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

shade

Well-known member
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.
Has this comparison article ever been posted? I didn't find it on the Battle Born site.
 

shade

Well-known member
I've been using them for years, any specific Qs?
I bought a CTEK D250S & SmartPass combo a few years ago when I was thinking lead-acid, but I've come around to an LFP battery. I'd like to know if the CTEK combo is a good fit, or if using it would be inappropriate with an LFP battery.

Since the CTEK gear is still new in the box, this would be the time to sell it and buy something more appropriate from Victron, Sterling, etc. I'd rather do it right than kill a battery. I'm concerned about the CTEK trying to push an LFP battery to 100% SoC, and I'm probably going to need a higher capacity solar charge controller anyway.
 
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john61ct

Adventurer
Absorption voltage for the CTEK is 14.4V, Float at 13.8V.

IMO way too high for LFP, but many think OK.

The current rate in DCDC mode is limited to 20A, often too slow.

Smartpass is just a bypass, up to 80A but voltage following, profile depends on upstream source.

LVD cutoff is 11.5V, way too low IMO.

But up to you, won't cause drastic "damage", very robust build quality, dependable. The MPPT component is meh.

Many think I am too perfectionist wrt LFP care, maximizing longevity.
 

shade

Well-known member
Absorption voltage for the CTEK is 14.4V, Float at 13.8V.

IMO way too high for LFP, but many think OK.

The current rate in DCDC mode is limited to 20A, often too slow.

Smartpass is just a bypass, up to 80A but voltage following, profile depends on upstream source.

LVD cutoff is 11.5V, way too low IMO.

But up to you, won't cause drastic "damage", very robust build quality, dependable. The MPPT component is meh.

Many think I am too perfectionist wrt LFP care, maximizing longevity.
It looks to me that some LFP manufacturers are trying to gain wider adoption by promoting the "drop-in" aspect of their batteries, even if existing LA charging systems really aren't a good fit with LFP chemistry. I can understand doing that, but I'd rather do a proper installation once, even if that means selling the CTEK gear at a loss to someone wanting it for LA charging.

The CTEK gear I have is automated, so I can't do much with the charging profile. I could monitor SoC closely and disconnect charging, but that doesn't seem like a good plan. Between the canned charging profiles and MPPT side being clunky & undersized for what I need, I think you helped me answer my question. Thanks!
 

john61ct

Adventurer
IMO all charge sources for LFP should be fully user-custom adjustable.

I have yet to see one actually marketed as for LFP that I would buy.
 

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shade

Well-known member
CTEK has new versions of the D250 and smartpass that will be out soon...Called the D250SE and Smartpass 120S. Not available until closer to the end of the year.
Thanks for the information. Time to get mine sold.

IMO all charge sources for LFP should be fully user-custom adjustable.

I have yet to see one actually marketed as for LFP that I would buy.
Either that, or part of a fully integrated system from a single manufacturer, including the battery. It'd be nice to see manufacturers develop a universal interface so the battery could tell another brand of charger what it wanted, but such commonality is rarely accomplished.

Being fully adjustable could pay off when new types of batteries are released, too.
 

john61ct

Adventurer
I do not like getting locked in.

One charger can service dozens of different chemistry banks / packs.

Even if you only have one,

new information comes out wrt impact of different charge profiles,

maintenance / testing protocols use different voltages / current levels from daily usage charge cycles

etc
 

WhatPants

New member
Has anyone tried adding a Renogy 40A DC charger between your Ctek and a lithium battery? I know it's not how you would design a system from scratch, but for 160$ you would be able to change whatever your cteck gives your battery to a proper lithium charge profile.
 

john61ct

Adventurer
Huh? putting 2 DCDC in series? Why?

neither one being user-custom adjustable

If the output of one matches what the target bank wants just use it on its own.

For the price of two you coulda bought a Sterling BB unit.

Or the KISAE ABSO DCDC looks great. . .
 

j_colter

New member
Hi everyone!

Here is some info that is not in the marketing materials. The BMS is not bucking or doing any voltage regulation. It is simply monitoring the voltages, current and temperatures and acting as a high current switch, when things are out of whack. Charging and discharging circuits may be opened independently. For each, we have a bunch of high-current MOSFETs (along with some snubber circuitry) doing the switching. Basically, the charging switches will open if one of the following is detected: one cell exceeds a prescribed high voltage, the cell temperatures exceed 140F, the MOSFET temperatures exceed 170F, the charging current exceeds 200A for 0.5s, or 100A for 30 seconds. The discharging switches open if one cell falls below a low voltage threshold, the cell temperatures exceed 140F, the MOSFET temperatures exceed 170F, the cell temperatures fall below 25F (deadband at 30F), the discharging current exceeds 200A for 0.5s, or 100A for 30 seconds. High current disconnects are automatically reconnected after 5 seconds. Note that discharging is still allowed under low temp and high voltage, and charging is still allowed under low voltage. The 0.5s high current allows for initial cranking currents which typically last a couple hundred milliseconds. It's our happy medium between allowing cranking and protecting against short circuit. The BMS also has a standard passive balancing mechanism, whereby cells that are charged faster than the rest bleed current through a resistor. The batteries can be connected in parallel (provided you use appropriate cables and fittings to handle the current), and in series up to 48V.

Operationally, the batteries should be bulk charged up to 14.3-14.6V, and absorb ideally at 14.4V. The person who suggested that Li-ion batteries should not float is correct. However, some chargers require a float, and we recommend setting it at 13.6V or below, since that is below the natural float of the charged cells. The cells leak charge at a rate of only 2-3% per month, so they can be stored for long periods of time without a trickle charge.

That's it in a nutshell. We would be happy to answer any other questions. Feel free to call: 855-292-2831
@battlebornliion I found this page on your site https://battlebornbatteries.com/charger-compatibility-table/
In the comments it says the ctek d250s/sa cannot be used with your lithium batteries. Is that correct or is it ok to use it with them?
 
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