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Old     (grant_west)      Join Date: Jun 2005       12-18-2013, 4:44 PM Reply   
Hey in my recent GEM car restoration project (Electric Car) I have come across a bunch of cool battery guru's & battery tech. In the electric golf car & electric car world battery monitoring systems are very common and much more Hi-Tech then anything I have come across in the 12v Stereo world.

And example is this Batt Six (BMS) module. They have 2 System's

#1 a Heads up 6 inch display unit. It gives you digital TFT display that shows you real time INDIVIDUAL battery voltage and strength

#2 A blue tooth unit that send's the battery info to your smart phone Android or I-phone.

Currently these unit's are set up for Battery systems running in Series, Our boats run our 12v ststem's in parallel.

Here is a look at the Smart phone display
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Old     (grant_west)      Join Date: Jun 2005       12-18-2013, 4:45 PM Reply   
Here is a Pic of the Heads up or Dash Display Unit.
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Old     (grant_west)      Join Date: Jun 2005       12-18-2013, 4:55 PM Reply   
This unit will show you instantly (in real time) each battery's condition. It can point out the week link in your battery bank. Often times these battery's can be addressed by removing them from the system and (charging & discharged) untill they once again become balanced with the rest of the system. OR removed and replaced. Often 1 week battery can drag down your entire system & sometimes destroy a entire bank of battery's. the Idea here, catch a small problem before it becomes a bigger more costly one.
They even make a data logger that records battery history on a Scan Disk and you can look over your discharge patterns and spot problems if you dont want a smart phone or display
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Old     (grant_west)      Join Date: Jun 2005       12-18-2013, 5:01 PM Reply   
Now before you get all excited and want to run out and spend $300 or $400 on this cool new toy! Wait did I just loose 1/2 of you at $300 or $400 This product dosn't exist in our configuration YET!!! It exist's in a Series configuration right now, you can buy it off the shelf. Mabey someone knows of a product like this that does.? Im sure if demand was high enough they could re-tool this BMS to work in Parallel systems
Old     (flapjack)      Join Date: Feb 2010       12-19-2013, 7:41 AM Reply   
You realize that getting voltage of the battery is easy in series but very hard in parallel?
Old     (grant_west)      Join Date: Jun 2005       12-19-2013, 9:00 AM Reply   
I understand how battery's in series are separated and measured.
The monitor has a lead for each battery. The monitor measures the voltage difference between the first battery and the second battery and so on. That's the way it was explained to me. I'm sure battery's can be measured in parallel it would just take some special programming and hardware. Like I said I'm sure if the demand is enough it could become a reality.
Old     (bass10after)      Join Date: Feb 2010       12-19-2013, 7:28 PM Reply   
grant who makes this system? do you know if it works for 2v batteries and different types of batteries as well? Thinking this would be awesome for my houseboat with 12 2v batteries that aren't all that easy to get to...
Old     (DavidAnalog)      Join Date: Sep 2013       12-20-2013, 12:39 PM Reply   
In an open series circuit you can measure each component individually. In a parallel circuit, whether open or closed, you cannot isolate and measure each component without introducing a disconnect.
Old     (trayson)      Join Date: May 2013       12-20-2013, 2:18 PM Reply   
Well, I only have 2 batteries... And they are on a switch so they tend to run isolated the vast majority of the time. I bought a couple of these 12v LED voltage gauges for under $5 each off ebay. My batteries are under the observer seat, so I mounted the gauges in the base of the seat. Cheap, simple, effective.

Just thought I would throw out a related solution for those of us with a lot simpler systems that are down for a cost effective solution.

Old     (grant_west)      Join Date: Jun 2005       12-20-2013, 6:42 PM Reply   
^^trayson^^ for people with 2 battery's that's a great option. But for the rest of us with Multi battery banks that's not a option. And with ur option you can only see the voltage when they are broken apart. The idea behind this product was to be able to see the battery's under load in real time.
Old     (mikeski)      Join Date: Aug 2003       12-20-2013, 8:34 PM Reply   
For batteries in parallel it makes more sense to use ammeters to see how much charge is going in or how much is coming out of each battery. This would require a shunt on one terminal of each battery then a unit that could read and display current draw or delivery. It can be done for probably about $30/battery. Here is a display that could possibly be configured to do what I am talking about.
Old     (ryanbush11)      Join Date: May 2003       05-28-2014, 9:56 AM Reply   

I've been scouring the internet for a soluction to this as well, did you ever come up with anything?

Old     (grant_west)      Join Date: Jun 2005       05-28-2014, 10:43 AM Reply   
I bought one of the Batt Six BMS units above and have been playing with it on my GEM car.
If we got enough interest lets say 20 units im sure the company owner Richard Brisken would make a unit that would work in our parallel configuration.
Old     (ryanbush11)      Join Date: May 2003       05-28-2014, 11:36 AM Reply   
I'm sure I could sell 2-3 plus one for myself, I'm sure you could sell a few as well... anyone else?
Old     (Houstonshark)      Join Date: Jan 2011       05-29-2014, 12:47 PM Reply   
I would be interested.
Old     (chadgreg)      Join Date: Feb 2008       06-10-2014, 11:36 AM Reply   
Spoke to owner of battsix for my 48 v golf cart (8 Batteries @ 6V) he doesn't have anything that will work for my set up but I did order a pack monitor from his engineer. I would love to get something that monitors the my boat batteries individually.

Here's what I bout for my cart:
Old     (CobraRob)      Join Date: Aug 2010       06-10-2014, 11:51 AM Reply   
You would have to have a high voltage solenoid it could control and separate the banks but then you would get false readings during load since whichever battery that was left closest to the system connection would see the full load of the electronics while the others were isolated.

You could do a crazy stepped solenoid so you could run though each battery and measure both under load and not under but way too complicated to be worth it and so many points of failure during normal use.

If you REALLY wanted though super easy to program using an Arduino or something like that.
Old     (grant_west)      Join Date: Jun 2005       06-10-2014, 1:57 PM Reply   
What would be realy cool is for Battery makers to have a balancing port for each battery's and a way of linking your battery's via a Balancing cable.

Depending on where your battery's are located and how they are wired you can have more drain on the battery closest to the draw and some times the oppasate. These variances in draw and voltage could be looked at like this The front battery's take a beating and the rear battery's hardly get a good constant draw or beat down. So this would mean your Battey charger would have to attend to the front battery's more often then the rears. A balancing port or cable would allow the charger to give battery A lets say 14.2 volts while it gives battery B 12.9 volts and so on. Your system is only as good as your weekest battery. A bad battery can and will draw down a entire system

Cars like the Tesla that use hundreds of individual battery's have these balancing properties.
They also have circuits that remove and take out week battery's from the system.
Old     (denverd1)      Join Date: May 2004       06-11-2014, 1:01 PM Reply   
Originally Posted by grant_west View Post
A bad battery can and will draw down a entire system
Sounds like the real problem is isolating each battery before you can measure it. may have to rethink your parallel system

edit: if you isolated everything you wouldn't kill the bank from one bad battery....
Old     (grant_west)      Join Date: Jun 2005       06-11-2014, 10:46 PM Reply   
"How do you Isolate 6 battery's under a load"
The advantage of having 6 battery's is linking them together. Isolating or breaking them apart defeats the advantages.
Old     (denverd1)      Join Date: May 2004       06-12-2014, 10:32 AM Reply   
well no ****! my point was that if you changed how they were linked, you might be able to measure them easier. Instead of using bus bars or directly linking them
Old     (grant_west)      Join Date: Jun 2005       06-12-2014, 11:38 AM Reply   
Nacho; please tell us how you would hook up multiable battery's to power a 12v source with out hooking them up in a Parallel.

There are many things that you may not be aware of like battery wire length runs and resistance created from longer runs from bank to bank and the voltage differances created from drawing your power from one end of the bank Vs the other All these minor things stacked together create problems and algorithmis that could be worked out by a complex BMS , but simply saying rewireing or adding a solonoid is not the solution. Seeing how the battery's draw down in real time is what we are after. You can't do that if they are not linked.
Old     (denverd1)      Join Date: May 2004       06-12-2014, 12:11 PM Reply   
algorithms?? Its a damn sound system, not a space shuttle.

You WAY smarter than everyone else, I'm sure you can figure it out.
Old     (grant_west)      Join Date: Jun 2005       06-12-2014, 1:15 PM Reply   
Yes Algorithms how do you think the bat six monitor figures out the voltage differences between batteries???? I'm not trying to sound like a smarty-pants or anything but this conversation sounds like it's way over your head in the spirit of discussion I was trying to explain it in hopes that brighter minds might inject some logic and or ideas. Nacho in your case I'll know not to get so technical in the future
Old     (CobraRob)      Join Date: Aug 2010       06-13-2014, 10:07 AM Reply   
Grants correct. The simplest way possible would require a controller that switched solenoids to do the isolation at the very least. This method is not even all that great since you would be bouncing the full system load across the batteries and they might not give a realistic value when a single battery is supporting the entire load.

You would need an algorithm to keep solenoids 1,2, and 3 open during normal operation. That would tie all 3 batteries together and the monitor would show the overall voltage.

Then maybe on a set schedule or with a manual trigger you close 3 and then 2, wait for the signal to debouce and stabilize then take a measurement that corresponds to battery 1 and record that. Then you open 2 and then close 1. Do the same measure and record battery 2. Open 3 close 2. Record battery 3, then open 1 and 2 again.

Not something that is ideal due to the voltage spikes. You could condition this some with a cap but then your ability to take a measurement would be slowed way down since you would be measuring the storage of the cap.

Now this is just giving a quick voltage read and doing it for a little longer to get ANY guess of battery run down and condition would require a bunch of more measurements since your Delta R resistance between runs will become important since you would be doing the calculations to extrapolate since you would not want extended runs on a single battery.

Last edited by CobraRob; 06-13-2014 at 10:09 AM.
Old     (grant_west)      Join Date: Jun 2005       06-13-2014, 3:58 PM Reply   
I know this is not a realistic approach but just an idea. Let's say you put four large. 3.2 volt batterys together wired in a series configuration
This would give you a 12.8 V battery source. These four batteries would work as cells to make up a 12 V source. Very similar how golf carts produce 48 and 72 volt configurations. This would allow you the ability to monitor each battery in your entire system independently as with the Batt Six monitor. The Batt Six monitor measures the voltage differences between the first battery and the second battery and the third battery and fourth battery these minor voltage variations are how the monitor measures battery strength and voltage.

I am sure if Richard Briskin had an order for 100 units they could and would figure out a way to make it work. So far it looks like two or three people are interested would you guys be willing to pay $300 + for such a monitor??
Old     (grant_west)      Join Date: Jun 2005       06-13-2014, 4:02 PM Reply   
By the way I installed one in my GEM car and the way that you draw power from the pack causes the batteries to jump up and down almost like an equalizer display the downside is I could see people being addicted to watching their batteries instead of out enjoying their time on the water here's a picture of the display in my car
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