Energizer 8 volt Golf Cart Batteries

Toby · March 2011

Hi To All,

I'm new and have a question regarding the use of my golf cart batteries for an emergency power system.

The batteries are Energizer ECG-8 8 volt. There are six in series which power the cart's 48 volt system. I would like the ability to use the cart batteries to power an inverter for 120/240 volt. The 240v is necessary for the well pump.

I found that the battery specs are:

Amp-hour @ 20 hour rate: 170
Minutes @ 75 amps: 75
Minutes @ 25 amps: 295

This may not be all you need, but it's the only specs I could find.

What could I power with these batteries?

Thanks!

mike95490 · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Toby wrote: »

.... What could I power with these batteries?

A lot. Hopefuly, you already tested this ? Whats the inverter ?

What's your recharge source ?

Then we can tell you more.

Cariboocoot · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Welcome to the forum.

A 48 Volt battery bank will power a 48 Volt inverter, like this Magnum: http://www.solar-electric.com/maenms4444wa.html

The question is: for how long?
Using the basic math on the Amp hours you get: 170/2 = 85 Amp hours @ 50% DOD * 48 Volts = approximately 4 kW hours.

Knowing the specs on the pump will give some idea how well this would work as an emergency power supply. But when you look at the cost of that inverter alone (one of the less expensive ones, believe it or not) you can see that a cheap generator is a better investment for stand-by or emergency power.

Toby · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Hi Mike,

I haven't got that far yet. Just exploring what I could do with batteries.

I have looked at the specs on the Outback VFX3648 and the Xantrex XW4548.

Peter_V · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Toby wrote: »

Hi To All,

I'm new and have a question regarding the use of my golf cart batteries for an emergency power system.

The batteries are Energizer ECG-8 8 volt. There are six in series which power the cart's 48 volt system. I would like the ability to use the cart batteries to power an inverter for 120/240 volt. The 240v is necessary for the well pump.

I found that the battery specs are:

Amp-hour @ 20 hour rate: 170
Minutes @ 75 amps: 75
Minutes @ 25 amps: 295

This may not be all you need, but it's the only specs I could find.

What could I power with these batteries?

Thanks!

How long do you expect the power to be out? A holding tank might be a better solution than trying to power the pump during short outages (1-2 days)
A holding tank will even work if the pump fails, at least until you empty the tank.

mike95490 · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Toby wrote: »

I have looked at the specs on the Outback VFX3648 and the Xantrex XW4548.

If looking at the XW4548, also look at the xw6048, for only a few $ more, you get a lot more possibility.

The only possible flaw, is if the batteries can supply the starting surge for the pump.
My 1/2 hp pump runs at 1,000W (are reported by the inverter display panel) At 50V, that's 20A , and starting load is at least 5x (100A) to 10X (200A) the running load. With the battery being a "hybrid" deep and SLI battery, it will likely be just fine.

Toby · March 2011

Re: Energizer 8 volt Golf Cart Batteries

To Cariboocoot,

Using the basic math on the Amp hours you get: 170/2 = 85 Amp hours @ 50% DOD * 48 Volts = approximately 4 kW hours.
Can you explain your math a bit? Why the 170/2? Also, what is 50% DOD?

Knowing the specs on the pump will give some idea how well this would work.........
Pump is 208/230 volt AC, 5.5 amp, 1200 watt, 1 phase, 1/5 hp.

But when you look at the cost of that inverter alone (one of the less expensive ones, believe it or not) you can see that a cheap generator is a better investment for stand-by or emergency power.
I have a 7500 watt gas generator that connects to the house via a manual transfer switch. It's the primary emergency power, as long as there is gas to buy!

To Peter,

I have looked at a holding tank too. I'm not sure about leaving standing water in a holding tank especially during the summer.

Cariboocoot · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Toby wrote: »

To Cariboocoot,

Using the basic math on the Amp hours you get: 170/2 = 85 Amp hours @ 50% DOD * 48 Volts = approximately 4 kW hours.
Can you explain your math a bit? Why the 170/2? Also, what is 50% DOD?

DOD = Depth Of Discharge. In other words you only want to take the batteries down to half their capacity at most, otherwise their life will be very short indeed. Hence the "divide by two".

Knowing the specs on the pump will give some idea how well this would work.........
Pump is 208/230 volt AC, 5.5 amp, 1200 watt, 1 phase, 1/5 hp.

A fairly easy pump to run, then. The start-up surge could be anywhere from 3X to 5X, as this is probably not a deep well pump.

But when you look at the cost of that inverter alone (one of the less expensive ones, believe it or not) you can see that a cheap generator is a better investment for stand-by or emergency power.
I have a 7500 watt gas generator that connects to the house via a manual transfer switch. It's the primary emergency power, as long as there is gas to buy!

So were you thinking of adding solar as well? If your battery bank is "mobile" it's probably a pretty poor investment.

To Peter,

I have looked at a holding tank too. I'm not sure about leaving standing water in a holding tank especially during the summer.

Large pressure tank = stored water and no worries. How large so you have water for how long gets to be a bit problematic, though. Non-pressurized storage is much less expensive.

Define your goals well and you can work out the best solution.

Toby · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Probably a difficult concept to grasp for us new guys. It's starting to make sense.

The well is not extremely deep. I believe the pump is at 140 ft.

No solar on this current idea but maybe in the future on a larger scale.

Back to your original math that equals 4 kW hours. This is where it gets foggy for me. Based upon the pumps specs, how do you determine how long the batteries will last? And I'm sure you're going to ask how long per day I plan to run the pump?

Cariboocoot · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Toby wrote: »

Probably a difficult concept to grasp for us new guys. It's starting to make sense.

The well is not extremely deep. I believe the pump is at 140 ft.

No solar on this current idea but maybe in the future on a larger scale.

Back to your original math that equals 4 kW hours. This is where it gets foggy for me. Based upon the pumps specs, how do you determine how long the batteries will last? And I'm sure you're going to ask how long per day I plan to run the pump?

Bingo! Got it in one.

The best way to plan any type of off-grid system is to know how much power will be use and for how long.

But now the pump figures are not adding up. A 140' well is considered "deep", and would probably have a 1 HP pump on it. Frankly "1/5 HP" is pretty odd for a well pump. Sure that isn't "1.5 HP" which would be about 1200 Watts (inaccurately)? Pumps are buggers to run because their mechanical HP rating doesn't give much of a clue as to their electrical power usage, especially not on start-up.

At 1200 Watts, the approximate 4 kW hours would run the pump for around 3 hours, surge allowance included: 1200 Watts * 3 hours = 3600 Watt hours. For most pumps that would be a lot of water: 10 GPM is not unreasonable for a pump this size, but even at the "low flow" outlet rate of 3 GPM you'd have 180 Gallons in an hour. It's not likely you use that much, but ...

Toby · March 2011

Re: Energizer 8 volt Golf Cart Batteries

You are correct Sir. I typed the hp wrong. It's a Red Jacket pump and from the data I have it's 1/2 hp. I didn't install it so it may be undersized. It does provide plenty of water.

Ok, so about three hours constant running. And without a meter to log how many kW per day it normally uses, it's unknown how long it would run on the batteries.

Thanks for everyones help.

mike95490 · March 2011

Re: Energizer 8 volt Golf Cart Batteries

For a 1/2 hp pump, go with my readings, call it 1,000w when running.

Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off 3KW PV array, no drain off batteries. I generally manage to still charge while the pump is running. Pumps up about 150' @ 8GPM

Runs off a XW6048 inverter.

Blackcherry04 · March 2011

Re: Energizer 8 volt Golf Cart Batteries

For 20 years I maintained a 3000 W Inverter and 1000 ahr bank to run a 3/4 hp AC pump. I didn't design the system, but I was looking at the pumping curve for it and found out the pump only only had .50 gallon per minute flow @ 50 psi. It pulled 12 amp ac and over 100 amps dc. Big waste.

A deep well submersible DC pump will give you the lift you need and piggy back on a 5 gpm diaphragm pump for the pressure side. Together they pull less than 20 amps dc.

mike95490 · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Blackcherry04 wrote: »

.....A deep well submersible DC pump will give you the lift you need and piggy back on a 5 gpm diaphragm pump for the pressure side. Together they pull less than 20 amps dc.

1) What's the model / cost of the DC pump ?

2) 20A dc at what voltage ? 12V ?

Blackcherry04 · March 2011

Re: Energizer 8 volt Golf Cart Batteries

mike90045 wrote: »

1) What's the model / cost of the DC pump ?

2) 20A dc at what voltage ? 12V ?

Here is the deep well. 3.5 Amps @24 V dc

http://www.solar-electric.com/sh93susowapu.html

I like this diaphragm pump. It's a variable speed and it's 5.5 gpm ( even if it says 80psi, it cut's out at 60 psi ). It's more than enough flow to run a house, laundry etc. and several fixtures at a time. 10 amps @ 12v dc. When pumping into a pressure tank it's still 3.3 gal @ 60 psi. it has a pressure transducer and is pulsed, no rapid on and off.

http://www.rvupgradestore.com/Aquajet-RV-Variable-Speed-Water-Pump-p/aquajetrv.htm

Edit : As was pointed the last time this was discussed, a diaphragm pump should have flexible lines in and out. You can buy the 3/4 in. lines already made up.

Peter_V · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Toby wrote: »

To Peter,

I have looked at a holding tank too. I'm not sure about leaving standing water in a holding tank especially during the summer.

Ever see those bottles of water in the store? Ever think about how many months go by between when they were bottled and when someone drinks them? And they have clear bottles.

In a dark tank hardly anything will grow. Look around most cities and you'll see huge holding tanks up on stilts, almost every farm had one 100 years ago.

When I lived in England back in the '80s our house had a holding tank up in the attic (along with every other house in town) They used this because the city water had very little pressure, just enough to slowly fill the tank, it had a float valve like a toilet.
Since they were all two story houses with the bathrooms and kitchen on the bottom floor, this gave you 25 vertical feet worth of water pressure at high volume.
The holding tank was basically like a tub with a flat lid on top, pretty common to hear stories of people going up to check their tank and finding a dead animal or bird floating in the tank.
The water there was pure, no chlorine or other chemicals. Never heard of anyone getting sick from the water, not even the ones with dead critters floating in their tanks.
I'm sure it happens, but apparently pretty rare.

Many people to this day collect rain water in 5,000-10,000 gallon tanks/cisterns and drink that water. In some dry areas it might go 9-10 months between rains.

The point being that holding tanks have been, and continue to be, widely used without problems.

mike95490 · March 2011

Re: Energizer 8 volt Golf Cart Batteries

Can we call them Water Tanks ? My friend has an RV, and it has a "holding tank" and you don't want to mess with that ! He has to pay to "dump" it at a campground.

At my Tank Farm, I have 4, 3,000 gal tanks. All dark green plastic, and 1 is for drinking water. Eventually, it will go stale, but I use an "Ozoneator" which is a UV light that generates ozone, and a large aqualrum pump and air stone in the bottom of the tank. Pulls about 55watts, but worth it, maybe next winter, I'll put it on a timer, and just run it a few hours a day.

Energizer 8 volt Golf Cart Batteries

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