New AGM house battery not holding charge

[soloalpinist]

I had the same problem and it turned out to be my MPPT controller. I reset my controller and all was fine after that. My controller does not have a "reset" button. Had disconnect the battery and PV cables, let set and re-install them.

[eejordan]

Thanks, everyone.

A few more details about the systems I have:
Solar charge controller - Blue Sky Solar Boost 2000E controller
Solar panels - 185W (did recently clean these as well)
Inverter - Magnum inverter/charger (12V to 110V)
Blue Sea ACR

Everything was working great until these issues started up about a month ago (with the old battery). Since the new battery didn't fix the problem, and I'm having issues charging it from the alternator, solar panels, and plug, I'm guessing it's a battery connection issue somewhere. Could it possibly be a fuse issue too??

I was out of town this weekend and came back to a completely dead house battery. (Solar charge controller screen blank, fridge off, etc.) I'll pick up a multimeter and see if I can do some more troubleshooting with that info.

@soloalpinist I don't see a reset button on my controller either, but I'll see if I can find a way to reset mine and see if that helps!

@1der I'll message you separately. If you'll be in Loveland next week, I'd greatly appreciate another set of eyes if I haven't been able to figure this out by then!

[Scalf77]

Sure it could be a fuse, but probably not. The magnum inverter installs almost always include a Class T Fuse , or at a minimal a ANL fuse. One side obviously goes to the input of the inverter, while one side goes to the battery. To get any basic protection of the Class T fuse for (AIC) purposes, any other connections should go on the inverter side of the fuse. I say should, but i have seen it not also.

So another data point would be what does the battery connections look like? multiple cables to ground and positive or just one?

Based on the data provided, all charging systems appear not to work. We can start to rule out individual system failures, highly unlikely that the Solar Controller, Inverter/Charger, and ACR are broken.

This data " When I turned the engine on, the battery reading on the solar charge controller immediately jumped to "fully charged" (not the usual behavior) but drained as soon as I turned the engine off." sounds to me like the ACR worked and the solar charger now saw the start battery, it is quickly giving you data based on what voltage to solar controller is seeing, which in this case is most likely the start battery. When you turn off, the engine the ACR finally disconnects.

The fact that you were seeing some voltage would rule out a completely blown fuse, I would expect a high resistive contact that shows some continuity at lower currents, but is impeding higher current transfer.

Generally SMB is not big on bus bars, they have a ground connection which is usually on the wheel well, one of those connection must also go to the battery. At this point I would look back from the battery and check each connection. In the picture I provided in a previous post it was an ANL fuse connection, the fuse was actually still good.


-greg

[BCam]

Originally Posted by eejordan

Thanks, @marret. I don't have a battery monitor but will see if I can track one down, and I'll double check all of the battery connections. Appreciate your help!

You don't need to spend a lot of money to get a battery monitor. Although the $200+ Victrons are probably the gold standard, something like this should serve your purposes:

https://smile.amazon.com/AiLi-Batter...%2C138&sr=8-30

I didn't see if you have a multimeter or not, but it's a definite must-have. A simple one will suffice but one with a clamp-on amp probe that reads DC amps as well as AC amps is even better. This is what I have:

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Cheaper ones are available but be extra careful to make sure the clamp-on probe reads DC amps. The descriptions, even on Amazon, can be misleading.

[daveb]

I'd go the cheap route and check the battery connections from the battery to where they terminate. Make sure the grounds to the chassis are also good. Just because they look good doesn't mean they are. Sometimes the battery wire lugs can be compromised without showing signs.

My work truck's winch quit working out of the blue and all the connections appeared fine but after moving the ground wire around I was able to see it was just a poor connection.

Who ever installed the new battery might have missed a bad terminal at the battery itself but more likely they would have never seen or checked the chassis ground connection and/or where the positive terminal ends at the fuse. I'd also look over the separator connections or standoff post if they used one.

The way my system is configured, only the solar and inverter/charger leads are connected to house battery side of the separator and the alternator is on the other side. But I've seen a few builds where all the charging leads are connected to the separator on the same side. In that case the separator itself could be the problem. Make sure the separator if working correctly and look for any compromised bus wires.

As mentioned it's possible the charge (or enough charge) isn't getting to the battery. If you can pull the leads off the battery and stick a car charger directly on the battery lugs (not the wire lugs) themselves, at least you should be able to rule out a bad battery and just as important watch the charge rate to see what is going on.

[Thorne]

There's a HUGE difference between batteries designed to provide lots of starting power, and batteries designed for RV deep-cycle battery banks. Since you had a body shop install "a battery" I'm guessing it is one of the former -- which will exhibit exactly the symptoms you describe.

Order (or go to an RV shop and buy) a proper deep cycle RV battery. They're several times as expensive as cheap starter batteries but worth every penny.

We also bought a used 2011 Sprinter 2500 SMB and had to replace the old batteries soon after purchase. We went with AGMs as the other hardware wasn't ready for Lithiums, which I suspect will also be the case for your rig.

Get as large a battery as will fit, with the maximum number of amp hours (ah) as you can afford. Even better would be to get a second battery and link the two together in a proper house battery bank. It isn't advised to later add another battery, even if it is identical to the first, as they'l never sync well or work together -- so this is a "do it now or never" option.

Check out the many YouTube videos by Will Prowse - https://www.youtube.com/c/WillProwse His books are also great for getting started, I rely on this $6 one - https://www.amazon.com/Mobile-Solar-...119/ref=sr_1_1

[BCam]

The conventional, flooded Marine/RV batteries that are typically sold for RVs and used as OEM for RVs aren't deep cycle batteries, they're dual purpose starting/"deep cycle" but are a compromise for both. I've read that all AGM batteries are deep cycle batteries but I don't know this for a fact.

For what it's worth, I put two Mighty Max 110Ah AGM batteries in my van but confess that I haven't worked them very hard. They've become pretty generic and are made by many companies, including Renogy. Some high end battery companies, like Trojan make premium AGM Deep Cycle batteries at premium price, some of which approach the cost of some well-reviewed LiFePO4 batteries. Given my level of usage, these have served me well:

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Note that AGM batteries can be installed inside your vehicle.

[Eatmorefish]

Have you checked the small ground wire from your blue seas ACR? I had a similar problem a few years back and got lucky with a simple fix.