I need advice on how to adjust the float voltage of this old battery charger.
The charger works just fine except the float voltage is about 13.15VDC, which is a bit low. (Shouldn't it be a bit closer to 13.8?)
So far, I can't find any schematic or circuit explanation.
I'll take any advice to reverse engineer this...measure voltages at various components...determine where I could change the value of a resistor or other component so that the float voltage is raised to the proper level.
Thanks in advance.
#Battery #Charger #Circuit #Electronics
@KrajciTom@universeodon.com
I would not mess around with this. I'd not bother about small differences in float voltage... and fancy chargers might temp compensate that anyhow.
Given the limitations of a float only charger I'd likely toss this and get one capable of doing bulk as well as float charge. Like the one I have: https://www.amazon.com/dp/B000FRLO9Y
Which will do 7A constant current charging... handy if needing to get a flattish battery charged again (although these and many other modern chargers will not charge a super-discharged battery (~<2V in this case)). I like that charger but have not characterized it's charge cycles/performance, but you don't need all the over the top fancy feature claims.
What is this for? For your car in the garage over winter?
You charging what battery specs? (what is C and is this VRLA, flooded LA, LiFePO4, etc. does it have a BMC?)
Is there a problem with the batteries?
Have they been checked with a discharged into a load that simulates real world load? Or maybe just ~C/20 discharge rate... since that's the rate used to define the battery marketing capacity. But good battery manufactures will provide discharge curves at multiple constant current loads. Old car headlight or similar make OK "constant current" loads. Yes this is not testing CCA but it's still very useful. Until you do that you don't have a good handle on battery health or what measuring a voltage and guesstimating a SOC from that really means.
@KrajciTom@universeodon.com There are just a few points between maintained and boiled dry. I suggest staying lower.
@KrajciTom@universeodon.com
A float voltag of less than 13.8V seems to boil off fewer batteries. I usually run about 13.5. If the charger bulk charges to 13.8 and then switches to a lower float voltage I wouldn't worry. Give it a bulk charge before use.
There's a chance that one or more of the blue resistors set the voltage, they are high precision. R7 and R10 appear to have been running a bit hot. It may be worth checking their values.
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@zl2tod@mastodon.online
I have used this charger many times. It pushes amps up until only 13.15VDC, then says charging is done, and holds things at that voltage.
@KrajciTom@universeodon.com
...
I'd guess they are 222Ξ© and 182Ξ© but I'm not entirely confident of that. If they are just ballast resistors for the LEDs you can ignore them, unless the charger is using one or more of the LEDs as voltage references.
@zl2tod@mastodon.online
I don't have a schematic, and I'm not good at analyzing circuits, but my hunch is that the two LED's are merely indicator lights (charging, and charged).
@zl2tod@mastodon.online
I don't have a schematic, and I'm not good at analyzing circuits, but my hunch is that the two LED's are merely indicator lights (charging, and charged).
@KrajciTom@universeodon.com
Can you photograph the back of the board, and transcribe the part numbers on the transistors?
@KrajciTom@universeodon.com
Can you photograph the back of the board, and transcribe the part numbers on the transistors?
@zl2tod@mastodon.online
SCR1 = TYN225
SCR1 = TYN225
Q1 = C9012 G 916
Q2 = 2N4401
Q3 = 2N4401
Q4 = C9012 G 916
VR1 = 93AFLL9 TL431C TI
The Green LED signifies "ON"
The red LED signifies "charged"
Circuit board is fed by a center tapped transformer. The center tap is also ground, which is connected to the green wire ground of the 120VAC wall plug.
R7 looks like it may have been running even hotter than R10.
Thank you for this!
@zl2tod@mastodon.online
SCR1 = TYN225
SCR1 = TYN225
Q1 = C9012 G 916
Q2 = 2N4401
Q3 = 2N4401
Q4 = C9012 G 916
VR1 = 93AFLL9 TL431C TI
The Green LED signifies "ON"
The red LED signifies "charged"
Circuit board is fed by a center tapped transformer. The center tap is also ground, which is connected to the green wire ground of the 120VAC wall plug.
R7 looks like it may have been running even hotter than R10.
Thank you for this!
TomKrajci πΊπ¦
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π³οΈββ§οΈ
