Oceanic Mako - Charger

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C

cavejunky

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Location
Cleveland, OH
# of dives
500 - 999
Just recently purchased a used Mako. The scooter is in excellent shape and works great. The only concern I have is than when I connect it to the charger it sparks and the fan and power light on the charger come on. The charger charges the battery just fine, but it is somehow backfeeding from the battery to the charger. This occurs even if the charger is not plugged in. I opened the charger and checked the circuitry. All diodes seem to be in working order and the voltage output is correct. Any ideas?
 
cavejunky:
Just recently purchased a used Mako. The scooter is in excellent shape and works great. The only concern I have is than when I connect it to the charger it sparks and the fan and power light on the charger come on. The charger charges the battery just fine, but it is somehow backfeeding from the battery to the charger. This occurs even if the charger is not plugged in. I opened the charger and checked the circuitry. All diodes seem to be in working order and the voltage output is correct. Any ideas?
Click to expand...


I believe that's an indication of a shorted diode in the bridge rectifier output circuit or a shorted voltage regulator.
With a digital meter, you should see two things when the charger is on and the batteries are full with the charger connected:
  • With voltage DC selected, you should be measuring about 27.3 to 28.0 volts.
  • Then with voltage AC selected, you should see less than 250millivolts measured.
 
Thanks for the reply. I agree with your diagnosis. I had come to basically the same conclusions, however checking the diodes in the bridge rectifier does not indicate a shorted diode. Also the voltage output is 28.2 VDC. The batteries are being properly charged. If there was a blown diode I wouldn't expect to see the correct voltage output. I will check the AC voltage. I assume that if there is a diode shorted I would expect to see a higher AC voltage. Is that correct? Wish I had an oscilloscope.
 
checked the ACV with batteries fully charged. Seeing about 61VAC which sounded suspiciously like 1/2 of 120VAC. Checked the bridge rectifier and didn't see any indication of shorted diodes, but it was an easy and cheap change out so I replaced the bridge. Same symptoms
 
cavejunky:
checked the ACV with batteries fully charged. Seeing about 61VAC which sounded suspiciously like 1/2 of 120VAC. Checked the bridge rectifier and didn't see any indication of shorted diodes, but it was an easy and cheap change out so I replaced the bridge. Same symptoms
Click to expand...

I agree, the 60+ VAC sounds like half of the 120 sine wave and I would have thought a new bridge would have fixed the issue. At this point, if it was mine, I'd go spend $70 and replace it with this (it's a far better charger anyway): Battery Defender 24 Volt 4 Amp Battery Charger: BatteryMart.com
 
I agree. Still bugs me that I can't pin down the problem. I've checked everything in the circuit and can't find anything wrong. The electrical engineer in me is embarrassed. Ordered the one you recommended. I will probably keep picking away at it. If I get it resolved will put it on ebay. Thanks for the info.
 
cavejunky:
Just recently purchased a used Mako. The scooter is in excellent shape and works great. The only concern I have is than when I connect it to the charger it sparks and the fan and power light on the charger come on. The charger charges the battery just fine, but it is somehow backfeeding from the battery to the charger. This occurs even if the charger is not plugged in. I opened the charger and checked the circuitry. All diodes seem to be in working order and the voltage output is correct. Any ideas?
Click to expand...

Are you referring to the green light? Its normal for it to light up when plugged to the battery without being plugged into an ac outlet.
 
cavejunky:
yes the green light comes on and the fan also turns. Is this normal?
Click to expand...

I still have a working Mako charger. If I connect the batteries w/o plugging in the charger to the wall, my green LED is dim but my fan does not turn. When it's connected to the wall, the LED is bright and the fan is running but when I measure the AC ripple, it's about 70 millivolts when the batteries are full.

I certainly don't think it's normal to have 60vac on the output :shocked2:
 
well, normal or not, my mako charger does the same thing. never checked the voltage at the plug end but the fan runs and the light is lit when I attach the battery.
 
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