Quantar Equalize/Float Dilemma

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ASTROMODAT
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Quantar Equalize/Float Dilemma

Post by ASTROMODAT »

The only way to Equalize/Float the Quantar station battery revert bank is via the RSS. The Remote RSS Option X288 (under Quantar: General Options) indicates: "Requires a wireline with modem at both ends."

I have a DIU3000 which interfaces via a 4-wire private line (3002 VF circuit) to the Quantar, with an ASTRO modem at each end.

xmo or XDC Labs: Does this mean that to use the Remote RSS feature (such as to Equalize/Float the emergency revert 28 volt battery bank) I must now lease yet a second dedicated private line, with an additional dedicated modem at each end, so I can "call" the Quantar RSS modem, and go from there? Or, can I leverage my existing 4-wire conection and DIU3000, etc.? (Yes, I know that an alternative is to physically go to the site with an RSS equipped laptop! Twice---once to Equalize it, and yet again 3 to 4 days later to return it to Float.)

Thanks!

Larry
RKG
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Post by RKG »

Equalizing flooded cell (or "wet cell") lead acid batteries without being on site is considered a dangerous no-no in any event.

Equalizing flooded cell batteries is done by force-feeding them a constant current at approximately 4% of nominal bank capacity, for 3-6 hours. In order to keep the current flowing, voltage has to rise far above where it normally would during standby, as much as 16-17 volts (for a nominal 12V system). For this reason, electronic equipment being powered by the bank being equalized should be shut down, as some solid state stuff will be harmed by such high voltages, and in any event, driving the batteries so high above the gassing point (which is about 14.3-14.4 at 70F for a nominal 12V battery) will generate copious quantities of H2 gas, which needs to be vented as well as protected from any onsite ignition sources. (Hydrogen recombinant caps, sometimes known as "HydroCaps," should be removed from the batteries before equalizing and replaced with the stock caps, to prevent acid splatter.) In addition, electrolyte should always be checked and if necessary topped up prior to equalizing, and again after equalizing, and electronic equipment drawing upon the bank should not be reconnected for at least 1 hour after the equalization charge has been shut down.

The foregoing assumes that you are using true "deep cycle" flooded cell batteries, which are batteries with heavy thick (min. 0.25 in.) plates, a generous above-the-plates electrolyte space, and a generous below-the-plates space for capturing any flaked-off solid lead sulphate. "Normal" car batteries (so-called "starting batteries"), even though of flooded cell construction, should not be equalized; you will warp the plates and either quickly shorten life or immediately short out a cell. Finally, gel cels, AGMs, and "sealed" lead acid batteries should never be equalized (at a minimum they will be ruined and in they may well explode).

For a whole bunch of reasons, including that Motorola knows a lot more about radios than batteries, using the battery backup harness on a Quantar and attaching it directly to batteries is not the best way to go. I described an absolutely bulletproof backup system, which produces 110VAC to the Quantar and costs about $2,000 or less (small potatoes in Quantar space), in an earlier post, which maybe Alex can reference by edit to this one. (I don't know how to do that, Alex. The post was entitled something like "batteries/generator for backup" and dates from July of this year.) This design will power a 100W Quantar, without the 3dB power reduction that M invokes, for about 2-10 hours (depending on how many G31s you use and what the duty cycle of the radio is), and the radio does not see, and therefore doesn't reboot, in the event of a LOOP (loss of off-site power). In addition, the system I described defines LOOP to include any situation in which offsite voltage rises above 135VRMS or falls below 90VRMS, or frequency drifts by more than a couple of cycles, which means that it protects the radio from bad power as well as no power. The G31 gel cels need no maintenance, do not gas and do not generate H2, and can be used in occupied spaces.
ASTROMODAT
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Post by ASTROMODAT »

Thanks for the information, RKG!

Motorola recommends to Equalize the 24 volt battery bank for 72 to 96 hours. But, this is in the context of the 650 watt Quantar switcher with the automatic 24 volt battery revert option, and a good set of sealed batteries that simply have been run down due to a condition requiring Emergency DC in the first place (e.g., asssumes that the batteries are all in good working order). I agree that it is not wise to remotely equalize, but in the middle of winter, oftentimes there's no choice.

I agree that there are much better solutions! Our commercial Quantar is connected to a power system that has an emergency generator, and then it's further backed-up by a big inverter system.

My requirement for back-up is for our Ham Quantar, where dollars are a big issue. Sure wish I could find your post---sounds interesting!

Larry
RKG
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Post by RKG »

1. You refer to "sealed batteries." Sealed batteries, even flooded cells, should NEVER be equalized. They will build up enough H2 to explode the case and get acid all over everything.

2. In fact, not to beat a dead horse, but equalization is not much of an issue for the batteries that back up a repeater in the first place:

A. The purposes of equalization is to compensate for the degradation in bank capacity that results from repeated discharging with inadequate recharging, such as happens when fixed-voltage engine-driven alternators are used as the charging source or when single-stage fixed-voltage battery chargers (such as ferroresonant chargers) are used. Since fixed voltage charging takes days to fully recharge the battery, some of the lead paste that was converted into lead sulphate during discharge is not converted back, and it hardens into a crystal form. This diminishes capacity two ways: some of the lead is lost, and some of the remaining lead is coated with hard crystaline substance that insulates it from electrolyte. Equalization compensates for this by forcing some of the newer crystaline sulphate back into lead and by physically zapping some of the rest off the good paste (letting it fall to the bottom of the battery case).

B. In the case of a radio backup battery (as opposed to the DC house batteries of a boat or RV), the battery will be very infrequently discharged, and usually to a minimal extent. No significant sulphate is formed, so there is no need of equalization to get rid of the sulphate.

C. In fact, what kills radio (or, for that matter, computer) backup batteries is that they typically supported during non-LOOP conditions by single-stage fixed voltage chargers. For all that I love Quantars, the charger that is incorporated into the battery revert option is an outdated ferroresonant charger of this type. These chargers continue to force current into the batteries long after they are fully charged, and the resulting heat, boiled-off electrolyte and high voltage causes the plates to physically deform and fall apart. It only takes a couple of hundred mils of current into a 200 AH bank to kill the batteries in a few months.

3. The fact that M recommends equalizing batteries for 72-96 hours proves that M knows more about radios than batteries. If you have ever seen flooded cells being equalized, they boil like a tea kettle. In 72 hours (3 days), there wouldn't be a drop of electrolyte left, and you'd be applying high voltage to dry plates, which has the same effect (electrically and otherwise) that made the electric chair so efficient. No equalizing charge should run for more than 3-6 hours.

The heart of the system I have described is a sophisticated, computer controlled multi-stage inverter/charger/transfer unit. It is not only significantly more efficient at charging after a good nick has been taken from the batteries (for instance, the 1 KW Heart Interface has a 50A charger that will restore 95% of 100 AH of discharger in under 3 hours), but once the battery is deemed "charged" (which is usually defined to mean acceptance of 2% of nominal capacity when a voltage just under the gassing point is applied), the charger reverts to a "float" stage which produces a voltage far lower than any single-stage charger could use (because it would never charge anything) and at which the batteries can remain indefinitely without cooking.


In short, I love Motorola (most days) and I love Quantars, but the battery revert board is worse than useless. End of sermon. Thanks for listening.

(I was able to find the prior post by doing a search on "Heart Interface." A number of things came up, but about halfway down the list was thread started by Dal-Com entitled something like "batteries/generator for repeater". You will find a list of the required components and instructions for wiring them, which are quite simple. Even for a Ham machine, the cost is well worth it.)
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batdude
Personal aide to Mr. Cook
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sooo....

Post by batdude »

maybe i am outta line here...

but for SHORT TERM (maybe 30 minutes or so) won't a nice APC UPS work just fine?


personally, i am very much more concerned about brown-outs and spikes/surges than i am about having a bank of batteries....


?



doug
RKG
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Post by RKG »

Actually, I doubt it.

To function properly, an inverter-based UPS must not draw the batteries down below the 50% point (at worst), and must be able to sustain at least 11 to 11.5VDC during load. A Quantar draws about 60W when not transmitting (regardless of receiver state) and about 600W when transmitting. This works out to 6-8A at 12VDC and 60-80A at 12VDC, respectively. To sustain voltage, you'd need at least 150-200 AH of nominal capacity, which translates into at least 2 G27 or G31 gel cells in parallel. I've never seen an APC unit that would handle this amount of battery.

That's problem No. 1. Problem No. 2 is that APCs, like most low end units, use ferroresonant chargers. These will (a) not effectively recharge the batteries if there is an outage and (b) will cook the batteries into oblivion while offsite power is good.

There are other problems. It is critical that an inverter-based UPS unit be smart enough and capable enough to bond the neutral and ground while in inverter mode and un-bond them when in charger/passthrough mode. The Heart Interface is the only unit I've enountered that will do this, though I've been told that a few other high-end units do the same.
ASTROMODAT
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Revert Board on Quantar Switcher

Post by ASTROMODAT »

Thanks again, RKG, for sharing your knowledge on battery systems. An area all to its own!

You peaked my interest in your comment about the Quantar's $300 board option for Battery Revert. If you order a new Quantar, and/or a new FRU Quantar P/S, they have two distinct types: One P/S has no revert capability, and yet the other supply has revert. The difference is $300. My understanding is that the revert function can NOT be added on later in the field, if you want the actual Motorola set-up. Is this only because the P/S is riveted closed (which I thought was only the case with the old Onan supply), so one supposedly can't just order a board and presto/chango, you now have a revert capable supply?

Larry
RKG
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Joined: Mon Dec 10, 2001 4:00 pm

Post by RKG »

I don't know about field installing the revert option so as to upgrade a CPN1047A PSM (625W AC no revert) to a CPN1048A PSM (625W AC w/revert). As I have suggested ever so subtly, I have no use for the M revert function and wouldn't use it even if available.

What I have been TOLD, however, by a source I consider pretty reliable is that the only difference between the two PSMs is the battery connector -- that is that the '1047A has all the hardware and software necessary to run the revert function, even though not implemented -- and that the connector can be field retrofitted. I have never had reason to try to verify what I have been told.
ASTROMODAT
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Joined: Tue Nov 05, 2002 12:32 am

Quantar Needs Two Telco Lines!

Post by ASTROMODAT »

So, the bottomline is what I feared: To properly operate a Quantar, one DOES need 2 separate Telco connections:

1) a 4-wire dedicated Telco 3002 VF circuit to connect the DIU3000 to the Quantar via the ASTRO modems at each end, and

2) a additional and separate dial-up POTS line (with modems at each end) to handle the remote RSS function (e.g., so one can Equalize/Float without being forced to go to the mountaintop in the middle of (a snowey) winter.

It's just money---arrghhhhhhhhhhhhhh!

Larry
ASTROMODAT
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Joined: Tue Nov 05, 2002 12:32 am

Post by ASTROMODAT »

O.K. on everything, RKG.

Not sure on your numbering nomenclature. I checked my current ECAT and it shows the Emergency Revert option on the 625 watt switcher as an "X30" option ($300). If you order the p/s as a part, the number is TLN3260 with revert ($2,300), or TLN3259 ($2,000) without revert. Also, the "X30" option is consistent with this as it is a $300 option.

The Quantar manual has yet a different set of numbers (TPN 6184A/6185A - w/o and w/ revert).

If you order through sales, the TLN numbers apply. From APD, it is the TLN numbers.

Someone said on this board that there are no schematics for the Quantar switchers. Not true---the board level maintenance manual has both block diagrams and the complete component level detail schematics, including 100% of the part numbers. One could troubleshoot and repair so long as you have the board level Quantar manual (in addition to the regular service manual).

The schematics do differ for the revert vs/ non revert p/s.

Still, I'm going to check with Parts ID tomorrow and find out what the full story is. As RKG pointed out, the revert option includes the battery cable, which knowing Motorola could be most of the $300.

Larry
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