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Old 03-23-2012, 01:13 PM
JRue JRue is offline
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Default LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

I've been thinking about using the Programmable Volt Meter from LightObject.com as a battery overcharge and over-discharge protector. I'm comfortable with my charger but I also like redundancy and since I charge at night in my attached garage so having another failsafe to help mitigate any potential risk of thermal runaway (FIRE!) sounds prudent to me. The recent talk about bricking of batteries in the Tesla got me thinking about my own EV and that I really have nothing on the discharge side to stop a slow drain from ruining my pack.

On the charge side:
I charge to a nominal voltage of 124.1 V and have observed this go as high as 125.1V during the CV charge phase. If I set the high voltage relay in the LightObjects voltmeter to say 0.5V higher than I've ever observerd (125.6V in my case) it can be used to disconnect my charger if this condition is ever encountered. The thing I really like about this method is that the worst case scenario is one of my batteries spikes 0.5V over its normal CV charge level. Reasonably I'd hope that this extra voltage is spread around to at least a few cells but regardless this should effectively limit the amount of power put into your pack.

On the discharge side:
I'm talking only about when the vehicle is parked. Say you leave the lights on for a few weeks or just are parking the vehicle for an extended period of time without properly disconnecting things and you need to keep parasitic loads from draining your pack down to dead. Set the low voltage relay for whatever low pack voltage value you're comfortable with. I'm thinking about 102.6V (2.85 V/cell). If I wire this relay in conjunction with some signal to indicate the car is off, not running, or current draw is below some small value I can run this to another contactor to disconnect my parasitic loads. Actually I'd just cutoff all my high voltage low current circuitry.

Ideally if the low voltage cutoff is triggered and everything shuts down. I want to just be able to plug in and everything will begin coming back up. I would probably need to pull some signal from the charger to energize the contactor that is between my battery pack and the vehicle parasitic loads.

I am wondering what the behavior of the device is when you power it off? Does it lose its memory? Am I going to have to reprogram my settings if it loses power? Do I need a small battery to keep it always on?

It sounds like a little bit of work but if it provides some added protection from burining my house down while my family is asleep (I know this is highly unlikely but without knowing the exact probabilities involved I'd rather err on the side of caution) and protects my batteries from accidently being allowed to drain down to nothing it seems like a cheap and straightforward solution.

Does this sound reasonable?

Last edited by JRue; 03-23-2012 at 01:16 PM.
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  #2  
Old 03-23-2012, 10:02 PM
swoozle swoozle is offline
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

Quote:
Originally Posted by JRue View Post

I am wondering what the behavior of the device is when you power it off? Does it lose its memory? Am I going to have to reprogram my settings if it loses power? Do I need a small battery to keep it always on?

...
Does this sound reasonable?
Nope, it keeps its memory when powered off just fine. No reprogramming needed. Boy, that would be a PITA.

Sounds very reasonable. I was planning to do the same (at least on the charge side) when I get my conversion done.
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Old 03-26-2012, 02:24 PM
m38mike m38mike is offline
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

I got one to use in a bottom balancer that I'm building. I'm putting the volt meter, a 2a AC-DC converter, a ev200 contactor, a 12v muffin fan and a 250w 0.1ohm resistor all in an ammo can with some assorted wires, and creating a compact but capable bottom balancer. When I'm not using it I just close up the ammo can and everything fits nicely inside. When I need to bottom balance a cell, I open up the can and pull out two cables. One for the 110vac power and one to connect to the cell with a pair of clips. I'm glad to hear that the volt meter has a memory. I'd hate to have to reprogram each time I used it.
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Old 03-26-2012, 02:58 PM
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

Quote:
Originally Posted by JRue View Post


Does this sound reasonable?
I think it sounds perfect. Git er done.

More and more ppl will go this way I think. It's just solid redundancy for bit of money... and a bit more work... .but well worth the peace of mind.
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Old 03-27-2012, 12:27 AM
StanSimmons StanSimmons is offline
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

m38mike,

Would you mind putting up a detailed, step-by-step walk thru of how you programmed that blasted thing? Mine is sitting on a shelf after spending a very frustrating couple of hours trying to decipher the instruction page on it.
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Old 03-27-2012, 07:21 AM
swoozle swoozle is offline
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

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Originally Posted by StanSimmons View Post
m38mike,

Would you mind putting up a detailed, step-by-step walk thru of how you programmed that blasted thing? Mine is sitting on a shelf after spending a very frustrating couple of hours trying to decipher the instruction page on it.
Circle, right, right, right, up, circle
Down, circle, Right, up....

How detailed?
ya, i know i'm not m38mike.

But you're right, it is a really crappy instruction "manual". And the interface must have been designed by the same people that did the celllog8. It becomes easy only after you've run through it a few times.
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Old 03-27-2012, 07:53 AM
gottdi
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

Then run through it a few times until your good at programming it. Thats how its done. It's never perfect the first time out. One step at a time.

Then once your done and good you can rewrite the manual and pass along the information.
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Old 03-27-2012, 08:08 AM
m38mike m38mike is offline
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

Stan,
Here's a link to the official Lightobject manual site for the volt meter. They have a 2 page downloadable sheet that helps a little but does not do much for me.
http://www.lightobject.info/viewtopic.php?f=14&t=157

I will go through the set up on mine again a few more times and try to write out some seemingly intelligent instructions. It may be this weekend before I get to it. I'm in the middle of building a new battery box out of oak for my Electro-Willys.
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Old 03-28-2012, 08:13 AM
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

Is it the same as the one on the EVTV store?
I was at a Starbucks when I asked the question, and couldn't pull up the Lightobjects page.

This is not the same one as on the EVTV store. This one does Volts only and as mentioned earlier in this thread, would be a great redundant shutoff for a charger. I toasted a couple of Headways when my charger ran amuck.

Last edited by ricklearned; 03-28-2012 at 08:55 AM. Reason: Answered own question
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Old 04-01-2012, 07:39 AM
m38mike m38mike is offline
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Default Re: LightObjects Programmable Volt Meter (for charge & battery slow drain protection)

I'm pretty sure the Lightobjects JLD 5740 Volt Meter is the same one that EVTV is selling. And I think I've got programming for it figured out. Mine's been working very well in my bottom balancer.

First, the keys. They look like this: [o] [>] [/\] [v] They are under that hard to open cover just under the number window. It hinges down.

All you need to have connected to program it is the 12v power source. Positive to screw 1, negative to screw 2.

First you need to tell the meter what voltage range it will operate in. It needs to get the password 0089 to know to do that. To do that power it up so you get 4 zeros. Now press [o] once. The decimal point dissappears and the first zero blinks. press [>] twice so the 3rd 0 blinks. press [v] until 8 appears. press[>] once so the 4th 0 blinks. press [v] until 9 shows up. press [o] to accept 0089.

Some criptic message appears. press [v] or [/\] to get to the numbers. they correspond to the numbers on the instruction sheet for the meter. 0-3 are for DC operation. 4-7 are for AC operation. Since I use it for single cell balancing I chose 2 which covers -2~+10vdc. Choose the code number which is right for your use. press [v] until you see "end" on the screen. press [o] to accept. Now your back at the readout screen.

Next you need to set the parameters for the meter. The password is 0036. press [o]. press [>] until the 3rd 0 blinks. press [v] to change it to 3. press [>] so the 4th 0 blinks. press [v] until it is 6. press [o] to accept. some text will appear. press [v] or [/\] until PuL appears. This sets your lower limit of voltage you want to read. Usually zero, but could be negative. press [o] to accept PuL and it will go to numbers. press [v] or [/\] to change the number to what ever you want your lower limit to be. press [o] to accept. the screen goes back to PuL. press [v] to change to PuH. This sets the upper limit you might measure. press [o] to get to the number. press [v] or [/\] to change the number up or down. I would double what ever max voltage I thought I might get to be sure you don't max out the gauge. once you have your number press [o] to accept. press [v] or [/\] to get to dot. This is how many digits are right of the decimal point. press [o] to go to the number. change the number with [v] or [/\]. press [o] to accept. next use [v] or [/\] to find FiLt. press [o] to go to the number. It should be 0, unless you have a lot of stray electrical noise around your gauge. press [o] to accept. use [v] or [/\] to find End. press [o] to accept. your parameters are set.

To set the relays in the gauge, the password is 0001. press [o] to start. press [>] until the 4th zero blinks. press [/\] to change it to 1. press [o] to accept. I use my gauge to help bottom balance, so I want to use the "upper limited" configuration because I want the upper limit of my cell voltage to be 2.708v. I only use the 1st relay. I set AH1 to 2.709 and AL1 to 2.600. With these numbers the balancer draws the cell down to 2.6v and shuts off. The cell will float back up over 2.709 and turn the balancer back on. The battery will go up and down for a while, and the balancer will turn on and off, until the cell simply stops floating somewhere between 2.700 and 2.708.

In general, Use the [v] and [/\] keys to change the settings you see on the screen. use the [o] key to start the programming, or accept what you have on the screen.

QUESTIONS???
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