{"id":271,"date":"2021-09-04T17:18:20","date_gmt":"2021-09-05T00:18:20","guid":{"rendered":"http:\/\/www.cafeelectric.com\/blog\/?p=271"},"modified":"2023-12-20T10:06:56","modified_gmt":"2023-12-20T18:06:56","slug":"elec-trak-dc-dc-converters","status":"publish","type":"post","link":"https:\/\/www.cafeelectric.com\/blog\/2021\/09\/04\/elec-trak-dc-dc-converters\/","title":{"rendered":"Elec-Trak DC-DC converters."},"content":{"rendered":"\n

I love my Elec-Trak lawn tractor. It’s about 50 years old though, and the lead acid batteries are not very cost effective anymore so I upgraded them to Lithium Iron Phosphate batteries and also added an inverter to run my shop if the power goes out.
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E15 with Lithium batteries and Magnum MS-4448PAE inverter<\/figcaption><\/figure>\n\n\n\n

If you also have upgraded to lithium, you’ve surely noticed that there is an issue with driving the 12V lights and the 18V lift motor; lithium packs can’t handle the imbalance of mid pack power taps. DC-DC converters are the answer, here is how I used inexpensive units from Amazon on my E15.<\/p>\n\n\n\n

I used a 10Amp unit for the lights:: https:\/\/amzn.to\/3BKPeEi<\/a>
I modified this 20 Amp one to put out 18V for Lift motor: https:\/\/amzn.to\/2WN8cLD<\/a>
using a 5.1k 0603 resistor like the ones in this kit: https:\/\/amzn.to\/3BLdbLl<\/a>
(any 5.1K ohm resistor should work if you can manage to fit it in there with fancy fingerwork)<\/p>\n\n\n\n

In retrospect it seems to me you could use two 20 Amp units for both applications for a slightly higher cost. I did the lights first and then ordered the Lift DC-DC so I didn’t think of this. I probably would do this next time.<\/p>\n\n\n\n

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E15DC-DC converters installed in Electrak E15 <\/figcaption><\/figure>\n\n\n\n

Lights<\/h2>\n\n\n\n

The 12V unit is pretty simple. The Control and Light fuses are connected to 36V Negative, and so these fuses are a good place to connect the DC-DC negative wires. For the 12V light DC-DC I connected negative (black) on the bottom of the light fuse in order to fuse it. The high voltage input (Red) I connected to the bottom (unfused) side of the Lift fuse. The 12V output (Yellow) I connected to wire #12 that used to connect to the battery pack. Mount the DC-DC with a couple small self drilling screws and the lights are all set! <\/p>\n\n\n\n

Lift Power<\/h2>\n\n\n\n

I was not able to find an inexpensive 18V output DC-DC so the Lift DC-DC requires modifications in order to get it to put out 18V instead of 12V. This is a little tricky as you’ll need to open it up and add a 5.1K resistor to the network that sets the output voltage. Fortunately there is an unused pad at R10 for a surface mount resistor. Soldering in a 5.1 K resistor on the empty pad labeled R10 raises the output voltage to about 18.5V. Mine had 25V rated output capacitors so I expect it won’t mind the higher output voltage. <\/p>\n\n\n\n

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Top left showing location of pad R10 for the 5.1K resistor<\/figcaption><\/figure>\n\n\n\n
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My scribbled schematic of the voltage regulator section<\/figcaption><\/figure>\n\n\n\n

Once the Lift DC-DC was modified I connected the HV input (Red) to the top side of the lift fuse to keep it fused (remove wire #17 from the fuse for later use.) The thicker negative wire (Blue) I combined with wire #51 that used to tap the battery and then connected both wires to the top of the light fuse for a unfused B- connection. Both negative wires (Blue and Black) are connected inside the DC-DC, so I capped the thinner black wire from the DC-DC since it’s unnecessary. The modified now 18V output of the DC-DC (Yellow) I connected to the wire that I removed from the top of the lift fuse, wire #17. <\/p>\n\n\n\n

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GE E15 wiring diagram<\/figcaption><\/figure>\n\n\n\n

This is the wiring diagram that I used for this E15. I think they are also available somewhere on the web. I’m guessing you already have one if you’ve done a lithium conversion. If yours looks different than mine, beware that the required wiring connections may be different.<\/p>\n\n\n\n

I switched the main power switch back on and everything (aside from the intermittent corroded light fuse) is working well and bringing smiles. <\/p>\n\n\n\n