Voltage Reducer 36v to 12v

[dougmcp]

Originally Posted by scottyb

Is THIS what we are talking about ?
Has anybody tried it yet to see what happens? You get 36v test it with a meter not your radio ... the problem is that the batteries are connected in series via the battery cables so even though you can grab 12v off of one poor soon to be doomed pair, when you grab 3 12v sources and connect them together the negative from the first 12v source and the positive from the last 12v source = 36v .... I hope this helps. Keep the brain teasers coming.

Sorry to say but the electrical rule is you cannot series/parallel wire batteries like that without a big bang.

[Spawn]

Thats what I thought, you can do one or another but not both.

[Gale Hawkins]

Originally Posted by scottyb

Is THIS what we are talking about ?
Has anybody tried it yet to see what happens? You get 36v test it with a meter not your radio ... the problem is that the batteries are connected in series via the battery cables so even though you can grab 12v off of one poor soon to be doomed pair, when you grab 3 12v sources and connect them together the negative from the first 12v source and the positive from the last 12v source = 36v .... I hope this helps. Keep the brain teasers coming.

Thanks scottyb. I think you captured what I was talking about. We had 6" of wet snow today and the temp got up to about 33 so I got the backhoe started without ether and used the front end loader to clear over a 1/4 of a mile of county road that is made up of two major hills. I think I will get an 8' blade for the 265 MF before next winter.

I will run back outside and get my church bulletin to review my diagram after I get cleaned up and eat. I used the leather gloves that I used to spread tobacco stalks and I smell like dark fired tobacco again.

[Gale Hawkins]

Originally Posted by dougmcp

Sorry to say but the electrical rule is you cannot series/parallel wire batteries like that without a big bang.

Doug my A and B schools Navy training in electronics was in 1974-1975 in Millington TN so I am sure I have forgotten most of even that.

If you or someone can find if such a rule exist that would be most helpful.

I am looking to a technical reason it can not be done since people are doing it I understand.

[Gale Hawkins]

Originally Posted by Spawn

Thats what I thought, you can do one or another but not both.

People are doing both to power headlights, etc now Spawn. I am just talking about tapping 12 volts from three different locations vs. one or two like most do.

If someone has technical info that states you can not do both at the same time that is all we need to settle this in my dense head.

[scottyb]

Okay...... You have 6 batteries strung in series = 36v. You tap 1 pr =12v or you tap another pr = 12v but you tie both pr together & because they are series wired, the series wiring over rides the parallel. Go get your voltmeter and jumper wires, you see what I mean. The "prs" are already in series so that when you parallel the last pr you will have 36v ... That is what I was trying to show with my drawing..... I hope this helps more than it confuses....

[dougmcp]

Originally Posted by scottyb

Okay...... You have 6 batteries strung in series = 36v. You tap 1 pr =12v or you tap another pr = 12v but you tie both pr together & because they are series wired, the series wiring over rides the parallel. Go get your voltmeter and jumper wires, you see what I mean. The "prs" are already in series so that when you parallel the last pr you will have 36v ... That is what I was trying to show with my drawing..... I hope this helps more than it confuses....

Sorry, this is still incorrect, if you take any line from the negative side and attach it to somewhere up the bank, you have a direct short across the batteries just like putting jumper cables from the positive to the negative on a single battery. Batteries in series can not be paralleled unless you break the series connection first.
If you insist on doing this you will have an explosion or at least lots of sparks.
Don't make it so confusing draw your series/parrallel circuit with just 2 batteries and you will see what I mean.

[Gale Hawkins]

scottyb I am going to use the volt meter. I may even take all the batteries out to make it easier to wire up a test set of parallel/series at the same time to get a physical picture of what you are saying. If what Doug expects to happen does happen at least it will not be in the cart.

I am guessing due to the date these batteries may never have been out of the cart so the sucker needs a good cleaning on a day warm enough to use water but I do have hot water. Thanks

??? scottyb in studying your diagram I take that you just omitted to draw the longer EZGO jumper wire on the left side of the the 36v bank?

[Gale Hawkins]

Originally Posted by dougmcp

I posted this in another area but will repost here:
You could only use 2 batteries on a 36v pack for an inverter, a series parallel connection will not work on a golf cart (a series/parallel hook up would leave you with the 12v power to operate an inverter but 24v short of operating the golf cart).
What are you planning to operate with an inverter?
IMO, a large inverter should not be run from the cart bank, you need separate batteries.
Not to say it won't work but a 2000 watt inverter will kill 2x6v batteries in 30 minutes running something like a 1200w coffeemaker. Recharging after using the inverter would overcharge the other 4 batteries in the pack so bad it would probably ruin them.

I agree about your coffee maker example and will just get it at McDonalds. What am planning to run with the 2000 watt inverter off the golf cart batteries is a pole saw to go around the edge of fields. 30 minutes of run time will give us about 4 hours of use which is as long as I can last using a pole saw. There should not be any overcharging issues because we plan to figure out how to extract 12v out each of the three sets at the same time and in equal amounts.

If you will look at scottyb's diagram and number the top row 1,2,3 and the bottom row 4,5,6 point out where the direct short(s) will appear. Assume there is a - to + jumper between batteries 1 and 4. Thanks.

[scottyb]

The short comes from the series cables themselves.