Inverter/charger

[steelguyshaun]

Hi guys. Hope I'm at the right forum/site for my question and hope someone out there can help. I have a cabin in the woods with no power available. We use a generator at night for lights, ect. I want to set up a battery with inverter/charger to power a TV, satellite dish box, and one light bulb (60W) to use during the day without having to run the noisy generator. The TV consumes 120 Watts, sat. box 25W, and a 60-watt light bulb (intermittant light bulb use). I have selected this 750 watt inverter/charger http://www.tripplite.com/en/products/model.cfm?txtModelID=2938 and according to my calc's I should have about 5-6 hours continuous usage of all three appliances with a 200AH deep cycle battery. Hopefully a little more with the light off. My questions are: 1) do my calcs look right? 2) Will the charger in this inverter/charger be enough to charge the battery each night when the generator is running for approx. 8-hours,..or less? 3) Any suggestions on what battery to get or steer clear of? I would like to locate the battery indoors (warmer)-does this mean I need a sealed battery? I could locate battery outside and run wires thru the wall if I can use a cheaper more conventional deep cycly batt. (like wal mart ones). Cost is a major concern. Anyone see any issues or have any suggestions for what I am trying to do?

 

[Kreij]

Hi Steel and welcome to TPU

The Tripplite unit should work well for you. You should get several hours even on a regular (non-deep cycle) battery.

Just make sure that the generator is capable of giving the battery the 20 amps it needs (along with whatever else the generator is powering) to recharge.

If you keep the battery in a warm environment (indoors) it will hold its charge much better. Batteries of all types that are out in cold climates (being from WI I'm talking less that 30°F) will drain quicker. My cordless power tools just suck when I leave the batteries out in -20°F.

If it must be outdoors, then bring the battery in and let it warm up before charging. Charging a cold battery does not work worth a diddly poop.

Where is the cabin and what temps are we talking ?

 

[Disparia]

"60w" fluorescents draw only about 14w. Even with intermittent use, the lower draw results in better use of your battery's capacity. And the less you discharge your battery, the longer it'll live.


Kreij, any recommendations on a place that'll ship me squeaky cheese?

 

[steelguyshaun]

Thanks Kreig, and fellow cheesehead! I'm in WI, but the cabin is in NW Missouri (pretty comparable temps to us). I did not think a standard battery would give me long lasting dependability because of the re-occuring charge and discharge.,.?? I had also thought regular lead acid batteries should not be used/recharged indoors due to the fumes/gasses they emit,..? So do you have any idea how long it would take to fully charge the discharged battery? If I was out hunting late, or did not get in until late and only ran the generator for a few hours,... I don't know how long Min. I would need to run generator to charge the battery for the next day. Also, would it matter if I had one 200KW battery, or two 100KW in parallel?

 

[steelguyshaun]

Sorry,..meant AH and not KW in ref. to the batteries.

 

[Kreij]

I'm not sure how long it would take to fully charge the battery, but I would think that 8 hours on the charger would be sufficient if it was drained completely. I honestly don't think you are going to drain a deep cell battery that quickly for what you are using it to do.

Yes, you want to charge it in a well ventilated area. If there is nowhere in the cabin that fits that then you want to charge it ourdoors. Better safe than sorry.

Using two batteries vs. one will not buy you anything. What you could do is get two 100AH batteries and use one and charge one as needed. I'm not sure what you mean by "long lasting depedability", but a normal car battery has the capability to be used and recharged constantly.

@Jizz : What kind of cheese do you want?

@Steel : Where are you at in WI?

 

[steelguyshaun]

It's from what I have read on standard car batteries,...they will go bad quicker than deep cycle when drained before fully charging repeatedly. Looks like I will have to keep the battery outside then. If it was a sealed battery, does it still need to be charged away from living space? I mentioned two batteries because the smaller ones seem to be more readily available (Down at farm and fleet).
I'm down southern WI, few miles from Lake Geneva.

 

[Kreij]

When you are talking about going bad quicker, we are talking about what? Years?
The deep cycle batteries are considerably more expensive (at least here) than the regular ones.
They will typically give you way more starting amperage for starting a vehicle but that is not really what you are looking for. Personally, I would buy a good quality regular battery and see now it goes for you. It should last forever for the small requirements you are asking of it.

Just my 2 cents

 

[steelguyshaun]

OK,...thanks for your help. I did not want to have to buy a new battery every year, if a deep cycle would last several. I should be good to go!,...Happy hunting!

 

[infrared]

Sorry to contradict you Kreij..

Speaking from experience, a car starter battery will die very quickly if you're using it in a deep cycle application. They have lots of very thin plates, designed to give a very short burst of high currant, but they errode away faster if being constantly cycled. When starting a car, which normally starts in less than a few seconds, less than 1AH is used. "going bad" could happen in as little as a month if it's being cycled daily.

Deep cycle batteries have much thicker plates that won't errode away as fast with use. A sealed battery would be fine to keep indoors, although it's still recommended to keep them well ventilated because they will gas if overcharged. In normal use though, the oxygen and hydrogen produced is recombined as water making them maintenance free.

Even on the deep cycle battery, I would advise not taking more than 50% of it's capacity before charging it again or it won't last long. If you can stick to this rule of thumb you can normally get over 300 cycles from a good quality battery. Some MFG's (Numax) even have a 500 cycle warranty.

Hope this helps

Edit:

Also, the 20 amps Charge output of the inverter isn't what is pulled from the generator, 20A x 14v = 280W, which is negligable. 2.5A from a 110V supply

 

[steelguyshaun]

Thanks for the input infrared. The inverter/charger has a low volt shutdown, so this should eliminate the possibility of overdrain and pre-mature failure, correct?

 

[steelguyshaun]

any idea of charge time from that 20amp charger if the 200ah battery is at, say 50%?

 

[infrared]

8 Hours should be enough. 20A will only be applied for the first part of the charge, until the battery is 70-80% charged, and then it trickles off for the last 20%, so I couldn't give you an exact charge time. If the generator's running continuously overnight, the longer the better. The battery won't be overcharged.

The low voltage cut will only kick in when you've discharged the battery very low, so it's best not to let it reach this point if you want the battery to last. Unless you get some kind of watt-hour or amp-hour meter it'll be hard to work out how much capacity you're using, but provided it's not hitting the low voltage cut the battery should be fine.