Sterling BB1260 Running 80C+, Normal?

john61ct

Active member
Firstly, the " Battery should be getting 60A." is dependent on the banks SOC.
And the battery's size in Ah, and the CAR of the chemistry involved.

If all that was involved was voltage conversion, they would be a lot cheaper.
 

marklg

Well-known member
You’re right, 60A spec is for input current.

Also per spec: B2B turn on at 13.3V, off at 13.0V (input)

In other words, the device should have turned off when In V is below 13V. It doesn’t.

Also, the device is never in boost (output V greater than input V). It does ‘t operate as advertised.

Edit
Where is output voltage set point on bb?
It is the newest green stripe unit that works down to lower input voltages to be able to work with the Euro 6 vehicles. I also have the motor running voltage enabling the B2B whenever the motor is running. In that mode it works down to 12.2 V or so.

The input varied from 12.5 to 14V and the output was always 13.5-13.6V so it was both boosting and bucking the output voltage. It is set to whatever they consider Lithium output voltage levels. I saw voltage rise and current go down when the batteries were close to 100%, so it seems it is in pretty good agreement with the batteries.

Regards,

Mark
 

calbiker

Well-known member
It makes more sense now that the device operates in either buck or boost mode. Efficiency in boost is about 80%, while in buck (when input voltage is greater than spec output V of 13.6V) efficiency goes to pot.

Consuming 200W for that small enclosure is not good. The mosfet you mentioned has an on resistance of just 4 mohm. Power consumed by fet is:

P = l^2*R = 60^2* 0.004 = 14.4 W

The fet isn’t the major heat source.
 

marklg

Well-known member
It makes more sense now that the device operates in either buck or boost mode. Efficiency in boost is about 80%, while in buck (when input voltage is greater than spec output V of 13.6V) efficiency goes to pot.

Consuming 200W for that small enclosure is not good. The mosfet you mentioned has an on resistance of just 4 mohm. Power consumed by fet is:

P = l^2*R = 60^2* 0.004 = 14.4 W

The fet isn’t the major heat source.
There are four FETs, so the current is divided among them, so the losses are even lower. There are two dual diodes. I think the current is divided among them too, but I did not trace out the whole circuit. As an approximation, the voltage drop in a diode is about 1 volt. Out of the 12.5V, that is already an 8% loss to start. I expect there are dynamic losses and inductor losses too.

I believe it to be what is known as a SEPIC converter from looking at the parts inside.

There are other syncronous switching converter topologies that can use FETs all around, so the diode losses are eliminated. Does anyone know if the other brands of B2B converters use those topologies?

Regards,

Mark
 
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john61ct

Active member
Obviously energy efficiencies are not a huge priority when an alternator is the input.

I do not know of any purpose designed B2B charger with Sterling's flexibility and customer service responsiveness, the Auusie and Renogy units are very one-dimensional.

The key issue here IMO is handling the heat, both ambient and internally generated.

How do you think that's going now with your new replacement unit?
 

marklg

Well-known member
Obviously energy efficiencies are not a huge priority when an alternator is the input.

I do not know of any purpose designed B2B charger with Sterling's flexibility and customer service responsiveness, the Auusie and Renogy units are very one-dimensional.

The key issue here IMO is handling the heat, both ambient and internally generated.

How do you think that's going now with your new replacement unit?
Works great with extra cooling. See post #30 if you haven't already. I'm considering it "good enough". At reasonable temperatures in the vehicle with the extra cooling, I get the max output. It handles the low voltages provided to it by the alternator. It stops trying to charge when the batteries are just about 100%.

Regards,

Mark
 

marklg

Well-known member
I'm curious what numbers you would see if you bypassed the b2b? Just use a regular isolator.
That is where I started. Didn't charge the batteries to anywhere near 100%. That is why I went through all this.

Regards,

Mark
 

marklg

Well-known member
I meant without that, obviously should not be needed once you start exiting the inner circles of Hell that you currently choose to inhabit :cool:
It would be at 1/2 power most of the time, so I might as well have bought the cheaper 30A unit. So, a custom 3D printed part and about $30 in blowers and hoses fixed that up.

Regards,

Mark
 

jbm-sd

Member
Hi Mark,
I recently purchased the same BB1260, green stripe. I live in the San Diego area, so we get hot, but not as hot as you. I am having similar issues and my installation is much more ideal. I mounted mine in the driver seat base, so my wire runs are much shorter. Here's the information I sent to Sterling.

My BB1260 is cycling between what appears to be its maximum output current and ~25A. I captured some more data this weekend. My alternator was holding pretty steadily right around 14V. I had discharged my 2 Lifeline GPL-4CT batteries to about 67% SOC and I removed all loads before starting my van.


Over the drive home, the charge started at 45A. I guess the charger just has a 75% efficiency? Ambient temps were around 75F.


Then after about 3-4 minutes, you can see the charger took its first dip in output current to 28.3A. There were no alarms audible from the BB1260, and the fans were cycling on and off normally. Input voltage was still ~13.8V-14.1V


It continued to do this even into the Absorption phase. The times along the X axis are Time of Day.


At this point I feel like there is a problem with my charger, or that it is grossly oversold as a 60A unit. I have installed it with the remote sense wire, the temperature sensor on the negative battery post (the one actually connected to ground, not the midpoint between batteries), and with the ignition sense wire hooked to the D+ terminal of my sprinter van.
 

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Wherever you go, there you are.
That pattern of peaks and troughs for current and voltage suggest to my non-expert brain that that the cycling of the current may be an artifact of a deliberate charging process or an undesired control system oscillation - hopefully Sterling knows which and will provide enlightenment. The 60 amp rating is an input current limitation; max output current will vary according to the output voltage difference from input with an efficiency factor I think.
 

marklg

Well-known member
If you had the Sterling remote, you would see the temperature rising until it cuts back to low power, then temperature falling, going back to high power, and repeating. It has inadequate cooling. If you mounted it in the seat base, I bet it is sucking it's hot air back in. It needs more cool fresh air.

See post #30 of this thread to see what I did.

Regards,

Mark
 
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john61ct

Active member
60A is indeed a marketing number, probably closer to the max **input** amps rather than output.

And of course subject to limiting if heat gets too high, certainly better than wrecking the unit.

See also 99% of the alternators out there.

If you need more amps, get an alt/VR setup rigged directly to the House bank.

Or if that is impractical, double up on the Sterlings.

No one makes more powerful or better B2Bs out there afaik.
 

calbiker

Well-known member
The drivers seat base can get extremely hot on my T1N. I know this from pressing the back of my heel against the seat base while driving. The feeling is: yikes, damn that's hot! Not sure what's going on. The fuel tank is located below the seat and that can get very hot.

It's possible the B2B has an overtemperature oscillation.
 

calbiker

Well-known member
The oscillating V/I data is interesting. One can calculate battery resistance.

The steep vertical V jumps are due to battery resistance when charging current makes a radical change.

Battery resistance = delta V / delta I

At the start: R = 0.268V / 16.8 A = 16 mohm

Close to the end: R = 0.525 V / 16. 25 A = 32 mohm

Resistance doubles as the batteries SOC gets to 80%.

Some of the calculated resistance is probably cable resistance from controller to battery. Perhaps 5 mohm cable resistance? That puts battery resistance at ~11 mohm.
 

jbm-sd

Member
If you had the Sterling remote, you would see the temperature rising until it cuts back to low power, then temperature falling, going back to high power, and repeating. It has inadequate cooling. If you mounted it in the seat base, I bet it is sucking it's hot air back in. It needs more cool fresh air.

See post #30 of this thread to see what I did.

Regards,

Mark
I agree, it's likely temperature limiting. I'm certainly not willing to invest in the remote to confirm that theory at this point. But it goes to show how marginal the thermal design of this thing is. I've felt around the exterior of the seat base including where it is mounted and it doesn't even feel warm. I wonder if the heat sinks aren't properly seated on the transistors/diodes.

The seat pedestal mounting may not be ideal, but as I said in the post, I did not hear the fans running full-bore during this time. I will pay more attention to that in the future. Also, I have alpine swivels, which have a 4~5" hole in the center which would allow a path for heat escape and more airflow. But frankly, I'm not willing to go to the extremes that you have to make this thing work as it should. This just appears to be a result of low efficiency and inadequate thermal design.

Anyway, my main goal for posting was to support your own observations and put more information out there for others considering the Sterling B2B chargers, as they seem to be highly recommended. They did seem to have the best charging algorithm to match the specifications for my batteries. I think I might try the Kisae DMT-1250 and try to work around the early absorption cutoff point for tail current, or simply use an ACR to handle the bulk phase while driving and rely upon my TBD solar system to complete the absorption and float phases of the charging cycle.
 

VanGuy6678

Member
Just to add two more cents to this topic, my BB12120 behaves similarly - always has. It manages to pump ~60+ amps into my 400Ah LiFeBlue battery bank, for about 3-5 minutes after starting the engine. This tells me the alternator is healthy. But then the BB cuts down to half that quite suddenly, then tapers to about 20 amps for the remainder of my drive. Solar helps increase the charge, but still. 20 amps from a beefy 120A Sterling Charger is...poor. My BB is mounted directly beside my house batteries, inside what I’d call a large, fairly well-ventilated cabinet.

In hindsight, wish I’d gone with a second, dedicated alternator with Balmar regulator.
 

john61ct

Active member
That is a BBW series, not as adjustable as BB.

Put an ammeter and DMM on the inputs as well as the output.

I bet it's the alt protecting itself.

Unless the LFP is hitting Full. . .
 

calbiker

Well-known member
Sterling isn't well designed. It doesn't meet specs.

I would not advise anybody purchasing this product.
 

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