48 Volt Questions

RudyLiPower

RudyLiPower

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Joined
Oct 20, 2016
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37
Anyone come up with an easy cell holder design for 48 volts?
From what I have found it seems like some combination of spacers would work, wondering what works for you?

I live in the US and would like to go with 240 Split Phase inverter - anyone got suggestions? That is 120 - 0 - 120 Hot - Neutral - Hot design where the 120's are the top/bottom to middle of the wave and you can take both sides to get 240 for things like well pumps. I have a Generator Lockout Panel for certain circuits, so I am starting with small loads and adding as the Ah builds.

Finally, Chargers - I have 4x 235W panels at 30.18Imp. I hooked one up to a 7210a and charged a 48 volt bank of free LA batteries out of a datacenter UPS. They hold a crap ton of power. I have 6 of those... I will be replacing them as I can. When I get enough Cells. Would it be possible to just run each panel on it's own charger to boost to 48V? Or should I just stop screwing around and get a real charger? I would like one that is UL rated and can be paralleled easily.

Lots of questions, I have not seen much 48V discussion in my searches. Any assistance or sharing is greatly appreciated.

Rudy
 
Im not from US so dont have much to input there but some just buy a 230V inverter that they hook to a transformer to get split fase out.


Most "bigger" systems here are 48V based. And thats the way to go for high current systems unless you go for the high voltage battery systems. Still not that common though.

I suggest you get proper MPPT charger directly. Unless you going to have your panels on different directions or often get partial shading on them. Its generally more costly to get several smaller chargers. For instance the 7210 on ebay do work pretty good and its a bost system that need lower input than output. 2 of those could work fine to. Link to ebay: https://goo.gl/h1RhJw
Thats just 1000W of solar panels so there is plenty chargers out there. But for instance the cheaper PCM60x would work but also any other.
 
Daromer,
Thanks for the reply. I would really like to stay 48v for the efficiency, but man the equipment in the US gets expensive for Inverters and charge controllers. That UL listing must cost some $$$. I would like to stay expandable on the Panel side so I am going to oversize the charge controller. The inverter is TBD...

I was really thinking about how many cells I need to power the couple of things I want. My office for the computers and such. Also my water pump for the house. I need to find the docs on how much that pump draws. Then I would load up anything else I can based off of excess capacity. I am guessing I am going to need a heck of a lot more panels to keep up with our real demand.

I see many people going with 14S80P. My harvesting is going slow but steady. I am wondering if I could get away with 14S40P. That would give me about 1A x 3.7V x 40 cells x 14 Series = 2072 Watts? with peak to 4000 Watts Total Capacity would be right around 4000Wh with somewheres around 560 cells.

If I could process more cells 80P would be nice, but I don't think I can get there in a reasonable period.
 
I'm thinking too in which configuration choose for my powerwall, I prefer to go step by step and will choose a mid size maybe 50p so changing task more often and dont get bored opening more than 200 batteries then testing 1400 cells and then make more than 5600 soldering until I can add some serie to my powerwall. I want to see some result soon.

So my choice is 14s50p and then expand with packs of this size too.
 
RudyLiPower said:
Also my water pump for the house. I need to find the docs on how much that pump draws.
Click to expand...

Now, make sure take a look at what your pumps "surge" wattage is. Some pumps/motors can have as much as a 30% surge over their runtime wattage. That initial kick-in can take a pounding on a powerwall if not suitably sized. Especially since you mention going 50p instead of 80p. Just take that into consideration.


Side Note: You "may" be able to put a capacitor in parallel with the pump to help with surge. AC compressors for the house usually have those as well to help with that extra jolt needed. Now, if I remember correctly, the capacitor is only charged momentarily before the pump is engaged, and then disengaged from the system. A set of relays are used. But, you could use that setup from an old heatpump/AC-pump to run your water pump. They are both 240V (unless you have a different type)
 
mike said:
RudyLiPower said:
Got a good source for DC breakers?
Click to expand...

You should be using HRC fuses with your batteries. Bricks of 18650 cells can put out a LOT of current which breakers won't be able to interrupt during a short circuit. It will probably just weld the contacts together.
Click to expand...

So with like a 40P Cell/Pack whatever would you use an 80Aof fuse? The fuse wires in the packs don't help this? I was thinking the breakers between all the components, like between the 14S pack and the inverter and Charger. Solar Panels to Charger... That sort of thing.

I don't recall seeing this type of fusing in any documents I have come across, most of it has been DC breakers that are designed to handle this.
Where would one put these fuses?

Thanks for the help.
Rudy

Korishan said:
RudyLiPower said:
Also my water pump for the house. I need to find the docs on how much that pump draws.
Click to expand...

Now, make sure take a look at what your pumps "surge" wattage is. Some pumps/motors can have as much as a 30% surge over their runtime wattage. That initial kick-in can take a pounding on a powerwall if not suitably sized. Especially since you mention going 50p instead of 80p. Just take that into consideration.


Side Note: You "may" be able to put a capacitor in parallel with the pump to help with surge. AC compressors for the house usually have those as well to help with that extra jolt needed. Now, if I remember correctly, the capacitor is only charged momentarily before the pump is engaged, and then disengaged from the system. A set of relays are used. But, you could use that setup from an old heatpump/AC-pump to run your water pump. They are both 240V (unless you have a different type)
Click to expand...

The inverter I am looking at has a 8500W 5 secondsurge, that should take care if it. I think they have good size capacitors inside to handle peaks likethat.
 
That's good. 8500W is a lot of surge. So you should be fine.

The only thing that might cause a problem (though might not with that high of surge capacity) is if your water pump and ac and maybe even the microwave/oven or some other high ac load kicks on simultaneously. Not likely, but possible. There was another who thinking of wiring up his ac unit(s) and fridge (i think) so that if there was a peak load within the last 5 seconds or so, that the other heavy loads would have to wait a few seconds before they kicked in. It's just basically an interrupt between the pump-motors and the device circuitry that turns on the units.
Can't remember who that was off top of my head, atm. Will have to look into that one (as I'm wanting to do the same thing)


Update: Found it :)
http://secondlifestorage.com/t-Load-management
 
Korishan,
That is a neat idea there. Not sure how all the new fangled IOT appliances would fair being rebooted like that, LOL. I hear you on the loads. I will be using my Generator Panel to feed only certain circuits. These are already wired into the circuit breaker now per their load, but they are not balanced well at all. My 5K gas genny does just fine. Limited battery capacity + Limited solar panels = limited output :(
Not sure how many KWh capacity I am going to end up with. I still need to figure out ground mounts, and a few trees gotta go...

I am really trying to concentrate on building the packs now. I need to understand which cell holder system works the best. I see there are 4 cell x5 cell holders widely avalible. I like HB's original design, but I was wondering if there are any improvements? I have seen the + and - at opposite ends of the packs to help with discharge balance.

I am starting to get bummed with my last pack haul 30lbs - I think I may be about 40% good so far.
I have learned some lessons with these.
1 - Don't get any that externally look like crap.
2 - Don't get the ones that are not easily identifyable as laptop packs.
3 - Only get the HP/Dell/Lenovo packs these seem to have the best LG and Samsung cells. There were some others with barcodes that did well too, but I forgot which batteries those came out of (they were teal-blue and purple cells)

Anyone got other advise?
 
RudyLiPower said:
Korishan,
That is a neat idea there. Not sure how all the new fangled IOT appliances would fair being rebooted like that, LOL. I hear you on the loads. I will be using my Generator Panel to feed only certain circuits. These are already wired into the circuit breaker now per their load, but they are not balanced well at all. My 5K gas genny does just fine. Limited battery capacity + Limited solar panels = limited output :(
Not sure how many KWh capacity I am going to end up with. I still need to figure out ground mounts, and a few trees gotta go...

I am really trying to concentrate on building the packs now. I need to understand which cell holder system works the best. I see there are 4 cell x5 cell holders widely avalible. I like HB's original design, but I was wondering if there are any improvements? I have seen the + and - at opposite ends of the packs to help with discharge balance.

I am starting to get bummed with my last pack haul 30lbs - I think I may be about 40% good so far.
I have learned some lessons with these.
1 - Don't get any that externally look like crap.
2 - Don't get the ones that are not easily identifyable as laptop packs.
3 - Only get the HP/Dell/Lenovo packs these seem to have the best LG and Samsung cells. There were some others with barcodes that did well too, but I forgot which batteries those came out of (they were teal-blue and purple cells)

Anyone got other advise?
Click to expand...

Actually, look for the 3 cell 11.1or 4 cell 14.8 packs. they often have 3000 or even 3400 mah cells if they are recent enough.

I can't remember what brand they are. I think Panasonic...
 
I take them all as long as they are free. If cost then i scrap the ones with out name brand.
 
@egam Thanks for the laptop battery hunting tip. I may be going to the local e-scrapper this week.

@daromer Free! Wow, I wish... I do not have a supply steady enough to even create a 2500KW PowerWall.
I see you have some different chemistry across your battery packs. Very interesting...

I ordered 40 of the 5x4 cell holders. I think this is what most everyone is using. Got all 20 of them for $18 I am waiting for China Post...
I think I have settled on 40P 14S for now. @1A then I am at just over 2kW draw with about 3500kWh of power. That should work to start with.

I am now wondering how to set them up so I can add more parallel packs as I harvest more good cells...
Well back to the harvest grind!
Rudy
 
I wish i had 3500kWh of storage :D

I have like 100.... ;)
 
:D :p :) :cool: :D :rolleyes: :shy: :) ;) :D :cool:
 
mike said:
I'm in the US too. I'm looking at Magnum inverters. A 4400w inverter that's UL certified will run you about $2100. It's 240v split phase so you can run it to a standard breaker box.
Click to expand...
The Magnum inverter package looks good completed with the subpanel. I too have been researching this and it currently looks looks like mu best bey for a grid-tie hybrid
 
RobertBaumer said:
mike said:
I'm in the US too. I'm looking at Magnum inverters. A 4400w inverter that's UL certified will run you about $2100. It's 240v split phase so you can run it to a standard breaker box.
Click to expand...
The Magnum inverter package looks good completed with the subpanel. I too have been researching this and it currently looks looks like mu best bey for a grid-tie hybrid
Click to expand...

It's also at the top of my list because they can be easily paralleled so if you outgrow 4400w, you can just add another and be up to 8800w.
 
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