Replacing ACDC Fridge With a 12V DC

[boywonder]

They are 81 amp hour capacity.....I just looked them up.

They are regular flooded batteries, so if you get the charge wizard you don't have to worry about equalization mode; that mode is for flooded batteries. For some reason Intellipower likes to call their various modes other names.

Since they are flooded batteries you need to check the water level on a regular basis.

Assuming that you have two of them for house batteries.......you've got 162AH of energy. Lead acid battery cycle life drops a lot if you regularly discharge them below 50% State of charge (SOC)......and 50% SOC is "roughly" 12.2V. Fully charged is 12.8V.

Ideally, you want a true battery monitor (warning: things that make your wallet lighter are dead ahead...) Victron makes a few models; I happen to be installing the Victron smart shunt in my van right now....it bluetooths everything to your phone. Xantrex also makes monitors. These devices are easy to wire up and tell you current in/out.....voltage, state of charge, capacity remaining, etc; they are very handy. Youtube Victron and Xantrex battery monitors.

Instead of guessing how charged your batteries are (or aren't) a battery monitor displays the exact state of charge and many other parameters.


https://www.amazon.com/Victron-Energ...ve&sr=1-5&th=1

https://www.amazon.com/Victron-Energ...904010ad0&th=1

https://www.amazon.com/Victron-Smart...63&sr=8-5&th=1

https://www.amazon.com/Xantrex-84-20...2-63e904010ad0

[TRAVRSS]

Oh boy, time to do math... Lol
Seriously appreciate all of your time and support with this!
Beers are on me next time your passing through...

[86Scotty]

Age of these batteries is a good question too. Are there dates stamped on them? Should be somewhere if you don't know.

[TRAVRSS]

Purchased in July of 2016.

[Scalf77]

I would say the "charge wizard" makes the 9100 smarter, but not really a smart charger. They don't really have a absorption stage , it is more like a high float.

In general it would be better to get home and plug in and make sure that your batteries have gone through a full charge. Not really possible with the straight 9100, better with the charge wizard.

The alternator is not designed to fully charge a battery, their general goal is to get it to 85% to 90%. And they're good with that. On my Transit I have a "Smart Alternator" the system even has a SOC meter, they stop charging at 80%.

In general while alternator voltage is high enough for a good charge it really has only one stage "bulk", once it hits the target voltage the current to the battery is nothing. Otherwise we would be overcharging batteries like crazy.

Certainly you can extend your batteries by idling the van, be aware the output at idle we be about half of the normal output. How long would it take, is kind of subjective unless you have monitoring.

As for battery monitors, I used to like the Balmar SG200, I got a couple unsatisfactory replies when dealing with issues after updating their firmware. Eventually I just stopped recommending them or installing them. They still work fine, just caused me a lot of extra work.

I now recommend Victron for battery monitors. If you like having a physical gauge and think you have a reason to use a relay controlled by the monitor, then I recommend the 712, if you are happy with using a phone app , and no relay the smart shunt is the next logical choice. The 712 can also be seen on a phone app. The Victron Connect App is getting strong improvements, I will say that Victron also has a lot of updates for all their devices. It is best to stay on top of them. They also now have a ip65 rated smart shunt.

-greg

[86Scotty]

7 years is pretty tired for any deep cell lead acid batteries, which I'm pretty sure these are. A good way to monitor them as Scalf and Boywonder suggested would be a great idea but I'd start with new batteries.

Consider AGM's. They are a good bargain compared to lithium which would require you to change a lot of other things, and they are much better than the deep cell FLA's you have now.

[boywonder]

This has been a great thread!

The OP asked about wiring in a 12V fridge, and now he needs new batteries, a charge wizard and a battery montior....lol

[TRAVRSS]

Originally Posted by Scalf77

In general it would be better to get home and plug in and make sure that your batteries have gone through a full charge. Not really possible with the straight 9100, better with the charge wizard.
-greg

So regardless I should get a charge wizard... Seems odd that they would build out a system that wasn't designed to charge a battery fully, but as boy wonder said "intellepower stuff is made for affordable high volume RV stuff". Thanks for the info, I'm still learning.

And 86Scotty, thanks for the suggestions to upgrade to better batteries, I'll definitely do that!

[TRAVRSS]

Any particular AGM batteries recommended. Looks like they aren't cheap... I paid $315 for both of those cheaper ones I currently have and they lasted 7 years. A quick look says the AGM type will last 10.
And am I looking for a 100Ah version?

[Scalf77]

The 9100 was designed to be a converter not a charger. Back in the day RV's did not use the battery much. Maybe for small stops, many times the fridge was a 3 way or propane unit. You didn't need a lot of battery power, so the converter was to just provide 12 volt power while plugged in.

As batteries got better, and systems went more 12 volts driven they realized their converter was what it was, so they developed the charge wizard to fix or make it better. I applaud them for coming up with it as a cheaper upgrade path. I don't understand why they didn't turn to making a better battery charger, they just stuck the charge wizard inside the 9200. Really no big design changes. Technology has passed them by, they probably still use "slide rules".

-greg