# PakTrakr - a must or nice to have?



## dimitri (May 16, 2008)

I have been driving Miata EV for 2 months now, just went over 1000 EV miles mark this week. I feel that I am coming down with a mild case of upgraditis  , so I am looking into getting a PakTrakr. I can think of other ways to spend $220 , so I am asking those who have experience with this device, is it a must or nice to have?

I read all the info about it on the Web site and came up with following questions:

- how accurately does it detect Low Water condition? Obviously it must figure it out based on voltage, but how accurate can it be? How does voltage indicate low water, unless its way too low and battery is already ruined. Does low mean plates are sticking out? If so, its not very useful.

- how do you work with display and buttons? What does default display show while driving? Overall pack stats or individual battery? How much do you need to fiddle with buttons to get basic info?

- are there any audible alerts?

- are there any display alerts that come up on their own?

- do you have optional current sensor? how well does it work? is it worth extra $50 ?

- how satisfied you are with PakTrakr overall? If you could change something about it, what would it be?

Thanks in advance


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## TelnetManta (Jun 5, 2008)

Dimitri,

I haven't, as you know, finished my EV yet but I did get a PakTrakr and have hooked it up to "test" it out a bit while I waited on other parts.

I felt that it was worth the extra cost over analog gauges as it could monitor each batteries voltage the whole pack voltage as well as give me a "fuel gauge". The biggest issue that I have with the unit is the small screen size and that its difficult to see in certain lighting conditions. Because of this I plan to pick up an additional screen to mount in my dash.

See it here: http://www.wacparts.com/index.php?main_page=product_info&cPath=7&products_id=41


I really think that the PakTrakr should come with a screen like this as an option. I also opted for the current sensor so that I could get all of my information from one source. The default display is the "fuel gauge" but you can toggle between the screens pretty easily with the two buttons to see total battery voltage as well as individual batteries.


HTH,
Ben in SC


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## TX_Dj (Jul 25, 2008)

PakTrakr is a neat device.

One of the NTEAA members is working on a similar product which I think is going to be more extensible than the PakTrakr product.

The biggest advantage, in my mind, is that you can watch voltage sag on a brick-by-brick basis to easily determine if there are any problems in the pack.

For example, the system that the guy from NTEAA is building was being tested in the chapter president's vehicle. They determined that one of the batteries in the pack was sagging substantially more than the others. When they looked at the suspect battery, they found one of the bus bars was incredibly hot, and the battery was burning up lots of power through a resistive loss at that junction.

Considering the chapter president has LiFePO4 batteries, this is a serious concern (it is for all chemistries, but this was no $100 cell).

Other planned features for that system include current monitoring, temperature monitoring, and more- with interfaces ranging from a simple display like PakTrakr, to USB port for laptop integration, to memory storage for telemetry replay.

I know almost nothing about PakTrakr other than some cursory reading, but if the entire system is only $220 to monitor voltages at each battery in the pack, I'd say it's well worth the investment.


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## dimitri (May 16, 2008)

Thanks guys, I wish someone who actually uses the device could chime in here.

One thing that I must know before I buy is how state of charge data changes when you accelerate and voltage sags, does SOC data "jump" every time you press the pedal? If so, when is SOC showing actual SOC? When you let go of the pedal? 

Same for individual battery voltages, will there be bunch of alarms when it sags under load?

Thanks


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## sailfish11 (Sep 15, 2007)

Does anyone know of a good digital (e.g. lcd) display gauge for higher voltage systems (144 and up)? I'm going with a 288V AC system and I'd like to get a good multi-function gauge.

My dream gauge would be one that's integrated into one of those stereos with the pop-up lcd screen. Electric Blue Motors (the guys in Phoenix -- not Wayne) has one like that they put in their conversions, but I don't know if they sell it separately.


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## Wirecutter (Jul 26, 2007)

I've been using a PakTrakr for over a year now on my gokart. Yeah, I know, it's not as "serious" as a regular vehicle, but you should see how I abuse it!

I don't use any "water monitoring" function - I didn't know one existed. I have the basic display, the 6-battery module, and a 500A current sensor. The display has 2 lines, and I set mine up to display pack voltage on the first line and battery current on the second.

When I power up, the first thing that comes up on the display is the selection for the max current for the current sensor. The default is 100A. So I hit the "advance" button until 500A comes up, then hit "go". The unit then calibrates itself for 0-500 amps. Then I advance a couple of items to the "SOC" (state of charge) where I can select either "FLDD" or "AGM". (Not sure about the abbrieviation used for "flooded lead acid") The default is "FLDD", so since I'm using Optimas, I select "AGM" (absorbed glass mat). When all that's done, I advance the first line to read pack voltage. Wait a sec for the selection to go away and the actual reading to appear, then advance the second line to read amps. Finally, I'm now ready to go.

I mostly like the PakTrakr. It keeps an eye on my batteries and I can easily see if one is getting weak or perhaps needing replacement. If it has any audible alarms, I've sure never heard them. It does reconfigure the display to "Remote alerts" when any battery voltage goes below a certain threshold. Continued use after that point really endangers the battery.

What I would like to see improved:

1. Have an option where I can buy the modules with connectors and cables unassembled so I can do that part myself. For the voltage monitoring module, the connections to the batteries are on a pigtail that is hard-wired into the box. If no allowance is made for wires to go bad and be replaced, the wires will most certainly go bad.

2. If I get "Remote Alerts", I'd like the option of pushing a button to acknowledge, then return the display to what I want to see. As it is, I have to ack the alert and then reconfigure to continue monitoring what I want.

3. I'd *really* like it to remember my default configuration, rather than having to do all that programming every time I power up. It's annoying, and it's not at all difficult to fix in software.

On the positive side, the PakTrakr is pretty much the lowest cost system I've found with its features. I wouldn't say it was suitable for a full sized car with $20,000 worth of lithium batteries, but for my little gokart, it does okay. When I got it, I weighed its cost against the cost of my battery pack and decided it was a good idea. YMMV.


Edit: The "update" rate seems to be about once every 2 seconds. I normally monitor voltage, not SOC, but I do see it sag under load, especially as the batteries run down. I also see the voltage creep back up when I stop drawing power and let it rest. There's a name for that "effect" but its name escapes me just now.

There's also a combined mode of both upper and lower display lines that I use a lot when I want to check the health of the pack. Basically it shows a bar for each cell whose height is proportional to the SOC. The display scrolls an arrow pointing down at each bar in sequence. When the arrow is over the bar for a particular battery, the lower line gives that battery's voltage reading. It's very handy for finding any weaklings.

Oh, and I also wish the system was waterproof. I really don't think it is.

-Mark


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## dimitri (May 16, 2008)

Mark, thanks for excellent write up! Really appreciate you taking time to respond in such great detail! I feel like I own it already 

It is really strange that you have to configure the unit every time, if its drawing its power from the pack and its hard wired to the pack, then it should be "always on", isn't it?


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## fugdabug (Jul 14, 2008)

Howdy,
I use a pak-trakr, in fact I just sprang for three more remotes to fill in my new 144VDC pak. I had a set of six 12V's (a simple 72VDC setup) that I was using a pak-trakr with remote on, in addition to the volt meter and amp meter. I have to say, I like it! It is multi-versatile tool to get a better look at battery pack temp and even monitor single battery states (the state of any one battery in the pack!)... so if you like to 'make sure'... it can't hurt! Get it. The nice thing is that the remotes come in an 8 battery array as well as a six battery monitor array. 
I LIKE IT.
*presently waiting for controller replacement am on 'down-time' right now.


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## Wirecutter (Jul 26, 2007)

dimitri said:


> Mark, thanks for excellent write up! Really appreciate you taking time to respond in such great detail! I feel like I own it already
> 
> It is really strange that you have to configure the unit every time, if its drawing its power from the pack and its hard wired to the pack, then it should be "always on", isn't it?


 Well, technically yes, but when I either put my kart away or charge it up, I turn off _everything_ via the big 5000A safety disconnect switch. I know it probably shouldn't draw much "vampire" power, but I'm being conservative here. I also wire the power to the PakTrakr to the (DPST) main controller on/off switch, so when the kart is turned off, so is PakTrakr. (And yes, in order to do this right, I had to pay attention to the wiring instructions, but as I understand them, it is indeed off when I turn it all off.)

I really don't have a big beef with it other than having to set it up every time, but it's a small nuisance. A lot of the every day technology I see has the ability to have non-volatile memory, either as flash or serial eeprom - it would be nice if the PakTrakr had this capability, too. (Maybe in the next version?) But like I said, it is just a gokart after all, and for the price, the PakTrakr is good for me. From what I can tell, it can be expanded to handle quite a large battery array, but I'm running a lowly array of 6 Optima Yellow tops on the kart. When I build up larger, I'll spring for a bigger, more feature laden battery monitoring/management system.

I thought I'd pipe up, though, since it is a system I'm pretty familiar with by now, and _some_ kind of system is definitely good for battery health.

-Mark


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