I drained the battery. (EDIT 6/2010: Add converter to CT.)

[digimark]

We've just completed a 3 1/2 day camping trip at the KOA in Harpers Ferry, WV, and I appear to have drained the battery.

My CT has a Class 24 Interstate battery, (2) 12V overhead dome lights, a Fantastic Vent fan, (2) unused porch lights and (2) wall power points. Into these I had plugged a (mostly useless and won't be returning) Vector 12V thermoelectric cooler and an iPod USB charger cable. The battery is connected to a Battery Tender Plus, plugged into the trailers' AC. The KOA site provided 30A to the trailer.

EDIT: It's a HD24-DP deep cycle battery.

My first poor assumption was that I didn't have to monitor 12V use since the Battery Tender Plus was plugged into AC. Oops.

I'm guessing I probably did some damage to the battery by letting it be sucked almost dry. Obviously I was draining it faster than it could recharge. I don't know why I had expected the BTP to keep up -- it got quite warm.

To avoid this situation in the future, what is my cheapest option? Replace the Class 24 cheapo battery with a better class 27 or 29? (That's going to require a larger/longer battery box, right?) Different charger providing more current? (I like the BTP -- don't really want to get another.) Or both? Or something else? Thanks.

[rainjer]

Are you using a deep cycle or a car battery?

Jeremy

[Woody]

I think part of the problem I see here is the use of a Vector 12V thermoelectric cooler. Peltier coolers are massive power hogs, the actual amp (5-6 amps) consumption is very high. They are very inefficent to begin with for the power cosumption they require to operate. Actually I am surprised that it took three days to drain the battery. Your battery tender was working overtime to maintain the battery with that load from the cooler alone, Battery tenders and battery chargers are not rated for constant usage as DC power supplies. Also I would get a deep cycle battery

[tonyj]

I remember reading somewhere that the some of the Battery Tender line could also work as power supplies. After two Battery Tender failures, I switched to another manufacturer.

[madjack]

...what AH rating on battery...what power on the BT...id it is the smaller 1.5AH unit, it is not meant to be a power supply...just a maintainer...even the bigger 5A unit would not have kept up with the thermoelectric cooler which is a terrible power hog...............
madjack

[Miriam C.]

Try an AC to DC power supply (converter) next time hooked up. That will not use your battery. The little battery tender I got will only maintain an unused battery........ http://www.sportsimportsltd.com/actodcp ... DAodGF7__A

[Bodyman]

I don’t understand why anyone should have problems with 12 volt. The main thing is minimal usage of 12 volt appliances and heaters.
I am building a cabin at my campground this summer and spend an average of three nights a week in my teardrop which has not moved since the first of April.
I have a three year old inexpensive Farm & Fleet marine battery (don’t know the AH rating). I do use the lights sparingly but play the radio/cd fairly often and watch movies on the DVD player almost every night I stay. I have only taken the battery home once so far this summer to charge and believe I still have another 2 weeks or so before doing so again.
In past years I have intentionally tried to draw the battery down and know it would last me 10 days to two weeks without a problem.
From my experience with 12 volt in the teardrop I plan on getting by with two marine batteries for my main power in the cabin with plans of installing solar chargers in the future.
Randy

[GeneH]

A Deep Cycle battery while more expensive initially will in the long run be less expensive than auto batteries. If you do much camping where AC is not available you can hurt an auto battery by not getting it on charge within 24 hours. A few such discharges and you'll find that a charge doesn't last long.

Since I prefer camping in remote sites and operating my portable ham radio I am going to use an AGM type deep cycle battery. This will allow me to put it in the space between the sleeping and the galley areas and not get a lot of gas venting from it when I do charge it.

As with most things involved with building a teardrop, the best quality you can afford is the route to go.

[mikeschn]

Use a power supply when you have 110v available. Only use the battery when you are roughing it.

You can use a double pole double throw switch to change between battery power and the power supply.



Here's the power supply I use...



I'll be wiring the Giant TD this weekend for the same arrangement as I have in these pictures...

Mike...

[digimark]

Surprise -- I've just remembered I have an Astron RS-7A DC power supply from my ham radio equipment... provides 5A continuous. I'll be ditching the Peltier cooler (I knew those things were not good, but I had to try it... 8-( ) and working on hooking this up. Thanks.

[digimark]

Double surprise -- the Astron only puts out 5A continuous -- meaning I'm not much better off than the Battery Tender Plus.

Can anyone confirm -- with my configuration now, even when I am connected to shore power, any time I use 12V stuff (lights, fans, power points) I'm drawing off the battery at the same time the BTP is trying to recharge it? I'm laying there watching TV, microwaving a burrito and basking in the cool air of the A/C, but if I turn on the 12V lamp or spin the ceiling vent fan, I'm tapping the battery?

If true, and if I'm getting this right, I need to replace the BTP with a real converter/charger with more continuous amps, like a WFCO 35A converter? I should unload the Battery Tender Plus and sell it on eBay because I won't need it with the WFCO in its place?

[madjack]

...if you get a WFCO you will have no need for the BTP other than charging batteries around the house...unless you are going extreme with 12v usage, the 25A model would be more than adequate...my experience with the BTP has it coming on and charging battery as needed...if a load is being drawn off the battery the charger will still cycle unless you are drawing 5+amps...both the BTP and the battery contribute power to the system and if more than 5A is needed that would come from the battery...in use, I tend to turn the BTP off at bedtime, running the Fantstic Fan off the battery alone...come morning(orso) I will turn the BTP back on and let it charge on up..........
madjack

[digimark]

There's a 25A model? I thought the min was 35A. I'll check, thanks.

I think the BTP is only rated at 1.25A, so it wouldn't contribute much to the power budget, and that would also explain why it takes so long to recharge the battery...

Is WFCO better or worse than IntelliPower? Is there another brand rated highly I should look at?

I need to take the decorative covers off my trailer and see how the wires are run. I've got red and black wires running between the BTP and the pos/neg poles on the battery (with the BTP physically sitting on top of the battery box) but putting a proper power supply/converter in -- is it enough to simply connect the converters' pos/neg to the battery -- presumably the trailer has a ground bar and a distribution bar behind a panel somewhere... no need to reply yet -- I'm trying to think it through...

[BrwBier]

If you were at a KOA and had power at the site why didn't you just plug the cooler into the 110 a/c? My cooler at any thing below 85 degrees will keep at the low 40s or below (43 below ambient). After paying $7 for ice in Canada on day I said I will never travel with out the electric cooler, and if needed I can also put ice in it just like any other ice chest.
Brwbier

[digimark]

The Vector cooler was 12VDC, and didn't come with one of those cheapo inverters for 110VAC, but truthfully I wanted to confirm my suspicions that it wasn't very good. This particular model had literally room for only 6-12oz cans and barely kept them cold; last year we also tried a much larger Coleman thermoelectric cooler/heater which came with an inverter, it wasn't much better. Now both are gone...

Of course all of our other food and drinks were in Igloo coolers packed with ice. I was really hoping the thermoelectric coolers, even the smallest ones, would work well enough to keep my younger son's insulin vials (he has type 1 diabetes at age 7) cold, but it's not worth it even for that. I'm putting his vials in a small Tupperware container and stored on top of the ice in the cooler. The air pocket in the Tupperware around the bottles moderates the ice and keeps it cold without freezing, which would ruin the insulin...