lithium low voltag cut off

[Jim C]

If using a reducer (controlled by the key) to power the meter for low voltage cut off, when the meter cuts the power, then how will it come back on if the meter isn't getting power to know that the voltage is back up?

I really don't want an accessory battery.

[Volt_Ampere]

Wire your reducer so it doesn't go off when the meter cuts power. What kind of relay are you using to cut power?

[Jim C]

JLD 404
While I havn't delve into the existing cart schematics it would be rather convenient to let it shut off via key or tow/run switch.
The reducer needs to be operated with the key so there isn't a load while cart is in use.

[Sergio]

Since the JLD404 relay outputs are not that strong You will need to add an external relay anyway.

The easiest way would be to add a N.C. relay to the key switch "cold" side circuit.

The "cold" side of the key switch would connect directly to the converter "trigger" wire as well as the "Common" contact of the new relay.

The rest of the "switched" power would connect to the N.C. contact of the relay.

That way the converter is still controlled by the key switch, but the JLD404 can activate the relay and disable power to the controller if needed.

Edit: It just occurred to me the JLD404 requires an isolated power supply to measure the voltage levels on your cart, do You have a dedicated power supply for it?

[Jim C]

Ok, I was going to shut off on the hot side so nothing would draw but I suppose there shouldn't be much draw anyway as I'll just turn key off till it gets to charger.

So what relay would you recommend to add?

I have searched the specs but didn't see where it said it required isolated power supply,
But I am looking for an isolated reducer, which correct me if I'm wrong, will have a 12v negative output, besides the 48v negative input.

[Volt_Ampere]

In isolated reducer will have two negative wires. One for the 12V and one for the 48V. And they won't be connected like on most reducers. Isolated reducers have a transformer in them to isolate the input and output. By the way most reducers are not of this type because isolating with DC requires extra circuitry and cost.

[Sergio]

The isolated converter will have no "reference" to the input negative.

Just about any amp meter that uses a shunt requires isolated power if the voltage being measured exceeds the "supply voltage" for the meter, which is 30v for the JLD404.

You can use a DC-DC converter off the full package voltage like this one for the meter:

http://www.ebay.com/itm/DC-Converter...item518ebba48b

I like these kind of 48v relays as they have a 20ma coil current which makes it ideal to run an LED in series with the coil without any resistors (so You can tell when the cart is being disabled by the relay):

http://www.mouser.com/ProductDetail/...B/T9AP5D52-48/

While it is a good idea to disable all power coming out of the batteries (Radio, headlights, etc), I can also see the benefits of being able to have "running lights" or a phone charger operational if you get stranded in the dark.

[Jim C]

Originally Posted by Sergio

The isolated converter will have no "reference" to the input negative.

So I should not be able to read continuity between the 48v neg. and the 12v neg.

[Sergio]

You should not be able to read any "voltage" with the meter positive probe on the +12v and the negative probe on the 48v negative wire

[Jim C]

Ok, but I will be able to read continuity between the two negatives?