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Old 01-08-2008, 08:08 PM   #1
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2,000 WATTS to work with.

Folks,

I know that anything I ask has been asked before. I would just like some verification that I am on the right track with my project.

Question: What can I expect from a 2 kw generator to support me in my long-term boondocking? My hope is to charge my two group 27 batteries as infrequently as possible without dropping below 12.3 volts.

I have two led dome lights, a single cfl in the kitchen and two more led fixtures in the bath and the gaucho. Outside of that I use the water pump just long enough to do dishes once a night. Not a lot of electrical demand, but I don't know what that means in terms of amp-hours.

-Will 2,000 watts fully charge my batteries (50 amp parallax with temp-assure converter)?

-How long might I have to run the generator if I am charging from 12.3 and to what voltage do I charge?

-what is the amp draw for the original AS reciprocating pumps?

I hope these are fair and specific questions. My internet surfing window is limited so I have not read everything on this subject.

Life is very minimal in my little trailer at the moment, but I am loving it. I'm living on land that I own outright in my own vintage aluminum can.

Cheers, Adair
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Old 01-08-2008, 08:25 PM   #2
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Adair,

Your 2K genny should have no problem keeping your batteries up, as long as you are using your converter to do the job......as in plugging in the trailer to the gen. Do not use the DC charging feature of the gen, as it is a constant voltage and will eventually cook your batteries or not completely charge them.

You also might want to invest in a battery monitorig system from Randy at BestConverter.com.

Happy boondocking!
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Old 01-10-2008, 03:32 PM   #3
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I appreciate the reply.

I do have a battery monitor from Randy. I wish I understood my batteries better, and in time it will all make sense I'm sure. Currently, when I turn the switch to my battery bank, my monitor reads about 12.45. Once I start using my lights (perhaps two 16 LED array dome lights at most) the voltage monitor shows a steady drop in voltage. After perhaps 1/2 hour the voltage is down to 12.3 so I shut off my lights and switch to the gas lamp.

There seems to be something wrong with this scenario. The next day when I flip the switch to the battery box again, my voltage meter shows a restored voltage of 12.45. Clearly, once the current is flowing the battery tender is reading something differently.

First, what voltage should a fully charged group 27 battery read? Off the shelf mine read the stated voltage above.
Second, how can I determine an accurate idea of my amp/hours demand?

Many thanks for any input.

Adair
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Old 01-10-2008, 03:58 PM   #4
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Quote:
Originally Posted by Adair
I appreciate the reply.

I do have a battery monitor from Randy. I wish I understood my batteries better, and in time it will all make sense I'm sure. Currently, when I turn the switch to my battery bank, my monitor reads about 12.45. Once I start using my lights (perhaps two 16 LED array dome lights at most) the voltage monitor shows a steady drop in voltage. After perhaps 1/2 hour the voltage is down to 12.3 so I shut off my lights and switch to the gas lamp.

There seems to be something wrong with this scenario. The next day when I flip the switch to the battery box again, my voltage meter shows a restored voltage of 12.45. Clearly, once the current is flowing the battery tender is reading something differently.

First, what voltage should a fully charged group 27 battery read? Off the shelf mine read the stated voltage above.
Second, how can I determine an accurate idea of my amp/hours demand?

Many thanks for any input.

Adair
12.8 VDC is usually considered a full charge. You might have damaged plates or a sulphated battery.From the description, it sounds like your battery is bad, as it should hold more charge with 2 LED arrays on.

The light manuf. should have a rating on the LED for amp draw, as any appliance will. Just find the numbers and add them up for the total.
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Old 01-10-2008, 04:03 PM   #5
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Hi Adair,

I'd recommend the following book to learn more about batteries. It's well worth the money.

Managing 12 Volts - Camping World

Your inverter 2 kw generator will work well to charge your batteries. Two Gr27 should have a combined 20 hr rating of 200 Ah. For charging, going from 50% State of Charge (12.2 vdc) you'll be shooting for 80% with the generator. That is around 12.5 vdc when the battery has stabilized from the charging.

200Ah Battery Capacity x 30% (80% - 50%) = 60 Ah

60Ah x 1.26 (26% extra for battery inefficiency) = 75.6 Ah required

75.6 Ah required / 55 Ah supplied by charger = 1.3745 hours or 82 minutes

Don't forget to include a desulfation maintenance cycle in your charging to prolong the life of your batteries. I use Power Pulse desulfators from Pulse Tech.
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Old 01-18-2008, 06:10 PM   #6
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I still don't know how to tell when the battery has been charged enough since it takes a while for to let them settle. I charged last weekend, brought the batteries up to 12.78. They easily lasted all week. It took just over an hour of charging. I appreciate all the help.

-A.
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Old 01-19-2008, 07:02 AM   #7
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It sounds like you've got the hang of it.
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Old 01-19-2008, 08:42 AM   #8
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Quote:
Originally Posted by rseagle
Don't forget to include a desulfation maintenance cycle in your charging to prolong the life of your batteries. I use Power Pulse desulfators from Pulse Tech.
I've never heard of this. Inquiring mind wants to know
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Old 01-19-2008, 09:19 AM   #9
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Quote:
Originally Posted by Lumatic
I've never heard of this. Inquiring mind wants to know
Here is information on a different brand:
Onboard Desulfator
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Old 01-19-2008, 11:55 AM   #10
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Quote:
Originally Posted by Adair
I appreciate the reply.

I do have a battery monitor from Randy. I wish I understood my batteries better, and in time it will all make sense I'm sure.
Unlike the generator produced power, batteries are using chemical reaction.
That makes them dropping the voltage under the load much more, than the house wiring would. Also with the discharge the voltage steady drops, till voltage consider full discharge (I remember about 10.5V) past which the future reaction will damage the plates.
Also while charging the batteries can take lot of current at the beginning stage, but to get them from 90 to 100% takes long time at low current. That's why better battery chargers have multi-stage charging.
While using generator just for battery charging it makes more sens to charge the batteries to only 90% to avoid wear and tear on generator with minimal load. Do you have good battery charger?
I use inverter/charger in my motorhome. That thing takes 2400W while starting the charge of my 4-batteries bank.
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