Navitron Renewable Energy and Sustainability Forum

Buying/Selling/Trading => Wanted => Topic started by: genawin on November 20, 2019, 01:52:30 PM



Title: DARFON / GROWATT Module
Post by: genawin on November 20, 2019, 01:52:30 PM
Does anyone have a spare module ? - I'm loooking for 1 of the 14 modules - to be clear they have 18 Boston Swing 5300 cells inside.
(https://i.postimg.cc/ts24zTh3/WIN-20191120-13-50-59-Pro.jpg) (https://postimg.cc/ts24zTh3)


Title: Re: DARFON / GROWATT Module
Post by: nowty on November 20, 2019, 07:23:36 PM
Afraid not, all mine are in use.

Are the cells dead ?

(https://i.postimg.cc/3wKm7yD7/Growatt-Batteries.jpg) (https://postimages.org/)


Title: Re: DARFON / GROWATT Module
Post by: genawin on November 20, 2019, 07:54:24 PM
I had one flat module so I stripped it and charged / tested all cells and couldn't find any obvious fault - reassembled it but it flattend itself again ?
I've admired your setup - nice , It looks like you're running without BMS - How often do you check and how often do you find they need balancing ?


Title: Re: DARFON / GROWATT Module
Post by: nowty on November 21, 2019, 12:31:55 PM
I had one flat module so I stripped it and charged / tested all cells and couldn't find any obvious fault - reassembled it but it flattend itself again ?
I've admired your setup - nice , It looks like you're running without BMS - How often do you check and how often do you find they need balancing ?

When you charged up the module, did you take note of how much energy was used in charging them up ?, something simple like x amps for y time at z volts ? So you could work out the approx capacity of them ?, i.e. to work out if the cells are normal or end of life low capacity.

Did the module flatten itself whilst running in the original the Growatt box with its BMS ?, i.e. could it be that a faulty BMS is causing this ?


I ran my system as a 24v system without BMS last year for nearly a year and most cells stayed within 0.05v and the worst one was only 0.1v different. This year, the system reconfigured to 48v the cells are similar in variance. I find if you limit the charge to 80% to 90% they stay in balance and you don't need to bleed off a high voltage cell with a BMS because you don't charge the cells high enough to get a high cell.


I use a remote voltage monitor so I can keep a close eye on the bank voltage so I instantly know what the approx charge level is.
(https://i.postimg.cc/jqHZFGL5/Voltage-Meter.jpg) (https://postimages.org/)



I also have a remote voltage test point so I can easily monitor the bank down to two or three cells at once.
(https://i.postimg.cc/1ttsjpKR/Voltage-Test-Points.jpg) (https://postimages.org/)



So the above checks will alert me to anything going wrong and require more investigation and approx once a month I pick a random bank or two and check every cell. Not found any problems yet.

In fact the only cells I have ever had to re-balance were the original ones which had been running in a Growatt box under their BMS before I re-purposed them.


Title: Re: DARFON / GROWATT Module
Post by: genawin on November 21, 2019, 01:56:28 PM
I used a Liitokala Lii-500 - Each cell took over 5 hours to charge @1000ma and recorded between 5400 and 5500 mah all appeared to be holding a charge voltage wise so i reassembled and left it for a couple of days only to find it flat , I'm convinced there's at least one bad cell but it's managing to fool me ?
If I can't find a spare module I will do individual discharge capacity testing but these modules are difficult to reassemble they wont spot weld like normal 18650 cells.
(https://i.postimg.cc/DmDM0r9G/WIN-20191121-13-39-03-Pro.jpg) (https://postimg.cc/DmDM0r9G)


Title: Re: DARFON / GROWATT Module
Post by: nowty on November 21, 2019, 02:45:32 PM
Did you put the module back into the Growatt box and run as normal with its BMS ?, is it possible the BMS is at fault ?


Title: Re: DARFON / GROWATT Module
Post by: genawin on November 21, 2019, 03:12:43 PM
No , It sat on it's own.


Title: Re: DARFON / GROWATT Module
Post by: Tiff on November 21, 2019, 04:00:34 PM

Do you have a IR thermometer? If the pack is going flat that energy is being disapated as heat, something will be getting warm. Even a cheap IR will help you identify a pack that is a few degrees warmer that you might not notice by touch.

I have the same BMS as Nowty, just coming up to 3 years now on two different banks and still not had to balance.


Title: Re: DARFON / GROWATT Module
Post by: genawin on November 21, 2019, 04:11:12 PM
Thanks , As I said - If I can't find a spare module I will do individual discharge capacity testing but these modules are difficult to reassemble so it's not worth another assembly to find the hot cell or cells.
What BMS are you using ?, I've go a couple to try.


Title: Re: DARFON / GROWATT Module
Post by: Tiff on November 21, 2019, 05:51:59 PM
Thanks , As I said - If I can't find a spare module I will do individual discharge capacity testing but these modules are difficult to reassemble so it's not worth another assembly to find the hot cell or cells.
What BMS are you using ?, I've go a couple to try.

Have you tried asking on some of the facebook 18650 groups? I think your best bet is to pick up a used growatt battery on ebay and keep the extra modules as spares or sell back on ebay. I've just had a look and didn't see any on there at the moment, they used to pop up quite often but seen one in a while so the supply may be drying up somewhat.

As for the BMS, perhaps I should have added a smiley when I said I have the same BMS as nowty described above. The only difference perhaps is that I added in leads so I can plug in a cell checker for ease of checking balance. I also have a scan over everything with an IR thermometer every once in a while and put the back of my hand over breakers and connections to check for anything getting warm. I'm around to do all of this so that's my preference over an electronic BMS. Oh, and like Nowty I keep well within the middle range of charge which greatly reduces to risk of a cell being over/undercharged.


Title: Re: DARFON / GROWATT Module
Post by: nowty on November 21, 2019, 06:40:37 PM
He he, should have had my BMS patented. whistle