Time to replace batteries

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Laura & Charles

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Could be anywhere. Originally from Ohio. Go Bucks!
Sometime overnight our shore power went out. This morning we woke up on inverter. The monitor read, “inverting 12.1v”. The power had been off for less than two hours. The water level was fine in all four 6v GC batteries… I think it’s time to replace them. I’ve never worried about batteries much because we’ve almost always been plugged into shore power. But Laura and I have both recently retired and anticipate a change to our MO. We considered downsizing (I always thought we would) but decided to keep the devil we know. We just ordered some replacement furniture, so that pretty much seals it.

Which brings me back to the batteries. We have plenty of room and can easily accommodate eight GC2’s (and possibly twelve.) We anticipate more boondocking. (I want to say, “much more” but, considering we’ve rarely done it, ANY more would be a lot.) ‘Maintenance free’ sounds good to me but from what I’ve read here, AGM is likely the most expensive option. So, “to lithium or not to lithium, that is the question”.

I think I can get the profile I need from the Magnum. Under battery type, I can select Flooded, Gel, AGM, and Custom. In Custom, I can set
Float Charging Absorb volts
Float Charging Float volts
Float Charging Equalize volts
In other menus I can set Absorb Time and Charge Rate.
Will those give me the profile I need for lithium?

What else should I be considering? DC2DC?
 
I've not gone down the lithium path, but I think you'll find that you've got that backwards. AGM should be more than a FLA battery but not nearly as expensive as a lithium. I could be wrong

My setup is much smaller, and only had a single FLA hybrid type battery. Last year I replaced with a renogy AGM.... more energy and less maintenance is good.

I would have looked at lithium, but for me that would have meant changing out my converter, and my solar charger and by BIM system..... not worth it for my needs
 
There are a number of issues with Lithium batteries that you need to be aware of. There is a ton of information on the challenges facing RVers who move to lithium. One that motorhomes face is the different chemistry and charging requirements between lead acid chassis and house lithium batteries. Do your research and get good advice so you are aware of and able to resolve/minimize the issues that can occur.
 
I switched to LiFePo4 Lithium almost 3 years ago, there is no way I would go back, but yes there are things you need to learn or more importantly unlearn, as Lithium is different from lead acid, and some things you have thought applies to all batteries may not apply to Lithium. As to the custom charging profile it should work, but I have not looked in detail at your setting options.
 
AGM should be more than a FLA battery but not nearly as expensive as a lithium.
It wasn't long ago that was true. But lead battery prices are rising while lithium is dropping. AGM and lithium is almost on parity just in terms of rated Ah, not counting potential advantages of lithium. The nod of cost per Ah still goes to FLA but today I'd be reviewing AGM vs lithium very carefully. Even if a given converter charge profile might not be optimum for lithium, an AGM profile will get you pretty close. Given the other advantages you may not worry about perfect. The question to answer initially is what you anticipate the Ah requirement to be, unless cost isn't a factor.

Mark B.
Albuquerque, NM
 
My 2 cents, we bought 12 volt batteries from Walmart, around 110$ each.
2 are now 4 years old and when we returned after 6 months away, the voltage was still 12.5.
Lithium doesn't interest us, batteries are a fuel source like propane and sometimes needs replacing.
 
Before you reach for your wallet reach for your digital volt meter and measure the voltage AT THE BATTERY TERMINALS.. the inverter may be seeing a lower voltage due to line loss.

May just need to clean the path up a bit.
 
We're about to replace our AGMs with Lithium batteries and we have a Magnum 2800 inverter/converter combo unit. As to whether or not yours will be able to charge Lithium batteries, it all depends on the serial number of the Magnum device. Older Magnums cannot fully charge Lithium batteries. Newer Magnums CAN charge Lithium batteries, but you must have the Magnum ME-RC50 series remote to control the charging parameters. Apparently, the older series Magnums cannot be controlled with the ME-RC50 remote.

I don't remember what serial numbers are considered "older" vs "newer" but Magnum was able to tell me over the phone.

Kev
 
Note there are sometimes work arounds for converter / inverter that don't charge at the perfect voltage, for example if you have one with a charge profile that is close but a fraction of a volt too low to fully charge, it is often easier, and cheaper to add a 100+ watt solar panel to the roof and Lithium compatible solar controller to get that last 1-2% SOC to fully top off the LiFePo4 battery and allow to balancing than it s to replace a thousand dollar inverter.
 
If anyone is considering the new(er) WFCO AD, which is a converter advertised as being able to recognize battery chemistry and automatically change the charging profile, think twice. I've had mine for less than a year and it performs exactly like the one it replaced, a 20 year old WFCO. I haven't done it yet, and haven't heard any reports by those that have, but WFCO has a firm ware update that is supposed to fix the problem.
 
My 2 cents, we bought 12 volt batteries from Walmart, around 110$ each.
2 are now 4 years old and when we returned after 6 months away, the voltage was still 12.5.
Lithium doesn't interest us, batteries are a fuel source like propane and sometimes needs replacing.
It all depends on how your RV is used. I decided to stick with the stock lead acid batteries in my Class A, but only after I did this so I can run high power stuff (MW oven hair drier, my ham gear, etc) without adding any drain to the stock L-A batteries while boondocked that control stuff such as lights, slides, etc.

IOW, my Class A now has two complete house power systems for boondocking for DC as well as AC stuff. The stock stuff L-A as well as my added high-power system.

-Don- Reno, NV
 
Sometime overnight our shore power went out. This morning we woke up on inverter. The monitor read, “inverting 12.1v”. The power had been off for less than two hours. The water level was fine in all four 6v GC batteries… I think it’s time to replace them.
That's not conclusive because you didn't state what the amp load on the inverter was or for how long. First of all, the voltage reading while actively inverting will be substantially below the same battery bank "at rest" (no load). If you had turned the inverter off, that voltage would have jumped up at least a couple tenths. Second, the amount of battery voltage drop would depend on how much power was being used and for how long. A reading of 12.1v is not "low" if there was even a modest load for several hours.

Lithiums are approaching the price of lead-acid AGM, so definitely worth considering, but you will need to be aware of the differences that others have pointed out.
 
Thanks for all the info and replies from everyone. Seems I have some research to do. The good news is I have plenty of time as we’ll not be doing any boondocking until beginning next summer.

I assumed I would be replacing due to the batteries age (6 yrs). My experience has been the batteries don’t last overnight with Laura’s (heated/humidified) CPAP. I don’t know for certain, but that thing seems to be a fairly steep energy user. We have a residential fridge and heated with Aquahot without her CPAP and go overnight with power to spare. So I will want to expand capacity to at least six 6 volt AGM or lithium. (Like I said, plenty of space available in the bay that houses them.)

I’m not sold on the need for lithium, but I DO want maintenance free. Considering AGM cost makes me at least want to consider lithium.
 
Before you reach for your wallet reach for your digital volt meter and measure the voltage AT THE BATTERY TERMINALS.. the inverter may be seeing a lower voltage due to line loss.

May just need to clean the path up a bit.
I agree; plus, batteries under a draw always have a lower voltage reading,1719264159781.jpeg my new Xantrex SW 3012 factory setting for battery cutoff is 10.5V while supplying the inverter.
When the inverter shuts down, battery bank voltage jumps up to 12.1V.
 
Sometime overnight our shore power went out. This morning we woke up on inverter. The monitor read, “inverting 12.1v”. The power had been off for less than two hours. The water level was fine in all four 6v GC batteries… I think it’s time to replace them. I’ve never worried about batteries much because we’ve almost always been plugged into shore power. But Laura and I have both recently retired and anticipate a change to our MO. We considered downsizing (I always thought we would) but decided to keep the devil we know. We just ordered some replacement furniture, so that pretty much seals it.

Which brings me back to the batteries. We have plenty of room and can easily accommodate eight GC2’s (and possibly twelve.) We anticipate more boondocking. (I want to say, “much more” but, considering we’ve rarely done it, ANY more would be a lot.) ‘Maintenance free’ sounds good to me but from what I’ve read here, AGM is likely the most expensive option. So, “to lithium or not to lithium, that is the question”.

I think I can get the profile I need from the Magnum. Under battery type, I can select Flooded, Gel, AGM, and Custom. In Custom, I can set
Float Charging Absorb volts
Float Charging Float volts
Float Charging Equalize volts
In other menus I can set Absorb Time and Charge Rate.
Will those give me the profile I need for lithium?

What else should I be considering? DC2DC?

Sometime overnight our shore power went out. This morning we woke up on inverter. The monitor read, “inverting 12.1v”. The power had been off for less than two hours. The water level was fine in all four 6v GC batteries… I think it’s time to replace them. I’ve never worried about batteries much because we’ve almost always been plugged into shore power. But Laura and I have both recently retired and anticipate a change to our MO. We considered downsizing (I always thought we would) but decided to keep the devil we know. We just ordered some replacement furniture, so that pretty much seals it.

Which brings me back to the batteries. We have plenty of room and can easily accommodate eight GC2’s (and possibly twelve.) We anticipate more boondocking. (I want to say, “much more” but, considering we’ve rarely done it, ANY more would be a lot.) ‘Maintenance free’ sounds good to me but from what I’ve read here, AGM is likely the most expensive option. So, “to lithium or not to lithium, that is the question”.

I think I can get the profile I need from the Magnum. Under battery type, I can select Flooded, Gel, AGM, and Custom. In Custom, I can set
Float Charging Absorb volts
Float Charging Float volts
Float Charging Equalize volts
In other menus I can set Absorb Time and Charge Rate.
Will those give me the profile I need for lithium?

What else should I be considering? DC2DC?
Four gc2's will provide around 400 Ah of capacity when new. A single 400Ah lithium will cost only $200 more than AGM. For the added lifespan and convenience that's a small price to pay. The battery BMS will take care of overcharging/discharging for you so you have nothing to do but use them. You can use AGM charging profile to charge,you will however not reach 100%soc but that shouldn't be a problem.
 
We're about to replace our AGMs with Lithium batteries and we have a Magnum 2800 inverter/converter combo unit. As to whether or not yours will be able to charge Lithium batteries, it all depends on the serial number of the Magnum device. Older Magnums cannot fully charge Lithium batteries. Newer Magnums CAN charge Lithium batteries, but you must have the Magnum ME-RC50 series remote to control the charging parameters. Apparently, the older series Magnums cannot be controlled with the ME-RC50 remote.

I don't remember what serial numbers are considered "older" vs "newer" but Magnum was able to tell me over the phone.

Kev
And be 1000lbs lighter LOL
 
I presume the Aqua Hot was using only diesel for the the heat in this test, only using the 12V for the fans, etc.
Correct… after Laura’s CPAP, we don’t have much nighttime energy need (unless it’s warm enough to need A/C… then it’s genny time or invest in @HueyPilotVN ’s awesome Bubba Edison approach)
 
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