diy solar

diy solar

Shore Power. Charging 2 12v Battle Born Batteries wired in series on a 24 volt solar system

That charger has two terminals for positive and two for negative 12V DC. So you should be able to connect each battery separate like so:
series-and-parallel-update.jpg
(image borrowed from NOCO)

The question then is, how to make sure that they are evenly charged. I'm guessing that's where a BMS comes in.
 
NinjaDeathMonk said:
That charger has two terminals for positive and two for negative 12V DC. So you should be able to connect each battery separate like so:
View attachment 4589
(image borrowed from NOCO)

The question then is, how to make sure that they are evenly charged. I'm guessing that's where a BMS comes in.
Click to expand...
Thank you! I am going to call BB today to be sure.
 
"PD9100L Series units can be connected both in parallel and in series. "

I'm not exactly sure, but they may mean you can hook up two chargers in series for 24v. If that's what they mean, it's not a two-bank charger and it will not work. It has two sets of outputs, but if both outputs are internally bridged you can not hook it to a 24v system (without disconnecting your busbar), and I'd look for a different charger.

I'd call BB or Progressive Dynamics to confirm.


Progressive does make some 24v versions, but I have no idea how good they are:

Amazon.com: Progressive Dynamics PD9125-24LV 24 Volt 25 Amp Lithium Power Center : Electronics

Buy Progressive Dynamics PD9125-24LV 24 Volt 25 Amp Lithium Power Center: Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
 
Okay, thank you all for your responses. Here is what I found out and have done. I called Battle Born. They were very helpful and had me call Dual Pro. Dual Pro told me exactly what I needed and suggested I order from Battery Mart. Here is the unit I ended up with. I could have used a "PS2", but i went with a "PS4" so when I add two more batteries I am set. These units come pre programmed for the Battle Borns. You can also have the parameters changed in the future if you switch to other battery types.

www.batterymart.com

Dual Pro Professional Series 12 Volt 15 Amp Lithium Battery Charger - Four 15 Amp Banks

Check out the deal on Dual Pro Professional Series 12 Volt 15 Amp Lithium Battery Charger - Four 15 Amp Banks at BatteryMart.com
www.batterymart.com www.batterymart.com

NinjaDeathMon above has the exact diagram in how you hook these up. They come with the wires and you simply connect them to each battery. Again, mine are in series. The charger figures this all out which is enhanced by the BB internal charge controller.

So, now up here in cold cloudy Wisconsin (and when the sun is low and a only get a couple hours because of trees) I can simply fire up my Honda Eu1000i, plug in unit above and top off my batteries. Sweet solution and set up. Of course I could always just run the generator, but now if I am low I can fire up when I am not around so I can always enjoy the peace.
 
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smoothJoey said:
Of all the solutions that one is pretty expensive.
Why did you choose it over a simpler cheaper solution?
Click to expand...

Multi-bank chargers are expensive, but probably worth it when charging lithiums in series. Each battery gets charged separately so no BMS between batteries is necessary. My 3 bank marine chargers can't do lithium, and only output 5-8 amps to each battery...and they still cost over $300!...so a lithium charger that can output 4 x 15 amps is gonna cost some bucks. But to protect $4000 in batteries, it's kinda worth it. It may be overkill for BB's, because I think their internal BMS's are designed to allow higher voltage series charging (???), but it's gotta be better and safer anyway.

I hope someday solar charge controller companies go the multi-bank route. Maybe someday they will start making CC's that are actually designed for today's batteries.
 
SolarRat said:
But to protect $4000 in batteries, it's kinda worth it. It may be overkill for BB's, because I think their internal BMS's are designed to allow higher voltage series charging (???), but it's gotta be better and safer anyway.
Click to expand...

No BMS between Battleborn batteries connected in series is necessary.
How does a multi-bank charger protect batteries better than a simple charger?
Why does it "gotta be better and safer"?
 
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One answer to my own question, the multi-bank charger is more flexible as it allows to reconfigure the battery bank.
 
smoothJoey said:
One answer to my own question, the multi-bank charger is more flexible as it allows to reconfigure the battery bank.
Click to expand...

Yes. I assume that the outputs on that charger can be doubled or quadrupled up. So it can be a 12v, 24v or 48v charger. So for a bit extra $ up front it allows future flexibility.

smoothJoey said:
How does a multi-bank charger protect batteries better than a simple charger?
Why does it "gotta be better and safer"?
Click to expand...

Each battery gets charged separately as a 12v battery. With a 48v charger, if a BMS fails on one battery it will may see 48v...
 
SolarRat said:
Each battery gets charged separately as a 12v battery. With a 48v charger, if a BMS fails on one battery it will may see 48v...
Click to expand...

I see people on this list bypassing the bms for their solar charge controller.
If the pack has a s# >1 that should be disaster, confirm?

example bypass bms for scc
 
smoothJoey said:
I see people on this list bypassing the bms for their solar charge controller.
If the pack has a s# >1 that should be disaster, confirm?

example bypass bms for scc
Click to expand...
smoothJoey said:
So a BMS can fail dangerous?
The fets fuse closed?
Click to expand...

I honestly don't know because I've always used LA's with multi-bank chargers. On LA's, if you have one cell in one battery go bad in a 4 battery series setup, being charged with a 48v charger, you can wipe out the whole bank. But it seems to me if you have 4 BB's or xyz's in series and one BMS shorts...sending 48v to the 3 others, that doesn't sound good. Also, how does BB's BMS handle one battery that charges before the rest? Does it disconnect from the charger? If so, how do the other batteries in series still get charged? I don't know...And I don't hear it talked about either. So it's either not a common problem, or not YET a known common problem.
 
A bms is generally a protection circuit + cell balancing.
A protection circuit that fails closed is not fit for purpose.

SolarRat said:
On LA's, if you have one cell in one battery go bad in a 4 battery series setup, being charged with a 48v charger, you can wipe out the whole bank.
But it seems to me if you have 4 BB's or xyz's in series and one BMS shorts...sending 48v to the 3 others, that doesn't sound good.
Click to expand...

A protection circuit should disconnect the battery if one or more cell's voltage goes out of range high or low.

SolarRat said:
Also, how does BB's BMS handle one battery that charges before the rest?
Click to expand...

A BMS only manages/protoects the cells it is connected to.

If another battery connected in the bank had a shorted cell and it's protection circuit did not open then the other bms's could see either over voltage or over current and activate their own protection circuits

EDIT: typing while hungry
 
Last edited:
smoothJoey said:
A BMS only manages/protoects the cells it is connected to.
If another battery connected in the bank had a shorted cell and it's protection circuit did not open then the other bms's would see over voltage or over current depending on whether they are connected in series or parallel and go into protection mode.
Click to expand...

Right. But let's say you have one BB battery that always charges faster than the others. Maybe it was bought first and used for a year, or whatever reason, but it always finishes charging first. When that battery is at full voltage and the BMS shuts it down from accepting any more, but the other 3 batteries still have 5-10% to go....what happens?

If the BMS "disconnects", the series breaks and the others don't get any more charge? If it just sheds excess, the other batteries just get a higher C charge but at the correct voltage?...I guess? Or do they get a higher voltage (48v between the 3 others)? <I'm talking about with a "dumb" 48v charger. I'm not sure, but it worries me that I don't know the answer and neither do most people that are currently doing it. With LA's, the charged battery for the most part just stops accepting the charge and the current increases to the others (which aren't accepting much current at this point anyway). But with a BMS protected lithium, it's up to the BMS to do that. And from what I see there is no "standard" that all BMS's adhere to. So I'm curious what exactly happens...

To me, it seems another "master" BMS should be used to "separate" the 4 batteries when using a 48v charger, even though they each have an internal BMS. Which would be unnecessary with a 4 bank charger of course.
 
SolarRat said:
Right. But let's say you have one BB battery that always charges faster than the others. Maybe it was bought first and used for a year, or whatever reason, but it always finishes charging first. When that battery is at full voltage and the BMS shuts it down from accepting any more, but the other 3 batteries still have 5-10% to go....what happens?

If the BMS "disconnects", the series breaks and the others don't get any more charge? If it just sheds excess, the other batteries just get a higher C charge but at the correct voltage?...I guess? Or do they get a higher voltage (48v between the 3 others)? <I'm talking about with a "dumb" 48v charger. I'm not sure, but it worries me that I don't know the answer and neither do most people that are currently doing it. With LA's, the charged battery for the most part just stops accepting the charge and the current increases to the others (which aren't accepting much current at this point anyway). But with a BMS protected lithium, it's up to the BMS to do that. And from what I see there is no "standard" that all BMS's adhere to. So I'm curious what exactly happens...

To me, it seems another "master" BMS should be used to "separate" the 4 batteries when using a 48v charger, even though they each have an internal BMS. Which would be unnecessary with a 4 bank charger of course.
Click to expand...

To give this some focus.
Lets say we are talking about 4 12 volt battleborns connected in series.
The batteries draw less and less current as they approach 100% charge(an aysmptopic curve).
The fact that one battery got there first doesn't have much effect on the rest unless the charger voltage exceeds the protection circuit limit, which should not happen.
Ideally the charger should go to float voltage or alternatively just disconnect when the current goes below a certain threshold.

If the protection circuit limit is exceeded then the charge stops because the protection circuit opens.
The charger is constant current and constant voltage.
 
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smoothJoey said:
To give this some focus.
Lets say we are talking about 4 12 volt battleborns connected in series.
The batteries draw less and less current as they approach 100% charge(an aysmptopic curve).
Click to expand...

That is not how lithium batteries bulk charge...they accept whatever current is thrown at them even when nearing full. That is why they will kill a car's alternator if unregulated.

smoothJoey said:
The fact that one battery got there first doesn't change have on the rest unless the charger voltage exceeds the protection circuit limit, which should not happen.
Click to expand...

The voltage in this case is already 48v, way above the protection circuit limit of any one battery...or the other three in series for that matter.

smoothJoey said:
Ideally the charger should go to float voltage or alternatively just disconnect when the current goes below a certain threshold.
Click to expand...

Float the whole 4 battery bank early? Hell, a lithium charger shouldn't even have a float stage (that's an LA thing). If it disconnects, how do the other 3 batteries in the series ever get charged?

smoothJoey said:
If the protection circuit limit is exceeded then the charge stops because the protection circuit opens.
Click to expand...

And here is my biggest problem. A protection circuit, BMS or otherwise, is a failsafe, NOT a charge controller! I don't want my "protection circuit" determining when my $5,000 battery bank is done charging...that is what the expensive and properly designed charge controller is for! A failsafe should kick in in very rare circumstances...not every damn charge cycle!

Maybe I'm overthinking things....or maybe everyone else is under thinking things. ?;)
 
SolarRat said:
That is not how lithium batteries bulk charge...they accept whatever current is thrown at them even when nearing full. That is why they will kill a car's alternator if unregulated.
Click to expand...

That is news to me and contrary to my experience.
During the CC phase the current flow is limited by the charger.
During the CV phase current flow is limited by the battery.
If I am wrong I want to know.
 
smoothJoey said:
That is news to me and contrary to my experience.
During the CC phase the current flow is limited by the charger.
During the CV phase current flow is limited by the battery.
If I am wrong I want to know.
Click to expand...

We are both correct. Bulk stage is CC. If the charger is putting out 20 amps, the lithium battery will accept it all...same with 60 amp etc. It's not until the final 5% or so that a lithium charger switches to CV and limits current.

But the dumb 48v charger sees all 4 of the series'd batteries as one big battery. If one battery is only at 85% (it had a fishfinder and bilge pump hooked to it say) and the rest are at 90-95% SOC, what does the charger do? Switch to CV ? Wait till the whole bank voltage reaches xyz volts before switching to CV? I dunno, but I'd think the latter.

The question was "why did I say multi-bank chargers are probably better and safer". I think my questions leave enough doubt, which answers the question, for me anyway. None of this matters with multi-bank chargers...so to me, they are safer and better.

And apparently by the OP's response from BB, they agree with me.
 
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