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treich
join:2006-12-12

treich to Inssomniak

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Re: OT: Small generator won't run APC ups

what you need is pure sine power inverter then connect it to your generator.

nunya
LXI 483
MVM
join:2000-12-23
O Fallon, MO
·Charter

nunya

MVM

Pure sine inverters really aren't necessary for these kind of loads (UPS). I have pure sine inverters on my trucks, and they aren't cheap: »dimensions.sensata.com/p ··· inverter
I think I paid $2,000+ for the smaller one, and $2,500 for the 240V model.
Even a crappy Chinese pure sine inverter will probably cost enough to consider just getting a decent generator. Throwing "good money after bad" should always be a consideration. Especially when your business is on the line.
lutful
... of ideas
Premium Member
join:2005-06-16
Ottawa, ON

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said by Inssomniak:

said by lutful:

Yes. These types of switching power supplies are usually designed for charging batteries. So the 12V models can provide upto 15V and the 24V models can provide upto 28V.

So would it just be a matter of wiring up the batteries and my loads ? Everything would run on the power supply and during an outage the power supply simply drops out?

Yes. Adjust power supply to provide 26.3V for float charging and connect to (pre-charged) batteries and PoE stuff. That setting is actually good for either Canadian winter or Indian summer.

*** You should always bulk charge batteries before connecting them for continuous float charging. You can do this step using a commercial charger or the same power supply set to 28V (indoors). Make sure PoE stuff is disconnected during this preliminary step. Approx 3 hours at 6A is good enough for 20Ah batteries. Float charging step will take care of the rest.
54067323 (banned)
join:2012-09-25
Tuscaloosa, AL

54067323 (banned)

Member

said by lutful:

*** You should always bulk charge batteries before connecting them for continuous float charging. You can do this step using a commercial charger or the same power supply set to 28V (indoors). Make sure PoE stuff is disconnected during this preliminary step. Approx 3 hours at 6A is good enough for 20Ah batteries. Float charging step will take care of the rest.

Yea that is untill there is an extended power failure them the OP has to run around disconnect the POE bulk charge the batteries reconnect he POE and move to the next site.

As such that is some pretty crappy advice.

Why not just use a device called a battery charger it can do all of the above un-attended and is actually designed for such a task.

Inthe ned it might cost a few more dollars than a $30 power supply but one truck roll will pay that back.
jcremin
join:2009-12-22
Siren, WI

jcremin

Member

said by 54067323:

Why not just use a device called a battery charger it can do all of the above un-attended and is actually designed for such a task.

Most battery chargers aren't designed to be used with a load on the batteries, and will end up cooking the batteries over time. I really like Samlex chargers because they are designed to be able to be a battery charger, a power supply, or both simply by changing a few dip switches. Here are the ones I use:

»www.cleanenergybrands.co ··· ply.html

»www.cleanenergybrands.co ··· ply.html

They also make 24v versions.
Porch
join:2005-06-19

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Tycon makes a series of DC-DC POE injectors. They take 9-36V in and output 18-24-48V depending on model. They are ideal for battery operation as they will provide consent and clean power to your gear regardless of how your batteries are doing. I have several at remote solar repeater stations and they work great. I run them off of 2 6V Trojan T-105 (for 12V) batteries and by my calculations, I can get 2 weeks of run time with no sun on the solar panel.

Get a real battery charger. I have seen a lot of people spend $$$ on good batteries, then buy the cheapest battery charger they can. It promptly kills the batteries in a year or two. If you are in a cold environment, temperature compensation is a must. Something with a 3 stage charging cycle too.
54067323 (banned)
join:2012-09-25
Tuscaloosa, AL

54067323 (banned) to jcremin

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said by jcremin:

Most battery chargers aren't designed to be used with a load on the batteries, and will end up cooking the batteries over time.

That all depends on the charger and it's ratings, yea a $19 Sears charger isn't going to do the job, but a Xantrex will, heck even Power-Max has a few inexpensive $50-75 units that can handle up to 20 amps of load and properly maintain the batteries.
54067323

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said by Porch:

If you are in a cold environment, temperature compensation is a must. Something with a 3 stage charging cycle too.

In Canada TC is a must and three stage charging is good advice too.
lutful
... of ideas
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join:2005-06-16
Ottawa, ON

lutful to Porch

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said by Porch:

Tycon makes a series of DC-DC POE injectors. They take 9-36V in and output 18-24-48V depending on model.

Separate DC-DC converter for equipment is always good if cost is not a factor.

*** Inssomniak See Profile 26.3V float charge voltage is actually OK for majority of 24V PoE gear. Check your equipment datasheet and calculate PoE voltage drop at sum of average current for all the devices.

Just in case there is any doubt created by those knee-jerk naysayers ... 26.3V float charge works in both Canadian winter and Indian summer. I know from in-depth knowledge of battery charging process and also because we have done this for 10 years now. Meanwhile 28V is OK for bulk charging step indoors. If you really want to bulk charge outdoors at 0C, you need 30V. Once again, float charging at 26.3V is OK down to -20C.
lutful

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lutful to Porch

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said by Porch:

Get a real battery charger. ... If you are in a cold environment, temperature compensation is a must. Something with a 3 stage charging cycle too.

I designed one of the smartest lead-acid battery charging circuit which made its way into some commercial chargers. If I identify them, their sales would plummet courtesy of my "fans" in DSLR forum.

*** Found a 2007 thread where we discussed UPS vs DC solution.
»[Equipment] DIY Battery Backup System

Inssomniak
The Glitch
Premium Member
join:2005-04-06
Cayuga, ON

Inssomniak

Premium Member

Im just getting more confused all the time here.

I don't want to go around bulk charging batteries after extended outage., Im OK with someone just telling me what to buy thats reasonably priced. I want 24 volts to power my stuff, I need 3 amps at most at 24 volts. I don't care how long it takes to charge the batteries, I don't want to replace them every 6 months. I want it to work with cheap generators so anyone (even the odd customer) can just unplug our box and plug into generator without getting into opening our enclosures and fiddling with cords.

I was going to buy this one charger I think you Lutful suggested, and even went thru the order process and got frustrated at some error regarding my address and paypal, etc so I never even finished the order.
It was the 24 volt 72 watt of this:
»www.powerstream.com/12V- ··· ckup.htm
I was going to connect this to 2 SLA batteries.
54067323 (banned)
join:2012-09-25
Tuscaloosa, AL

54067323 (banned) to lutful

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said by lutful:

Just in case there is any doubt created by those knee-jerk naysayers ... 26.3V float charge works in both Canadian winter and Indian summer. I know from in-depth knowledge of battery charging process

Really, then why do the people who manufacture standby batteries and have in-depth knowledge of the battery manufacturing process and therefore having engineered the batteries the proper charging process (Enersys) recommend a float voltage of 31.2 at -30 C and a float voltage of 27 volts at 30 C?

It would appear there is a disagreement between two sources of "in-depth" knowledge here.

Also if your theory is true, then why is it companies like Xantrex. Acatel-Lucent, and Eltek offer remote probes for their battery chargers, to measure the battery temperature at the battery, to in turn control the chargers voltage curve, it seems to me by your theory, they could save a whole lot of money by just locking all their chargers at a single output voltage, but that is not how lead acid charging works in the real world and their customers would be soon pissed off if they did.
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54067323

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Re: OT: Small generator won't run APC ups

said by Inssomniak:

I was going to buy this one charger I think you Lutful suggested, and even went thru the order process and got frustrated at some error regarding my address and paypal, etc so I never even finished the order.
It was the 24 volt 72 watt of this:
»www.powerstream.com/12V- ··· ckup.htm
I was going to connect this to 2 SLA batteries.

For where you live and the temperatures you work with that is not a good choice.

Give me an idea of the temp levels you need to work with, the power you have available, standby time needed at 3 amps, budget and I wil see what I can find.
Porch
join:2005-06-19

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The OP seems to be lacking a bit of knowledge here.

Just because your POE are rated at 1amp at 24V, does not mean they are drawing that amount. You need to measure this.

A 24V battery system needs over 24V to fully bulk charge. 29V for unsealed led acid. If you are using sealed gel cell style, you need much less or you will boil the battery. About 28.2V or so.
Your wireless equipment will need to handle this higher voltage. I know Ubiquiti gear will not.

Ubiquiti will handle 12V fine and if your cable runs are short, you can run them directly off a 12V battery.

However, for long cable runs, you might need 24V. Go with the DC-DC converter like I posted above, and use a 12V battery, or two 12V batteries wired in parallel. By staying 12V, it gives you more and cheaper options for charging the batteries.
The battery charger is the item that will be taking the brunt of the power surges, and may die. Having access to a 12V battery charger at any auto part store is handy in a pinch.

Relying on voltage drop in a cable to get 29V down to a safe 24V in your equipment is a shoddy way to do things and should be avoided. The device will be operating above recommended voltages for periods of low load. Even if it's microseconds. Design it right and you won't have any problems. cut corners and you will be driving to the tower every month to reset stuff due to random lockups.

Battery chargers have to be designed for the type of battery they are charging. Lead acid need a higher voltage then sealed gel cells. If you don't get the right one, you will be replacing batteries often.

I would go with this charger.
»www.xantrex.com/power-pr ··· e-2.aspx
It has a wide range of input voltages (90-265 Vac, 47-63 Hz) so it can handle even the worse generator. Along with the 3 stage charging and TC.

Inssomniak
The Glitch
Premium Member
join:2005-04-06
Cayuga, ON

Inssomniak

Premium Member

I understand that I am not necessarily drawing 1 amp out of my supply (although close, I wire several radios to one 1 amp supply).

But 12 volts kinda scare me on 150 foot runs? I mean I think Im losing 4 volts per 150 feet at 24 volts. (at least thats what mikrotik meter is telling me), and I thought lower the voltage the more the drop. leaving me with 8 or less volts at 150 feet at 12 volt POE?

So you are saying, convert the charger voltage to 24 volts, send that up to the top, but use 12 volts to charge the batteries.

I haven't looked, whats that charger worth? and what are those DC-DC 24 volt injectors worth? Does anyone know if they come in anything bigger than 24 watts to save me buying multiple of them?

nunya
LXI 483
MVM
join:2000-12-23
O Fallon, MO

nunya

MVM

What's the wire gauge?
Porch
join:2005-06-19

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Lower the voltage does not necessary equal more of a drop. Other factors play a part.

If you have 3 1 amp power supplies with several radios each? On the same tower? And you are running multiple radios on one cat5 run up the tower? We really need more details of your setup. This is just confusing.

At this point, I think you are running too many radios off of a too long of a cat5 run.

The Tyco TC-DCDC-1224 is $40.
»www.streakwave.com/itemd ··· &eq=&Tp=

I don't know what the charger runs. Google is your friend.
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Porch

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Re: OT: Small generator won't run APC ups

The issue with using a "power supply" to charge batteries is the regulation and over current protection.
Assume the power is out, and the battery is drained to, say half voltage. When the power comes back on, the load on the power supply, from the dead battery, may well be over the amps it's rated for. Unable to maintain it's rated power, the protection circuits will kick in and it will turn off.

Now if you size the power supply large enough, and the battery small enough, then the power supply might have the amps to overwhelm the battery and drive the voltage up before the protection circuits kick in. But this is not good for the battery at all. Most are designed for a C/8 or C/20 charge rate.

For your application, you want a small charger and a large battery. The size of each you will know when you do the math on your load.

If you want to charge a battery, buy a battery charger. If you need to run a DC load, use a power supply.
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Inssomniak
The Glitch
Premium Member
join:2005-04-06
Cayuga, ON

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Inssomniak to Porch

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Re: OT: Small generator won't run APC ups

said by Porch:

Lower the voltage does not necessary equal more of a drop. Other factors play a part.

If you have 3 1 amp power supplies with several radios each? On the same tower? And you are running multiple radios on one cat5 run up the tower? We really need more details of your setup. This is just confusing.

At this point, I think you are running too many radios off of a too long of a cat5 run.

My sites that have easy access at the top have several radios (max 4) on a single cat 5 run with a 1 or 2 amp supply. I've always done it this way with no problems to date.

2 cat 5 runs gets me 16 radios if I use all the pairs for power and no data.

The first site I want to do has 10 radios or devices. For quick math I figure 6 watts max. 60 watts. Probably less as a device may be a camera or an rb750 which I think only draw 2-3 watts.

I have space for 2 batteries that are 12ah, power supply or charger. The current ups gets me 30-40 minutes. Apc 550va. Reasonably moderate winters except this year being the exception. The small enclosure probably holds some heat from power supply warming.? I would think the summers it probably gets pretty warm in some of them exposed to the sun.
Porch
join:2005-06-19

Porch

Member

What radios?
lutful
... of ideas
Premium Member
join:2005-06-16
Ottawa, ON

lutful to Porch

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said by Porch:

Assume the power is out, and the battery is drained to, say half voltage. When the power comes back on, the load on the power supply, from the dead battery, may well be over the amps it's rated for. Unable to maintain it's rated power, the protection circuits will kick in and it will turn off.

FYI these power supplies are actually designed to be provide continuous float voltage to battery banks in industrial and telecom applications. The scenario you describe will NOT happen ... by design.

When power comes back ... voltage will again be equal to the adjusted value (let's say 26.4V max on the Meanwell PS-150-24 model) and current drawn by the battery bank will become equal to the rated maximum (6.3A on that model) MINUS the sum of all PoE device currents. Battery current will gradually become lower and lower and will eventually become insignificant when battery voltage approaches 26.4V.

Curiously I have been making a living off both battery charger and power supply designs since closing up my WISP hardware design company a few years ago.

I will design a few universal WISP power modules which charges 12V to 48V lead-acid battery banks and simultaneously provides adjustable 5V to 55V output at each of 2 to 8 PoE ports. I will put up videos of working prototypes on a kickstarter project ... just for a kick.
54067323 (banned)
join:2012-09-25
Tuscaloosa, AL

54067323 (banned)

Member

said by lutful:

FYI these power supplies are actually designed to be provide continuous float voltage to battery banks in industrial and telecom applications.

Sorry but you will not find those supplies in "real" Telecomm applications as they lack any form of a NEBS rating.

Inssomniak
The Glitch
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join:2005-04-06
Cayuga, ON

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said by lutful:

When power comes back ... voltage will again be equal to the adjusted value (let's say 26.4V max on the Meanwell PS-150-24 model) and current drawn by the battery bank will become equal to the rated maximum (6.3A on that model) MINUS the sum of all PoE device currents. Battery current will gradually become lower and lower and will eventually become insignificant when battery voltage approaches 26.4V.

Assuming: I have the above meanwell power supply. I have 2 12ah batteries wired in 24 volts. My loads all connected to the batteries as well as the power supply. All good. batteries charge and float at 26.3 volts.
So, power dies, batteries deeply drained. Power comes back on, stuff powers up, batteries charge, no questions asked. Im just confused why one says this will work, and one doesn't (protection circuits?)

I shouldn't worry about most of my stuff rated 24 volts max.? I have one site with runs only 40-50 feet.
I could do the same thing above in 12 volts? and then throw in the DC-DC converters if I was worried?

Oh and this thing will run on a Chinese generator?
lutful
... of ideas
Premium Member
join:2005-06-16
Ottawa, ON

lutful

Premium Member

said by Inssomniak:

So, power dies, batteries deeply drained.

Remember that your goal was to make the battery last longer! You should always install a low-voltage cut-off module on each 12V battery to prevent deep discharge. They are widely available in auto shops and on-line.
said by Inssomniak:

Power comes back on, stuff powers up, batteries charge, no questions asked. Im just confused why one says this will work, and one doesn't (protection circuits?)

That worry was for a generic power supply.

As I mentioned earlier, power supply modules like the PS-150-24 are designed so they also be connected to a battery bank for continuous float charging at 26.4V upper limit. Meanwhile the PS-150-27 model also handles bulk charging at 29V in addition to float charging.
said by Inssomniak:

I shouldn't worry about most of my stuff rated 24 volts max.? I have one site with runs only 40-50 feet.

You should always check and stay within maximum allowed PoE voltage.

If they are truly rated maximum 24V, you can't run such equipment straight from even a "24V" battery! You will need separate 24V DC-DC regulator or a smarter PoE injector which incorporates the DC-DC function.
said by Inssomniak:

I could do the same thing above in 12 volts? and then throw in the DC-DC converters if I was worried?


Yes. Same Meanwell datasheet shows 12V models. Safest float charge voltage is 13.2V and you will find 2 models which cover that. One will be OK for just float charge and the other for float or bulk charge.
said by Inssomniak:

Oh and this thing will run on a Chinese generator?

Yes, crappy AC was the original reason to provide this suggestion. In some old thread, I posted photo of a circuit I had designed which handles 80V to 400V AC of terrible quality (think Made in India) and outputs clean DC.

P.S. Just for completeness ... the very best option is actually to convert crappy AC directly to high voltage DC using a bridge rectifier module and then use 150V input DC-DC ... that was actually my first suggestion. But the cost is higher than such a power supply and you have to make the high voltage AC and DC connections.

Inssomniak
The Glitch
Premium Member
join:2005-04-06
Cayuga, ON

Inssomniak

Premium Member

said by lutful:

Remember that your goal was to make the battery last longer! You should always install a low-voltage cut-off module on each 12V battery to prevent deep discharge. They are widely available in auto shops and on-line.

Didn't know there was such a thing you could get.

I could use 12 volts at my site with short runs.

Im probably going to get yelled at, but Im going to try it, that power supply is reasonably priced, and seems the simplest, 2 batteries and this power supply. I will skip the DC conversion bits if I test this power supply OK on the generator that won't power the UPS.

Now, is it appropriate to talk about runtime in this thread?

I have to add a few devices to this site, so I added up all the max watts of all current and future devices. and Its a whopping 100 watts.. little more than I thought.

If its 24 volts using 2 12ah batteries, is it 24ah total or still 12AH?
lutful
... of ideas
Premium Member
join:2005-06-16
Ottawa, ON

lutful

Premium Member

It is still 12AH at 24V. 100W means approx 4A - average could be much less.

In addition to low-voltage cut-off, you should also put a 4A in-line fuse to limit current to/from the battery bank. Those items are actually suggested for all battery setups for both safety and longevity.

P.S. Princess Auto is a good source.

I am thinking of setting up a quick project (Kickstarter or IndieGoGo) to build a single compact module which has both adjustable cut-off voltage and adjustable current limit with auto-reset. It will be useful for all WISPs using batteries.

Inssomniak
The Glitch
Premium Member
join:2005-04-06
Cayuga, ON

Inssomniak

Premium Member

Im open to links on a place that has this cutoff switch, all the ones Ive seen seem to be more expensive than the power supply/charger