lithium low voltag cut off

Volt_Ampere · 04-05-2016, 02:37 PM

No. You should not have continuity between the two negatives. That is what Isolated is all about.

Jim C · 04-05-2016, 02:43 PM

Ok, thanks. That's what I thought. I'm talking to a local shop that has a 5 wire 35 amp so he thought it was. I stopped by, none of his techs were there but I got him to check the two negatives and there was continuity on them. So I just wanted to confirm it.
Thanks for the help.

Sergio · 04-05-2016, 02:48 PM

Just because You don't get continuity it may not mean it is isolated as you don't know the internal circuit or how it was tested.

It could just have an internal diode to protect against reverse polarity or even disabled until powered up.

If it is truly isolated You should not get a voltage reading using the input negative and the output positive wires.

Volt_Ampere · 04-05-2016, 02:49 PM

Almost all of the reducers I have researched are not isolated. You can buy an isolated one from an electronics supply house - and you can get a very low current one just to run your meter.

Jim C · 04-05-2016, 03:08 PM

Ya it looks like that's what I'm going to have to do.
I'll probably get the one Sergio linked for the meter and get a reducer from ScottyB.

Jim C · 04-05-2016, 03:14 PM

I kept meaning to post this question on another thread http://www.buggiesgonewild.com/elect...-question.html

So is this quote from the above mentioned thread correct or not?

Quote:

Originally Posted by rottie

iI will work for any system, but it must be in the negative lead if you use it w/o a isolated supply.
If use an isolated power supply, it can go in either lead regardless of controller.

Sergio · 04-05-2016, 03:41 PM

It is correct for that kind of meter linked:

Power Supply 10V~90V (external/Internal power supply)

Measuring range:
(1)Volt 0~120.0V / Amp 0~500A, external power supply
(2)Volt 10~90.0V / Amp 0~500A Internal Power supply

Please note that when not using an "external" power supply (2) you are limited to the max of the internal supply (90v). The JLD404 is only 30v power supply.

Some meters have a pretty good internal voltage isolation and can be used without any special "isolated" power requirement, but unless specifically noted in the specifications, I would used the cheap POL (Point of Load) reducer.

By the way, do You need to keep that meter powered all the time to track AH used?

Jim C · 04-05-2016, 03:47 PM

Ok so that one didn't even need a separate power supply.

From what I understand the 404 doesn't loose it's memory when off.

Thank you.

04-05-2016, 02:37 PM	#21
Volt_Ampere Gone Wild Join Date: May 2012 Location: Rio Verde, Az Posts: 7,183	Re: lithium low voltag cut off No. You should not have continuity between the two negatives. That is what Isolated is all about.

04-05-2016, 02:43 PM	#22
Jim C Gone Wild Join Date: Oct 2008 Location: Wildwood, FL Posts: 742	Re: lithium low voltag cut off Ok, thanks. That's what I thought. I'm talking to a local shop that has a 5 wire 35 amp so he thought it was. I stopped by, none of his techs were there but I got him to check the two negatives and there was continuity on them. So I just wanted to confirm it. Thanks for the help.

04-05-2016, 02:48 PM	#23
Sergio Gone Wild Join Date: Sep 2012 Location: Charlotte, NC Posts: 9,329	Re: lithium low voltag cut off Just because You don't get continuity it may not mean it is isolated as you don't know the internal circuit or how it was tested. It could just have an internal diode to protect against reverse polarity or even disabled until powered up. If it is truly isolated You should not get a voltage reading using the input negative and the output positive wires.

04-05-2016, 02:49 PM	#24
Volt_Ampere Gone Wild Join Date: May 2012 Location: Rio Verde, Az Posts: 7,183	Re: lithium low voltag cut off Almost all of the reducers I have researched are not isolated. You can buy an isolated one from an electronics supply house - and you can get a very low current one just to run your meter.

04-05-2016, 03:08 PM	#25
Jim C Gone Wild Join Date: Oct 2008 Location: Wildwood, FL Posts: 742	Re: lithium low voltag cut off Ya it looks like that's what I'm going to have to do. I'll probably get the one Sergio linked for the meter and get a reducer from ScottyB.

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04-05-2016, 03:41 PM	#27
Sergio Gone Wild Join Date: Sep 2012 Location: Charlotte, NC Posts: 9,329	Re: lithium low voltag cut off It is correct for that kind of meter linked: Power Supply 10V~90V (external/Internal power supply) Measuring range: (1)Volt 0~120.0V / Amp 0~500A, external power supply (2)Volt 10~90.0V / Amp 0~500A Internal Power supply Please note that when not using an "external" power supply (2) you are limited to the max of the internal supply (90v). The JLD404 is only 30v power supply. Some meters have a pretty good internal voltage isolation and can be used without any special "isolated" power requirement, but unless specifically noted in the specifications, I would used the cheap POL (Point of Load) reducer. By the way, do You need to keep that meter powered all the time to track AH used?

04-05-2016, 03:47 PM	#28
Jim C Gone Wild Join Date: Oct 2008 Location: Wildwood, FL Posts: 742	Re: lithium low voltag cut off Ok so that one didn't even need a separate power supply. From what I understand the 404 doesn't loose it's memory when off. Thank you.

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