What would you folks reckon is better , using a battery bank powering your radio equipment directly on 24V / 48V or a standard UPS system? Which one of the two will give you more standby time? Also , I have 24V equipment on my tower and 48V equipment … do I need seperate battery banks for these or is it posible to have one 48V bank which gets converted to 24V for my lower voltage equipment?
Thanks in advance.
if you have hard utilities at the site then use a UPS. we use the APC 1000XL - the XL means you can add extra battery packs. you can also add (and i would highly recommend) the SNMP network monitoring card so that you can know what the power situation is at the tower. also the APC’s protects your equipment (and you investment) by automatically smoothing out the power so that your equipment doesn’t get spikes and notches (brown outs).
With a 1000XL and 3 extra packs we can power a site for 12 hours with:
2 - moto PTP400
2 - moto PTP100
3 - moto 5.7 AP’s
1 - moto 900 AP
1 - moto CMMmicro
router and switch
if there are no utilities and you are planning on using solar then size and build a 48VDC system and get a 24VDC step down.
some people want to skimp on the battery backup because of cost. For me how much is it worth to be able to sleep through the night and not have to worry about the network being down or having to drag a generator up a mountain at 3am.
I would love to have a 1000XL with snmp and extra packs in all the mountain nodes…but until that we have to do it with 12 hours battery backup using inverter and several bateries.
Depending on the load we have 2 x 24A (2ptp100) or 6 x 100A(several licenced radios, several ptp100, several other radios). But our policy is at least have 12 hours backup, and we use a bad SM for monitoring the AC supply.
Not converting back to 240v is generally more efficient.
48-24vdc converters are available.
We use APC RS1500’s and RS1300’s however we don’t use the stock batteries
We put 2 car batteries hooked in series to get 24v and use an external dual port charger to charge the batteries
We get about 18-36 Hours depending on what equipment is at the tower and has made my life so much better now that is power drops I don’t have to run out to the tower at night anymore!!
On a side note the remaining time on the APC unit is exaggerated once you use external batteries because you are going from 9AH batteries to 90-110AH batteries.
I did something like that once, but couldnt find the 24v changer or 12v dual charger…
When you do that, and dont put external charger, it may take about a week to get the batteries fully charged…
another disadvantage is that if you use acid batteries yo must check every 3 month the level…