Deep Cycle battery question

https://www.batteriesplus.com/batte...LngDFin3j2W5cQEUmD2Ap-C9Ol3qn8uXP0aAlP88P8HAQ

 

Pics or its just smack talking!!

 

I know, I know... I have the write up pretty much finished. I just need to take some time to get some good/useful photos of the entire setup. Patience.

 

Now that is not my strong suit. Running wire and getting switches done is. Cmon

 

Which model battery are you using? And is the battery in your factory location?
Thanks

 

That is beautifully done.

 

I think you're going at this a bit backwards.

Figure out your usage first and that will direct you to the battery. A phone charge will suck about 4 amps. No idea what your fridge draws but an Engle refrigerator/freezer pulls 2.5 amp/hours. And that's one reason they cost $900.

A Group 31 marine battery (which are not deep cycle) are rated for about 100 amps but if you suck it below 50 amps, you'll damage it.

SB

 

I just recently purchased a Engel fridge and wanted to run a battery box to power it. I was looking at something like this small 20ah battery. Wasn’t sure if this would be big enough? Or could go even smaller? Thanks

 

"the Engel 12-Volt Refrigerator Freezers use approximately 0.9 - 3.9 amps for the smaller units to 1.4 - 3.6 amps for the large 84 Quart MT80 unit."

Read more: http://driverlogbooks.com/t/engel/engel-12-volt-fridge-freezer-faq.htm#ixzz56pIqrgtv

AGM batteries (and I think that's what that is) can take a drawdown of about 55--60% of its rating. Thus that battery is good for about 12 amps. So using the above information on the 84-quart unit–lets say 3 amps for simplicity–that battery would work for four hours before you'd start damaging it.

SB

 

I have the Engel MT45 -45 quart.
I was thinking about a old car battery but the weight/space is killer. I’ll probably go with a 30 ah and hook up a small solar panel to keep it charged.
Thanks for the info

 

Don't fridges have a volt setting where they cut off so the battery doesn't get damaged?

 

I like the idea of not splicing etc. However, I don't know if I'd use the 7pin terminal to run a fridge. What guage are those wires? How much voltage drop are you suffering from those wires. To charge a deep cycle and run a fridge off it is one thing...but I would consider not running a fridge directly off it.

 

You have a few questions that are better answered by contacting the fridge manufacturer. I can’t comment what wire gauge the fridge requires because I don’t know the load of the fridge. As far as a fridge having a low voltage cut off once again those are questions for the fridge manufacturer.

https://www.wirebarn.com/Wire-Calculator-_ep_41.html

 

Excellant points.

Adding to the discussion....personally, I wouldn't purchase a fridge with out a cut off.

Edit: I wasn't seeking an actual answer to my questions. I know the answers to those questions regarding my own fridge, dual battery and solar set up.

I was more referring to questions that one setting up their own system should ask themselves of their own set up.

In my case the trailer wires would be far too small. I learned this because I had to replace the wire I first set up with due to excessive voltage drop.

 

Thanks for the info. I was looking for a new battery for my land cruiser. Cheers

 

What fridge do you run off the battery? Looking to find an AC powered cooler I can run off the same Exide XMC-31 marine deep cycle battery (with DC/AC converter) and charge laptops, run a small hot plate etc for 2-3 days while camping.

 

I did some digging and the Exide XMC-31 has a 100ah rating. My first question is how are you charging it on the go?

A hot plate draws a huge load and why wouldn’t you invest in a propane or camp stove? You couldn’t even run the hot plate off of the stock Tacoma inverter. You also want to charge laptops and run a fridge. IMO you are either very uneducated on solar/ battery/ inverter setups or completely delusional. Not trying to be a dick but I don’t see one battery doing the job unless you run this as part of a dual battery setup with an isolator and charge directly off the alternator and run the truck to keep things charged. Even then you might not have a very convenient or capable system.

I am starting to hate the word solar. To go solar people seem to have this assumption that they are spending a little up front and then it is free to run. They are somewhat right. The problem is you need to match the charging capacity, storage capacity and load to each other. To do this in the most cost effective way you need to go online and start hitting all of the solar sites and plug your numbers into the free calculators found on those sites. By the time you properly size your system for anything but the lightest of loads it is EXPENSIVE. A generator is much more cost effective both in the short and long term. My current setup with 4 massive 12v golf cart batteries @150ah each and 400w of charging capacity still has a 2000w generator for heavy loads as needed (tire warmers for the racebike). My GC batteries were at cost from a family friend at interstate but still were $800 @50% off plus the panels @$800 and then the controller, wiring etc and I am pretty much at $2000CDN and still have the generator cost on top of that.

Do the research, find the calculators and start doing the math. Otherwise be ready to be disappointed.

 

You're on the right track.. the phone charger will push up to 4A... but at 5V. That's only 20W, which is only ~1.6A from a 12V battery.

First convert your loads into watts (or watt hours). For instance, if you have a compressor fridge that averages 40W, figure 40Wh per hour. That's 3.33A @12v. 24 hours of that will take 80Ah from a 12V battery. Charging a cell phone is almost trivial in comparison, so I wouldn't consider it using more than a couple Ah per day.

So figure out how much energy you're going to use in a day. Figure out how many days you might go without any sort of charging. Factor in solar (I figure a 100W solar panel on a GOOD day will generate about 50Ah at 12V) if you want to charge off-grid or without some external source.

 

I am an electrical engineer and I went down this road several years ago. Your best bet is a separate true deep cycle battery, like a golf cart battery. A marine/deep cycle battery is not a deep cycle battery, so don't waste your time with one. More importantly is how you charge your deep cycle battery. If a deep cycle battery isn't charged correctly, chemical by-products build up on the plates and reduce the battery life. If you just hook it to your alternator with an isolator, it won't last but a few months. Low amperage trickle chargers (2A) do a pretty good job, but they take a long time and won't help on your camp out. The only real solution is a deep cycle charge controller that uses a charge algorithm specially for deep cycle batteries. The controller starts with a high current, and then reduces current based on plate voltage. You can pay anywhere from about $75 to $300 for one, but believe me they are worth it. You would put this controller in between your trucks alternator/charging system and the deep cycle battery. Then run your camper off of the deep cycle. Put in a switch to run off your truck battery if your deep cycle runs out. You could also use the charge controller for a low voltage solar panel to help charge the deep cycle. I'm in the Arizona forest right now hunting turkey, but I'll be around next week and can answer more questions. Just send me a PM next week.

Mark

Also, a 12vdc refrigerator uses much less power the an gas/12v refrigerator. They also cool much better. Without a solar charger, I could get two or three days on one charge using a small electric refrig and lights. LED lights use around 60% less power.

 

Hi, anyone have ideas on how they are tying down the battery box in our truck beds? I have a similar group 31 battery box setup with a 20A DC-DC charger from ctek (D250S).

Thanks,