the nanotech packs had a fire break out in his lipo pack while he was riding and he had given me some lipoly 6S packs that had 2 cells overcharged and holding voltage at 4.55V and two pouches totally dead, 0V, that he had been bulk charging, at work. so i tried to help him out by building a 24S lipo pack under a D131, but never heard back from him.
 
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