Schumacher versus Battle Born — no winners

JMc

Solar Enthusiast
I have two new 100ah Battle Born group 27s and the instructions are to charge them before use. My Schumacher charger has a selection for AGM/Gel and I set that to try and top off the BBs using a 15A charge rate. On the first battery the charger only ran for a few minutes before announcing the battery was at 100%. The second battery took a bit longer and the charger‘s display went from 72% to 100% in about 15 minutes. After disconnecting the charger and resting for a few minutes I measured the voltages and one battery is at 13.5V while the other is at 13.7V.

Obviously something is not right as there is no way the 15A charger added 28ah of charge in 15 minutes. I’m thinking the BMS in the BBs is terminating the charge current and this fools the Schumacher into declaring the batteries are “full”. The company claims its batteries are drop-in replacements for AGMs. Has anyone here used an automotive battery charger to top off BBs?
 

JMc

Solar Enthusiast
Model of the Schumacher charger? Is it one of those simple transformer and rectifier type?
This charger is their “smart” model (or what passed for such in 1995) and it weighs about five pounds so I doubt there is much of a transformer inside. It has a CPU and LED display and supposedly tailors the charge cycle to each type of lead acid battery.
 

time2roll

Photon Sorcerer
Need to measure the voltage and current to confirm the shut down. I would try the GEL setting if available. Or AGM as a second choice.
 

JMc

Solar Enthusiast
Need to measure the voltage and current to confirm the shut down. I would try the GEL setting if available. Or AGM as a second choice.
The charger has a combined AGM/Gel setting. There is no way to know what the BB BMS is doing. When charging at 15A there is a 0.2V difference between the charger’s voltage display and the voltage I measure at the battery terminals — from the resistance of the cables. This difference goes away indicating no current flow when the BBs terminate charging. The voltage at the terminals never rises above 14V during the charging.
 

time2roll

Photon Sorcerer
I thought BB went to 14.4+ before high voltage cut off. Maybe the battery is full. Give it some use and see what goes.
 

JMc

Solar Enthusiast
I thought BB went to 14.4+ before high voltage cut off. Maybe the battery is full. Give it some use and see what goes.
Thanks — I’ll give that a try tomorrow when I hook up to the inverter for the first time. The inverter has a built-in charger which by default is set up for AGM so I’ll have to figure out how to change it to the mode for Lithium.
 

JMc

Solar Enthusiast
I conected one of the BBs to my inverter today (Samlex EVO) and it looks like their batteries are indeed shipped with close to a full charge. The Samlex charger initially put 15A into the battery at 14.4V (bulk mode) but quickly reduced the current to less than 2A, same behavior and pattern as the 25-year old Schumacher. I’d like to run a full power test and cycle the batteries but the 4/0 battery cables aren’t ready yet (I used a set of jumper cables) so it’ll have to wait.
 

Substrate

Solar Addict
Oh man, PLEASE do not use a lead-acid Schumacher smart-charger, or so-called "Speed-Charger"

Their main purpose is to resuscitate that dead lead-acid in the garage and get you speedily back to work - or the battery store. But not so good for regular maintenance.

Part of their routine is that if the "smarts" in the charger thinks you need an EQ, it will do so, but it will NOT show it on display. Ie, I tracked several models that put 15.5v into an agm battery - measured at the battery terminals - where the "absorb" was only displaying 14.6v to the user. I freaked when I saw this on my new CBA-IV analyzer. But the damage was done to my agm which wasn't designed for 15.5v.

The LFP BMS should protect against this type of overvoltage of course.

When I was starting out with my own GBS prismatic cells, there was NO WAY I would ever let a Schumacher speed-charger near them!

So please be cautious with automotive chargers basically designed for lead-acid.

Lately if it isn't a programmable bench supply that I use, I sometimes fall back to purposely designed LiFeP04 chargers like those from Tecmate-Optimate (Model TM-271) for 12v LFP. Built in diagnostics helped my peace-of-mind when I didn't want to drag out all my testing stuff....
 

JMc

Solar Enthusiast
Oh man, PLEASE do not use a lead-acid Schumacher smart-charger, or so-called "Speed-Charger"

Their main purpose is to resuscitate that dead lead-acid in the garage and get you speedily back to work - or the battery store. But not so good for regular maintenance.

Part of their routine is that if the "smarts" in the charger thinks you need an EQ, it will do so, but it will NOT show it on display. Ie, I tracked several models that put 15.5v into an agm battery - measured at the battery terminals - where the "absorb" was only displaying 14.6v to the user. I freaked when I saw this on my new CBA-IV analyzer. But the damage was done to my agm which wasn't designed for 15.5v.

The LFP BMS should protect against this type of overvoltage of course.

When I was starting out with my own GBS prismatic cells, there was NO WAY I would ever let a Schumacher speed-charger near them!

So please be cautious with automotive chargers basically designed for lead-acid.

Lately if it isn't a programmable bench supply that I use, I sometimes fall back to purposely designed LiFeP04 chargers like those from Tecmate-Optimate (Model TM-271) for 12v LFP. Built in diagnostics helped my peace-of-mind when I didn't want to drag out all my testing stuff....
I agree that the older chargers were not very gentle — lead acid can take quite a bit of abuse compared to lithium. The issue with BB is they claim their LFPs are drop-in replacements, plug-n-play, and there is no way to monitor what the BMS inside the battery is up to. When I hooked up the Schumacher it was set for AGM and 15A and that is what it delivered at 14.4V for a few minutes. Then the BB BMS terminated the charge and the Schumacher assumed it was finished and showed 100% capacity.
 

Zwy

Solar Addict
I agree that the older chargers were not very gentle — lead acid can take quite a bit of abuse compared to lithium. The issue with BB is they claim their LFPs are drop-in replacements, plug-n-play, and there is no way to monitor what the BMS inside the battery is up to. When I hooked up the Schumacher it was set for AGM and 15A and that is what it delivered at 14.4V for a few minutes. Then the BB BMS terminated the charge and the Schumacher assumed it was finished and showed 100% capacity.
I see this is an old thread but.......LA Smart chargers will throw a higher voltage out in order to increase charging amps and possibly reduce some plate sulfation LA batteries. I've seen mine bump up to over 16V on a LA battery, a BMS in a BB will not like that and will cut charging off immediately.
 

Substrate

Solar Addict
That's a big problem for manufacturers, having no idea what the end-user is going to use it to charge - and possibly damage it, so the BMS with it's own protection circuitry is the front-man for establishing a warranty.

Most of the lead-acid charger do all sorts of shenanigans not applicable to LFP. Such as doing 16v "de-sulfation" spikes when encountering terminal voltages of 10.7 to 11.7v or lower etc etc.

These days it is a bit easier to find just simple 14.6v CC/CV chargers. Batterspace.com has them in a wide range of amperages. So do many EV outlets.

On the consumer side, one of my favs are the Tecmate-Optimate Lithium (LFP ONLY) chargers for small to middle sized banks. Even Noco has gotten their act together with the LATEST versions (Black Body, NOT the earlier gray-body models) which have dedicated LFP settings. Without getting too far into marketing, at least they automatically shut down with no attempt to "float" and seem to do the right thing when you track the whole charge profile (like with a CBA-IV analyzer). The earlier models (gray body) with lithium settings were a bit problematic for me.

But yeah, as Will found out, the old transformer based chargers can be a death-sentence for an expensive bank, and the lead-acid shenanigans of most automotive smart-chargers can either result in a poorly charged battery, or testing the capabilities of the BMS to protect your investment.

So sure, sometimes "drop-in" can be a precarious thing the manufacturers have to deal with. I just spent $1K for my lifepo4, but I'll charge it with my $14 Battery-Tender and save some bucks! Yikes, false economy but you just don't know. I feel sorry for the manufacturers.
 
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PopDBop

Solar Enthusiast
I'm late to the party (thread) here, but isn't it the function of the BMS to correctly charge the individual cells in a commercial mfg'ed LFP battery, as long as the charger outputs a voltage in the BMS's input voltage range? Of course the charger would need to be able to provide enough amps at that voltage to handle the charging load.

However, unlike 'dumb' lead acid batteries that benefit from a smart charger, the lithium batteries with BMS's have the smarts built-in. A smart charger would at best be suboptimal (one set of smarts in the charger outsmarting another set of smarts in the battery), and at worst damaging to the lithium cells, especially if the charger is jacking up the voltage above the battery's BMS rated Vmax input .

I'm using large lithium for the first time and want to make sure I get this straight in my head before plunking down $$$ for a battery charger.
 

Zwy

Solar Addict
I'm late to the party (thread) here, but isn't it the function of the BMS to correctly charge the individual cells in a commercial mfg'ed LFP battery, as long as the charger outputs a voltage in the BMS's input voltage range? Of course the charger would need to be able to provide enough amps at that voltage to handle the charging load.

However, unlike 'dumb' lead acid batteries that benefit from a smart charger, the lithium batteries with BMS's have the smarts built-in. A smart charger would at best be suboptimal (one set of smarts in the charger outsmarting another set of smarts in the battery), and at worst damaging to the lithium cells, especially if the charger is jacking up the voltage above the battery's BMS rated Vmax input .

I'm using large lithium for the first time and want to make sure I get this straight in my head before plunking down $$$ for a battery charger.
No, the BMS's purpose is to protect against cell damage from overcharge, low volts protect, low temp protection, high discharge rates and keep cells balanced.

It is not a charger controller.
 
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