Novice questions

SouthAfrica75 · April 2008

Two part and totaly different questions

1. The system I put together is just for power outages after a hurricane.
Should I keep the batteries wired to the inverter or should I connect them
only if and when I need to use it.

2. Refrigerator states 6.5 amp at full power at 110v. I have 2 105 amp
batteries in parallel making 210 amp of battery power.
However the motor just does not seam to want to start on the
refrigerator.... any clues or should I just think about getting a small
bar type for storing things in during a power outage

westbranch · April 2008

Re: Novice questions

SA75,

Q 1- I assume that this is a back up system..if so I would have the batteries connected full time. How are you keeping them charged?

Q2- Others will chime in, but to get you started the amperage rating is the 'running' rating, not the startup rating, it will be in the range of 3 times run rating, therefore about 20 amps @ 110 v . This is a momentary draw.

Secondarily what type and size of inverter are you using, MSW or True Sine wave? this has a lot to do with startup ans running efficiency.

thirdly, you most likely need more 12 v amps, remember watts = amps x volts

12 v x 100 a = 1200 w
120 v x 10 a = 1200 w

cheers, HTH
Eric

mike95490 · April 2008

Re: Novice questions

A fridge likes to have a pure sine wave inverter. Mod-Sine wave inverters are much less expensive, and appliances are less happy with them. You need about twice the starting current, of the running current, to start a motor.

6.5A fridge, needs 13A to start. Your inverter needs to supply that current for about 5 seconds.

mike95490 · April 2008

Re: Novice questions

SouthAfrica75 wrote: »

should I just think about getting a small
bar type for storing things in during a power outage

No, because it will take several hours to cool itself down to keep the food cold. Better leaving it all in the main fridge, with the door closed. No Peeking to see if it warmed up.

SouthAfrica75 · April 2008

Re: Novice questions

The system is used for back-up after power goes out. I would physically have to get out to where the system is and run power line into the house where I need the power. That would be done after storm passes.

I trickle charge and in the event of a pending hurricane would fully charge using a charger.

The inverter is an MSW 2500 surge and 1200 running.

System2 · April 2008

Re: Novice questions

Food for thought. DO NOT expect this system to run your fridge for more than a very few hours. Perhaps half a day at most, before the batteries are totally flat and dead. Compared to a couple of CF lights, fridges are extreme energy hogs. They don't need to be really, but the manufactures produce what we buy, and that's very poorly insulated, thin walled energy pigs.
AND, if the batteries are allowed to discharge beyond half way, their life is greatly shortened. They must also be constantly maintained and properly looked after, otherwise when you need them, they will be ready for nothing but the graveyard.
In your case, for what you want, I would suggest a little 2500 watt gas fueled generator
Wayne

crewzer · April 2008

Re: Novice questions

2. Refrigerator states 6.5 amp at full power at 110v. I have 2 105 amp
batteries in parallel making 210 amp of battery power.
However the motor just does not seam to want to start on the
refrigerator.... any clues or should I just think about getting a small
bar type for storing things in during a power outage

SA75,

My fridge has the same 6.5 A “Full Load” Spec. That’s worst case conditions, such as initial start-up and/or all defrosters on. Typical running current once the compressor settles down is in the 1 A to 1.5 A range.

The problem you’re seeing is multi-fold. One issue is that the fridge may draw more current from the MSW inverter. Let’s say it’s 7.5 A. For a 12 VDC to 120 VAC inverter, that means a 75 A load. Assuming 90% inverter efficiency, the start-up load on the battery bank may be ~83 A.

83 A is a significant load on a 210 Ah battery bank. It’s probably causing the battery voltage to momentarily drop (the battery “coup de fouet”, or "crack of the whip") below the inverter’s low-voltage cut-off value, which in turn is shutting down the inverter and keeping it from starting your fridge. And, this problem only gets worse as the battery SOC drops and the fridge cycles on and off.

A battery’s “Reserve Capacity” (RC) spec is based on a 25 A load. I think that’s rather severe for a Group 24 or Group 27 (~105 Ah) battery. For a parallel pair of batteries, that would be 50 A – far less than the fridge’s likely start-up draw on your battery bank.

You may need a healthy and well-maintained battery bank rated for at least 12 V x ~400 Ah to be able to reliably start and operate your fridge in back-up mode.

HTH,
Jim / crewzer

rplarry · April 2008

Re: Novice questions

SA
I agree with Wayne on this one. In the long run trying to maintain and charge batteries will be a lot more hassel than just getting a small, reliable generator like a Honda and having some gasoline on hand to power it during during or after hurricanes. I have an 18cf sears upright refer that I ran for 2 weeks on a Honda 1000i while I was putting my solar system together, so I suspect it will work for you also.
Larry

SouthAfrica75 · April 2008

Re: Novice questions

Thanks for the info........ very interesting

I would love to be able to use a generator. Problem is I live in a condo and cannot use one on my balcony. I have my battery set up in a nice closet outside on the balcony.

There is one way I could run one for about 5 hours a day. I live on the top floor of my building. I have access to the roof and could run a honda or similar on the roof during the day I guess with an extension over the side of the roof and into my balcony would do it.

A 1,000 watt should be able to run just the refrigerator... I shouldnt need anything else....

System2 · April 2008

Re: Novice questions

Hopefully a 1000 watt unit will start the fridge.
I say that, because fridges and freezers are notoriously hard to start, but most people are unaware of that until they try to start them off something other than mains, or a bigger generator. Hopefully the 1000 watt gen will start it OK. No problem once it's running, it's the starting that's the bugger.
Good luck with it. Too bad you didn't know someone with the exact gen you might be buying, you could try it to be sure it would start the compressor.
Good luck.
Wayne

BB. · April 2008

Re: Novice questions

Generators and apartments... Those don't work too well together either.

From the issues of storing fuel (no apartment manager or fire marshal is going to allow you to store and transfer 5+ gallons of gasoline in/on an apartment) to the dangers of running the generator (fuel leaks and carbon monoxide)...

And then back to the issues of using batteries for emergency power to run your fridge... Basically, a full sized fridge takes about 1 kWhr per day... And one "car sized" storage battery stores about 1kWhr.

So, to run your home fridge during frequent power outages, you would need roughly 2 car sized storage batteries for every day without power you want to run your fridge.

I think you are going to have to look at "out of the box" type solutions and prioritize your needs. Gets back to the old truisms of of how long you can live without:

3 minutes without air
3 days without water
3 weeks without food

Relying less on refrigerated food and more on dry/canned/freeze dried foods. Having a good water supply (is your water heater available for you to use? Have water filtering/disinfectant supplies/equipment?) first and foremost.

For me, I have always thought in terms of "camping" for my emergency supplies. Backpack, water filter/disinfectant, tent of some sort, camp stove+fuel, tarp, sleeping bag, then onto food ("wet food" if not moving, light weight freeze dried / jerky / powdered / cereals / nuts / candies / etc. if you need to bug out).

That being said, we have way too much food in our freezer to make use of in a real power failure situation (earthquake in our area). Fuel for cooking/heating/lighting is probably more important to me than fuel for a few extra days of fridge time... Eating fresh food first to make use of the perishables, then on to the dry/canned/preserved foods for longer term issues.

If you have special needs (i.e., special diet, refrigerated medications) then looking at specific solutions (such as a small chest freezer converted to a fridge which uses 1/4-1/3 the power of a normal home refrigerator--so your batteries/generator/fuel last longer), or keep a few gallons of ice in the freezer and have a very well insulated cooler which can keep things cold for 5+ days--plus you can drink the ice as it melts.

-Bill

System2 · April 2008

Re: Novice questions

Some very good points there Bill. Excellent more like it.

RCinFLA · April 2008

Re: Novice questions

You should always keep lead acid batteries charged. Continous float voltage should be 13.2 to 13.4 vdc.

You will not get very far with 200 amp-hrs of battery. I doubt your statement about 6.5 amps. The explaination involves a couple of refrig attributes. About 5 hours battery life if you don't get hit by a defrost cycle.

There is start current, run current, defrosting, and misc. (ice maker, lights, etc.)

For an average refrig in 15 to 18 cu ft. range, run current depends on when it was made. If older then 10 years, run current will be around 2-2.5 amps. Newer energy star will be lower, 1.2 amps to 1.5 amps.

Start current will be 9 to 15 amps. Generally need at least a 2kw inverter to get past the start up surge.

Other big issue is defrost cycle. Typically a 1 kw heater, done typ every 16 hours. Cycle last for about 20 minutes but is not a continuous 1 kw load during this period. Average about 5-8 minutes worth of 1 kw load during defrost cycle. Don't try to disable defrost heater, I did it last hurricane and evaporator coils iced over is less then two days with extra humidity (no air conditioner) causing refrig to run continously without sufficient cooling.

SouthAfrica75 · April 2008

Re: Novice questions

Thanks all for the tips and advise.

My thoughts of running the refrig is definately out. And a portable gennie is out as well.

I prepare for hurricane season every year. Have pleanty of water, canned and dryed food to last me a week. Will get bags of ice and pack the freezer if storm is pending..... Will also get another cooler to assist in keeping items cold as well.

If food is begining to thaw, I'll turn on the portable propane camping stove and grill and start cooking.

My set-up will definately help out running some fans, tv/dvd, cf lights and a couple of other items as needed.....

I'll also be able to charge these batteries during an outage as the condo complex I live in has a commercial generator to run elevators, emergency lights and club house air and lights. They also have power to their maintenance shop and I spoke to them about plugging in a charger to charge my batteries next to their golf carts and they have no problem in me doing that.

Guess I can say I have definately upgraded after going though Katrina and Wilma and living with a 5" b/w tv, 2 lanterns, no coffee, no fans for 5 days.

System2 · April 2008

Re: Novice questions

:cool: Sounds like you're doing all you can do - - - under the circumstances.
Hopefully this year we all will escape any really serious storms. In any case, we wish you all the best.
Cheers
Wayne

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