Fluorescent lights and battery life

marchesi · 12-15-2008, 08:09 PM

I have been trying to figure out if my house batteries on my van are not holding a good charge or if sportsmobiles use too much electrical for the batteries they have. I owned a Eurovan and was able to get at least 2 days of battery life (with small and unexpensive house batteries). With my sportsmobile, being very conservative, normally only running the refrigerator and one light at a time I only get 1 day and one night and then I go below 12.00V. To conserve battery life, I tried to take out one of the two flourescent tubes from the light fixtures (since I don't need that much light) but then the other doesn't work. Any idea how to take one out? I know a lot has been written about battery life but I haven't been able to read a good answer (maybe it's an impossible subject). Running only a refrigerator and some lights, should I be able to get more than a day and a night of battery life? I have one of the lifeline monster 135 pounds $400+ batteries (I imagine they are standard).

NRL · 12-15-2008, 09:30 PM

Quote:

Originally Posted by marchesi

I have been trying to figure out if my house batteries on my van are not holding a good charge or if sportsmobiles use too much electrical for the batteries they have. I owned a Eurovan and was able to get at least 2 days of battery life (with small and unexpensive house batteries). With my sportsmobile, being very conservative, normally only running the refrigerator and one light at a time I only get 1 day and one night and then I go below 12.00V. To conserve battery life, I tried to take out one of the two flourescent tubes from the light fixtures (since I don't need that much light) but then the other doesn't work. Any idea how to take one out? I know a lot has been written about battery life but I haven't been able to read a good answer (maybe it's an impossible subject). Running only a refrigerator and some lights, should I be able to get more than a day and a night of battery life? I have one of the lifeline monster 135 pounds $400+ batteries (I imagine they are standard).

Flourescent lights should only use up 1 amp if not less. LED's use even less. Certainly both of them use less then candenscent bulbs.
You might want to take a look at getting something like a LINK 10 or something that tells you how many amps your putting in and taking out; which the Link 10 does.

In my case, I had a similar problem that I solved by using the Link10 which told me that even though my battery was charged, and I was hooked up to shore power, the 12v devices where stealing the battery power on the backend.

So when I took off on Monday's, My Powerverter (Tripplite) thought I was fully charged as far as it was concerned (it when thru the charge cycles), but I wasn't really fully charged...

In my case, I also put in a cutoff switch (heavy duty) where all the 12v devices came together(12v fuse panel), and using the Link10(which showed me any amps being drawn) from the house battery..
For a good charge, I make sure all the 12V stuff is turned off.. and the Refrigerator switched to Shore power 110v..

In your case, I have no idea how old the battery is, but a Solar Panel "might" help augment what the refrigerator is drawing from the house battery.

LenS · 01-19-2009, 08:31 PM

You would be surprised how much power some things use when they are 'turned off'. Our laptop charger through the 110 volt inverter is a very big drain. The radio in the off position is still a moderate drain...added a real off switch to that (loss preset stations but stop all drain). You might want to get a handle on how much power that refrig. is really using. I know some people have reduced refrig. power consumption by adding insulation to them.

I see from the Sportsmobile site that the 2.7cf refrig draws 30 watts. If running 24 hours a day that would consume 30 X 24 = 720 watts from your battery. That is a lot for a single house battery.

How much power your battery can supply depends on its size. We uses a Delco M30HMF rated at 115 ah (when new). You should only draw a house battery down to 50% of its capacity if you want it to have a reasonable life. 50% X 115 ah = 57.5 ah That is equivalent to sucking 57.5 ah X 12 volts = 690 watts out of it.

An 18 watt two tube light would consume ... 5 hrs per night .. 5 X 18 = 90 watts used in 24 hours

So in a 24 hour day you could use about 720 + 90 = 810 watts of power. That would drain your FULLY charged battery from 12.7 volts down to below 12.1 volts. All depends on refrig. size and duty cycle. Bigger the refrig, hotter the day, poorer refrig insulation.....faster battery drain. The refrig. is the big user of power.

Below chart is approx. of what can be used from a new group 30 battery

VOLTAGE STATE OF CHARGE AUXILIARY BATTERY AMPS USED WATTS USED
12.75 100% 115 0 0
12.66 90% 104 12 146
12.56 80% 92 23 290
12.47 70% 81 35 433
12.37 60% 69 46 576
12.28 50% 58 58 717

12.18 40% 46 69 857
12.09 30% 35 81 996
11.99 20% 23 92 1134
11.90 10% 12 104 1270
11.80 0% 0 115 1406

**daveb** · 01-20-2009, 08:32 PM

My Fluorescent lights pull about 1 amp per fixture and the big one pulls almost an amp and a half. The refrigerator pulls about 3+ amps when it cycles. The inverter pulls about 3 amps in the on and idle position not running anything. I keep it off when not needed and use 12v stuff whenever possible. Those stereo amplifiers can also suck up the juice. It doesn't take too long to pull down a single 4-D battery over a a few nights.
Dave

Psomaki · 01-21-2009, 12:28 AM

One ampere hour (AH) of batter capacity means the battery can produce an ampere of current for an hour. One watt of power is one ampere of current at one volt. Watts tell us the power we're getting out of the battery; a watt is a watt whether we use it for one second or 24 hours. Let's say your fully charged battery produces 12 volts. Actually it'll be more like 13+, but 12 is close enough. So you're gonna run a refrigerator that draws 3 amps. Volts times amps = watts, so 12x3=36. It takes 36 watts of power to run that fridge, whether it's for three minutes or three hours or three days. What we want to know is, "How long can my battery hold out with this thing running?" Okay, that's where the ampere hour (AH) rating of the battery comes in. Say you have a 100 AH battery, and as stated in a post above, it's safe to discharge it to one half of full charge. You've got 50 AH to play with. Your 36 watt fridge draws three amps when running. 50 divided by 3 is 16.66. So the fridge could run over 16 hours before the battery is getting down to the "recharge me quick" point. Add a couple of lights, the water pump, a TV, maybe a fan, and you see why two big batteries are not a bad idea.

**daveb** · 01-21-2009, 04:56 PM

Another thing to mention is most battery manufactures don't really rate their batteries for the real world. For instance cold freezing temps cut the AH rating big time. So what worked in the summer might not cut it in the winter. Also the quality of the battery matters. Some manufactures might claim they make a 210 AH battery when in reality it truly might be in the area of 190 AH. How old the “new” battery is and how long was it stored can be another demon especially if it sat under-charged for any length of time on a shelf. Then you have to factor line losses, resistance from corrosion and these types of variables. Safe to say what you pencil out on paper may never be reality and generally ends up being less in true field operation.