Inspected the variable 100A charger today.
In spite of my worries about it's construction, a close inspection revealed a couple of screws that needed an 1/8th of a turn to get them nice and tight.
Looking round for dry or solder joints didn't reveal anything.
A quick test with the meter for blown semiconductors showed everything was fine.
It also showed that the metal case of the unit was only connected to the -VE DC output via a small capacitor. Now that isn't to the UK spec (and I suspect most of the rest of the world) where anything with a metal case must have the case connected to earth just in case the internal circuitry shorts out and connects mains directly to the output terminals. This is easily sorted with a new 3 core mains cable with the earth connected to the right places.
Happy that all was good as far as I could tell, plugged in to the wall and turned on.
All good.
Max voltage is 29.2V, minimum charging current is as low as 6.3A which is better than I was lead to believe, having been told that the minimum was around 20A. That's good news as I can still charge the batteries (albeit very slowly) when the solar panels are producing as little as (6.3A @ 24V) 150W.
Connected to the battery and out with the digital thermometer to see how hot parts inside the charger get.
Set it to 20A and everything is room temp (20 deg C) apart from the main HF transformer (30 deg C) and a balancing resistor between the high V main push - pull transistors (50 deg C).
Set to 50A charge current and HF transformer is upto 33 deg C, balancing resistor is 65 deg C.
That resistor is a ceramic enclosed wire wound type with has a max operating temp of 250 degrees C, so it is well within it's rated power, although it is down between the main HF transformer and a huge choke on the other side, so the air flow provided by the twin fans won't get that much air past it. I'll test it a bit more later on and may move it up further into the air flow if it gets over 150 deg C.
The absolutely massive heatsink increased in temp by 5 deg C after 10 mins @ 50A.
Overall it runs a LOT cooler than I expected it too. I've only run it upto 75A for a short period, as I suspect a brand new LifePO4 battery will not appreciate being charged at its absolute maximum charge rate for the very first charge!
I'll do a few cycles of full charge & discharge with the inverters and then do a 100A charge and check the charger temperatures.
Overall I'm very happy with it.
Yesterday I realised I'd forgotten to buy any fuses for anything - they're on the parts list but got overlooked. So an order for the large DC fuses and smaller AC fuses plus holders and a nice little DC fuse panel which will be perfect was put in earlier today. Should be here towards the end of the week when I'll be able to lay out everything and sort out the cabling.
No comments:
Post a Comment