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Sharing my litle project (opinions needed)
Hello everyone! 
Its been a while since I started my interest in energy storage. and a slow ride alsoDodgy
 You guys gave me a lot of help/information to start my project. 

I have harvested and bought some 18650 about a year now from laptops and electric bikes. +/-600cells for approximately ---------  500€

I also bought an inverter EASUN Isolar SMII 5KW, I think its the same as the PIP 5048MG for                                     ------+/- 600€ 

6 * 400w redsolar  + installation with the inverter  (I did it)----------------------------------------------------------------------------------+/-1700€ 

For the battery pack I decided to set up a 14S36P  giving me 4.84KWh nominal , 93.6ah , 51.8V all in one pack! yees!
I also bought the Kweld since I didn't want to iron solder 504cells. too muck heat!!!

I wanted to have the batrium bms but...€€€!!! So I tested several BMSs, the smart xiaoxiang and the dally both between 60 and 70A I realized the xiaoxiang is very unstable a not so good to tweak, giving me internal errors that don't reset, I fried 2 xiaoxang bms. The support from the producer is inexistent, but what do you expect! 
For now I connected another xiaoxang with a dally in parallel to handle at lest 60A easily. But I don't like this bms paralleling setup because of the downsides it as so I will buy a 100 or 120A Dally bms to solve this.

My total investment with solar panels, inverter, battery pack, all the other little accessories, (I did not mention because they are plenty) for under 3000€ Some may say its a lot but, take in mind it feeds the entire house, and is capable of heating the water also. considering the battery pack also I think it is quite cheap if you compare with my local pv/bat specialists that offer 900w pv installation with a 1.1kw inverter with no battery starting at 1900€...

My consumption was hight, I managed to reduce  at least 60% of the bill. I use an average of 15kwh per day, and mostly produce between 7 and 10 depending. I know I can reduce the bill even more because the batterie charges and that extra solar goes nowhere most of the time, I'm doing some stuff with tasmota and nodered to turn on the water heater when that happens.

To do so I bought ICC software, this way I have all the inverter topics easily sent to node red. I tried to do it with myself with Daromer's tutorial but some connection problem between the inverter and raspi wasn't working well, anyway, I have the inverter connected to the icc in the raspi sending data to nodered where I'm doing the function to control the heater, and in the future more stuff like weather prevision for charging the battery at night, Dashboard....etc.
I also want to add at least one more pack so it handles completely the loads of the house, I've been distributing the loads so it doesn't exceed 3500w during battery mode.

here are some more pics of my work!

You can see here I soldered the cells in a way that the load is evenly spread between all cells connected in the same parallel

I'm also doing some king of modem/router backup using the same 18650cells. To do so I'm using the battery cases from the electric bikes, I bought a 3s40A bms, some DC-DC XL6009 Step Up modules to stabilize voltage for each output (I'm going to have 3) since the curve of these 18650 cells with this bms goes from around 10 to 12.6 V. and then I'm going to have the 3 dc sockets on the case to connect to the devices.
For the power supply(and here relies my doubts) I bought a 12V+-0.5v LED driver capable of 12.5A.power supply
Everything is ok but in my test the power supply doesn't charge the batteries when the pack is under a certain voltage(not sure ow much), When connected, the power supply ticks and it doesn't charge, but when the pack voltage is over 12V it maintains charge. 
Does somebody know what's the problem? do I need a stable 12.6V supply? is it 

I would like some feedback since I'm doing this all by myself.
Thanks a lot guys!!! Smile
keep safe
Redpacket and ajw22 like this post
For the last part about the ticking power supply, when the battery voltage is lower, it thinks there is a short circuit. You need a charger type device that can deliver a constant current vs the constant voltage PSU now that tries hard to put out 12.0V only.
miguelrgramos likes this post
Running off solar, DIY & electronics fan :-)
(11-11-2020, 12:31 PM)Redpacket Wrote: For the last part about the ticking power supply, when the battery voltage is lower, it thinks there is a short circuit.  You need a charger type device that can deliver a constant current vs the constant voltage PSU now that tries hard to put out 12.0V only.
Thanks, what do you mean by short circuit? do you thing the 12.5A is in conflict with the bms? for the constant voltage maybe I can use the XL6009 step up module from the power supply to the pack, I will try as son as I get the modules. but for current I'm not sure what to use. 
what about power supply? I cant find one that is 12.6V at least 10A suitable for both the battery pack and loads of devices.
If the battery is eg 11V and you connect that power supply it will try hard to get the voltage to 12.0V and try to put out too much current. Trouble is, the type of limiting it has is not designed to run at eg 11V & provide stable controlled current limiting until it gets to 12V like a charger. The design of a power supply vs a charger is different inside.
SOME power supplies can do what you need, just not the one you have.
miguelrgramos likes this post
Running off solar, DIY & electronics fan :-)
[quote pid='69372' dateline='1605093615']
I would like some feedback since I'm doing this all by myself.
Thanks a lot guys!!! Smile
keep safe

Congrats Miguel, looks real good. I suppose you have great satisfaction from doing this by yourself, great!

About your last point, the backup system for your modem/router I'm doing something similar. I just did some tests for now but I wanted to ask you:

- How much does current the modem/router require? The 3S 40A BMS seems quite big for me. Maybe you have some special kind of router with a high nominal wattage. Did you test the router current usage with an amperometer?

- For how long do you want to keep modem/router running on batteries?

The modem/routers I'm working on run, each single router, with 10-15W from a 12V DC source.

I was looking into a product of this kind:

- XH-M601 Battery 12V Intelligent Device Power Supply Control Board Automatic Charging and Blackout Integrated Circuit

or (seems even better for what I need)

- YX-X804 power failure automatic switching battery controller board DC 12V-48V emergency automatic conversion module

In my scenario, for each router and for a 3 hour backup power supply from the batteries, having 3A 12V should be enough. Considering I wouldn't drain batteries right down to 0% (3V) i could consider doubling the battery amperes and go for 6A 12V battery pack for each router.

My main concern is about using a 3S, which is quite at limit (nominal 3.7V x 3 = 11.1V). I would check out a 4S (3.7V x 4 = 14.8V) although it's true we can charge lithium up to 4.2V making 4.2V x 3 = 12.6V. In this case you would go under 12V quite quickly, that's why I would suppose 4S is better.

For charging the lithium batteries I'd put a protection for the battery pack to avoid overcharging and other stressing conditions.

Yes, I also look for cost-effective solutions!

Keep us updated and thanks for sharing.

It's one big 504 cell battery? Must weigh over 20+kg? Most people split it into smaller 80~200 cell modules. Any regrets going that big?
Modular PowerShelf using 3D printed packs.  60kWh and growing.

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