24 volt system

HWR MKII · Post by **HWR MKII** » Wed Jun 30, 2010 3:22 pm

Ok i have a 24 volt electric system with a 12 volt stem on it. the 24V system is 2 bridged 12 volt batteries. The unit has a 24V pos and neg leads and another 12 volt secondary lead for powering the basics of the system. Im assuming that the 24v neg lead is also the neg lead for the 12 volt.

My big question is on the 2 batteries bridged neg to pos, which battery in the system would i hook the 12 V lead to in order to prevent it getting 24V through it and blowing the system. The 12 Volt lead is also the on off switch for the unit. WOuld i hook it to the first battery in the series or the second battery?

Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Wed Jun 30, 2010 6:52 pm

The first battery in the series, the one that the negative lead comes off.

HWR MKII · Post by **HWR MKII** » Wed Jun 30, 2010 7:05 pm

Thanks for the response Umi. Im hesitant to hook this thing back up as it is a very expensive system. Its for a 1/6 scale RC tank, i know you are knowledgeable of RC equipment as well. If you would like to better help me understand i can take pictures of the components. I just want to be sure that i have the right info before i have resistors and such exploding and i release the magic white smoke.

Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Thu Jul 01, 2010 3:29 am

I have it right in my mind...

...-|I|I|I|I+ -|I|I|I|I+
GND........12v.........24v

But pictures might be good.

Sparky · Post by **Sparky** » Fri Jul 02, 2010 2:44 pm

Hook up the batteries as you expect to use them, leaving the wiring leads for the 12 volt and 24 volt system unconnected but clearly marked (mayeb in a polarized connector of sorts), then measure them out.

you probably have a common negative/ground. If you have more than one ground going into the device but they should be common, you can confirm the wires are common with an extra step please advise if you need this.

So get a volt meter (digital multimeter set to DC volt meter) and measure like this:
Take its negative/black/ground probe and clip it to the common ground, should not move this connection during the rest of the measuring process.

Take the positive/red probe and measure the '12 volt' lead, confirm you read 12 volts, or 13.x volts as some sealed lead acid batteries show this voltage if they are measured without a load (a volt meter does its best to not load what ever it is measuring).

Take the positive/red probe and probe the '24 volt' lead and confirm you read 24 volts. . . .

There is an alternate wiring connection method that would work but I think it best not to confuse the testing methods. Please confirm the above connections sound like plan.

HWR MKII · Post by **HWR MKII** » Sat Jul 03, 2010 12:30 pm

Thanks guys.

Yes i believe it is a common ground as the only negative lead it for the 24V neg. That is why i question hooking the 12V pos to the same terminal as the 24V Pos. I have tried to use a meter on it and dont get any real reading off it on any setting. I know the unit isnt faulty. Its new.

Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Sat Jul 03, 2010 1:32 pm

Make sure the test leads are plugged into the correct sockets.
Make sure the meter has a good battery.

The 12v positve and 24 volt positve terminals are NOT the same.

Set the meter to DCv 200 (something higher than 24v).
Put the black lead to the negative ground terminal, then
put the red lead of your meter to the positive terminal of the same battery.
It should read 11-13.6 volts depending on the charge.

When you move the red lead of your meter to the second battery inthe series, it should read 22v-27v.

Where's that picture you were gonna post?

My ASCII diagram shows the voltage pattern.

The negative is common. Both the 12v and 24v use the same
negative(black) terminal.

Where the two batteries are linked,
Positve to Negative.... That is where you will get 12v.
(The "first" battery" the one with the "common ground")

The second Battery should have it's negative terminal linked to
the "first" battery, and will supply 24v from its Positive terminal.

This will be verified by your multimeter.

....... Batt#1 ........... Batt#2
...-|I|I|I|I+ -|I|I|I|I+
GND...........12v.............24v
Common

HWR MKII · Post by **HWR MKII** » Sat Jul 03, 2010 3:26 pm

sorry about no pics. Been busy as heck here. 4th of july is celebrated on the 3rd here if it falls on a sunday. I am hopping on when i get a 5 min break. Ill try to get a pic on tonight. Ill link the batts and tape the leads to the batteries near their respective terminals. That way you can see how it " should go" and direct me from there. They will be taped so i dont risk blowing the control unit.

Sparky · Post by **Sparky** » Tue Jul 06, 2010 3:01 am

Sounds like the confusion is, what wires are coming out of the unit that tell us you need a separate 12 volt and a 24 volt supply.

There must be at least 3 wires coming out of the device. there could be 4.

But there cannot be less than 3 if it needs 2 different DC voltages.

Are you sure it is 12 volts DC and 24 Volts DC? I suppose you could have one being AC and the other DC? There are ways to make 2 wires carry 2 different voltages if one is AC and the other DC.