Battery Back-UP for Sump Pump -

[BBJoe]

I have a battery back-up sump pump system from the following manufacturer:

http://www.zoeller.com/zcopump/products/backupsystems/aquanot.htm

Here is a brief description.

Aquanot II comes with these 25 amp electronic charger features:
- Mounting bracket.
- L.E.D. status indicators.
- Automatic battery recharging.
- Microprocessor controlled.
- Each unit individually tested.
- Circuit breaker protected.
- 3.5A AC input; 12V DC output

The battery used to power the system is a deep cycle Marine Lead Acid 12V battery. I have wired in parallel a 2nd battery in order to extend the time of operation when AC power is interrupted. Is this acceptable? Is there any danger of over-charging/exploding the battery. I cannot find any reference to this one way or the other in the manual or on the net.

Any insights would be appreciated.

-BBJoe

 

[powerwagon75]

According to the manufacturer, you should be using a group(size) 31 battery with the system you have. Guessing you added a second equal-sized battery. A 25 amp charger ought to be able to handle recharging just fine-- recovery time will likely take longer, though.

 

[waross]

The main concern will be the charger. It depends on the design of the charger. Some chargers will overload and overheat if connected to too many parallel batteries. Some chargers will limit the current and just keep on working. The echarge time will be related to the run time. Two batteries should give twice as much maximum run time, and recharging from a complete discharge will take twice as long. As long as the run time is equal or less than that available with one battery, the recharging time should be close to the recharging time with one battery. Amp hours in equals amp hours out.
respectfully

 

[itsmoked]

Do not worry about a battery on a concrete floor discharging quickly that is non-sense. However you may want to protect the floor and the batteries by using a marine battery box or two. Make sure some air turnover is possible. And absolutely heed the, "replace the batteries every two years" to continue to get the duration you expect.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

Hi Keith;
I have a theory that the urban wisdom concerning batteries discharging on a concrete flor is partly grounded in truth.
I believe, however that the effect is a result of the initial contact with the concrete floor.
I haven't dismantled a battery since I was a financially challenged teenager trying to start my car. In those days, "everyone" knew that a battery would discharge if it was sitting on concrete.
A common failure mode of batteries was a build-up of debris in the bottom of the battery. This was normal as the active material on the surface plates would tend to fall away over time.
My theory is that sudden abrupt contact with an unyeiling concrete floor would shake loose enough surface debris to raise the debris level in the bottom of the battery and short out the plates, leading to discharge and battery failure.
As anecdotal support;
At an installation in the Yukon territory, a generator was started by an "8-D" battery. The battery was working well but it had to be removed from the set for some reason. The battery holder was a bad design. The battery had to be tipped at almost 45 Deg. to be removed.
Given the weight of the battery, and the haste to avoid loosing electrolite, the battery hit the concrete floor quite hard at about a 45 deg. angle. From that time the battery would not hold a charge for more than a few hours.
In support of your post, Keith, I like to see batteries in a box of some type and prefer about 2 inches of wood seperation from concrete floors.
Comments?
respectfully

 

[itsmoked]

Hi waross. I cannot agree based on the fact that most batteries probably don't hit the floor at damaging velocities. I'm careful! But, I totally agree with a serious jar wrecking a LA battery! In fact probably most batteries in pickups and other vehicles that dish out harsh rides fail due to the 'flaking plate' phenomenon. I just had one do it! It shifted to a 5 cell battery and my 120A alternator wailed on it! We stopped on the side of the road to check a noise and saw steam coming out of the hood gap. I was horrified to find it was one of the batteries!! We'd just translated Death Valley (Off road).

I can easily picture some sort of,(early-on), concrete floor discharge method when battery cases were sealed with tar, etc. Also, concrete floors are extremely good heat sinks. Ever tried sleeping on concrete? An air mattress doesn't even help! So a battery set on some cold garage floor verse one sitting on the work bench will likely be many degrees colder. Which certainly drops the available current.

How also can one square the 'Evil Concrete' with the fact that 95% of LA batteries are mounted in steel holders which are vastly better conductors than concrete. My vote is a noted output reduction due to temperature.


Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

Hi keith;
I agree with the temperature issue also. Part of my reason for the wood supports. Also, this is an urban legend. Probably for every battery that failed on a concrete floor, (for what-ever reason), a hundred people were told, "Don't put the battery on the floor or it will go dead." That's how legends spread.
Respectfully

 

[itsmoked]

Hehe, Yeah, I easily see the urban legend getting a grip due to some statistical non-sense like; because batteries left on say.. the floor are left longer than batteries left on a bench top... "It must be the concrete!"

Cheers.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[EEJaime]

I would verify what the charger loading capacity is before you hook up additional batteries as others have suggested. We recently had a DC power plant feeding the main telephone system of a major acute care hospital fail.

I got a call from the IT facilities manager saying that the panel we had feeding his inverters and chargers was overheating and they had tripped some breakers and lost about 30% of the hospital's voice communications capability. Not a good thing. When I got to the IT building I found the branch panel with the cover off and two fans blowing on the interior. You could feel the heat radiating from the panel. It was cooking.

It turns out that although we had designed this as an N+1 system with a redundant unit connected in case of a unit failure, they had had such a failure the previous summer and decided they still had sufficient capacity to feed their system. Well when they lost a second unit, the remaining units picked up the additional load and provided the needed power to charge all the units. Of course this started periodic breaker trips as the units were being overloaded. They still did not call us or replace the failed units. That started a cascade of failures as every time a breaker tripped, the remaining unit's picked up the load and the breakers got hotter and hotter. We had 40 Amp 2-pole breakers running with almost 50 Amps of load on them. We also found that they had almost doubled the originally designed load on the panel itself so it was running over maximum capacity.

We had to run a new feeder from the distribution panel, install a second panel and distribute the load. They have since replaced the inverter/charger system, and fortunately, the IT manager.