What is a battery tender?

[H-Balm]

So as the progress continues... I need to start learning about electrical.

I am building with mental plans, as I go, for fun (and craziness).

I have seen a number of DC systems with tenders.
What do they do?

[Shadow Catcher]

Battery Tender is a brand name of battery maintainers/chargers. Check sdtrippers index above for a fairly exhaustive review of what is what, and why (about 1/3 down the page under electrical).
The care and feeding of a deep cycle battery with the goal of keeping it alive and well is fairly complex, keep it fully charged, if it is a wet cell keep it full of water...
A battery tender (generic is a low watt/amperage often multiple stage battery maintainer) that keeps the battery fully charged and will slowly recharge it.
A converter will recharge the battery more quickly and the better ones will also maintain the charge level.
The latest wrinkle is "power centers" which have the converter 110AC and 12V DC fuses and circuit breakers neatly packaged and easy to wire i.e. http://www.progressivedyn.com/all_in_one_pd4000.html (this is what is in ours so I am familiar with it)

[ERV]

I plug my tenders in every night. We get pretty cold here, so it just keeps my two big batteries in the back of the truck warm and charged. They are a very slow charger tho, so it will not keep up with your uses if you run them down a lot. They are meant to keep the battery up during the off season.
I run an inverter for work so I can run my tools. Very hard on them. They get their charge off the truck as I drive, then the tenders just keep them up. So far my batteries last around 3-4 years, very happy with that.

[absolutsnwbrdr]

I have the 12v/5A Battery Tender Plus, and I don't even have a battery yet

For now, the Battery Tender just acts as a 12VDC power supply for my trailers axillary LED lights and Fantastic Fan whenever I can plug into campground/shore power.

When I can't plug into power, then my simple 12VDC electrical system is powered directly from my tow vehicle battery.

[bobhenry]

F.Y.I

Coleman solar battery maintainer $48 regularly reduced on clearance at our local Wally world to $35.

I was tempted but short on $$$$

[planovet]

Here is mine installed in my tongue box along with my battery.

.

[H-Balm]

Thanks for the helpful replies!

Yes, I am using the electrical index, but thought I'd spawn some discussion, and most wonderfully, pictures!

I'll be back... stay tuned!

[mcspin50]

I'm at that point where I must start to wrap my muddled brain around the electrical system in my teardrop build.
So if you have a power converter like the WFCO 8725, do you still need a Battery Tender thingy to keep the battery charged but not overcharged?

[Shadow Catcher]

mcspin50 that is correct. The WFCO fills the same need and charges much more quickly.

[Senior Ninja]

We use two "Trickle Chargers" to keep our Deep Cycle Marine Batteries "up."
We bought them from Harbor Freight.
Steve