Choosing the right Charger -> how to?

[Just]

Hello All,

My question is "How to choose the right Charger?"

Actually there are many of them in the market... Prices are vary from several dollars to several hundreds.... There are "smart" chargers, there are "cleaver" ones, there are "intelligent" and so on... So, how to choose?

Actually I need 24V charger for my LiFePo4 10Ah pack. Hopefully it may have a battery internal resistance meter, but not for extra $100 price...

Any comments are welcome.

Thank you!

[Just]

Any responses? Comments?

[Cornelius]

A you can guess; there's no 'right' charger out there, but for me, this one come close:

http://www.jun-si.com/EnProductShow.asp?ID=93

The price are around $200, and you have to be able to make your own connections for balance etc...

[MAGICPIE3FOCUSPOWER]

I charger

Hyperion

[Cornelius]

That kind of posting are not very helpful... 

I'm sure the Hyperion are good chargers, but the deciding issue for me was the iCharger's ability to show me the IR for all the cells individually; I couldn't find that in the Hyperion specs...

But nothing are perfect; not even the iCharger...

[MAGICPIE3FOCUSPOWER]

Yes they have!
Just download the manual en have a look
Hyperion support is great, firmware etc etc...

Also I own a lot of chargers, Icharger blows up after couple of charges.
My friend owns Icharger and he hate it when he switched to Hyperion.

[Just]

Thank you guys for your posts! And what's about all these terms like "smart", "cleaver" and "intelligent"? Are they just marketing term or technical meanings as well?

Actually I need a charger, which is able to determine whether the cells full or not, and if they are then stop the charging. I don't need a balance port in the charger since by battery has BMS, which balances of the cells during the charging.

As for the Internal Resistance measurements, just take a look at this device: http://www.ebay.com/itm/160504165351?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

What's your opinion on this charger: http://www.ebay.com/itm/271057048976?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649 - it's cheap enough... What questions should I ask the manufacturer before purchasing this charger?

Thank you!

[MAGICPIE3FOCUSPOWER]

The resistance looks fine to me!

The charger is dumb charger (no inetrnal bms).
But I prefer this kind of charger, because your battery back has an internal bms.
This charger has fixed output, so if you like to play with output (current) go for an intelligent charger.

But when you will buy Icharger etc etc.
You have too unhook the battery pack bms, soo...make your choice

[Bikemad]

The resistance looks fine to me!

You will have to be very careful not to accidentally reverse the polarity or it will blow the meter.

Check out this review by Dr Bass on YouTube for more details.

Alan
 

[MAGICPIE3FOCUSPOWER]

Haha that's bad!

So maybe looking for another model with reverse protection?

[Just]

Alan, thank you for your warning!

What about these devices:
http://www.hobbyking.com/hobbyking/store/__22631__Turnigy_7_in_1_Mega_Meter_.html
http://www.hobbyking.com/hobbyking/store/__22412__Turnigy_Mega_Checker_4_in_1_Battery_Checker_Monitor.html

Thank you

[Just]

And what about these device:
http://media.hyperion.hk/dn/sentry/

Interesting how does it able to measure a remaining battery capacity...

[truly_bent]

I don't see any reference to LiFeP04 cells in the info - only LiPo. Do the different cell types have internal resistances in the same range?

With my limited knowledge of chemistry, i'm probably lucky to be alive
Jeff

[Bikemad]

What about these devices:
http://www.hobbyking.com/hobbyking/store/__22631__Turnigy_7_in_1_Mega_Meter_.html
http://www.hobbyking.com/hobbyking/store/__22412__Turnigy_Mega_Checker_4_in_1_Battery_Checker_Monitor.html

7 in 1 video review

4 in 1 video review

I really don't like the idea of having a pair of male bullet connectors on the battery supply lead for the current measurement on the 7 in 1 meter, if the unit was accidentally pulled and the battery leads came out, a short circuit across the battery would most likely occur.

The reviews on HobbyKing's website do not inspire confidence either.
The 4 in 1 Mega Meter has suffered numerous failures due to an incorrect polarity on the USB charging lead  , and the 7 in 1 Mega Meter apparently has a very inaccurate Internal Resistance meter:

The IR measurement is hopeless. Uses a roughly 0.5Amps load and two wire method which is useless for modern LiPos.
I got readings varying from 104mOhm to 41 mOhm per cell on a 4S 3700 mAh battery as I watched.
The actual IR per cell is between 3.96 mOhm and 4.20 measured with an ESR/IR meter!!

Perhaps my estimated internal resistance of 2.5 mOhms is about right for my almost new 5Ah pack.

And what about these device:
http://media.hyperion.hk/dn/sentry/

Interesting how does it able to measure a remaining battery capacity...

The estimated remaining battery capacity is presumably based on the actual battery voltage and would have to be measured with the battery under a no load condition.

Alan
 

[Just]

"The estimated remaining battery capacity is presumably based on the actual battery voltage and would have to be measured with the battery under a no load condition" - is dependency linear? What's the cell voltage be considered as 25% of capacity? 50% of capacity? 75% of capacity? 100% of capacity?