Dual Battery Setups! Let's see them! Multiple Batteries Thread!

I installed the Off-Grid Redarc setup yesterday. I don’t have a solar panel yet. So far so good.

 

Anyone running the Red arc smart start battery isolator kit??

 

TL;DR - battery shows 13.8v while charging, but is losing charge? Halp!

Riddle me this one….

Blue Sea ML-acr. Solar + PWM controller. Flooded start battery. Flooded deep cycle house battery. Both are less than a year old. Renogy battery monitor for house battery.

Start battery shows ~13.8v while the truck is on. ML-acr connects, and house battery shows the same charge as the house battery.

Battery monitor shows charge - voltage and amperage - increasing when the truck is off and house battery is charging via solar.

With the truck running and both batteries connected via the ML-acr and no solar charge (night time), the battery monitor shows ~13.8v but an amperage draw of ~.4 to ~.8 amps while charging.

After a 3 hour drive home yesterday in the dark, the house battery which charged via the alternator for those 3 hours had 96% charge, instead of 100% which it started at before my trip.

Something is drawing current while the truck is running and both batteries are connected.

Went to leave for work this morning and the house battery had charged back to 100% via the solar panel with the truck off and the batteries disconnected.

I had an issue with the Renogy monitor freezing randomly and displaying inaccurate readings until you disconnected/reconnected power to it. It’s since been replaced under warranty.

I have yet to dig into anything but would love some insight while I sit here at work waiting….

 

I have dual AGMs with a Blue Sea ML-ACR I installed many years ago.
Are there any battery monitors I can add to this system? I'd like to see Incoming and Outgoing amperage of my aux.

Is this the best option:

$64 Renogy 500A Battery Monitor with Shunt, High and Low Voltage Programmable Alarm, Range 10V-120V up to 500A, 20ft Shielded Cable, Compatible 12V Lithium Sealed, Gel, Flooded Batteries,Black

https://smile.amazon.com/dp/B07RP5B5P7?th=1

 

Read the post above yours.

 

I plan on getting this. I think someone told me to keep an eye out on ebay too, as they sometimes drop down towards $50

 

Non renogy brand version of these are half the cost on ebay.

 

I paid 60$ for mine off of eBay. They definitely drop.

 

Might be a bad battery or a bad alternator.

 

I wouldn’t be surprised if the battery is bad. It’s a junk Advanced Auto battery and it’s been replaced under warranty once already because the first one had 2 dead cells.

I haven’t really tested much just because I’ve been lazy the last couple days.

The alternator shows between 13.8v-14.1v with the truck driving. It drops down to about 13.5v at idle. I need to test the amperage output still.

Battery shows 12.6v-12.7v with the truck off.

I went through and cleaned all the grounds and 12v+ contacts just to rule that out.

I need to reset the shunt/monitor just to rule that out as well.

 

Belt okay?

 

~1 year old. New bearings in the idler pulleys. Factory tensioner.

I’ll have to double check it though.

I ordered an amp clamp to test the alternator, just waiting for it to arrive.

 

Just kicking it around. Your numbers are similar to mine except for the idle voltage and that’s only a couple tenths low. I installed a volt meter just to see how charge and output change over time and I’m still early in the curve. My battery is a couple years old now but I’m anticipating having to finish the life cycle before I get a grip on it.

 

By "isolator" are you referring to the MLACR? If so, how did you wire-in the bcdc to work with the MLACR? I'm adding a Redarc 1225 to my OGE dual battery system with MLACR, and would like to also have the ability to isolate the starter battery.

 

Quick napkin math help? Currently running an optima yellow top AGM, using a bcdc1225 to charge on the road. So far, it powers my fridge and lights for about 2 nights, and maybe 2 days. I have an EB55 backup to get me through the next leg or day of alternator charging, etc.

Would a group 34-35 size LiFePO actually be significantly more efficient at 60Ah (the only sizes that fit the Rago battery box), than the 40Ah AGM battery over time? How much more?

Thanks?

 

60ah is 50% more than 40 so yeah. Also you can run a lithium battery down more, much more.

 

I wouldn't put an expensive LiFePO4 battery in the engine compartment. But that's just my opinion.

https://www.sciencedirect.com/science/article/pii/S1002007118307536

 

Agreed. But that's not just your opinion; most LiFePO4 battery manufacturers recommend against installing their lithium batteries in the engine compartment. The associated high temperatures far exceed the operational parameters of lithium.

 

I read all that as well. There’s one anecdotal Aussie video on the University of YouTube, and looked like (with thermal wrap) he had one issue (case warping) but otherwise no issues. LiFePO after all, doesn’t blow up. Just less efficient at extreme temps.

 

The PowerQueen unit of equivalent size and performance costs less than the Optima I have. ‍

I’m also not referring to Lithium-ion. Come over to 2022.