Kawi2strokes.com Forum

I posted this on the other board as well. I thought maybe Jim could chime in with his vast knowledge of electrical stuff??

I have an EZ Go Sport 2+2 golf cart.  It is a 36 volt set up.  I have mounted a 2000 watt inverter to hopefully do some small work with tools requiring 120 volts.  If would be nice not to drag the generator out to the field.  My question is, how do I reduce the voltage to run the 12 volt inverter safely and efficiently?  I have some ideas with some relays to alternate the wiring on the bank of six 6 volt deep cycle batteries, but I think there may be an easier and more practical way.   :scratch:

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Crankshaft Testimonials viewtopic.php?f=25&t=7593

"Let's keep your crankshaft great!"

You could wire (3) 12V cells together in series to run the cart and patch off the 12V from one cell required for the inverter.

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74 H2B with reeds and 34mm carbs
75 S3A Ram Air with reeds and 30mm carbs
73 S2A (wife's bike)
71 Yammi RT1B
83 HD Sportster
03 Yammi R1
06 Kaw 750 Vulcan (wife’s bike)
12 Yammi vstar 250 (wife’s bike)

That's a common problem, Charlie. The simple solution is to get a 36v inverter. Exeltech has a really nice line of high quality sine wave inverters that includes that input voltage. Alternatively something like you're thinking of, with relays to run it off one battery, and be able to change which one, to share the load, is a solution. If you don't have to do it very often, I guess you could get the appropriate Anderson Power-Pole connectors to allow you to drive the cart to where you need 120v power, reconfigure the three batteries so they're in parallel, and run the inverter, using great care to connect them correctly, of course.

It would be smart to put fuses right at the battery terminals. High current DC is no joke, especially when it gets over 12v!

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If it surges, that's normal, upshift.

Thanks for the info Jim. I can't post the pic here because of the size but I can post the link to the other site which is a bit more user friendly in posting pics, at least for me. In the pic you can see the inverter will run off of all of the batteries using the relays to switch between series and series/parallel. Running off of one section of a bank of batteries designed to run in series as a whole can damage one or more batteries. Basically the relays would "reconfigure" the batteries rather than physically rewiring them each time the inverter is needed. Does that make sense

Thanks too usernameandpassword. Hope the crank is doing well!

Here is the link with the "schematic" lame as it may be:

http://kawasakitriples.myfastforum.org/ ... highlight=

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Crankshaft Testimonials viewtopic.php?f=25&t=7593

"Let's keep your crankshaft great!"

It should work fine, but after going through things like this before, I'd choose the 36v inverter solution. My suggestion is for you to sell the one you have and buy a 36v one. I know that's not easy, and might cost money, but that also describes what you're going to have to do with your proposed solution, with all the high current contactors you'll need.

If you can convert to 48v, I'll make you a great deal on a brand new 1100 watt Exeltech sine wave inverter. It's good for 2200 watts of surge, so it can do things like start and run my 3/4 hp bandsaw.

I have a 48v electric boat. The main contactor has magnetic "blow outs" so when it opens, magnets push the arc out of the contacts before it destroys them. DC voltages above 12 are serious business.

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If it surges, that's normal, upshift.

Dang. Thanks for the offer and advice. For me to switch to 48 volts would involve a lot as everything on the cart like the controller and motor are 36 volt. The relays would run me about $50 total. The HF inverter was only $130 so nothing really lost there. Maybe I will go the new inverter route but was hoping to run the 12 volt winch as well. I guess a separate battery for the winch would work. Or should I say, is working

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Crankshaft Testimonials viewtopic.php?f=25&t=7593

"Let's keep your crankshaft great!"

Your contactor solution might be best if you need the winch too. I guess you just have to work out the cost both ways. An Exeltech XP1100 is around $700-$800 new. You can find them on eBay for $200-$300 used, but 36v is rare. I see 12, 24, and 48 regularly. They are bullet proof with all the self-protection circuitry they have.

Converting the 36v to 12v electronically would be cost prohibitive for the high current you need. After all, the input current for a 12v to 120v 2000 inverter would be around 200 amps at full output.

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If it surges, that's normal, upshift.

I haven't gotten to the crank loaded in the motor just yet. I want to get just a couple more parts before I go through the excursion of resurrecting this critter. Probably hit it real good in May. I want to have it available for Bike night. I have about 95% of a complete bike now. This thing was missing quite a few parts and I thought some of the S3 parts were high.

Now back to your regularly scheduled programming......

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74 H2B with reeds and 34mm carbs
75 S3A Ram Air with reeds and 30mm carbs
73 S2A (wife's bike)
71 Yammi RT1B
83 HD Sportster
03 Yammi R1
06 Kaw 750 Vulcan (wife’s bike)
12 Yammi vstar 250 (wife’s bike)