And the battery's size in Ah, and the CAR of the chemistry involved.Firstly, the " Battery should be getting 60A." is dependent on the banks SOC.
If all that was involved was voltage conversion, they would be a lot cheaper.
And the battery's size in Ah, and the CAR of the chemistry involved.Firstly, the " Battery should be getting 60A." is dependent on the banks SOC.
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.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?
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.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.
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%.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?
I meant without that, obviously should not be needed once you start exiting the inner circles of Hell that you currently choose to inhabitWorks great with extra cooling.
That is where I started. Didn't charge the batteries to anywhere near 100%. That is why I went through all this.I'm curious what numbers you would see if you bypassed the b2b? Just use a regular isolator.
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.I meant without that, obviously should not be needed once you start exiting the inner circles of Hell that you currently choose to inhabit
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.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