Battery Problems

If you have your UPS long enough, you will probably have battery problems. Here is what John Walker has to say about APC UPS batteries:

I thought I'd pass on some information I've obtained which you'll probably eventually need. Besides, by writing it down I'll be able to find it the next time.

I started installing mine in 1995-1996. Lead-acid batteries have a finite life even if not subjected to deep discharge cycles. For the batteries used by APC, this is typically four to six years. As part of the self-test cycle, the UPS measures the voltage of the battery at full charge (which falls as the battery ages), and if it's below about 90% of the value for a new battery, it sets off the "Replace battery" alarm, which it repeats every day. [on apcupsd versions prior to 3.8.0, this message is sent once, on version 3.8.0, it is sent every 9 hours - KES].

You will occasionally get a false alarm. It's a good idea if you get an alarm to repeat the self-test the next day and see if the alarm goes away. If the alarm is persistent, you need to replace the batteries, which can be done without powering down the UPS or load-you just open up the battery door, take out the old batteries, and hook up the new ones.

APC makes "Replacement Battery Units" for each of the SmartUPS models, but they sell them directly only in the U.S.

It's best to wait until the low battery alarm before ordering a replacement-keeping batteries on the shelf reduces their life unless you keep them fully charged.

And André Hendrick says:
[For replacement batteries] You need to goto you your local Yamaha SeaDoo shop. There are 35 AMP Hour deep cycle marine batteries that are direct replacements. These are gel-cel and will double the runtime and/or cut your recharge time in half.

Jet Works
1587 Monrovia Ave.
Newport Beach CA 9266?
Tel: +1 714 548-5259

J-W Batteries, Inc.
Tel: +1 714 548-4017

WPS 49-1200
For those that do not know what this means........
I found the best battery for APCC UPS products that use In the two systems below:

SMART-UPS 3000 10.9% is running at 327W runs for 47.0 min.
Smart-UPS 1250 22.3% is running at 279W runs for 54.0 min.
APCUPSD UPS Network Monitor
Thu Jan 18 21:55:36 PST 2001
System Model Status Battery Chg Utility UPS Load UPS Temp Batt. Run Time Data
Linux ATA Development SMART-UPS 3000 ONLINE
100.0 % 120.2 VAC 10.9 % 36.9 C 47.0 min. All data
Linux ATA Development II APC Smart-UPS 1250 ONLINE
100.0 % 119.6 VAC 22.3 % 45.9 C 54.0 min. All data

Look at the numbers and see that these batteries are better and have more total running energy than standard ones.

SMART-UPS 3000 10.9% is running at 327W runs for 47.0 min.
Smart-UPS 1250 22.3% is running at 279W runs for 54.0 min.

APCUPSD UPS Network Monitor
Thu Jan 18 22:00:45 PST 2001
System Model Status Battery Chg Utility UPS Load UPS Temp Batt. Run Time Data
Linux ATA Development SMART-UPS 3000 ONLINE
                      100.0 % 120.2 VAC 19.2 % 36.9 C 27.0 min. All data
Linux ATA Development II APC Smart-UPS 1250 ONLINE
                      100.0 % 119.6 VAC 21.8 % 45.9 C 55.0 min. All data

SMART-UPS 3000 19.2% is running at 576W runs for 27.0 min.
Smart-UPS 1250 21.8% is running at 273W runs for 55.0 min.
Smart-UPS 1250 46.1% is running at 576W runs for 26.0 min.

Kind of cool.

The 1250 can outrun the 3000 by a factor of two under identical percentages, or run head to head for the same time.

SMART-UPS 3000 is a 48V based or 4 batteries
Smart-UPS 1250 is a 24V based or 2 batteries

Andre Hedrick
Linux ATA Development

Finally, here is what Carl Erhorn has to say about batteries:

Hi, Folks.

Well, Kern was absolutely right. The problem with my UPS was batteries. It was unexpected though, because there was no indication of a bad battery right up until the UPS failed entirely.

For those who might encounter the same thing, and don't know what's happening (I didn't either), here's what happened.

A week or so ago, I turned on one of my SmartUPS 700-NET models. The load is a small dual P-III unix server (Solaris 8, X86) and a 4MM tape drive. During the normal selftest that runs when you first turn on any APC UPS, the UPS 'freaked out'. The alarm stuttered at about 4 or 5 beeps per second, and all the panel lights flashed spasmodically, as if something was loose inside the UPS.

I turned off the UPS and it's load, then turned the UPS on again. This time, everything seemed fine. I booted the system that was attached, and there were no problems. The status monitor showed 9 minutes runtime (which indicates fairly low capacity), but the batteries showed fully charged. I began to suspect a bad inverter in the UPS.

However, Kern told me that he suspected the batteries. So I took the UPS offline, put an old SU-600 in it's place (just barely big enough to handle the startup peaks - I get an 'overload' lamp lit for about 2 seconds during boot), and checked out the batteries. They did indicate that they were near the end of life, so I ordered a replacement set. Those came in on Friday, and after the initial charge, a complete charge/discharge cycle to recalibrate the UPS, and some testing, I put it back in service.

Surprise! (Or maybe not?) Kern was right - there is nothing wrong with the inverter or the charging circuit, and the new cells fixed everything.

What confused me is that there was no 'replace battery' indication from the UPS, even when it failed, plus a fair amount of runtime indicated with a full charge. So if you see such behavior on one of your UPS models, it makes sense to replace the batteries, even if there is no indication that the batteries have failed yet.

One of the things I learned during this process is that the UPS internal calibration will lose accuracy over the life of the battery. I always do a recalibrate when I install new cells, but rarely do it after that, as it's time-consuming, and you really can't use the system attached to the UPS while doing it. Since my systems are almost constantly in use, it's a pain to schedule a recal, and I tend to put it off. This time it bit me. I'd suggest that folks do a recal at least once every six months. It will make your runtime estimates much more accurate, and also allows you to keep track of the state of your batteries.

For those who don't know how to do this, here's what you do. This proceedure should not be confused with the 'Recalibrate' feature in the APC PowerchutePlus software. They do not do the same thing.

>From APC's web site:
Perform a Runtime Calibration. This is a manual procedure and should not be confused with the runtime calibration performed through PowerChute plus. The batteries inside of the Smart-UPS are controlled by a microprocessor within the UPS. Sometimes it is necessary to reset this microprocessor, especially after the installation of new batteries. Stop the PowerChute plus software from running and disconnect the serial cable. There must be at least a 30% load attached to the UPS during this procedure, but the process will cause the UPS to shut off and cut power to its outlets. Therefore, attach a non-critical load to the UPS and then force the UPS on battery by disconnecting it from utility power. Allow the unit to run on battery until it turns off completely. Make sure a 30% load is present! Plug the UPS back into the wall outlet and allow it to recharge (it will recharge more quickly turned off and with no load present). Once the unit has recharged, the "runtime remaining" calculation should be more accurate. Remember that if the unit is an older model, then the runtime will not improve significantly.

An APC Smart-UPS has a microprocessor which calculates runtime primarily based on the load attached to the UPS and on its battery capacity. On the right side of the front display panel there is a vertical graph of five LEDs. Each LED is an indication of battery charge in increments of twenty percent: 20, 40, 60, 80, 100% (bottom to top). For example, if the battery charge is 99%, then only four of the five LEDs are illuminated.

To ensure that an operating system receives a graceful shutdown when using PowerChute plus or a SmartSlot accessory, an alert is generated by the Smart-UPS indicating that the UPS has reached a low battery condition. The alert is audible (rapid beeping), visual (flashing battery LED or LEDs), and readable through the graphical interface of PowerChute plus software (or a native UPS shutdown program within a particular operating system.) In order to calculate this "low battery condition," all Smart-UPS products have a preconfigured low battery signal warning time of two minutes (this is the factory default setting). There are a total of four user-changeable settings: 2, 5, 7, or 10 minutes. If the low battery signal warning time is set for 2 minutes, then the alerts will activate simultaneously two minutes prior to shutdown. Similarly, if the total runtime for a particular UPS is 30 minutes with a low battery signal warning time set at 10 minutes, then the UPS will run on battery for 20 minutes before the low battery alert begins.

Total runtime is primarily based on two factors, battery capacity and UPS load. UPS load and runtime on battery are inversely proportional: as load increases, battery runtime decreases and vice versa. When utility power is lost, the UPS begins discharging the battery in order to support the attached load. Once power returns, the Smart-UPS will automatically begin to recharge its battery.

My comments on this proceedure:
I believe this proceedure works for all APC models that calulate runtime, not just the SmartUPS. It's important that you load the UPS to 30% of the UPS capacity, as reported by apcupsd or another UPS monitor program. I've found that normal house lamps of different wattages allow me to adjust the load to almost exactly what I want, which is between 30% and 35% of the UPS capacity. This is critical te getting an accurate reading (according to the APC web documents). Always bring the UPS to 100% charge first, as indicated by the front panel lamps, or your UPS monitoring software.

Set the UPS shutdown time to 2 minutes, all other settings to nominal, and disconnect the serial port cable from the UPS before running the recalibration. If you leave a monitoring program running through the serial port, it will turn the UPS off early, and you don't want to do that during a recalibration run. When the run is complete, and the UPS turns off, you can reattach the serial cable, and the normal loads, and recharge the batteries normally. If you think you might have a power outage during the recharge time, allow the UPS to recharge to 20% or so (indicated by the panel lamps) before trying to use the computer system. This will allow the UPS to handle short dropouts while it recharges. Of course, if you can leave the computer off during the recharge time, the UPS will recharge much faster.

As an aside, when the batteries failed, my total runtime at 100% charge and an idle state was 9 minutes, which is pretty bad. I replaced the batteries with extended capacity cells, which add about 15% to the stock capacity. Now, after two complete charge/ discharge cycles, 100% charge shows the available runtime to be 42 minutes on the system when it's idle, and 33 minutes when the system is very busy. The differences are due to the load of the computer, when the disks are busy, and the cpus are not in a halted state (my system halts the cpus when they are idle, to save power and lower heat, as do other OS like Linux), when compared to an idle state. Apcupsd indicates the load is about 27% when idle, and as much as 37% when heavily loaded.

I've found that two charge/discharge cycles result in a more accurate recalibration when installing new cells. It appears that some batteries need to be put through a couple of complete cycles before they reach their full capacity. I've also noticed that the full-charge voltage is different for each battery until they have been through two cycles. On the initial charge of my new batteries, the 100% charge voltage on the two cells was almost .5 VDC apart. After two complete cycles, the batteries measure within .01 VDC of each other!

I hope this information helps anyone who might encounter the problem I saw, and also shows folks how to recal their batteries. If you haven't done a complete recalibration in a year or two, I'd recommend it, so that you have warning of a low battery instead of what happened to me.


Where Carl Suggests to get Batteries

Hi, Folks.

I'm just replacing the batteries in one of my SmartUPS models, and it occurs to me that some of you may not know about the place I get them from. I have no relationship with this company, other than as a customer, but I feel they know what they are doing, their prices are fair, and they have some interesting batteries available that you can't obtain from APC.

These are the reasons I use them, and I thought this information might be useful to the US list members. They will ship outside of the US. If you have questions, you can contact them through the email address listed on their web pages. They have always responded pretty quickly to my questions.

The company is called Battery Wholesale Distributors, and they are located in Georgetown, Texas. If you have questions, you can reach them by phone at (800) 365-8444, 9:00AM to 5:00PM (their local time), Monday through Friday. I've gotten email from them on the weekends, although the office is not open then.

I won't post prices, as you can get current pricing from their web site. They have an entire section dedicated to APC replacement batteries, and it's easy to find what you need. You can order over the web, or by phone. They accept all the usual credit cards.

The web site (as you might guess) is:

The thing I really like is that they have found manufacturers who make batteries in the standard case sizes, but have additional capacity over the original batteries shipped with the APC UPS models. Often, the difference is as much as 15% or so, and this can result in additional runtime. It's a nice upgrade for a minor increase in price.

They are also 'green-aware', in that they encourage you to recycle your old batteries, and will accept the old batteries back from you if you cannot find a local place that recycles them. You pay the shipping, but I think other than that, there is no charge. I've never done this, as I have a battery retailer just down the street who will accept my old batteries.

Anyway, if you didn't know about these folks, put the info aside where you can find it when you need replacement batteries. I won't make any guarantees, but I've been very pleased with their products, service, and pricing. I hope you find them as helpful to you as I do. I've been dealing with them since about 1994, and have never been disappointed. The owner of the place also is very good on technical issues, so if you have questions on their products, he can get as technical as you need to go.