Battery Charger Fan

[RoyMercer]

This is a reply I did from another forum from somone asking about failing fan(s) on their Lawnbott Battery charger / power supply:

A drop of 3-in-one oil will make it last a bit longer. If the charger is inside with good ventilation, that power supply probably does not need the fan. Unless you have four batteries that are completely drained and its over 100 degrees, even outside with good ventilation, I doubt the fan is required. The transmitter does not draw enough current to fully load that power supply even charging two batteries. However, you can remove and replace the fan. The fan is connected via a two pin connector on the circuit board. On each end of the power supply there is a "frame-face" plate. A small flat head screw driver (trying to remember but I think you will see a small gap on each side)will lift the plate and give you access to the screws you will need to remove.

A quick search reveals Digi-key's part number is 259-1199-ND. However I don't think that part number will get you a fan with the connector.  The fan is made by Sunon. The OEM part number is: KD1204PFS1. If I had more time I would have done more research for you but that should get you on the right path.

Most importantly is what Oscar said, keeping the dirt and dust out. That stuff insulates the components and blocks air flow.

Steve Amelung

[RobotLady]

That's a great idea, Steve.  We also noticed the power supply is rated for indoor temperatures.  Therefore, we always encourage people to keep it inside if they can. 

[RoyMercer]

 That is a great observation RobotLady!

For people that have out of warranty power supplies and a KNOWN good accurate multimeter and know what your are doing, you can adjust the output voltage very easily. You probably only need to do this if you have a LB3500 that does not charge past 2920 or so. The charger is  (regardless what the label says)  factory set at 29.3 volts.  There is a blue potentiometer on the circuit board side that has the output charging voltage. Turn the pot clockwise to increase the voltage. I would only adjust it 1/10th of a volt or ½ /10th at a time. I would never go past 29.6 volts or so or you risk destroying your batteries.  Set your voltage with the supply un-loaded or no robot in the charger. You may wish to do this if you use a disturbance filter too because of the Vdrop the filter creates.

If you set it too high and it works, you may have an intermittent or dirty connection that all the sudden becomes a good connection and destroy your battery(s)!!

**DOING THIS WILL VOID YOUR WARRANTY!!**

*DO THIS AT YOUR OWN RISK*

*ONLY DO THIS IF YOU KNOW WHAT YOU ARE DOING*

[cullen]

Here's how I ended up replacing the power supply fan.  I used a replacement fan I found at Radio Shack with the same specifications.  However, the fan had no connector on the end (bare wires) and in my limited search I did not find a good replacement.

1. remove the fan from the power supply (after unplugging, naturally).
2. desolder the leads from the fan.
3. trim the leads on the new fan fairly short (about 2 cm) and strip the ends.
4. solder the new leads to the old leads (red to red, black to black).  You now have a new fan connected with a connector on the end.
5. insulate the soldered connections (heat shrink tubing would be very good for this, but electrical tape works).
6. reinstall.

I suppose someone more deft with a soldering iron than I would have soldered the old leads directly to the fan.  Or someone might have figured out where to get a new connector or how to attach the old connector to the new leads directly.

[Bill S]

What is the charge voltage for the lead acid batteries ?  Mine is reading about 27 volts.