[cmason]

Hello,

So my first house AGM battery died after less than a year of light use. The manufacture replaced it under warranty, but I want to make sure that the replacement doesn't also die an untimely death due to any mistake on my part.

Here are the relevant details:
- 200aH AGM house batter
- connected to a Sterline BB1230 battery to battery charger.
- I have a Victron system monitor connected to the system.
- Victron shows charging voltages (on the positive busbar) inline with the Sterling's indicated output voltage.
- a Voltage meter at the batter monitors shows no voltage drop from the positive busbar.

- I asked the manufacturer for charging details, and they weren't able to provide anything (in terms of correct 3-stage profiles), but this is printed on the side of the battery:

Constant Voltage Charge at 20c | Voltage Regulation | Initial Current
Standby Use | 13.6-13.8v | no limit
Cyclic Use | 14.6 -14.8v | 60a

I interpreted these to mean that the bulk|absorb voltage for this should be 14.6-14.8v at no more than 60a (the charger only puts out 20 or 30) and it should float at 13.6-13.8a.

The sterling charger has a number of profiles. The "AGM 2" one is the closest in terms of voltage, it has the following specs:

Bulk/Absorb 14.6v, cond: 14.1v, float: 13.7v. min absorb minutes: 60, max absorb min: 480


Am I correct that I can just turn this system on, (never discharging the battery below 50-60% of capacity) and it should take decent care of it? Am I missing anything? How does the b2b charger know when to switch phases, i.e. if the battery is fully charged will it "cook it" by attempting to force absorption when it should be in foat?

Pretty new to the electrical stuff.
Thanks in advance! I know there are a lot of details here.

 

[Truck]

You don't want to discharge below 80% for an Agm battery

 

[cmason]

The specs for mine show 1200 cycles at 30% depth of discharge, and 500 at 50%...
honestly I'd be fine with either of those numbers - just not the 50-80 cycles I got (at probably 20% DOD) on the previous one, so I want to be sure I don't kill this one.

The last one could well have been defective, I'm just making sure I'm not doing anything careless with this one.

 

[orton]

You should consider having a solar panel. The panel does a fine job of completing the battery charging to extend battery life. Relying solely on charging from the vehicle probably never gets the AGM battery fully charged.

With my single 300 watt panel with MPPT solar controller I have yet to need to charge from the vehicle with my power usage and climate. My sold Sprinter 255 amp-hr Lifeline battery lasted 9 years.

 

[ranxerox]

Do you have an battery temperature sensor?
My Sterling BBW1260 does. (So does my Morningstar solar controller and Magnum inverter/charger.)
A temperature sensor keeps the batteries from charging too fast, important for AGMs because it will boil the water out of them ruining the battery. Most battery temperature probe charging systems for AGM reduce charging if the battery temperature rises above 120 degree's because that is the point where the AGM start to gas. (Also why the Transit AGM batteries are mounted under the seat because the engine compartment is too hot for AGM.)

There is more to it then this but it requires a lot of writing to explain it, Explore the web. here is an link to maybe get you started understanding it:

https://batteryuniversity.com/learn/article/bu_002_introduction

I should also point out that some battery charging systems do not include an temperature sensor at all, or else it is an option, in these cases the charging systems become less automatic and you yourself have to take a more active role in controlling the charger.

 

[cmason]

Orton -
I don't currently have solar - that (and a fridge/freezer) will be my next upgrades, but I need to get the disposable money together first.

ranxerox -
The bb1230 does have a temperature sensor, mine is connected to the negative terminal of the house battery.

 

[ranxerox]

Try this one, the story is mostly about an Sterling install.

https://marinehowto.com/installing-a-marine-battery-charger/

 

[impatient]

Cmason, Could you disclose the brand / model of the battery?


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[cmason]

This is the original battery:
https://www.amazon.com/gp/product/B010TXTNP0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

The replacement has different branding, but (I am told) was built to the same specs,

 

[impatient]

This is the original battery:

https://www.amazon.com/gp/product/B010TXTNP0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1



The replacement has different branding, but (I am told) was built to the same specs,

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[tthrsn]

This is the original battery:
https://www.amazon.com/gp/product/B010TXTNP0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

The replacement has different branding, but (I am told) was built to the same specs,

This one doesn't seem to be one of their deep discharge models. I think that you need deep discharge.

 

[stockrex]

I have had very bad luck with Amazon battery purchases, go to sams club and grab a deep discharge agm, charge it often with an agm compatible charger,

 

[Truck]

I am surprised at how expensive that is for 200 ah. And people only expect to get 4 or 5 years out of these? The value proposition leans towards those with money to throw away.

I know people like AGM but this one says it's SLA, which, whatever. Even if it was AGM...

I bought two 6v, 260ah FLA Crown batteries to make a 12v 260ah bank. Delivered from the local Crown distributor for $268, made in USA, and right off the production line. Lead plates 40% thicker, true deep cycle. Not just a label saying it's deep cycle. Since I can actually maintain these batteries (maintenance free actually just = you can't maintain them), and based on other's experience, I expect these to last 10 to 15 years. I only discharge them to 80%. A couple times I got down to 78%.

If you can't check the specific gravity of each cell, how do you know your charging technique is actually working? YOU DONT. The MFGs just want you to consume more products. Gross!

Trojan's are also an excellent choice.

Acid batteries want to be fully charged as often as possible.

In the end the buyer must choose between performance and supposed marketed convenience.

 

[Eiko]

This one doesn't seem to be one of their deep discharge models. I think that you need deep discharge.

I know people like AGM but this one says it's SLA, which, whatever. Even if it was AGM...

Product description says AGM, SLA. Answered questions in the amazon link says deep discharge FWIW. AGM is an SLA battery with the sloshing liquid contained in the glass mats. You may be thinking of FLA.

Speaking of which, after thinking about the value calculation of FLA and AGM (and Li-ion for 2 msecs), I bought a 100aH deep discharge FLA battery from Walmart for $75 ($87 since I didn't have a core). Walmart starter batteries have tested very well by Consumer Reports (I'm assuming it carries over to the deep discharge models).

 

[Truck]

From what I've read, and there is a ton of information/misinformation around batteries: The only way to know if it's a true deep discharge is to know how thick the plates are (for lead acid).

 

[impatient]

The specs for mine show 1200 cycles at 30% depth of discharge, and 500 at 50%...

honestly I'd be fine with either of those numbers - just not the 50-80 cycles I got (at probably 20% DOD) on the previous one, so I want to be sure I don't kill this one.



The last one could well have been defective, I'm just making sure I'm not doing anything careless with this one.

Maybe comparing apples-to-oranges, but the C&D brand deep-cycle batteries claim 5700 cycles at 20% discharge, and 1800 at 50%. (Bar chart, hard to interpolate to 30% discharge). I was also told that battery weight is a reasonably good guide to quality (comparing like-sized batteries; more metal = better).

I also have a bias against batteries made in China, based on limited personal experience. I shouldn’t call it a bias; in my experience, the US-built batteries lasted much longer, had much more consistent quality. But this was a different application: DataCenter UPS. FWIW, C&D has recently undergone some corporate restructuring / merger, so I don’t know if you would get USA-made batteries from them next time. In fact, the last one I saw was made in Mexico. You would have to hunt for C&D anyway; they don’t cater to the RV market. But you might run across them in large solar arrays...or DataCenter applications.

The other thing I have noticed is that some brands require (or suggest) much high recharge current. I have a wimpy charge system (20 amp max from the DC-DC charger from CTEK, and a solar setup capable of only 7 or so amps real world). So I like that C&D appears to spec lower recharge currents; however, there is probably a downside to that.


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