LiFePo4 Confusion

[camelracer]

My 125ah POS Vmax AGM battery has given up after 3 years so I'm looking into a 100ah LiFePo4 replacement. Most of these are advertised as a drop in replacement but because of the cost I contacted the venders to find out if my solar/charging system was adequate. The batteries under consideration are BattleBorn, StarkPower and LiFeBlue.

My charging system consists of the truck alternator through a Blue Sea ACR, 200w of solar through a Morningstar SunSaver 15 MPPT controller and an IOTA DSL30 without the IQ4. When I contacted the battery vendors I forgot to mention the IOTA.

BattleBorn's reply was that the Morningstar solar controller would over charge the battery because the float voltage was too high (0.1v over their spec).

LiFeBlue's reply was that the Morningstar solar controller would over charge the battery because the absorption cycle was too long. They also said I needed a switch or solenoid on the alternator input.

StarkPower actually called me to say that their battery would be fine with my system but there doesn't seem to be any low temperature charge protection. He said that internal battery heating would take care of the low temperature problem - not sure I believe that.

Morningstar said that they haven't tested with a LiFePo4 but some of their customers have changed the internal settings to make them work. Morningstar won't modify my controller but they will sell me a module to interface the controller with a PC to change the charging parameters. Besides the cost of the interface the main problem with this solution is that I would have to go over to the dark side and get a Windows PC.

So much for a "drop in LiFePo4 replacement" being an easy upgrade. Any input would be appreciated.

 

[PaulT]

—snip—The batteries under consideration are BattleBorn, StarkPower and LiFeBlue.

My charging system consists of the truck alternator through a Blue Sea ACR, 200w of solar through a Morningstar SunSaver 15 MPPT controller and an IOTA DSL30 without the IQ4. When I contacted the battery vendors I forgot to mention the IOTA.

BattleBorn's reply was that the Morningstar solar controller would over charge the battery because the float voltage was too high (0.1v over their spec).
—snip—
So much for a "drop in LiFePo4 replacement" being an easy upgrade. Any input would be appreciated.

I’m looking for a similar upgrade. My emails with Battleborn indicated that Iota with IQ4 works fine. Battleborn has Trimetric configuration instructions on their website. That leaves the alternator and it has no float mode.
I’m still waiting to learn what the new IQ4 for lithium batteries has for voltages.
https://www.iotaengineering.com/IQ/#!/detail/IQ-LIFEPO

Paul

 

[rando]

I have a DIY 150Ah LiFePO4 battery, as described in the DIY Lithium thread, and have put a lot of thought into figuring out exactly how these batteries work.

For charging you want to bulk charge until you reach 14.4, then go directly to a 'float charge' around 13.2v - which doesn't really float charge the battery, just stops it from discharging. It is also good to have easily adjustable charge set points, so that when you are not using the camper you can easily turn down the charge voltages so that the battery can be rest at 50-70% SOC as opposed to 100% SOC, which is better for longevity. You also want to avoid charging at a significant rate (> 0.05C) below freezing.

If you are spending all this money on the battery I would recommend updating your charging and monitoring to make sure the battery will be well taken care of. With the Victron 'Smart' MPPT and BMV-712, you can set all the parameters to match your lithium battery, and if you run your loads through the MPPT as well, you can include an LVD so you never have to hit the limits on the battery BMS. You can also program a low temperature charge cutoff using these two devices.

Charging from the alternator is not a problem, with the exception that the battery likely won't ever get to full charge as the alternator voltage is probably not high enough at the camper, but this doesn't hurt the battery, Because you generally only drive for a few hours at a time, float charging from the alternator is also not a big deal - a couple hours of float (even at 13.7) is not going to effect things, it weeks or months at float that will do damage.

The IOTA is probably the biggest issue. I never plug in, so I haven't worried about this. If you can get their IQ4-litihum module, that would work, but unfortunately that won't work with the newer iota's that already have iq4 built in. If you don't use shore power often, the easiest solution would be to unplug the iota and not use it. If you do want to use shore power, the simplest solution would be to go the iq4-lithium if it will work with your iota. If that doesn't work the next easiest would be to use a programmable on board charger:
http://shop.pkys.com/Victron-Blue-Smart-Waterproof-Battery-Charger-127-with-Bluetooth_p_7588.html
Finally, you could do things manually, and just unplug the charger once your battery reads full - you can even set an alarm on the BMV-712 to remind you to do this.

I have been super happy with my system - 150 useable amp hours at < 50lb is hard to beat!

 

[Vic Harder]

+1 to what rando said. The Victron gear is great and always getting better.

rando, the OP states in his tagline that he has a "2500 Fiat CTD" - Dodge/Ram I assume. I wonder about your comment that the alterntor is unlikley to exceed 14.4 at the camper battery. My 2500 GMC easily exceeds that number... more like 14.9 most of the time.

I do like the idea of setting an alarm on the BMV to alert me when I've reached a certain charge state! I'll have to implement that pronto!

 

[PaulT]

If your Iota DLS-30 has a built in IQ4, you could buy a replacement that has a jack for the IQ4. As I recall, the footprint is the same so it shouldn’t be that tough to switch as long as working in tight spaces isn’t too much of a deterrent.

I have studiously resisted the temptation to go the DIY LiFePo4 route although it has great appeal. I am old enough to be concerned that if I precede my wife to the great dispersed campsite, the camper would have off the shelf, quality electrical system that would not be an impediment to a quick sale.

Paul

 

[Stokeme]

I will join this discussion as a student who has learned a little & still needs to learn a lot. I welcome correction ...
A Victron (Smart) MPPT is a must, the controller has be completely lithium friendly. Everything has to be lithium friendly. I question the need for a BMV-712. My SP battery is Bluetooth capable, as others should be now as well. I can, using the App from my phone, see the overall charge, the temperature, the # of cycles, & with a password see the 4 individual cells & their charge.
A 7amp battery charger, I found, was way undersized. You need more amps with lithium, but just as important, not too many. I purchased a 30 amp lithium specific charger.
Lastly I would research using your truck to recharge. Your alternator “might” be within the acceptable range but make sure it is not generating too much amperage. Also, since your truck & house batteries are two different chemistries, with two different resting V, your house lithium, at rest, may discharge back to your truck as it rests at a lower V. You may need a, not cheap, specific battery to battery regulator.
I am starting from scratch with a Shell. I am spending the money to be light. I see long term value. I will use only 12V.

Rando, what will a BVM-712 do for me? If I need, I will get.
If you manually disconnect your house from truck, assuming your alternator itself does not overpower, is a B2B regulator needed? I will initially attempt to have enough solar to recharge, no truck, all light flex.

 

[camelracer]

This has all been good feedback but I still don't understand how these can be considered drop in replacements. My IOTA can probably accept the lithium IQ4 but that's not a problem right now since I don't plug in often. I can also change my solar controller to an adjustable one - just extra $$ and work.

My concern after reading your posts is with the truck charging. I just went out and ran the truck and was getting 14.1v to the camper at idle. This would put it in the bulk/absorption range and above the float voltage limits of all these batteries. If their BMS can tolerate this charge voltage from my truck why is my Morningstar controller overcharging the batteries?

Another problem is the dual sense ACR that I just installed. The higher standing voltage of the LiFePo4 battery will probably keep the ACR engaged and the LiFePo4 connected to the lower voltage FLA battery. I may have to reinstall the original battery separator.

 

[rando]

I will join this discussion as a student who has learned a little & still needs to learn a lot. I welcome correction ...
A Victron (Smart) MPPT is a must, the controller has be completely lithium friendly. Everything has to be lithium friendly. I question the need for a BMV-712. My SP battery is Bluetooth capable, as others should be now as well. I can, using the App from my phone, see the overall charge, the temperature, the # of cycles, & with a password see the 4 individual cells & their charge.
A 7amp battery charger, I found, was way undersized. You need more amps with lithium, but just as important, not too many. I purchased a 30 amp lithium specific charger.
Lastly I would research using your truck to recharge. Your alternator “might” be within the acceptable range but make sure it is not generating too much amperage. Also, since your truck & house batteries are two different chemistries, with two different resting V, your house lithium, at rest, may discharge back to your truck as it rests at a lower V. You may need a, not cheap, specific battery to battery regulator.
I am starting from scratch with a Shell. I am spending the money to be light. I see long term value. I will use only 12V.

Rando, what will a BVM-712 do for me? If I need, I will get.
If you manually disconnect your house from truck, assuming your alternator itself does not overpower, is a B2B regulator needed? I will initially attempt to have enough solar to recharge, no truck, all light flex.

If I remember correctly, your batteries have bluetooth built into the BMS which tells you state of charge, current, etc, in which case the BMV-712 doesn't add much. If your battery doesn't provide these details, it is very useful.

In would only be in an unusual situation that I would charge my battery from shore power, so for me a 7A charger would be fine, but it all depends on your situation and usage.

 

[rando]

You can just drop one of these batteries in. The BMS will cut off the charger to prevent overcharging, drop the loads to prevent over discharge, maybe shut of charging when the temperature goes below a certain point, and protect against overheating. This is an acceptable but not optimal situation for the battery unless you adjust the various parameters. This is also true with different flavors of lead acid batteries. It is up to you how much effort you want to put into optimizing the situation, some people take this further than others and there is no right answer.

I don't see truck charging as such a big deal - 14.1V will get your battery most of the way charged and in the unlikely event the alternator is going to overcharge the battery, the BMS will disconnect. Float charging is not ideal (and the BMS can't deal with that) but it we are only talking a few hours now and then. As I mentioned before noticeable damage only occurs when lithiums are sitting of float full time like a lead acid.

The dual sense ACR is designed for lead batteries (I have one too) but this is not a huge issue. My lithium battery sits at ~13.2V and thus the ACR is usually engaged, but all this means is that my car battery is sitting on a gentle float charge, which it likes. My solar more than replaces this small amount of energy every morning. I can always over ride the ACR if I need to, and if I were starting from scratch I would buy/make and adjustable ACR.

This has all been good feedback but I still don't understand how these can be considered drop in replacements. My IOTA can probably accept the lithium IQ4 but that's not a problem right now since I don't plug in often. I can also change my solar controller to an adjustable one - just extra $$ and work.

My concern after reading your posts is with the truck charging. I just went out and ran the truck and was getting 14.1v to the camper at idle. This would put it in the bulk/absorption range and above the float voltage limits of all these batteries. If their BMS can tolerate this charge voltage from my truck why is my Morningstar controller overcharging the batteries?

Another problem is the dual sense ACR that I just installed. The higher standing voltage of the LiFePo4 battery will probably keep the ACR engaged and the LiFePo4 connected to the lower voltage FLA battery. I may have to reinstall the original battery separator.

 

[rando]

I think your alternator maybe a little on the spicy side and maybe should be dialed down a notch, even for lead acid.

But it is not the alternator that really sets the voltage at the battery, it is the battery. If your alternator could produce 14.9V at unlimited amps, and the lithium battery was at 14.4V (and ideal) the battery would suck as many amps as it could until the voltage drop across your wires equals 0.5V. Usually it is a combination of the battery internal resistance (low for lithiums), the resistance in the wires and the alternators ability to source current that limits things, but it could still be a lot of current. I have the notoriously low voltage Toyota alternator, so I only see a few amps at most.
But I am not sure that is actually what you are asking. If the battery does end up fully charged and the battery rises above a safe voltage the BMS will disconnect.

+1 to what rando said. The Victron gear is great and always getting better.

rando, the OP states in his tagline that he has a "2500 Fiat CTD" - Dodge/Ram I assume. I wonder about your comment that the alterntor is unlikley to exceed 14.4 at the camper battery. My 2500 GMC easily exceeds that number... more like 14.9 most of the time.

I do like the idea of setting an alarm on the BMV to alert me when I've reached a certain charge state! I'll have to implement that pronto!

 

[Vic Harder]

rando, the ONE time I discharged my batteries to 60% was during a test to see how long they would last with all lights on, fan on full and fridge door open and set to max cold. 3 days!

I then started the truck and connected the batteries with the ACR remote switch and watched the amps on my overhead console gauges. 80A. I can't recall the volts at the time, but likely .5 over 12.3.

Yeah, a little spicy for sure.

That said, the BMS on these LiFePo4 batteries sounds wicked smart. Love it!

 

[camelracer]

I talked to the 3 battery vendors again today and a different person at BattleWorn said the Morningstar controller would be ok. The other 2 vendors kept to their original opinion - LifeBlue no and StarkPower yes. They all advised against charging directly from the alternator either by using a DC to DC charger or a switch in the truck battery to house battery connection.

I've got a desert trip planned in a couple of weeks so I'm going to order the StarkPower battery since it's the cheapest and has the built in BlueTooth monitor. I'll disconnect the alternator for this trip and deal with that later. If the Morningstar controller causes a problem I'll switch over to the Viltron after I get home.

 

[Scott_H]

Sorry for the late reply. I was reaching Lithium Batteries and ran across this thread. I found this information on the Battle Born site as a recommendation for charging from your truck using a Battery to Battery Charger:

https://battlebornbatteries.com/sterling-pro-batt-ultra-battery-battery-charger/

I hope this helps someone out West!