Sterling Pro Charge Ulta for LiFePO4 battery

[Hayden Watson]

How effective is the Sterling Pro Charge Ultra for LiFePO4 batteries? It seems that in bulk and float, it uses the same voltage of 13.8V and in maintenance it still holds at 13.2v. My understanding is that they like to charge then shut off. Is there a better charger for these batteries?

 

[IStream]

The Pro Charge Ultra has a fully programmable charge profile in addition to its various pre-programmed settings so in principle it should be just fine. I have a 24V/10A unit and it's great. The only issue I have with it for use with LiFePo batteries is its limited current capacity. Their largest 12V model tops out at 60A and their 24V model tops out at 30A. If you really want to take advantage of the high current acceptance of these batteries, you should size the charger at half the capacity of your bank (e.g. a 200Ah bank with a 100A charger).

It can be argued that it's much more important for the alternator to meet this spec than for the shore charger because you want to minimize engine charging time and you're generally not in a hurry to charge when plugged into the dock. However, as you point out, it's best to keep the batteries stored somewhat discharged (~30-70%). Given this, you'll want to kick off a charge when you first get to the boat so by the time you get her prepped for departure the batteries have been topped up. With a 60A charger and a 300Ah bank that's sitting at 50% SOC when you get to the boat, you'll need 2.5 hours to top it up, plus another 30 minutes typically for top balancing if you're really finicky. With a 150A charger, that 2.5 - 3 hours turns into 1 - 1.5 hours. I don't know about you but I can easily spend an hour getting the boat ready to go out while it tops up. Despite my wife's complaints about how long it takes me to get the boat ready, even I can't spend 2.5 hours futzing around while the battery gauge crawls upward.

 

[Maine Sail]

How effective is the Sterling Pro Charge Ultra for LiFePO4 batteries? It seems that in bulk and float, it uses the same voltage of 13.8V and in maintenance it still holds at 13.2v. My understanding is that they like to charge then shut off. Is there a better charger for these batteries?

You don't mention which LFP batteries you are using? I will give you the same answer I did the other day....

The ProCharge Ultra is a great algorithm for lead acid, not very good for LiFePO4. The longer the bulk stage the longer the absorption stage will be. LA batteries loves this. LiFePO4 is basically all bulk which means the charger will calculate a very long absorption on every cycle, and over-absorbing is not the best choice for LFP.

If you insist on using one for LFP I would suggest using the custom setting and programming it for a max of 13.6V then drop below that for float to your desired "storage" SoC. We know of at least one major LFP battery maker who actually disallows the use of these chargers with their LFP batteries for the exact reasons I've laid out above. If you program it so the battery is only getting to 3.4VPC (3.4VPC X 4 Cells = 13.6V) then it could work.

This could also be problematic, especially with drop-in batteries, where you may have hundreds of cells with unknown capacities and internal resistances that actually may need to get to 14.4V to 14.6V to top-balance for 20 or so minutes each cycle. Unless you have another charge source that can be programmed to do this, you may find out a year or two down the road that your batteries are too far out of balance for the internal mA level shunt-balancers to correct.

Oh, and DO NOT use the supplied temp sensor with LFP!

The other issue with this charger is the lack of dedicated voltage sensing. This is not insurmountable, with close proximity and large gauge wires, but LFP is very sensitive to charge voltage and the window is narrow.

The Victron Skylla IP44 (60A) is considerably more programmable as are their inverter chargers such as the MultiPlus Series.

 

[Maine Sail]

The Pro Charge Ultra has a fully programmable charge profile in addition to its various pre-programmed settings so in principle it should be just fine.

The ProCharge Ultra & ProNautic P are only programmable for absorption & float voltages but not for absorption duration. Fully programmable would mean you can set more than just absorption & float voltages. With LFP the duration at target voltage is a critical one and this cannot be set in these chargers.

Again, these are very excellent charger for lead acid but caution should be used for LFP.

 

[Hayden Watson]

Thanks for the info. It sounds like you would prefer the MultiPlus C 12/1600/70 for this application. I am looking at a 390 AH bank made from 190 AH cells. I have an Ample Power 105 amp alternator with a Xantrex external regulator but will probably upgrade the reg. I am assuming that I will need to limit the alt output because I cannot find a serpentine belt kit from my M25XP and the single belt cannot handle the full output. I do not have solar but will probably add a couple of 100W panels.

I have 12v refrigeration and wonder how that works into the mix if I want to leave it on. If the float is set at 13.2 will the fridge run just from battery until the voltage drops to that level and then the charger will keep it from going below that?

 

[Maine Sail]

Thanks for the info. It sounds like you would prefer the MultiPlus C 12/1600/70 for this application.

Not unless you're in Europe and your boat is 230V. You'd want the 12/2000/80..

 

[Maine Sail]

I am assuming that I will need to limit the alt output because I cannot find a serpentine belt kit from my M25XP and the single belt cannot handle the full output.

With a 3/8" belt you'll need to dial that Ample Power alt back to around 60A or so when charging LFP.

Joe Joyce at Westerbeke thinks the crank pulley for the D950 (M-25-XP) will fit the D850 (M-25). The crank pulley for the D950 is the one the Balmar kit works with and is Westerbeke PN 302189.

 

[IStream]

The ProCharge Ultra & ProNautic P are only programmable for absorption & float voltages but not for absorption duration. Fully programmable would mean you can set more than just absorption & float voltages. With LFP the duration at target voltage is a critical one and this cannot be set in these chargers.

Again, these are very excellent charger for lead acid but caution should be used for LFP.

Good point, thanks for the correction.

 

[IStream]

Thanks for the info. It sounds like you would prefer the MultiPlus C 12/1600/70 for this application. I am looking at a 390 AH bank made from 190 AH cells. I have an Ample Power 105 amp alternator with a Xantrex external regulator but will probably upgrade the reg. I am assuming that I will need to limit the alt output because I cannot find a serpentine belt kit from my M25XP and the single belt cannot handle the full output. I do not have solar but will probably add a couple of 100W panels.

I have 12v refrigeration and wonder how that works into the mix if I want to leave it on. If the float is set at 13.2 will the fridge run just from battery until the voltage drops to that level and then the charger will keep it from going below that?

Yes. When the batteries are sitting at a higher voltage than the charger, it'll idle until the battery voltage sags to the float voltage setpoint, at which point it'll kick in to supply whatever current is necessary to stay at that voltage. If a load is suddenly imposed, the charging current will increase accordingly to hold the setpoint. The charger doesn't know or care where that current eventually goes, whether to the battery or to the loads or to some combination.

 

[Hayden Watson]

Not unless you're in Europe and your boat is 230V. You'd want the 12/2000/80..

With a 3/8" belt you'll need to dial that Ample Power alt back to around 60A or so when charging LFP.

Joe Joyce at Westerbeke thinks the crank pulley for the D950 (M-25-XP) will fit the D850 (M-25). The crank pulley for the D950 is the one the Balmar kit works with and is Westerbeke PN 302189.

Thanks for the info.
Is the 12/2000/80 the same size at the 12/166/70? I have limited space available for the inverter/charger under the nav-station on my Mk2 C30 and there is no place else that would work. Is there a good site I can look at to get a better understanding of the capabilities of the MultiPlus inverters and what they can be programed to do?

My engine is the D950 M25 XP so it sounds like i need the 302189. The last time that i checked, there was a kit for the M25XPB but not the XP so it sounds like they have added a new pulley.

 

[Maine Sail]

I have 12v refrigeration and wonder how that works into the mix if I want to leave it on. If the float is set at 13.2 will the fridge run just from battery until the voltage drops to that level and then the charger will keep it from going below that?

Yes that is how it would work. If you're not charging beyond 13.6V the Sterling can work, but you'll really need to understand your bank and how well matched the cells are. If you are building this bank yourself please ensure you get A grade cells with matched capacities and internal resistances. We have seen far too many folks getting scammed on Alixxxx to ever recommending risking this on your own. When it doubt call Carl at Electric Car Parts Company and get quality cells.

 

[mermike]

All Posts - Victron Energy is an active forum for all things Victron. The main website www.victronenergy.com has all the documentation.

Here's the link for the 12/2000. MultiPlus - Victron Energy

Is there a good site I can look at to get a better understanding of the capabilities of the MultiPlus inverters and what they can be programed to do?

 

[Hayden Watson]

In looking at the specs for the MultiPlus, it appears that the physical size of the 12/200/80 is too tall (20.5") to fit in the only good place i have to mount it but strangely the 12/300/120 is short enough (14.3") and both are the same width at 10". It is really strange that with 50% more power it is 6" shorter.
How many watts of AC does it use to charge at 120A? My guess would be V x I = P so 14.4v x 120A = 1728W. Given 92% efficiency 1728W / .92 = 1878W max input.
So theoretically, a 2000 W generate should be able to run this. Am I close or where did I go wrong?
3000W is FAR more and any load I would ever put on my boat but a 400AH bank of LFP could use the 120A. I really only need about 500W of invert to run a couple of laptops. Is there a better way to get a little inverter and a straight LFP charger for a 400 AH bank?