Convince me again...

[katou]

I'm about to purchase a Meanwell unit to modify to charge my A123 pack, aiming for a voltage around 48v (either 13 or 14s).

Then a friend said why not just buy a commercial charger for lifepo4? I had the answer before, but now I'm sort of confused...

Katou

 

[hydro-one]

cost?

 

[TPA]

Charge rate.

A123 and lipo can be charged much faster than other chemistry batteries. The meanwells can supply more current than most other type of chargers, so you can recharge in less than an hour if you get the right stuff.

 

[katou]

Is that the reason then? Charge rate?

The meanwell I am considering is this one: http://tinyurl.com/2bwu5zx

CC 0-5a
CV 41-56v

60$ + modification cost

disadvantage - no warranty
benefit - hit voltage of 15s right on

I'm just wondering why I wouldn't purchase this one instead: http://tinyurl.com/ygu55ew

CC 6A
CV 51.2v

95$
disadvantage - have to go to 15s (54v) but will only charge to 51.2, pack slightly undercharged
benefit - I get a warranty

Help?

Katou

 

[hydro-one]

Twice the price , twice the weight. No mods are required if you get the 50$ meanwell 3-350 48v. just cut one shunt out of three. Add a small fuse on the charge lines and your set!! well it worked for me!!

 

[TPA]

Sorry, I did not mean to represent myself as an expert in power supplies. However it is my understanding that the output voltage can be modified slightly internally, and a little more with diodes.

Type meanwell in the search box, and see if you can get some better info.

 

[AussieJester]

Sorry, I did not mean to represent myself as an expert in power supplies. However it is my understanding that the output voltage can be modified slightly internally, and a little more with diodes.

Type meanwell in the search box, and see if you can get some better info.

If your talking about meanwel voltage regulation ? TPA then yes they have a lil pot on the
front panel that is accessible easily, using screwdriver you can adjust the output voltage by turning
this pot, they have 2-3 or so volts + & - of their rated voltage i.e for example i have
a 48v meanwel, i set this to 50.2 volts to charge my lipo pack, you could also set it at 46v
if required. Goes in 0.1v increments.

KiM

 

[katou]

Thank you all, this has helped me make my decision. I will go the Meanwell route for the main reasons:

1. Cost of the meanwell after modification (I'm not doing it, I'm paying a friend to do the work) is still less than the cost of the commercial units
2. the commercial chargers miss the target voltage, which means undercharging cells

Thanks,


Katou

 

[MitchJi]

Hi,

I will go the Meanwell route for the main reasons:

2. the commercial chargers miss the target voltage, which means undercharging cells

OUTPUT
* CCCV (Constant Current Constant Voltage) charging mode
* Cut-off voltage: 58.2VDC
* 6 A current Max

58.2/16 = 3.6375 which is close to perfect (the Gary/Richard BMS is set for 3.60):

Actually, what many have found is that it does seem to prolong the life of the cells if you pick a "full" point a little below the generally recommended charge voltage for each type. For LiPos, the recommended number is 4.20V and for LiFePO4 it is 3.65V. What I'm using for LiPo is 4.15V and for LiFePO4, 3.60V. This is what we are fine-tuning the fully on shunt set point to be at.

 

[katou]

I see your point about the cutoff voltages, and it is clear that the $95 charger above would fit the bill.

Even so, it's much more money, which might be worth it to get a warranty. I think I'll go the Meanwell route for the lower cost, thanks for the math help,

Katou