Help with Water Pump

[DerStrom8]

You will need a pretty good sized battery if it needs to run 2 pumps for 24 hours. Maybe a 30 40 amp hour sealed lead acid.
Let us know if you have any questions.

I don't suppose two 12v automotive batteries would work, would they? They have great capacity and will last you a little while. I'm thinking they have >100Ah capacity.

 

[KeepItSimpleStupid]

Yep, that's what I said LONG ago. Job for a generator.

For fun, I went here: https://easycalculation.com/physics/classical-physics/battery-life.php

And just picked two numbers out of the hat: 20,000 or 20 Amp hour battery. and 2000 mA or 2 Amps. Got 7 hours of life.

This is a 12 Amp-hour SLA battery: https://www.apexbattery.com/12-volt-12-amp-fp-sealed-lead-acid-battery.html

Wrong technology, guys.

Generator or Fuel Cell, preferably Natural Gas

 

[ronv]

Yea a car battery would work. Most are about 45 or 50 amp hours. Actually they are pretty well sealed now days aren't they?
KISS I think 2 pumps will only draw about an amp so 35 amp hours would make it 24 hours according to your calculator. What am I missing.

 

[KeepItSimpleStupid]

Probably nothing. I just remembered a 1 A @ 24 VAC power pack, so I used 1 A and multiplied by 2 and forgot about the 12 V.

Remember NO CAR BATTERY! Deep Cycle Batteries Only.

A trolling motor battery is what came to mind when you want a deep cycle 12 V battery: **broken link removed**

And your right 44 Amp (order of magnitude) hours. The battery isn't cheap either.

So, in retrospect, I guess a battery option is doable.

This guy: **broken link removed** will last 20 hrs to 10.5 volts at a 7.7 Amp rate. The max charging current is 40 Amps, though.

And why not a commercial product? **broken link removed** Batteries are expensive.

Here is the website of the charger manufacturer: https://www.dualpro.com/

 

[DerStrom8]

Sorry guys, I'm just starting to pick up on this thread, so guess I missed some of the important stuff that was said a while back

Don't mind me

 

[KeepItSimpleStupid]

Yep, you missed a post that basically said "Don't use a car battery". In a car battery, the plates are closer together than in a deep discharge battery. Sulfurization shorts the plates much easier in a car battery. This precipitation occurs when the battery is discharged. Closer plates - higher short circuit current. One deep discharge of car battery and it's done. Usually, batteries are shipped dry, BTW.

 

[salty joe]

Yep, you missed a post that basically said "Don't use a car battery". In a car battery, the plates are closer together than in a deep discharge battery. Sulfurization shorts the plates much easier in a car battery. This precipitation occurs when the battery is discharged. Closer plates - higher short circuit current. One deep discharge of car battery and it's done. Usually, batteries are shipped dry, BTW.

I knew it was bad to kill a car battery-now I know why.
I was looking around for deep cycle batteries and Deka came up a couple times.
Their 12V, 32.5Ah AGM battery is less expensive than their 12V, 31.6Ah gel battery. They both are rated at less than 2% standing loss/month. I’m pretty sure they were both deep cycle-I’ll double check.
Anyway, for my application is gel technology worth paying for?
Am I correct to assume battery replacement every 5 years or so whether it gets used or not?

 

[ronv]

I think a lot depends on your circumstances. If the power never goes out any battery will work.
Where I live we have thunderstorms in the summer so we get maybe 3 short power failures a year - less than 1 minute. In 12 years the longest was about 4 hours for a transformer. We think we have had a big storm if we have 2 inch drifts.
I think I would look at AGM batteries - often called sealed lead acid. They are kind of in between a starter and a deep cycle and often used for backup appications. I don't care for deep cycle inside the house. But if you decide on them try Trojan.
As the charger goes. A commercial one should also work. It just depends on how much you want to spend and if you want to build one. The one posted is probably <$5 in parts.

 

[KeepItSimpleStupid]

Let's ask the wizard: **broken link removed**

Batteries that require water need venting. So, a garage may be OK.

SLA's and gel can be operated in any position. SLA's in a UPS (Home) and a Fire alarm and Fire alarm (warning system), the 1200 mAH ones, last about 5 years.

Temperature at the low end is bad. With a discharged battery and low temps, the battery can freeze and crack for wet cells. They also loose capacity when cold. Too warm is also a problem and that usually results from non-temperature monitored overcharging. I usually get about 7+ years out of a car battery unless something stupid happens. The bozo's forget to add water to one cell, or forget to tighten the battery clamps when it's in for service where the battery needs to be disconnected. Laptop batteries - about 3 years, then they start loosing capacity.

Wet cells require maintenance (add water) and venting. I don't like the batteries in a car that you cannot add water too. You cannot check the state of charge with a hygrometer and the lifetime seems lower.

Batteries have improved. Electric vehicle batteries have a pretty good lifetime.

 

[salty joe]

I think I would look at AGM batteries - often called sealed lead acid. They are kind of in between a starter and a deep cycle and often used for backup appications. I don't care for deep cycle inside the house. But if you decide on them try Trojan.
As the charger goes. A commercial one should also work. It just depends on how much you want to spend and if you want to build one. The one posted is probably <$5 in parts.

I can easily cut into a 1 1/2" PVC vent pipe, add a T fitting, then plumb 1 1/2"PVC pipe to a homemade battery enclosure. I could make the enclosure almost, but not quite airtight to allow constant venting through the roof. (Would an AGM battery not need to be vented?) That would put the battery about 5 feet from the pumps. Otherwise, the battery is in the garage, about 50 feet from the pumps.

I definitely like the idea of building a charger-thanks much for the design. I'll need to get a few more parts.
I have a fault module and the alarm module built-as soon as the next batch of parts arrive the speed module will ger wrapped up and we can tie it together for a test run.

 

[ronv]

I don't think I would put either type in a small closed space with the tank, but I don't think a special vent would be needed for the SLA type because they recombine most of the gasses especially as we will be very conservitive with the charge voltage.
Here is a write up on them.

https://en.wikipedia.org/wiki/VRLA_battery

If you are going to order parts you might pick up a few 1Ufd. caps like these:
https://www.mouser.com/ds/2/40/skycap-sr-8826.pdf
and some 100 ohm resistors. This is a just in case if one of the modules starts to oscillate like the fussy pumps.

 

[alec_t]

I have a fault module and the alarm module built-as soon as the next batch of parts arrive the speed module will ger wrapped up and we can tie it together for a test run.

Progress! Fingers crossed....

 

[4pyros]

Anyway, for my application is gel technology worth paying for?
Am I correct to assume battery replacement every 5 years or so whether it gets used or not?

I would go for the SLAs, do not wast your money on the gel cells as you will have to replace them if they get used or not.Replacment time will depend on your comfort level. IE do you want to depend on a set of 5 year old batterys.
You can test them periodically to see if they are up to capacity if you want to stretch it.

 

[salty joe]

I added a 0.1uf ceramic cap paralell to C4 on both of my PDM15s.
I have 12V consolidated at a terminal point. From there it goes to where it's needed to both PDM 15s. (I have two PDM 15s on one board) I added a 10uf, 50V cap and a 0.1uf ceramic cap in paralell at the 12V terminal point. (where 12V enters the board) I sent the negative side of the 12V caps to signal ground. So, I have one set of caps for the 12V that handles both PDMs. Do I have it hooked up correctly?

4pyros, it sounds like you're talking about more than one battery. I'm thinking just one battery. I hope I've got that right. SLA battery sounds good. The first thing I thought of when I saw SLA was Patty Hearst.
I have a perfect spot in the basement directly under the tank for all the electronics to spread out. I'm thinking an SLA battery could live there too. Getting close, thanks all you guys.

 

[KeepItSimpleStupid]

My mom has a SLA battery under the bed in the 500 VA UPS for the answering machine, cordless phones, light and even more backup power for the personal emergency response system. The battery lays on it's side inside the UPS. Never the hint of a smell. Battery gets replaced about every 5 years. The UPS won't run without a good battery.

 

[4pyros]

4pyros, it sounds like you're talking about more than one battery

Yes more then one
The smaller ones IE 7ah are more common and there for cheaper than the big ones.
But you will need a few to get any good run time.

 

[salty joe]

Ohhh, thanks. I'll have to look into a few small ones.

 

[KeepItSimpleStupid]

Joe, a bigger single battery is better. It's MUCH more difficult to put batteries in parallel.

 

[4pyros]

Joe, a bigger single battery is better. It's MUCH more difficult to put batteries in parallel.

For a battery backup its not bad.
Whare replacement cost is concerned every 5 years or so it may be worth any additional complexities to go with a common size battery in parallel.

 

[alec_t]

So, I have one set of caps for the 12V that handles both PDMs. Do I have it hooked up correctly?

Should be fine.

You guys know more about batteries than I do so I'll keep my head down.