WS-12-DC Power Supply Recommendation

[sirhc]

Another solution would be both an AC-DC power supply to power equipment while there is grid power, the charger, and a transfer switch that switches over to using the batteries when the grid goes out. Otherwise the batteries are just sitting there being charged.

Can you tell me what kind of load you are running at one of your sites with a MinnKota charger? And does it permanently stay in float mode once the batteries are charged?

This person got back to me saying either DualPro or MinnKota chargers would be good for up to 2A per output, over that and the charger will reset itself requiring it to be rebooted.
Makes no sense to me really.
He's just trying to help me, but it's making the whole thing cost more.

EDIT: Just called DualPro: explanation: if there is a load accepting much more than 2 amp, it won't allow the charger's voltage to raise the way it would expect a battery to. It then presumes there's a battery fault, and sets a fault code, which kills the charger.
So yeah... calling MinnKota next :)

Yes that would be the Tripp Lite inverter/charger that we also use a lot and has been mentioned here before.
http://www.neweggbusiness.com/Product/P ... Hwod0X8Irg

But an AC site is less efficient and will not stay up as long as a DC site when power fails. All comes down to if you have grid and how often and long it fails.

[mlow]

We are working to convert all of our AC sites (except 2 with backup generators) to DC.

Word back from Minnkota is essentially the same. There are two scenarios the charger will fail in:
A) If the battery voltage falls below 10.5 volts, and the charger can not get them above 10.5 volts in 3 hours, it will shut down
B) If the charger remains in bulk mode for 20 hours before battery voltage reaches 28.8 volts, it will shut down

You can solve A by using low-voltage cut-off switch (maybe even software configurable, even if only shutting down PoE ports, on the WS-12-250-DC? :) (or does that already exist?? I don't have a WS yet)) to prevent ever going below 10.5 per battery
Solve B by sizing the charger appropriately for the connected load and battery capacity: you want the job to get done in under 20 hours. In bulk mode (constant current) whatever current that's not going to your load will go into the battery.

[sirhc]

Forgive me but the MinnKota 4 battery charger can charge at 10 Amps per battery so 48V 40A

If you have a site that is using even 10A total that is a MASSIVE site.

48V 10A is a boat load of power

If you had all this at your tower:
(1) WISP Switch 24 A that is 48V .25A
(3) AF24 radios that is 48V 1.5A
(10) airMAX radios at an average of 8 watts each so 80 watts @ 24V is 3.3A @ 48V
(1) Router less than 1A @ 48V

So total power of a large tower 6.05A @ 48V

So you could easily keep the battery bank fully charged, I know this because I do

[mlow]

It's all just formulas - the MinnKota can put out 10amp at 12v per output. If you use them on a parallel battery setup, you get 40A @ 12v total, series it and you get 10a @ 48v. If you have a 6A load on 48V, each battery will be supplying 6A. Therefore, when the charger is in bulk mode, each output will be supplying 6A to the load and 4A will be flowing effectively in reverse through the battery. So, if your bank was made of 40AH batteries, you could expect it to take little more than 10 hours to charge from flat while supplying the 6A load.
Generalized but I think that's the gist of it.

[sirhc]

It's all just formulas - the MinnKota can put out 10amp at 12v per output. If you use them on a parallel battery setup, you get 40A @ 12v total, series it and you get 10a @ 48v. If you have a 6A load on 48V, each battery will be supplying 6A. Therefore, when the charger is in bulk mode, each output will be supplying 6A to the load and 4A will be flowing effectively in reverse through the battery. So, if your bank was made of 40AH batteries, you could expect it to take little more than 10 hours to charge from flat while supplying the 6A load.
Generalized but I think that's the gist of it.

Yea, Messed up my math there!

[cdavis]

What types of cable do people use for DC power up a tower? Is shielded cable necessary?

Thanks

[Omniflux]

THHN in conduit, SOOW if exposed.

This is what I used for my last run up a grain elevator where getting conduit installed was problematic:

https://www.amazon.com/gp/product/B00EUH6DP0/
https://www.amazon.com/gp/product/B000NI1FZS
https://www.kjmagnetics.com/proddetail. ... =MMWR-B-X8

I would like to find a source of stainless steel mounting magnets with an integral stud, but no luck so far.

For network cable, we always use shielded for exposed runs as the sheathing often seems to pick up an electrostatic charge from the wind...

[cdavis]

And what type of fuse and where in the system do you install it? I *think* I will have about 4 Amps in POE devices on a 24 volts system.

[Omniflux]

I don't have a photo of what we are currently doing, but here is a photo of what we were doing at our AC sites before we began switching to DC Netonix and MinnKota chargers.

Battery with MAXI fuse

Pictured is a Stinger SPD5601 in line fuse holder with an 80 amp maxi fuse to connect to the Tripp Lite APS750 inverter / charger. It is placed a few inches from the positive post on the battery.

https://www.amazon.com/gp/product/B001HXHKPC


Now that we feed directly from the battery into the Netonix switch, we are using a generic inline splice ATC fuse holder with a 30 amp fuse. It is placed in the same location as the SPD5601.

https://www.amazon.com/gp/product/B017BAF920

The MinnKota has its own ATC type in line fuses already build in.

[Omniflux]

I use a 30 amp fuse because I don't want to have to remember to change my fuse size every time I add or remove equipment.

Current DC model Netonix max is 250 watts
Min. voltage is 9 volts (in case of extended power outage and slow response to bring generator on site)

250 watts / 9 volts = approximately 28 amps