Anyone using both lead acid and lithium (battle born) through d250s b2b charger?

[JCDriller]

I'm pretty set on the CTEK d250s and maybe a Smartness to charge the lithium battery faster. I would like to keep my factory starting battery and add a battle born lithium house battery. Battle Born says the d250s is perfect for their lithium and built in BMS. Anyone see any issues combining different types of batteries through the battery to battery charger??

 

[john61ct]

Battle Born, like other "drop-ins" are touted as not requiring anything special, have a proprietary BMS internally that may well "buck convert" the voltage down to the 13.8V max LFP prefers for longevity.

But I have found most LFP vendors don't know or care about the issue, and when you think about it why would they want you to get 20 years out of their battery?

Personally I would use a ProMariner or Sterling and use their Custom profile at 13.8V.

If willing to spend the money, get close to matching the amps put out by your alt to recharge quickly on short trips.

PS their G31 fits perfectly into the ArkPak 730, makes a nice portable unit.

 

[DiploStrat]

Hmmmm. The purpose of the CTEK D250S is to raise the voltage of your vehicle to 14.xV for an AGM battery. Some Toyotas run at 13.9v. Why would you pay extra to boost the voltage of your vehicle when your battery only wants 13.8v?

This is one case where a simple, key controlled relay is a far better choice.

N.B. Use big wires, LiFePO4 batteries can suck a lot of amps! You have been warned.

 

[JCDriller]

It's my (limited) understanding that the voltage in the 4Rs isn't high enough. I may eventually go with 2 of these batteries, but it'll be a little while.

 

[dwh]

According to the FAQ on the Battle Born site their battery should be bulk charged at 14.4v and floated at 13.6v.

Which is baby talk. LiFE don't float. (Charlie don't surf!) The BMS cuts off the incoming power when the cells are full.

So what that probably actually means is that the BMS needs to see at least 13.6v to be able to charge the battery at all, but 14.4v will get it done faster, and over 14.4v isn't needed because the BMS will limit the voltage to 14.4v anyway.

For what it's worth, just going by the specs and FAQ (couldn't find a manual online with a quickie search), the Battle Born appears to have a fairly sophisticated BMS with both voltage and current regulation/limiting as well as cell balancing and temp sensing.

It is current limited to 100a continuous output (surge to 200a for 30sec). Also current limited on the input to C1 (capacity x1 or 100a), but for long life the recommend no more than C.5 (50a).

So the 250s, without the SmartPass would be a good fit for long life, but take longer to charge. With the SmartPass, also within spec, but if you actually do get 80a to the battery (probably won't happen very often), then again a good fit, withh possibly shaving a hair off the ballery life.

 

[dwh]

Why would you pay extra to boost the voltage of your vehicle when your battery only wants 13.8v?

To add a solar panel?

 

[DiploStrat]

Voltmeter is your Friend

It's my (limited) understanding that the voltage in the 4Rs isn't high enough. I may eventually go with 2 of these batteries, but it'll be a little while.

Any discussion of charging a camper battery from your vehicle's alternator starts with knowing the nominal charging voltage of your vehicle's system. Modern vehicle run the voltage up and down depending on the needs of the vehicle and the needs of the battery. Many Toyotas run at about 13.9v while most modern AGM and FLA batteries want a charing voltage of 14.4v. (All of this at 70F/20C and adjusted for temperature.) The easiest way to get a swag on this is the slap a voltmeter on the terminals of your battery, before, during, and after starting. In a perfect world you will see something like 12.7v at rest, a sudden drop during starting, then a rise to about 14.4v righting after starting. The 14.4v will last for a time as the battery charges.

With voltages like that, there is little need for any form of B2B. Go with a simple, ignition controlled relay, or, especially if you have solar or shore power, an intelligent relay.

If the voltages are lower, then you may be in the market for a B2B or something to simply boost your vehicle's voltage to the desired point.

All of this is for AGM or FLA.

With LiFePO4, everything goes out the window.

Basically, "12v" AGM or FLA batteries are made up of 2v cells. Actually 2.x, so that your resting voltage, fully charged, is around 12.7v. "12v" LiFePO4 batteries are made up of different cells, and typically end up with a resting voltage of around 13.xv.

AGM batteries have high internal voltage and FLA batteries have even higher internal voltage. This has three effects:

-- You must have a relatively higher charging voltage to overcome the internal voltage.
-- And, due to sulfation, then it is critical that you achieve a full charge as often as possible.
-- The final effect is that the rising internal voltage of the battery limits the charge rate - that is, the number of amps that the battery will accept.

All of this changes with LiFePO4.

-- You have relatively low internal voltage, thus you do not need the higher charging voltage.
-- More importantly, you have a flat internal voltage curve. This means that the battery takes a full charge up to almost the last moment. This means that the amp flows can be tremendous.
-- LiFePO4 batteries do not sulfate and thus do not have to be fully recharged.
-- LiFePO4 batteries do not need to be floated and, in fact, are better off without a float current.
-- LiFePO4 batteries rest at 13+v and thus most intelligent relays will not work properly as their disconnect voltages are down at 12.7v. (Victron makes a special relay with a 13.xv voltage disconnect and you can find some devices, like the Magnum SBC that let you adjust the voltages.)

Auto manufacturers have recognized the advantages of higher voltages for AGM batteries and so that is what most (but perhaps not Toyota) provide. As noted by another poster, there is thus tremendous pressure on LiFePO4 manufacturers to make their batteries "plug and play" with those higher batteries, even if they are not. Most of this "magic" is accomplished through the BMS and, in most cases, it is simply a brute force high/low voltage cut off - nothing fancy like a buck/boost circuit - no matter what they imply. (Battle born falls into this category.)

Sooooo, if you have a Toyota that runs at 13.9v, I would suggest that you start with a simple ignition key controlled relay, properly sized wires, and call it blessed.

 

[DiploStrat]

... With the SmartPass, also within spec, but if you actually do get 80a to the battery (probably won't happen very often), then again a good fit, withh possibly shaving a hair off the ballery life.

(Sorry - did not see that dwh had posted before I pressed "go.")

FWIW - in my limited testing with LiFePO4, the manufacturer provided me with a "dead", as in the BMS had shut off, 100Ah battery. Connected to my truck the charge rate jumped to over 150A and stayed there for an hour. Indeed, we had to disconnect the jumpers several times as the insulation started to melt (!!) The voltage stayed at 13.xV until the end, when it jumped to 14v and the amp rate dropped to about zero. But the battery was fully recharged in less than 90 minutes. Again, !!!

Leads me to speculate, speculate because I have not actually tested, that really big LiFePO4 banks, say 200+Ah, are going to provide a whole new set of challenges. While we used to look to B2B to boost voltages, now we may consider them to limit amps.

 

[dwh]

You saw those kinds of amps with the dual alternators of the Tiger?

A stock Toyota with a hot alternator probably won't even do the 80a the SmartPass is rated for.

 

[DiploStrat]

You saw those kinds of amps with the dual alternators of the Tiger?

A stock Toyota with a hot alternator probably won't even do the 80a the SmartPass is rated for.

Indeed. OK, I did exaggerate a bit, but not by much. We did not conduct a very rigorous, well documented test, but you may enjoy these numbers:

LiFePo 10v 160A

LiFePo 13.3A 120A

LiFePo 13.8v 106A lead 14.3V

LiFePo 13.9V 96A lead 14.4v

LiFePo 14.0v 83A lead 14.48v

LiFePo 14.1v 65A lead 14.48v

LiFePo 14.3v 46A lead 14.7v

LiFePo 14.5v 31A lead 14.7v

LiFePo 14.6v 20A lead 14.8v

LiFePo 14.7v 11.6A lead 14.8v

LiFePo 14.9v 0A lead 14.8v

​

Basically, the left number is the voltage at the LiFePO4 terminal, amps measured on the cable, and the voltage at one of the starter batteries of the Tiger.

You will note that the battery was really dead, 10v. The Chevrolet maintained a voltage over 14v the whole time. The big concern was that the alternators might overheat. The insulation on the jumper cable we used melted, so we had to disconnect every few minutes to let things cool down. Measurements were noted about every 5-10 minutes.

I might speculate that the greatest danger that the original poster might face is that the Toyota's alternator may overheat and fail. This is what happened to a friend of mine with a LiFePO4 battery bank of well over 400. Unlike AGM and FLA, the charge rate on the LiFePO4 did not drop and the battery continued to pull amps right up to the end. This was only a 100Ah battery. I would speculate, again, I have not yet been able to run tests, that the problem will be much more serious for a big LiFePO4 battery bank.

The good news is that with the proper charging equipment you may be able to get some amazing recharge numbers and thus may not need as large a battery bank.

Again, my experience only, YMMV, caveat emptor, advice worth what you paid for it, etc.

 

[battlebornliion]

Hello Everyone,
I am from Battle Born Batteries and wanted to join the discussion about LiFePO4 packs and how they recharge with alternators.

We are willing to be a resource for all of you when it comes to LiFePO4 batteries.

Couple of things I can add to this conversation at this point.

We are in the process of testing some DC to DC converters up to 30 amps on our alternator test bench.

We will be testing the CTEK d250s next week too. I received an email from the author of this post, asking us to join the thread.

The review of this charger and the DC to DC converters results will be posted soon, we will link them for you.

There is some good feedback here about LiFePO4.

They do charge quickly off of an alternator, due to the fact they have less resistance when compared to a lead acid battery. Power flows in easily.

What questions can we answer for all of you? We are happy to help.

Also I personally invite any of you to a tour of our factory in Reno, NV. If you are in town give us a call, we would like to see you.

Sean

 

[Semi-Hex]

Thank you for posting! I've been looking at lithium batteries for a short while but am confused as to charging them using only solar with my Victron Bluesolar mppt 75/15 controller and a 180 watt panel. My rig is a teardrop and my needs aren't huge.
I honestly just like the idea of an almost worry free and lightweight system.

 

[DiploStrat]

Thank you for posting! I've been looking at lithium batteries for a short while but am confused as to charging them using only solar with my Victron Bluesolar mppt 75/15 controller and a 180 watt panel. My rig is a teardrop and my needs aren't huge.
I honestly just like the idea of an almost worry free and lightweight system.

180w of solar should get you just under 10A of charge with good sun.

Assuming that the Victron is rated for a 100% duty cycle; that is that it doesn't overheat/shut down, etc., you can expect that a decent LiFePO4 battery will recharge at close to the rate of 10A per hour. LiFePO4 batteries have the advantage that they don't require a significant overcharge to recover - thus 50Ah of discharge really only requires about 50Ah of recharge.

Sooooo, you need to know:

-- How much power do you need overnight?

-- How much sun will you have the next day?

My instinct is that I would still want to harvest power from the vehicle alternator.

 

[dwh]

Hi Sean,

Welcome to the forum. Most people around here have a decent understanding of lead-acid batteries (and solar->lead charging), and most have seen the comparisons between lead and lithium. So putting any sort of sales spin on your posts could end up being counterproductive. Straight up tech talk will be highly valued. Also keep in mind that there are some engineering types around here who will check your numbers to see if they add up.

When it comes to lithium "drop-in" replacement batteries for deep cycle use, the great mystery is the BMS. Knowing precisely how it operates will be a major boon to those trying to make a decision to move to lithium.

For instance, as I mentioned in a previous post on this thread, the FAQ on the Battle Born site says to bulk at 14.4v and float at 13.6v. These are obviously the numbers for a typical lead-acid charging setup, and it makes sense to use them to reassure buyers that their existing system will work with the lithium drop-in replacement.

BUT...for people who understand batteries and charging, it is, as I said, baby talk.


So...

What exactly is the BMS doing? (Technical details please - assume we've already read the marketing materials.)

What is the actual full charge voltage of the battery?

What is the perfect charge voltage?

I.e., if the cells total up to say 13.8v, what is the BMS doing when the supply voltage is over 13.8v? Regulating the voltage internally, obviously, but how? PWM fast-acting chatterswitch or what?

Sure, existing tech will work, but for those with expensive and sophisticated fully programmable systems (not me, I'm just a gadfly), what exactly would be the perfect programming to make your batteries most happy?

Knowing exactly how the BMS behaves is crucial to figuring out how to integrate the drop-in replacement to an existing system - for example a system based around a battery to battery charger such as a CTEK or Sterling Power Products (both popular around here), or a system built around an automatic connection relay (ACR) such as those from Blue Sea, National Luna and Samlex, or even just a dumb ignition-controlled split-charge relay.

And that doesn't even touch on dialing in a programmable solar charge controller. "Enquiring minds want to know."


The next most common concern would be temperature. Aux batteries used in "overlanding" can see some temperature extremes at both ends of the scale. The FAQ says your BMS protects the cells from low or high temps.

How exactly?

(Obviously, that is not the same as the "temperature compensation" that solar charge controllers do for lead-acid batteries, but people could easily confuse the two.)

What are the temperature set points programmed into the BMS, and what exactly does the BMS do when it hits those set points?




I'm sure there will be lots more questions. You might keep in mind that this forum has well over 100k subscribers, most with disposable income, and at any given moment there could be more than a thousand lurking and browsing and learning, even if only a few of us are posting.


Cheers.

 

[JCDriller]

Sean,

Thank you for taking the time and calling me today, posting to this forum and getting a D250S to conduct testing. Assuming the tests go well next week and the D250S and Battle Born lithium are a good match I'm going to place an order.

Just to recap what we discussed on the phone for others who may have similar questions

After discussing this combo with you it sounds like as long as I just use the d250s and don't install a Smartness I don't need to be worried about over taxing my alternator or cables because the d250s will limit the amperage to only 20 amps.

We also discussed that I will be running a 100w solar panel full time on my roof and that the battery should not be damaged by the 13.6v float charge the d250s puts out since it will just equalize with the voltage of the fully charged Battle Born battery.

Finally, on our first conversation last week you guys said that the BB battery can be used in freezing temps, but when the internal temperature sensor on the battery gets below freezing the BMS keeps the battery from taking a charge to ensure it isn't damaged.

I'm appreciative of everyone's input, I'm trying my best to follow it, but I'm still having to do some additional reading to make sure I understand what is being said. I've got 3 college degrees, but this stuff is very different from the field I'm used to working in.