Buffer mode does mean on battery. Those tolerances are probably mostly
accurate. The BCMU "360" is really rated for 240W continuous. And then
take off about 15W for maintaining the battery. That's exactly why I
load them up to no more than about 220W.
When we lose utility power, I do see the voltage drop somewhere abouts
46-47VDC. Again, the internal DC-DC converter isn't all that efficient.
Temperature is another factor (which is why they say 3 min "boost mode").
I've got 50Ah on a couple. One site is around 165W and will run for
almost 2 hours. Maybe a little more, I forget. About 210W on another and
it'll run a little over an hour. Usually enough time to run out a generator.
You shouldn't be seeing 44 volts under normal operation. However, if you
have 300W on it, and it's on battery, that really wouldn't surprise me.
On 1/30/2018 2:35 PM, Mathew Howard wrote:
That makes a lot more sense... I (and Paul too, I assume) must be
reading the spec sheet wrong. I thought buffer mode was referring to
when it was running on battery (I assumed that because of something
else I read further down the spec sheet), but it must mean something
else if it actually does put out 48.0v.
Output voltage / current
– Normal Mode
24 VDC mode:
Vin – (0.4 - 0.8V); 15 A max.
48 VDC mode:
Vin – (0.4 - 0.7V); 7.5 A max.
– Buffer Mode
24 VDC mode:
22.2 – 22.9 VDC; 10 A
(15 A in boost mode for 10min)
48 VDC mode:
44.6 – 45.3 VDC; 5 A
(7.5 A in boost mode for 3min)
On Tue, Jan 30, 2018 at 2:27 PM, George Skorup
<[email protected] <mailto:[email protected]>> wrote:
The BCMU360 is definitely 12VDC on the battery side. It uses an
internal DC-DC converter. I'm using several. At 24, it puts out
24.0. And at 48, it puts out 48.0. Disconnect the power supply
from the BCMU and make sure it's putting out 48.0. The transfer
relay in the BCMU runs the load direct from the supply and
switches to battery (and DC-DC) when it senses low input voltage.
It puts out regulated 48 when on battery. But when the battery
gets low, the voltage will sag. I think it's only about 80%
efficient below 12.8VDC or so.
The pot on the BCMU is to adjust the battery float voltage. It
should be set to 13.6 or 13.8 from the factory. The trick there is
that if the battery is disconnected, it doesn't put out any
voltage. I usually connect a new battery and let it sit running
over night. Then put a meter on it the next day to see where it's
at and adjust a bit if needed. You'll also want to do this at room
temp with the remote probe disconnected.
The BCMU does have LVD. IIRC, the BATT-OK contact will open at
44-45VDC to give you an early warning. I believe the LVD cutoff is
about 42VDC (which means the batt will be at 10.5, or 1.75 volts
per cell which is a good limit for a stand-by UPS).
If you're getting 44 volts, as I said, check that the voltage
adjust pot on the supply is set correctly with no load. Or you
have too much load on it. I'm looking at a SiteMonitor right now
and it shows 47.6. The 5ch PDU reports Vin = 480. TSP180-148 +
BCMU360. Using about 100W at that site. I've got 200-ish foot runs
and the radios all run fine.
On 1/30/2018 12:49 PM, Mathew Howard wrote:
If I'm looking at the same thing, that one has a built in AC/DC
power supply... it's just adjusting the output voltage of the
power supply, and there's no DC-DC converter involved, so it
makes sense to just run on battery voltage (as far as I can tell
it needs 24v or 48v batteries).
On Tue, Jan 30, 2018 at 12:36 PM, Paul McCall <[email protected]
<mailto:[email protected]>> wrote:
Yet, the BCM-148 says adjustable Output up to 54v. Unless
you are on battery. Silly
*From:* Af [mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of *Paul McCall
*Sent:* Tuesday, January 30, 2018 1:35 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] Traco BCM
Actually, the BCMU is the model that takes 12v in and
upconverts it to 48V. It charges the battery array (in
parallel) to about 13v per batter. So, why in the world they
would design a device that would upconvert that to anything
less than 48v (without load) is just silly. We have UBNT
EP-S16s that will not turn on radios plugged in, if it gets
anything less than 45.5 to 46 volts.
But, even on the BCM-148, (where you run 48v in series, it
seems to have the same design) 45v max output when on battery.
Pretty bizzare
*From:* Af [mailto:[email protected]] *On Behalf Of *Adam
Moffett
*Sent:* Tuesday, January 30, 2018 1:25 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] Traco BCM
When running on battery, the load gets battery voltage. The
load being on battery (or charger) voltage seems to be the
normal behavior for these types of systems, so you'd have to
really hunt for something that does it differently.
You can hunt for something with a regulated output, or add a
DC-DC converter inline.
I haven't yet encountered a 48V device that didn't accept the
whole range from "batteries nearly dead" to "bulk charging",
so I'm wondering what that device is that needs >46v.
.....and I'm not a Traco lover. I'm kind of disappointed
with it actually. We must have bought 40 of those kits about
3 years ago, and we now have 3 faulty BCM modules....they
work except they no longer charge batteries. I also received
a whole box of them where the sticker indicating which pin
does what on the BCM was 100% backwards. By following the
sticker rather than the manual I ended up with the
temperature sensor (thermistor) connected to the reset
switch. Didn't break anything, but they units won't turn on
that way.
At the time I needed something 48V at a higher wattage than
Meanwell's 48V options, and Traco was suggested. I don't
think I'd go there again.
------ Original Message ------
From: "Paul McCall" <[email protected] <mailto:[email protected]>>
To: "[email protected] <mailto:[email protected]>" <[email protected]
<mailto:[email protected]>>
Sent: 1/30/2018 12:59:12 PM
Subject: [AFMUG] Traco BCM
Am I missing something or are the Traco BCM series not
very usable in the real world?
Meaning, the BCMU360 can only put out 45v (for a couple
minutes, then 44v and change), when running on the
battery. Not very usable with some gear that requires
about 46v to work properly. Add in voltage drop on a
long run and no-go.
I thought maybe the straight BCM 48v series would be
better, but they appear to have the same spec.
I have to think I am missing something or who the heck
would they sell these to? The industry standard is 48v
(54v with float) so, outputting 44v sustained seems dumb.
Or is me 😊
Enlighten me please, you Traco lovers
Paul McCall, President
PDMNet, Inc. / Florida Broadband, Inc.
658 Old Dixie Highway
<https://maps.google.com/?q=658+Old+Dixie+Highway%0D+Vero+Beach,+FL+32962%0D+772&entry=gmail&source=g>
Vero Beach, FL 32962
<https://maps.google.com/?q=658+Old+Dixie+Highway%0D+Vero+Beach,+FL+32962%0D+772&entry=gmail&source=g>
772-564-6800 <tel:%28772%29%20564-6800>
[email protected] <mailto:[email protected]>
www.pdmnet.com <http://www.pdmnet.com>
www.floridabroadband.com <http://www.floridabroadband.com>
