Review of Charger Xtar XP4

as i said, it is no problem. just insert 3 or less cells :)

otherwise it is clearly a charger error :p

HKJ, is there an auto restart feature for LiIon's like the 3.9V threshold of the WP2s? my 10440's have dropped below 4.1000V within 24hrs in the charger and the charger has not started the recharge yet omg! :|

Yes, there is a restart level, but it was to close to the termination voltage to get a good reading of it.

Are we talking about LiIon?

True, termination voltage of Eneloop AA and AAA at 0.25A and 0.5A is sometimes 1.38xxV or even below 1.3800V.

But my question referred to LiIon. I don't see any restart near 4.1V

Hi,

I was using my XP4 to charge some 18500s (6 of them) tonight, using the 1.0 amp setting, and they all came off the charger at between 4.16 - 4.17 volts.

Is that ok? It seems a little low…

Does the XP4 have problems terminating Li-ion too soon also?

Thanks,
Jim

4.16 to 4.17 is ok, it will depend on the age of the battery and the charge current, using a lower charge current will get you a slightly higher voltage (Because the termination current is less).

Xtar chargers usual works very good with LiIon.

Hi,

These were all 18500s from an older, but “new” laptop pack, supposedly about 1700 mAh capacity:

I’ll try using a lower current next time, but would you recommend 0.25 amps or 0.5 amps charge rate for these?

Thanks,
Jim

I will not recommend it, but if you need the maximal capacity a 0.25A charge is best (The termination current is about the same on 0.5A and 1A, i.e. you do not really get anything extra at 0.5A).

Do not expect much, you get maybe 1% extra.

Hi,

Ok, thanks for the info.

Jim

The 18650's in the thermal image, were these protected cells or unprotected cells? Protected cells have naturally a higher thermal resistance at the plus pole because of the altered and longer thermal path (and at the minus pole because of the added PCB).

Unprotected 18650's get considerably hotter in the XP4 than protected 18650's.

Just crazy.

I usual uses unprotected for testing, but am mixing button top and flattop.

Number 1 and 4 in the thermal image is button top, the rest is flattop.

excellent test!

yes, number 4 is less hot :)

50°C or maybe 53°C, not more. The hot part is the charger.

Any ideas on whether charging to 4.2V (while charging) with 1A, then switching to 0.5A till 4.2V and then 0.25A to finish could cause any problems? I was thinking about this because for some reason an old cell in my VP1 got hot, and I was thinking having a lower maximum current at the end would be a bit safer.

I cannot see any problems in that.

Hi,

For the 18500s I mentioned earlier, not sure if this is good or bad, but I’ve put them in my Jetbeam i4 pro afterwards, and let that finish them off, and ended up at about 4.21V - 4.22V.

The specifications says 4.20 volt +/- 0.05 volt, i.e. the charge voltage must be between 4.15 volt and 4.25 volt.

The battery will end up slightly below that voltage, depending on age and termination current.

This means that both your result are perfectly fine.

I hope there will be a REV A-3 to fix the problem.
Did XTAR say anything about the bug?

Your picture only shows the led pcb, not the main pcb. Does it also say revision A2 on that?

These picture are not mine, I found them here .
YES, also REV A-2 on main pcb.

When reported to them, they said that they will bring it up in their Weekly meetings and will be dealing with it.