Battery Power

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chas

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Sep 8, 2008
27
ma
can anyone point me in the right direction I am looking to purchase a marine battery and attach it to an inverter. thanks for any help you can offer
 
It would help to know what the load you intend this to power is.

In general you want as much battery as you can afford, a float type charger, and an inverter no bigger then needed to feed the device load. Inverters are not very efficient, so you don't want to waste any more power then you need to just running the inverter and it's fans (if it has them). Large deep cycle batteries can be found at most boat stores.. medium sized ones can be found at wallyworld etc.. inverters can be had many places. A internet search for "battery backup solutions" should find some good hits and the possibility of finding a matched system that does what you want.
 
I have a big one from Walmart I use at the cabin during the winter. They also supplied a cheap inverter, but I don't use much electricity up there.

You really have to figure out what you want to run, the amps it requires, and then how many hours you want to run it. Since batteries don't work as well in the winter remember to oversize it 50%.

Becareful not to oversize the inverter as an oversized one will hurt more than help.

Matt
 
thanks to all for the info I am looking to only have a power backup for my pellet stove. Hopefully I can get a system that can switch to the battery in a power outage then recharge the battery when power is restored.
 
How many hours do you want to run your pellet stove on the battery? You may need to run multiple batteries or even go into something like golf cart batteries in order to get the amp hours you will need.

Matt
 
Then you need to figure out the load you need to supply, in amp hours then build a system that can supply those amp hours for the length of time you anticipate. Honestly, if you are looking at anything longer then a few hours, I will bet a small generator will work better for you.

A quick look at a set of specs for a pellet stove chosen at random says it needs 400 watts to start, and 110 watts to run on high. A 105amp hour deep cycle battery, powering a 500 watt inverter, will give you *about* 4 1/2 hours run time with the stove on high, which as far as I am concerned is the only number to plan for. You can of course use more or larger batteries, although a 105AH deep cycle is pretty big. By the time you build a system big enough to keep you in heat during a real outage, you will have spent quite a bit of money on a system that has a fatal flaw in my opinion, no way to "refuel" until the power comes on.. a generator is probably a way better way to go if you anticipate power outages longer then a few hours.

I would recommend one of the small Honda inverter generators, like eu1000i, the electronics in small fans and auger motors will be sensitive to "dirty" power.
 
Don't know the "electronics" in your stove, but Harbor Freight has a small generator for less than $100. A good inverter will cost nearly as much.
 
John_M said:
dogday, you might want to check out this site for info. and links regarding inverters: http://www.westmarine.com/webapp/wc...catalogId=10001&Nao=0&Ne=712&Ntt=Distribution Panels&N=377 710 1651&page=CategoryDisplayLevel1&y=0&x=0&omniTag=Category:Inverters&PopularCat=No&storeId=10001&Ns=WMPrice|1

Good luck, John_M

Edit: Apologies. For some reason, the link does not work unless you "copy and paste" it.

This is fairly common - it relates to a feature / bug in the forum software... Essentially the W3C standards for writing a URL or link say that certain characters like spaces are "legal" but because of the way HTML is interpreted, it is possible to use these characters to hide malware code using them, and thus do evil things to the computers of people clicking on such a link... Because of this the software authors have decided to make the link software not recognize these problem characters and not display the link code properly. Their logic (which I agree with) is that it is better to have a broken link than to risk having a damaging link... The solution, as mentioned is to do a manual cut and paste.

Gooserider
 
dogday said:
thanks to all for the info I am looking to only have a power backup for my pellet stove. Hopefully I can get a system that can switch to the battery in a power outage then recharge the battery when power is restored.

My neighbor recently borrowed one of my marine batteries to do just what you want. I told him it would run that inverter and pellet stove all night, but I was wrong. He only got about 4 hours out of my standard size marine battery. So get one battery if you only want to be prepared for short outages. Get 2 or more (or a small generator) if you want to be prepared for longer.

We thought we'd never see a 36 hour outage, then it happened a week later. Good thing he had wood heat too.
 
Here’s a thought I had.
I have a power washer that has a bad pump (left water in it over the winter) If I were to put a pulley on the shaft and mount a cheap 140amp alternator on it I would have a poor mans "charging cart" capable of recharging my battery bank. If you pulled 50 amps out of your battery bank (1/2 of a 105 amp marine battery) you could recharge it in less than a 1/2 hour and be good for another 4-5 hours. Of course adding another battery in parallel would double everything.

I have a 7550 watt generator but wouldn't want to run it 24/7, and it only has a 10amp 12 volt charger. To me the advantage of the inverter is its quite, only powers that one critical system, and is great for camping!

Is my thinking correct or did I miss something?
 
Greg, You have probably already researched battery chargers, inverters, connecting multiple batteries for increased amp hours @ the same voltage and increased voltage @ the same amp hours, charging multiple batteries connected in series and parallel, various battery technologies and their different charging requirements, prices, and availability. Just one caveat, humbly offered: Improper charging can quickly ruin a very expensive battery. Be sure you know what will happen to any battery before you connect cables from a home modified charger. Potential effects can be expensive, dangerous, or disasterous. Good luck, John_M
 
Thanks John.
Since my batteries are of different capacities and ages I would ony use them one at a time, and charge them one at a time. As for my potenial charger I was just thinking that an alternater turning at the proper speed wouldn't know if its in a car or not same for the battery.
 
Instead of direct attaching a car alternator to the deep cycle battery perhaps you would be better served by attaching a high capacity charger to the battery and powering it with AC current from a genset. The proper charger knows how to vary voltage to properly charge a deep cycle battery without burning it up. The voltage will be varied to change the charge rate.

See, a car alternator was never designed to bring a deep cycle battery up from zero to full. Car alternators are designed to maintain the full charge by applying a constant 14 or so volts to the battery.

The RV world is full of smart folks that have been charging and discharging deep cycle battery banks for decades. They use onboard converters to charge their battery banks with 110 AC power.
 
Greg H said:
Thanks John.
Since my batteries are of different capacities and ages I would ony use them one at a time, and charge them one at a time. As for my potenial charger I was just thinking that an alternater turning at the proper speed wouldn't know if its in a car or not same for the battery.

The big difference when it is in a car, is that you typically have a lot of other loads present, which soak up a lot of the amperage put out by the alternator, thus limiting the charge rate to just the "left over" juice... Without that extra load, I'd be worried about pushing to much current through the battery if just running the alternator alone... Most batteries have specs on them for the maximum sustained charging current they want to see, and exceeding that can cause serious problems...

Gooserider
 
cars also have voltage regulators so not to over charge the battery. also, i'm not sure how much but i think it would take more than 2 or 3 horsepower to run a 60 or 90 amp alternator. if you were to over charge a wet cell battery ( car battery ) you would do one of two things. boil the battery so that the water boils off leaving to much acid and you would damage the plates in the battery, and take it from exp. it doesn't take long. and that is what happens most times, but the other thing that could happen while the battery is boiling is that little box that we know as the battery can explode. it's a small hydrogen bomb. they can do alot of damage.
 
This will depend on the alternator you choose. I would expect that you select the standard GM 1-wire alternator that is super common and super adaptable. It has an internal regulator and you don't need a seperate curcuit to excite it. A wonderful one wire invention. Cheap and usually under 100 amps.

One HP is equal to about 750 watts. 750 watts divided by 12 volts is like 60 amps. So your typical 5 HP pressure washer engine could put out 300 amps but you will certainly have some efficiency losses in there.

The biggest/fastest battery chargers I have seen for RVs are less than 100 amps. So you'll have plenty of engine. The internal regulator will act to not overcharge the battery but it will not taper the voltage down to 12.8 like a good battery charger will, it will work to keep the voltage at 14 which will keep sending juice to the battery even when it's charged which will boil it dry over time.

I'll be honest and say that I have set up an alternator this way to charge up a deep cycle battery. The battery was used to power an electric fence for 45 horses and the "engine" was actually a slick paddle wheel that used diverted creek water piped down from way up on the hill to spin the wheel fast which was pulleyed to the alternator. It worked but we didn't really know enough to worry about the battery being damaged. The only other option was to hook it up to a pickup with jumper cables and idle the truck for hours.
 
Highbeam said:
This will depend on the alternator you choose. I would expect that you select the standard GM 1-wire alternator that is super common and super adaptable. It has an internal regulator and you don't need a seperate curcuit to excite it. A wonderful one wire invention. Cheap and usually under 100 amps.

One HP is equal to about 750 watts. 750 watts divided by 12 volts is like 60 amps. So your typical 5 HP pressure washer engine could put out 300 amps but you will certainly have some efficiency losses in there.

The biggest/fastest battery chargers I have seen for RVs are less than 100 amps. So you'll have plenty of engine. The internal regulator will act to not overcharge the battery but it will not taper the voltage down to 12.8 like a good battery charger will, it will work to keep the voltage at 14 which will keep sending juice to the battery even when it's charged which will boil it dry over time.

I'll be honest and say that I have set up an alternator this way to charge up a deep cycle battery. The battery was used to power an electric fence for 45 horses and the "engine" was actually a slick paddle wheel that used diverted creek water piped down from way up on the hill to spin the wheel fast which was pulleyed to the alternator. It worked but we didn't really know enough to worry about the battery being damaged. The only other option was to hook it up to a pickup with jumper cables and idle the truck for hours.

how long did your battery last? (not the charge but the battery itself)
nice hookup.
 
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