Sharing my little project (opinions needed)

miguelrgramos

New member
Joined
Jan 16, 2020
Messages
10
Hello everyone!
Its been a while since I started my interest in energy storage. and a slow ride also:dodgy:
You guys gave me a lot of help/information to start my project.

I have harvested and bought some 18650 about a year nowfrom laptops and electric bikes. +/-600cells for approximately --------- 500
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I also bought an inverter EASUN Isolar SMII 5KW, I think its the same as thePIP 5048MG for ------+/-600
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6 * 400w redsolar + installation with the inverter (I did it)----------------------------------------------------------------------------------+/-1700
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For the battery pack I decided to set up a 14S36P giving me 4.84KWh nominal , 93.6ah , 51.8Vall in one pack! yees!
I also bought the Kweld since I didn't want to iron solder 504cells. too muck heat!!!
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I wanted to have the batrium bms but...!!! So Itested several BMSs,the smart xiaoxiang and the dally both between60 and 70AI 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 connectedanother xiaoxang with a dallyin parallel to handle at lest 60A easily. But I don'tlike this bms paralleling setup because of the downsides it as so Iwill buy a 100 or 120A Dally bms to solve this.

My total investment with solar panels, inverter, batterypack, 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 entirehouse, and is capable of heating the wateralso. considering the battery pack also I think it is quite cheap if you compare with my local pv/bat specialists that offer900w pv installation with a 1.1kw inverter with no batterystarting at1900...

My consumption was hight, I managed to reduce at least60% 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 batteriecharges 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.
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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'stutorial 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!
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You can see here I soldered the cells in a way that the load is evenly spread between all cells connectedin the sameparallel
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I'm also doing some king of modem/router backup using the same 18650cells. To do so I'm using the batterycases from the electric bikes, Iboughta 3s40A bms, some DC-DC XL6009 Step Upmodules to stabilizevoltage for each output (I'mgoing to have 3)since the curve of these 18650 cells with this bmsgoesfrom around 10to 12.6 V. and then I'mgoing to have the 3 dc sockets on the case to connectto the devices.
For the power supply(and here relies my doubts) I boughta 12V+-0.5v LED driver capableof 12.5A.power supply
Everything is ok but in my test the power supplydoesn'tcharge the batterieswhen the pack is under a certain voltage(not sure ow much), When connected, the power supplyticks and it doesn'tcharge, but when the pack voltage is over 12V it maintainscharge.
Does somebody know what'sthe problem? do I need a stable 12.6V supply? is it
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I would like some feedback since I'm doing this all by myself.
Thanks a lot guys!!! :)
keep safe
 
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.
 
Redpacket said:
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 voltagemaybe 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.
 
[quote pid='69372' dateline='1605093615']
I would like some feedback since I'm doing this all by myself.
Thanks a lot guys!!! :)
keep safe
[/quote]

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
https://nl.aliexpress.com/item/4000765057461.html

or (seems even better for what I need)

- YX-X804 power failure automatic switching battery controller board DC 12V-48V emergency automatic conversion module
https://nl.aliexpress.com/item/4000074867977.html

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.

Bye,
Jes
 
italianusercs said:
[quote pid='69372' dateline='1605093615']
I would like some feedback since I'm doing this all by myself.
Thanks a lot guys!!! :)
keep safe



Thanks for your feedback! Much appreciated!
My router's/modems are the regular 12v 2A max. I found me the 40A and since amperage is never to much I thought it would be ok if I needed to had more output ports to supply other 12V devices like NAS and security cameras.
I find the comercial solutions or to expensive or not enough for what I want. That's why I want do to one.
About your concern in a 3s or 4s configuration you can keep the 3S if you add stepup dc-dc module, this way you can drain the batteries and guarantee a 12v supply, you just need to make sure that the module and batterie can handle the extra current that will be required.
I ordered this one
https://a.aliexpress.com/_BUOAxP
but I still haven't received it so I don't know for now if it works well for now.
 
Overall from what I'm reading you have
- 14s42p (600 cells) and somewhere in 100ah @ 48v range - e.g. a 4.8kwh battery bank.
- 2.4kw PV array
- 5000w inverter
- Average 15kwh/day consumption.

In my own system I have
- 81kwh battery bank - that runs at 42% DOD
- 12.8kw PV array
- 24,000w inverter
- Which delivers an average of 42kwh/day (after 16% losses due to inverter and other inefficiencies)

If we do some extrapolations based on 2.4kw PV is 19% of 12.8kw PV array and assume similar sunshine and losses (15%)I can offer some rough comments based on my yearly production of 14,505kwh consumed so far this year with an 81kwh battery bank buffer.

I would expect you to....
- Generate an overall yearlyaverage of 8kw/day. 15kwh/day at max (spring/summer) and 3.5kwh/day in winter and 7.5kwh/daybetween. Obviously more panels are always better.
-Need at least 8kwh as minimum (100% DOD'ish) battery bank andsuggest for a long life span (50% DOD)you want get your battery in therange of 15kwh. Without a minimum battery sizeyou may findyou can't store all the PV power generated thru a day that isn't consumed... I don't mean this as a criticism and there's nothing wring with starting with a smaller battery - just suggesting you leave room(2 or 3 or 4 times larger) so you can expand your battery bankonce you have stats from your operating system. and discover the need. Also, adding more panels will increase the need in proportion.

Really enjoy seeing the pics/work - great job!Its a lot ofFUN, don't you think? :)
 
OffGridInTheCity said:
Overall from what I'm reading you have
- 14s42p (600 cells) and somewhere in 100ah @ 48v range - e.g. a 4.8kwh battery bank.
- 2.4kw PV array
- 5000w inverter
- Average 15kwh/day consumption.

In my own system I have
- 81kwh battery bank - that runs at 42% DOD
- 12.8kw PV array
- 24,000w inverter
- Which delivers an average of 42kwh/day (after 16% losses due to inverter and other inefficiencies)

If we do some extrapolations based on 2.4kw PV is 19% of 12.8kw PV array and assume similar sunshine and losses (15%)I can offer some rough comments based on my yearly production of 14,505kwh consumed so far this year with an 81kwh battery bank buffer.

I would expect you to....
- Generate an overall yearlyaverage of 8kw/day. 15kwh/day at max (spring/summer) and 3.5kwh/day in winter and 7.5kwh/daybetween. Obviously more panels are always better.
-Need at least 8kwh as minimum (100% DOD'ish) battery bank andsuggest for a long life span (50% DOD)you want get your battery in therange of 15kwh. Without a minimum battery sizeyou may findyou can't store all the PV power generated thru a day that isn't consumed... I don't mean this as a criticism and there's nothing wring with starting with a smaller battery - just suggesting you leave room(2 or 3 or 4 times larger) so you can expand your battery bankonce you have stats from your operating system. and discover the need. Also, adding more panels will increase the need in proportion.

Really enjoy seeing the pics/work - great job!Its a lot ofFUN, don't you think? :)

Actually I have a
-14s36p configuration 504 cells 93.6Ah 4.8kwh

you have a big setup, is the battery itself made by you?
I started a couple of months ago with the installation, and wasn't sure what to expectin terms of production, but your expectations are correct!
In summer I reached 14,6Kwh in one day and now(winter) like today I got 3.9 and it was quite a good day with some sun.
I know my pack is under the recommended capacity but its still an expensive thing here in europe. I wish we had easy access to used battery packs like in the USA.
No bad criticisms taken! I completely agree with you, I need to have a biger battery.
From my pack i'm doing a 70% DOD, I'm going to reduce this as soon as I grow the pack.
But for now i'm diverting excess power with mqtt devices and nodered to the water heater, I have a 300l tankand it can store around 19Kwh of heat so that's a relief, a cheap power storage optionif the hot water is something we use a lot:D

Im going to put my hands on a custom made battery pack with32650 lifepo4 cells with equivalent capacity but I need to confirm if it is possible to mix chemistrys (the standard 18650 li-ionandthe 32650 lifepo4)

YES!!!!I really love doing this kind of stuff:D
 
>you have a big setup, is the battery itself made by you?
Yes. I have 6 x 48v@260ah (e.g. 14s88p - 120p) so far and finishing up 2 more for just a little over 10,000 cells over the last 3 yrs. After all this effort - I want this puppy to last as long as possible so I strive for as low a DOD as I get manage :)

>diverting excess power with mqtt devices and nodered to the water heater,
Diverting to water makes perfect sense. I wish there was some way to extract electricity from hot water (as it cools) and then it could serve as full-cycle battery.

> if it is possible to mix chemistrys (the standard 18650 li-ion and the 32650 lifepo4)
It is. I believe 14s 18650 and 16s lifepo4 are recommended as a good match - but you need separate BMSs due to different voltage ranges and lifepo4 has a 'very flat' discharge curve. Just means you have to be a bit more aware and match things up for overlapping/compatible charge/discharge voltage ranges to reap the best result.

Look forward to hearing about your next steps - good luck!
 
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