24v Input for both Motor & Logic?

[nickosinski]

Hello,

I'm looking to run the RoboClaw (2x5a) at 24v, but when I do so I get the dreaded error light. I think that it has to do with the logic power as I have the jumper set to draw logic power from the main batter source (used to power/drive the motors). With this jumper setting and using 12v, I have no trouble, but when I attempt to use 24v, I get the error light.

Would someone please confirm one way or the other how to go about this the correct way?

Thank you in advance!

Nick.

[nickosinski]

One more thing... I ran the Read Voltages functions and this is the output that I get:

MAIN Voltages: Min = 0, Max = 336
LOGIC Voltages: Min = 0, Max = 180

Thank you again,

Nick.

[Basicmicro Support]

Based on the maximum voltage settings I assume you are using a Roboclaw 2x7a? If not please tell me what version you are using. I beleive the default setting for the 2x7A is 18v max on the logic voltage whether that voltage is coming from the main battery or a seperate logic battery. Youcan change it to upto 33.6 volts.

Also you may want to update the firmware on the board if yours is older than 4.1.16 or 4.1.19. I suspect it is older based on the default max voltage for the logic battery.

[nickosinski]

Hello and thank you for the reply.

I wrote in my first message that I have 2 of the (2x5a) roboclaws - assuming that your instructions are the same, is there any drawback to running the logic off the 24v as well?

Thank you again for your help,

Nick.

[nickosinski]

I found an old thread that suggests the old 2x5a shouldn't be run any higher than 18v... so if that is, in fact, the case, I have a 2 related follow-up questions:

1) When powering the RoboClaw logic and motor's separately, is there an order to how the power should be delivered. For example, should the 5v for logic always be applied before the main motor voltage (which is 12v or 24v), or should the main battery voltage be flowed to the RoboClaws before the logic (5v) is delivered? ...or does it not matter?

2) If the RoboClaw has the 12 or 24 delivered to it while there is no 5v powered being delivered for the logic, is there any potential harm to the boards? What about the other way around... any harm to the boards if the logic power is delivered, but the main motor voltage is 0 (zero)?

Thank you again,

Nick.

[Basicmicro Support]

We dont recommend running higher than 18v on the old 5a but the linear regulators are rated for at least 30v so you can run 24v even on them. It will just get really hot(the regulator) which will bleed heat into the rest of the board.

For efficiency sage using a seperate external switching 5v regulator is much better(we've switched to a 5v switching reg on the latest 2x7a boards).

1. On the older units you may need to turn main battery on first and then logic so they dont through an error since the mosfet drivers will not be powered until the main battery is connected(this is assuming older firmware). On the latest firmware order really doesnt matter.

2. The mosfet driver chips have internal pulldowns and will latch the mosfets off when main power is connected but no logic power is connected so it is safe to turn the main battery on first.

[nickosinski]

This is a perfect explanation. Again, thank you for taking the time to explain and elaborate on the "why" and "how" for best case usage.

I know that they're older boards, but they work... for now, and I'm learning so much from you guys. I've been recommending RoboClaws to everyone

Thank you again!

Nick.

[Basicmicro Support]

We appriciate it. Thank you. Let me know if you need anything else.