E-Trek Battery Monitor Install

[gregmchugh]

Originally Posted by markopolo

Would adding the 4 parallel wires drawn in yellow in the attached schematic cause any problems?

(attachment deleted, caused shorts)

I'm still stuck on trying to balance the voltages with minimal effort and cost and working within the confines of this system.

In this example I would leave the Cooper in place functioning as an equalizer. (not as a converter)

This example completely ignores trying to add a monitor to the system.

We need some input here. Maybe fresh eyes could check connection points with a virtual voltage meter. I'm not suggesting anyone do this before it is determined to be safe.

Looks to me like you are shorting the batteries with the yellow connections.

Am I missing something??

[markopolo]

Specifically, we're do you see a short? (So I can take a look)

[avanti]

short.jpg

Boom!

[markopolo]

I'm suitably embarrassed. It's clear now!

(going to delete first image)

[markopolo]

Thanks Greg & Avanti.

How about E+ to G+ ? (almost terrified to see the answer)

[gregmchugh]

Originally Posted by markopolo

Thanks Greg & Avanti.

How about E+ to G+ ? (almost terrified to see the answer)

I am a software engineer, you just jumped past my electrical engineering expertise, which is pretty shallow...

But it still looks like a short to me across F and G...

[avanti]

Originally Posted by gregmchugh

I am a software engineer, you just jumped past my electrical engineering expertise, which is pretty shallow...

But it still looks like a short to me across F and G...

Yep. Same thing, just twice the voltage.

[markopolo]

I'm trying to add more parallel connections to balance voltages.

The three existing parallels are shown here in yellow:

E-Trek Battery Layout how to create more parallel connections.jpg

Paralleling (at 6v) the high voltage batteries with the low voltage batteries would equalize voltages. It would be far from perfect but better than the overcharge / undercharge that exists now.

[gregmchugh]

Yes, you can connect the two halves of the battery bank at 6v, 12v, and 18v in addition to the ground and 24v points but that is it. You now have 4 sets of two 6v batteries that are connected in parallel and then connected in series. Without the interconnects you have two sets of four 6v batteries connected in series then connected in parallel.

4 X 6v = 24v, 2 X 200 ah = 400 ah, or 9600 watt hours.

That covers my level of expertise

[BobB]

First, I only understand batteries on a very very basic level - how many Ah do I need sort of level.

Reading all of this makes me realize (1) how much I don’t know about how to put together an RV electrical system, beyond a basic 12v battery and charger (2) why this forum is so good, with everyone exchanging ideas and opinions, back and forth, with the goal of helping photolimo solve his problem. RT should just hire all of you.

Avant reminded us a few posts ago about ROI. So without hijacking this thread, I have some basic questions. Why a 24v system? And is all this worth it, i.e. ROI.

I have a basic understanding of avoiding voltage drop with long wire runs and the efficiencies of a 24v system with increased electrical loads. I sail and in the world of boats, almost all boats up to 40 or 45 feet have 12v systems. For boats larger than that, say above 50-60 feet, things get interesting. From what I read, above that size, 12 v systems can get “challenged” especially with more/higher electrical loads. On a 12v system, getting power to a windlass at the bow from the battery bank at the back of the boat is problematic to say the least. Wire sizes get huge and voltage drops increase. Larger boats also tend to carry more things like watermakers, larger windlasses, bow thrusters, larger inverters to run more 110v toys, etc.

So I can understand a 24v system on a big Class A RV. But a 20-24ft long Class B? I know there are those out there who want A/C 24/7, so need a huge battery bank, so the efficiencies of a 24v system might make sense. But this example is only 400Ah (lithium). Is the fact that RT separated the batteries driving this?

I do understand there are some wiring and balancing issues here regardless of 24v or 12v.

If the pros and cons of 24v vs 12v and ROI has been addressed in another thread, please direct me there. I don’t mean to hijack or divert this one.

[markopolo]

Originally Posted by gregmchugh

Yes, you can connect the two halves of the battery bank at 6v, 12v, and 18v in addition to the ground and 24v points but that is it. You now have 4 sets of two 6v batteries that are connected in parallel and then connected in series. Without the interconnects you have two sets of four 6v batteries connected in series then connected in parallel.

4 X 6v = 24v, 2 X 200 ah = 400 ah, or 9600 watt hours.

That covers my level of expertise

Thanks again. I see the 12v parallel connection now.
So there are 4 existing parallel connections.

E-Trek Battery Layout how to create more parallel connections.jpg

[booster]

This is a first shot, probably got plenty of holes in the idea. To rewire and put the front batteries on separate series strings, putting the ground all in one place, no new long big wires to install, keeps the series stings parallel at each battery, still have 12v center tap.

Red is new, yellow is remove, green is the final parallel between the strings, one front battery turned around.




strings are

H/G battery one parallel +24v

D/F battery two parallel +18v
+12 v between battery two and three
C/E battery three parallel +6v

A/B battery four parallel - ground

Running the balancer ground to the chassis and then back to the shunt with the rest of the loads would probably be OK.

[gregmchugh]

Originally Posted by booster

This is a first shot, probably got plenty of holes in the idea. To rewire and put the front batteries on separate series strings, putting the ground all in one place, no new long big wires to install, keeps the series stings parallel at each battery, still have 12v center tap.

Red is new, yellow is remove, green is the final parallel between the strings, one front battery turned around.




strings are

H/G battery one parallel +24v

D/F battery two parallel +18v
+12 v between battery two and three
C/E battery three parallel +6v

A/B battery four parallel - ground

Running the balancer ground to the chassis and then back to the shunt with the rest of the loads would probably be OK.

I don't see a diagram...

[booster]

Originally Posted by gregmchugh

I don't see a diagram...

It should have showed up in the post, not as an attachment. It does show on mine. I will go back and attach it also.

Are you able to see the attachment now, I just added it.

[markopolo]

photolimo - would you be able to post the voltages at each battery with the engine running and revved to get the 24v alternator going?

Edit: you only need to measure each of the 4 rearmost batteries: E F G H

I really curious to know if any batteries get above a really high voltage like 7.4V. The Etrekbloggers have reported as high as 15.12V measured on the 12v side: WEBASTO AND WINTERIZING WOES | The Etrek Blog

[gregmchugh]

Originally Posted by booster

It should have showed up in the post, not as an attachment. It does show on mine. I will go back and attach it also.

Are you able to see the attachment now, I just added it.

I can see it now...

[markopolo]

I can see the attachment but I'm having trouble following it.
Are the series connections:
A/C/E/G & B/D/F/H

[booster]

Originally Posted by markopolo

I can see the attachment but I'm having trouble following it.
Are the series connections:
A/C/E/G & B/D/F/H

From + to minus

H/D/C/ A or B

G/F/E/ A or B

It can be A or B as the last of either string because of the single cable between the third and forth pairs.

[booster]

I made a quick sketch of how I think the markup would look in schematic form. Should be a bit more easily followed compared to all the lines crossed off, etc.

[markopolo]

Originally Posted by BobB

.............. Why a 24v system? And is all this worth it, ...........................

I think you have a very good understanding from reading the rest of your post. 1/2 the amps needed at 24v, reduce wire size by half. Also, I've read that the higher input inverter can be more efficient. Quality counts though.