Single cell charger with adjustable voltage?

J

jkirkeboe

10 mW
Joined
Jun 3, 2009
Messages
25
I have aquired 26 Leaf modules I will use as an off-grid battery pack. Befor assembling the pack I need to make sure they are all at the same voltage as I will have to parallell 13 of them. Also I plan to get ahold of quite a few more which I will then need to integrate into the pack.

Therefore I would like to charge all the cells to 4.05V first (I will limit charging to that to extend battery life as this pack will spend most of it's time fully charged). So I am looking for a charger with an adjustable voltage. 1S is okay, I prefer to do one cell at a time. I don't need much amperage either, 2A or so should be enough.

Any suggestions?

The pack will be 13P2S at first, if I get enough extra modules the goal is at least 10P7S or maybe even 14P7S. BMS will probably be an Orion Jr. and the chargers are twin Outback FlexMax80 (one will do when I upgrade to 48V) connected to 6 327W Sunpower panels on a dual axis tracker. Inverter is one Outback VXF2612E for now, will be two VFX3048A in the future.
 
http://endless-sphere.com/forums/viewtopic.php?f=14&t=60770
 
Matt Gruber said:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=60770
Click to expand...

Thanks for the suggestion, but I'm really looking for something finished, in a case, can be connected to 230V AC and with a display for setting the voltage.
Price up to $100 is fine.

I was looking at the iCharger 106B+ but it didn't seem like the voltage could be adjusted? The manual is kind of vague...
 
Might be best to balance with a one time charge to 4.2v, which can easily be done with any RC charger.

Or pick 4.1v, with the lilo setting.
 
why does the battery have to remain fully charged at all times? 4.05V is not close to full charge. about 10-15% away from full charge.

i use a kingpan 40W single cell charger that i can adjust the output voltage. there are others on ebay.
 
dogman said:
Might be best to balance with a one time charge to 4.2v, which can easily be done with any RC charger.

Or pick 4.1v, with the lilo setting.
Click to expand...

Can't do that. Since the pack will usually be charged to 4.05V I have to charge new modules to the same voltage when I add them to the pack. If not there will be sparks and significant current flow.
 
dnmun said:
why does the battery have to remain fully charged at all times? 4.05V is not close to full charge. about 10-15% away from full charge.

i use a kingpan 40W single cell charger that i can adjust the output voltage. there are others on ebay.
Click to expand...

The battery is for off-grid storage in a cabin in the norwegian mountains. When we leave we might not return until 5-6 weeks later. The battery will probably be charged full in a few days after we leave, thus staying at fully charged for several weeks.

I have picked 4.05V as my fully charged voltage because that is what Nissan uses for the 80% charge mode in the Leaf. This is done to extend the life of the battery, I hope it will last 12-15 years at least.

I will check out the Kinpan, thanks for the tip.
 
if you intend to use the charger to charge up individual cells in that battery then you could just use a DC/DC converter with the 4.1V on the output and use the full pack for the current source.

you have to use a DC converter with the input and output ground separated.
 
dnmun said:
if you intend to use the charger to charge up individual cells in that battery then you could just use a DC/DC converter with the 4.1V on the output and use the full pack for the current source.

you have to use a DC converter with the input and output ground separated.
Click to expand...

No, new cells will be charged ut at home and put into the battery when I go to my cabin. At that time the battery should be at 4.05V and thus the new cells should also be at that voltage.

I already have 26 modules not assembled, where 18 are at 7.58V (2S2P in each module) and 8 are at 8.1V. So I need to charge up the 18 to 8.1V before I assmble all modules into a 13P2S battery. Each 2P cells in each modules can be charged separately BTW, there is a center tap.
 
I think I finally found a suitable model: http://www.myrcmart.com/rcx-bc168-intelligent-battery-lipo-life-balance-charger-parallel-charging-p-4768.html

It slooks like it can do three of the 2S2P modules at once too :)
 
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