Need a LifePo4 charger....

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Chicken Drumstick
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Need a LifePo4 charger....

To charge some large 6500mAh 32700 batteries.

I have an old 4Sevens charger that does LifePo4, but will only fit a 26650. Also something seems to have gone wrong with it and it doesn’t always charge these days. So I’ve tried using my iMax B6AC hobby charger, it has a LiFe mode. But it just doesn’t seem to charge to the correct voltage and terminates very early.

Any suggestions on what charger I should look at? Don’t mind if it is a dedicated bay charger or if is it a hobby charger, so long as it’ll work and not break the bank. Thanks.

chops728
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With the Imax you can set the termination voltage to where ever you want —— terminating early on a LifePo4 cell isn’t a bad thing — I set mine 3.5v – 3.55v — you don’t gain much above that —- I have a couple MiBoxer chargers that will do LifePo4 also —- Just make an adapter with a dowel / wires screwed to the ends with magnets soldered to the wires

With the Imax —you have to program in a Preset mode , charge rate and then you can set the termination voltage

alpg88
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Chicken Drumstick
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chops728 wrote:
With the Imax you can set the termination voltage to where ever you want —— terminating early on a LifePo4 cell isn’t a bad thing — I set mine 3.5v – 3.55v — you don’t gain much above that —- I have a couple MiBoxer chargers that will do LifePo4 also —- Just make an adapter with a dowel / wires screwed to the ends with magnets soldered to the wires

With the Imax —you have to program in a Preset mode , charge rate and then you can set the termination voltage


Thanks.

Don’t suppose you could tell me how to do this on the iMax?

When I select the LiFe mode it says 3.3v (LiIo 3.6v and LiPo 3.7v). In the charge mode you can change this from 1S through to 6S and multiply the voltage. But I can’t see how you can change the actual voltage charge/termination voltage without selecting a different program.

The issue I have is, on my DMM it says the battery is 3.24v

But when I put it on the charger, in less than a second it’ll flash something like 3.28v, then instantly show 3.60v and not change. It’ll terminate shortly after only putting in a handful of mAh and won’t really increase the voltage.

I don’t fully understand what it is doing. When I Google everywhere says LiFe is the same as LiFePo4, but I’m not 100%.

The charger works great in LiPo mode, when you set one charging, the voltage reads out the actual voltage of the pack (not the target voltage). Which then changes as it charges. And it’ll terminate right around the 4.13-4.2v mark depending on exact pack. Mostly 2S and 3S for RC planes and cars.

chops728
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Yeah I’m not 100% sure either —- I can’t remember if I’ve ever used the Imax for LifePo4 — I have other better chargers I use — LifePo4 is 3.2v — maybe ask HBK in a PM

chops728
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I just tried the exact same charger you have in the picture on a Lifepo4 Valence cell —- On “Life Charge” 1S 1amp it worked perfectly —- are you sure that cell is Good/Empty

Chicken Drumstick
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chops728 wrote:
I just tried the exact same charger you have in the picture on a Lifepo4 Valence cell —- On “Life Charge” 1S 1amp it worked perfectly —- are you sure that cell is Good/Empty

Thanks.

Cells are new. I also have some 16340 and 14500 LifePo4’s they do the same on here. Do you use a DMM to check the voltage once charged? What mode do you use on the charger?

chops728
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I use Charge Mode with whatever cell type I’m charging—— Unless it’s a pack with a balance lead — Does your charger work properly with other cell types — You might have a charger or connection problem

flydiver
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You could try Lipo in [storage mode]. It would be a slight overcharge (~3.75), but Life is very tolerant of that. It will shed the excess charge fairly rapidly. I overcharged a 18650 to 4.2v once, and expected a disaster. Didn’t get hot, and was down to 3.6v in a couple hours.

From “Battery University” [Voltages – 3.20, 3.30V nominal; typical operating range 2.5–3.65V/cell]
If you watch the current during charge it will start dropping as the cell gets full. You can pretty much tailor it to any termination you want with observation.

I assume you’ve seen the review:

Vapcell IFR32700 6500mAh G65 (Blue) 2020

To Air is Human, to Respire….Divine.

Chicken Drumstick
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flydiver wrote:

I assume you’ve seen the review:
https://lygte-info.dk/review/batteries2012/Vapcell%20IFR32700%206500mAh%...(Blue)%202020%20UK.html


Link doesn’t work.
UliBär
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BTW: The values from your iMax Charger are absolutely ok. You charge LiFEPO4 to 3.6-3.65V charging end voltage and that’s it. The voltage will drop quickly to around 3.2-3.3 Volts. That is absolutely ok, this is the resting voltage for LIFEPO4-cells, so that’s no problem.

Aloha, Uli

Chicken Drumstick
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UliBär wrote:
BTW: The values from your iMax Charger are absolutely ok. You charge LiFEPO4 to 3.6-3.65V charging end voltage and that’s it. The voltage will drop quickly to around 3.2-3.3 Volts. That is absolutely ok, this is the resting voltage for LIFEPO4-cells, so that’s no problem.

Thanks, but I thought they had a resting voltage more like 3.43 – 3.45v? I know when my 4Sevens charger worked on my 16340’s that was the sort of voltage they’d display.
flydiver
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Chicken Drumstick][quote=flydiver wrote:

Link doesn’t work.

Fixed. Did not check it for integrity. Thanks.

If you look at the graphs in the review link of the battery, it’s apparent that the test voltages START at ~ 3.3v, hang in that vicinity for a VERY long time, before they fall off the end abruptly.

To Air is Human, to Respire….Divine.

snakebite
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As mentioned could be full or your setup could have high resistance and you are dropping a lot across the holder and wires.
Lifepo4 has a very flat charge/discharge

Hoop
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I have this charger and also use magnets and alligator clips to charge individual cells.

One time my magnets were dirty and this caused the behavior mentioned in post #4 where the voltage rose instantly and then the charge terminated. I cleaned the magnets and alligator clips with alcohol and everything went well after that. Most likely you have a poor electrical connection and it can’t carry the current. I recommend connecting the magnets to the rear flat part of the alligator clips, and make sure to maximize the surface contact of all connections. Don’t allow the leads to twist so that only a tiny corner of the magnet is in contact.