E-Trek Battery Monitor Install

[avanti]

Originally Posted by markopolo

Welcome GerryM - that's a heck of a first post!

Maybe after awhile, he will start to tell us what he really thinks!

Just teasing. Welcome GerryM. You are clearly going to fit right in.

[markopolo]

Greg mentioned Victron so I looked at their site and saw this balancer:

https://www.victronenergy.com/batter...ttery-balancer

[gregmchugh]

Not sure about the Victron battery monitor but I don't think there is a problem with installing a Bogart Trimetric with the shunt on the +24v side of the battery bank, good idea to put a cover over the shunt since it is now hot instead of at ground.It handles 24v banks with no problem and there are two leads to separate the negative power for the monitor and voltage measurement from the signal line, these two are normally tied together one side of the shunt with the other signal line on the other side of the shunt. Last of the wires goes to +24v.

[markopolo]

Definitions for my benefit

Equalizer / Converter = better way of getting 12v from 24v system

Balancer = way to make sure individual battery voltage matches others in the battery bank(s).

[gregmchugh]

An equalizer is functionally more like a balancer than a converter but The Cooper diagram shows their unit configured either way or both at the same time I guess.

[markopolo]

My take on it is that they are used for different purposes in the system.

Equalizer / Converter = get 12v from 24V directly, no tap ins that create imbalance

Balancer = eliminate voltage mismatch that occurs over time

Balancer
balancer.JPG

Equalizer used as a converter
equalizer used as converter.JPG

[gregmchugh]

My understanding is that the Victron balancer has just the balancer function and the Cooper can be configured as a balancer/equalizer or a converter or both at the same time. At least that what it looks like to me. The Victron does have a lower current capability I would expect since it just needs to balance.

[markopolo]

I don't see how the Cooper would balance the 8 individual 6 volt batteries in an etrek.

I can see it eliminating a single cause of imbalance by doing away with the center tap.

I can't see how it would make battery A and G or C and F (for example) be the same voltage.

Ref. http://www.classbforum.com/forums/f5...html#post35767

Without a physical connection to each battery the individual voltages are left to chance.

[gregmchugh]

Wouldn't the Cooper connected as shown for the Victron be doing the same balancing as the Vectron? No different is it?

I agree that for the 8 battery eTrek with no 12v tap you should just eliminate the balancer/equalizer, I suppose you could do the cable tie across the battery bank at 6, 12, and 18v if you want to, no harm no foul on that.

[markopolo]

Originally Posted by gregmchugh

Wouldn't the Cooper connected as shown for the Victron be doing the same balancing as the Vectron? No different is it?.............

Definitely, different. The Victron balancer would result in the same voltage at each and every battery (if using 12v batteries). Near exactly the same. By itself and in a etrek with 6v batteries, you would still have to center tap to get 12v. Some batteries would be cycled more and deeper than others. It looks to be limited to 0.7A so recovery would be slow.

The Cooper unit still allows variation of voltage between batteries.

The Cooper would probably work fine if installed with new batteries and if all wiring was the same length etc.

The batteries at the front of the van and the center taps both create imbalance. The Cooper would solve only one of those issues.

A 6v version of the Victron would be more suitable for the Etrek for precise voltage control.

GerryM's paralleling would be as effective as the Vicron (because of 6v batteries in etrek).

[gregmchugh]

I guess there might be a communication problem here, take the Victron diagram and replace the Victron module with a Cooper module with no change in battery wiring. How can one produce a different result than the other? I must be missing something...

[markopolo]

This is my understanding:

Four 12V batteries in series. 51.2 volts, fully charged at rest.

Victron balancer 4 x 12v in series
12.8v + 12.8v + 12.8v + 12.8v = 51.2v

Cooper as equalizer 4 x 12v in series
?v + 12.8v + ?v + ?v = 51.2v

Cooper as converter 4 x 12v in series
?v + ?v + ?v + ?v = 51.2v

? = unknown voltage (you'd have to measure it to know)

[gregmchugh]

I got you now but you are using 3 Victron modules not the single one shown in the diagram. 3 Cooper units would work for that too, I expect, but the cost would be ridiculous since they must be much more expensive than the Victron.

I still think they both do the same thing when used as a balancer/equalizer, one also has enough current capability to use as a converter and is more expensive because of that.

[markopolo]

My example isn't great because I used too high of a voltage (beyond Cooper specs).

Yes, one Cooper device per two 12v batteries would do it. $$$$$ as you said.

The Cooper would work great with only two 12v batteries. It still won't balance 6v batteries though. It will pump out 12v but 12 can be 7+5 at the two individual 6v batteries.

However, only one Victron needed to balance "several" parallel strings of series connected batteries at 24v. The photo I posted shows 6 batteries and one Victron balancer.

[gregmchugh]

You still need 3 Victrons to balance all the 6v batteries in 8 battery 24v Etrek and with the two locations it is lots of wire to run from front to back. Not something needed I would hope.

[markopolo]

Remember, the Victron is for 12v batteries. It's hardly suitable for an etrek. I've been using it as an example of a balancer and to explain what a balancer does.

Originally Posted by markopolo

A 6v version of the Victron would be more suitable for the Etrek for precise voltage control.

GerryM's paralleling would be as effective as the Vicron (because of 6v batteries in etrek).

Two Sterling BD244's should keep all eight 6v batteries at the same voltage:

http://www.sterling-power-usa.com/li...ct%20Sheet.pdf

I can only find the BD244 pdf though so maybe it is not a current product.

Here's another basic balancer: Battery Balancers Search Page

At float, these are photolimo's etrek voltages with a Cooper device installed by Roadtrek.

Group 1
6.33v + 6.43v + 6.94v + 6.88v = 26.58V

Group 2
6.43v + 6.34v + 6.94v + 6.88v = 26.59v

If you could balance the 6v batteries you'd likely see this:
6.5v + 6.5v + 6.5v + 6.5v = 26.6v

The system still needs a Cooper used as a voltage converter (or other brand) to directly supply 12v loads.

[gregmchugh]

I guess the basic question is that if larger RVs with 8 6v AGMs configured for 12v seem to work fine without any sort of balancing of the 6v batteries why would an 8 6v AGM etrek configured for 24v require balancing? Or is the issue that these other RVs are getting some reduced performance in terms of battery life, charging, capacity, etc. that balancing would mitigate?

[booster]

Originally Posted by markopolo

Trying to keep up with the ideas ............

Booster is this the basic idea?

AB parallel 6V
ACEF series 24V
BDGH series 24V
ACEF / BDGH parallel 24V

Welcome GerryM - that's a heck of a first post!

Is this a partial summary of your idea?

AB parallel 6V
CD parallel 6V
AB / CD series 12V
EF parallel 6V
GH parallel 6V
EF / GH series 12V
AB/CD EF/GH series 24V

Wow, I go out to get some work done and you guys have a whole another page full!--good job

Yep, that is how I envisioned it. If you didn't do the parallel at each pair, you could also look at is at A/C/E/G in series and B/D/F/H in series, and then the two strings in parallel (could be any letter batteries though). Common plus end, common minus end, preferably no 12v tap, use a converter.

[markopolo]

Originally Posted by gregmchugh

I guess the basic question is that if larger RVs with 8 6v AGMs configured for 12v seem to work fine without any sort of balancing of the 6v batteries why would an 8 6v AGM etrek configured for 24v require balancing? Or is the issue that these other RVs are getting some reduced performance in terms of battery life, charging, capacity, etc. that balancing would mitigate?

Center tap and mismatched wire lengths both cause imbalance.
Larger coaches don't need to have two house batteries so far away from the rest of the batteries.
Getting rid of the center tap solves only one issue as you still have those two batteries way up at the front of the etrek in the engine compartment.

[booster]

Originally Posted by gregmchugh

Not sure about the Victron battery monitor but I don't think there is a problem with installing a Bogart Trimetric with the shunt on the +24v side of the battery bank, good idea to put a cover over the shunt since it is now hot instead of at ground.It handles 24v banks with no problem and there are two leads to separate the negative power for the monitor and voltage measurement from the signal line, these two are normally tied together one side of the shunt with the other signal line on the other side of the shunt. Last of the wires goes to +24v.

As I mentioned in post #60, I don't think you will find a digital ammeter or monitor that can have the shunt in the positive line. I looked for months unsuccessfully for our setup. They will work in the positive line for analog ammeters, though.

The problem comes in that the digital meters are not designed to be able to handle 24 volts (to ground, not across the terminals as that would still be milivolts) on the Kelvin (sensing) lines that go on the shunt. Those inputs only want to deal with milivolts, and have to be very sensitive, so making them also able to handle high voltage is probably pretty tough. The system voltage signal comes from the input source of the meter power, which is totally separate from the shunt circuits. As mentioned, the Inpower inductive pickup MIGHT work with the Trimetric and can go on any current carrying wire.

Having the shunt in the front would not be that big of a deal as all you would need would be a single twisted pair of wires for the Kelvin connections. They are super low voltage and current and can be run nearly anywhere.