power distribution


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CrankyCoder

Member
Joined
Mar 11, 2017
Messages
95
So I have a question for everyone. My install is small. Right now it's 4s80p. Mainly to get me around that 12v mark and I can use some 12v inverters I have. I am not too interested in AC power at this time, most of my requirements for this are all for DC.

The problem I have is placement. I am hesitant about putting it all on my back porch as I live in FL and the humidity is unkind. I would like to put it in my garage, but one of my main uses for this is for a water pump that is 12v/10a. The distance I am concerned about. I need to go about 70ft from garage to where I want the pump. With 10amps at 70ft just about everything shows I need to go with some 6awg wire or even 4awg.

So I was wondering if anyone has any suggestions?

Thanks!
 

jdeadman

Member
Joined
Mar 28, 2017
Messages
967
Move it closer to the load. Build a battery box (shed) that's insulated from the heat and humidity
 

DarkRaven

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Joined
Sep 2, 2017
Messages
1,223
Well, three options:

1. Use the thick 6AWG or 4AWG, this is just how it is when transporting DC over a longer distance.
2. Convert to AC and use an AC pump.
3. What jdeadman said.
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
7,008
or build a boost converter to jump the voltage up to 48V or so to transmit the long distance, and then buck it back down.

or, rather, you do a square wave AC inversion and transformer it up to transmit it, then drop it back down and rectify it at the load end.

It's some work to be done, but those are basically your 3 options for 12V source (jdeadmans and my 2 options)

Addendum: Make that 4, #2 option from DarkRaven ;)
 

egam

Member
Joined
Mar 9, 2017
Messages
109
Classic problem of heat and enclosures. As the enclosure heats up, the air expands and it is pushed out. As the enclosure cools, the air in it contracts and moist air from outside is sucked in. As the temperature drops further the water condenses out of the air. This "breathing" can build up a lot of water over time and corrosion on your battery ends.


Your best bet is to use some kind of sealant or dielectric grease (Vaseline) on the ends of the cell connections to keep the ends from corroding. Then ventilate the battery enclosure to allow the heat to escape the top and cool air to enter the bottom. Lastly, you need to keep rain or irrigation water from getting into the enclosure or collecting inside the enclosure. You also need some fine screen over the ventilation louvers to keep out the bugs, spiders, and rats.

What kind of duty cycle and charge cycle do you have on the pump and batteries? 10 amps from an 80P pack is only .12 amps per cell. I don't think they will heat up much being that lightly loaded. If you are charging them with solar, what wattage of panels are you using and what direction and angle are you pointing them?
In Florida, you will get a lot of sun which is a plus.
 

CrankyCoder

Member
Joined
Mar 11, 2017
Messages
95
ok. That's kind of what I figured. I thought about the 48v.

Would using something like this work?

boost to 48v
https://smile.amazon.com/Zowaysoon-...ule-Waterproof/dp/B00DR4TV2O?sa-no-redirect=1

then run some thinner wiring
then buck it back down with this?
https://smile.amazon.com/ZIUMIER-Co...coding=UTF8&psc=1&refRID=RND1CC0RNP749GCB4GDR

Any thoughts?


jdeadman said:
Move it closer to the load. Build a battery box (shed) that's insulated from the heat and humidity

after the Irma storm im afraid of having a powershed. :(


egam said:
Classic problem of heat and enclosures. As the enclosure heats up, the air expands and it is pushed out. As the enclosure cools, the air in it contracts and moist air from outside is sucked in. As the temperature drops further the water condenses out of the air. This "breathing" can build up a lot of water over time and corrosion on your battery ends.


Your best bet is to use some kind of sealant or dielectric grease (Vaseline) on the ends of the cell connections to keep the ends from corroding. Then ventilate the battery enclosure to allow the heat to escape the top and cool air to enter the bottom. Lastly, you need to keep rain or irrigation water from getting into the enclosure or collecting inside the enclosure. You also need some fine screen over the ventilation louvers to keep out the bugs, spiders, and rats.

What kind of load (watts) and charge cycle do you have on the pump and batteries? If its lightly loaded, you won't have much problem with heating or need for ventilation. I charge/discharge at 1 amp per cell, and the cells only seem to get warm if there is a burner cell. I plan to build a pack to power a 24Watt 12Volt fountain pump. That pump will only draw 2 amps at full load. If I build a pack to supply power for 24 hours, thats a 48 amp hour pack. Thats a 4s/24P pack if using 2000 mah cells. (i'm going to use all of my reject 1000 mah cells. so thats a 4s/48P pack)
If I charge up the cells over 4 hours using solar, then the current to each cell is 48amp hour / 4 hour = 12 amps. So I need 144 watts of solar production at 12-16 volts.

I had not heard about the vaseline on the ends. I have heard of putting hot glue over the connection, but that sounds like a NIGHTMARE if you have to work on it at all.

The pump should only run at max 1 hour a day. The pump at full load runs about 10amps.
 

jdeadman

Member
Joined
Mar 28, 2017
Messages
967
Ahh gotcha. Yea that's definitely a consideration. I like the higher voltage but run your PowerWall at a higher voltage and buck down to the voltage the pump needs. Make sure to over spec the current for the buck as the inrush with motors can we much higher. So a 10A pump may draw 30A when it starts
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
7,008
Yes, the heaviest current draw of an electric motor is during start up. This draw can easily be 3 or 4 times the rated the amperage. The reason this is usually not an issue as most wiring and breakers can handle high current surges for about 2 seconds. Which is normally plenty long enough for a motor to kick in and get up to speed.

However, the cells may not be able to handle that heavy draw for very many rounds. Definitely something to consider. Another thing you could do is get some super-Caps to help with the current draw. They'll charge up when the pump isn't being used and will deliver all that the pump can use in that brief moment. But, what I'd do with that is put a timer so that when the pump pressure switch kicks on, it turns on the super-Cap charging for about 30 seconds (or what ever is needed for it to fully charge), and then engage the pump. As long as the pump is running, the cap will still low. Then, when pressure is reached, disconnect the cap from the circuit. This is for safety reasons so someone doesn't get zapped by mistake if work is needed to be done.

Are you running an AC pump or a DC pump?
 

daromer

Moderator
Joined
Oct 8, 2016
Messages
5,662
You can also add a 2nd battery bank on the other end.. Thinner cable that will charge that bank. The bank on other side have to big enough to support the load for the amount of time you average run it. When its done the thinner wire will charge the bank up. Yes some % lost in transmission but less then using a thin wire without battery bank.

Its a common use to have a 2nd back or super cap and it works. No extra electronics needed for more than balancing on the other end.
 

mormor1971

Member
Joined
Sep 18, 2017
Messages
37
I would make the battery voltage higher i.e. split your packs into say 16S10P or stay at a more conventional 14S configuration and perhaps find a few more cells to get you to a nice number that are easier to build cell-packs around than 11.42. :p

The idea is to have a higher voltage on the battery pack / distribution network so you can run smaller cables and then use a suitable buck converter to get it to the required voltage for your well pump.

Having a 14S configuration also allows you to add solar panels and so on and it would be easier to find inverters and chargers that could work with the nominal 51.8V. You will obviously need a BMS of some sort that can monitor the battery pack but you would need that anyway.
 

CrankyCoder

Member
Joined
Mar 11, 2017
Messages
95
Korishan said:
Yes, the heaviest current draw of an electric motor is during start up. This draw can easily be 3 or 4 times the rated the amperage. The reason this is usually not an issue as most wiring and breakers can handle high current surges for about 2 seconds. Which is normally plenty long enough for a motor to kick in and get up to speed.

However, the cells may not be able to handle that heavy draw for very many rounds. Definitely something to consider. Another thing you could do is get some super-Caps to help with the current draw. They'll charge up when the pump isn't being used and will deliver all that the pump can use in that brief moment. But, what I'd do with that is put a timer so that when the pump pressure switch kicks on, it turns on the super-Cap charging for about 30 seconds (or what ever is needed for it to fully charge), and then engage the pump. As long as the pump is running, the cap will still low. Then, when pressure is reached, disconnect the cap from the circuit. This is for safety reasons so someone doesn't get zapped by mistake if work is needed to be done.

Are you running an AC pump or a DC pump?

I found some bigger boost/buck converters. I may give them a try so I don't have to drag giant wiring. I am going to check in to this super cap idea too. That sounds interesting even if i don't go that route.


mormor1971 said:
I would make the battery voltage higher i.e. split your packs into say 16S10P or stay at a more conventional 14S configuration and perhaps find a few more cells to get you to a nice number that are easier to build cell-packs around than 11.42. :p

The idea is to have a higher voltage on the battery pack / distribution network so you can run smaller cables and then use a suitable buck converter to get it to the required voltage for your well pump.

Having a 14S configuration also allows you to add solar panels and so on and it would be easier to find inverters and chargers that could work with the nominal 51.8V. You will obviously need a BMS of some sort that can monitor the battery pack but you would need that anyway.

I have been wondering about that. I would like to be at the 48v setups but since my source of batteries is slow but steady it would take me awhile to get enough batteries. I was going to go with the 12v stuff because I have enough to go that route and have inverters for that if needed (which I did need when IRMA took a shot at us lol)
 
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