E-Trek Battery Monitor Install

[photolimo]

Originally Posted by markopolo

I can see A+ and F+ both being 12V+ but I don't see them connected in the schematic.

They are connected. I cleaned up the schematic a little to help. Is that more clear?

E-Trek Battery Layout (1).jpg

[gregmchugh]

Did I miss an explantation of the purpose of the 6v connection cable?

[photolimo]

Originally Posted by gregmchugh

Did I miss an explantation of the purpose of the 6v connection cable?

As I understand it, it was used to balance the 12V bank and the 24V bank. This destroyed batteries B and E. I also believe batteries A and F are in poor condition. To remedy this situation they installed a "Battery Balancer" that is an actual box that coverts voltages to help balance the two sides to the system. We used our E-Trek for a year without the balancer box just using the 6V balancer cable. I believe AGM batteries are supposed to last more than 6 years with fairly continuous use although that is a difficult parameter to gauge.

[markopolo]

Just an opinion here - I don't think it is coincidental that B & E are ground points and that they both failed. My take on this is that those two batteries would work the hardest in the system.

I don't understand how the 6V line would help balance any batteries except B and E which were paralleled because of that wire. A & B for example are in series. They will coexist at different voltages because they are in series.

I bought 12 x 12v used batteries in one container (second time I did this). 6 in series paralleled to the other 6 that were also in series. I took a chance on it because it was a 72V bank and I measured 70V. One battery from each string turned out to be dead, below 7 volts. You can have a dead battery in series and still see a reasonable voltage. Some of the batteries in each group of 6 were very good at 12.6 or 12.7 even after months of sitting as military surplus. Basically, series connected batteries have little or no affect on other batteries in the string other than affecting the total voltage and total capacity of the bank. Two batteries in series will not balance out.

[photolimo]

Originally Posted by markopolo

Just an opinion here - I don't think it is coincidental that B & E are ground points and that they both failed. My take on this is that those two batteries would work the hardest in the system.

So would a solution to this problem be to remove the 6V balancing wire?

It would be convenient to use as a grounding wire bringing it back to the 500A shunt. Not sure how to solve the voltage difference.

[BobB]

Please, whoever figures this out correctly, please post your hourly consulting rate, so I (or others) can hire you when the time comes, to work on my RV.

I wondering if the RT engineers are following this?

[markopolo]

photolimo - lets wait & get some other opinions here on whether the parallel wire being in place or being ground points is more likely to cause those two batteries to fail sooner. I have nothing to back up the being ground points theory.

One could have failed and being in parallel because of that wire would cause the other to balance with the failed or failing battery.

[booster]

I was also thinking about using the "balancing" line to bring the ground back to the shunt, as it really doesn't do much as I mentioned earlier.

I am not a shunt expert, so this may be way off, but what would happen if you used two shunts to keep from having to run a huge ground line back to the rear. My understanding is that monitors measure milivolts of volatage across the shunt, so I would think if you put the sensing lines to the shunt in series, the milivolts generated should add and give an accurate reading?

I have never heard of anyone doing this, but it could sure simplify wiring if it did actually work.

[markopolo]

Seems like it would work but maybe not as they also offer the Pentametric with up to three shunts. Or maybe the Trimetric and Pentametric serve different needs. It's worth asking Bogart Engineering.

[booster]

Originally Posted by markopolo

Seems like it would work but maybe not as they also offer the Pentametric with up to three shunts. Or maybe the Trimetric and Pentametric serve different needs. It's worth asking Bogart Engineering.

I "think" the multishunt units are so you can monitor 3 battery banks separately, and there would be 3 separate amp, volt, SOC displays also, but I will have to look to be certain. If the series thing worked it would give all the information as one bank, just like it would if you brought the ground connection to the rear.

[markopolo]

I've run two cheap unidirectional meters with shunts in series. One shunt (meter) was reversed. I needed to do that to see both input and output. I had to do the math part manually That doesn't specifically answer this question though.

[booster]

I just took a quick look at the Pentametric instructions, and they do have 3 shunt imputs maximum, and interestingly they have feature that allow shunts one and two amp, SOC, readings to be combined together. That would take care of the issue we are talking about here, i think. They say they have to have common ground, but didn't really say common cable, so I think they mean chassis ground, I hope. I need to get a better look at their system diagrams.

[Davydd]

Originally Posted by BobB

Please, whoever figures this out correctly, please post your hourly consulting rate, so I (or others) can hire you when the time comes, to work on my RV.

I wondering if the RT engineers are following this?

Silly question? I am assuming every Roadtrek E-Trek so far is still under warranty. Wouldn't this be something that should be worked out with them? If Roadtrek engineers are following I would hope they would get in touch with Photolimo. It would be in their interest to do so as speculation like this is damaging to their brand.

[booster]

Originally Posted by Davydd

Silly question? I am assuming every Roadtrek E-Trek so far is still under warranty. Wouldn't this be something that should be worked out with them? If Roadtrek engineers are following I would hope they would get in touch with Photolimo. It would be in their interest to do so as speculation like this is damaging to their brand.

Logic would make you think so, but Roadtrek still claims they are perfect and that the B forum folks are frantic worryworts , so I doubt they would lower themselves to react to anything on here. Once someone posts here about a problem, they probably wind in on the "naughty list" so they get worse service than ever.

[BobB]

Originally Posted by Davydd

Silly question? I am assuming every Roadtrek E-Trek so far is still under warranty. Wouldn't this be something that should be worked out with them? If Roadtrek engineers are following I would hope they would get in touch with Photolimo. It would be in their interest to do so as speculation like this is damaging to their brand.

Absolutely agree, Davyyd. But I am making a SWAG (simple wild ass guess) that he is not getting RT response/support, which is why photolimo is posting here.

Just a guess

[markopolo]

This is a for an owner proposed upgrade to the unit.

If it was my RT and under an extended warranty I'd present the plan to them for a review and comments.

I keep thinking of 5, 10, 15 years down the road when 2nd, 3rd, 4th owners etc are doing E-trek upgrades. It will be interesting and any info like this topic will be very useful.

[markopolo]

photolimo - two questions

1. What is the brand and model # of the battery equalizer in your E-trek?
2. Is there (or was there) a wire from batteries C+ to G+ in your RV?

I looked at two other e-trek battery bank photos and both have a wire connecting battery terminals C+ and G+.

This site: What Battery Equalizers Do | All About Lead Acid Batteries - looks to me to show that, in a 24v system such as yours, 12v loads are supplied through the battery equalizer.

Utilizing an equalizer that way would eliminate tapping in for 12v via a direct wire to the battery.

Using the equalizer to directly supply 12v loads is what these installation instructions show: http://www.cooperindustries.com/cont...ST_180156a.pdf

[booster]

The C+ to G+ is what I also saw as missing in the diagram compared to the other systems.

http://www.classbforum.com/forums/f5...html#post35756

It doesn't appear to be an important connection though, and would do the same function as the big 6v connection from front to back on B+ and E+.

I seem to remember something about the balancers being either the only source of 12v power (large capacity ones), or that the 12v power would come from the batteries and then the balancer would rebalance the string in time at a lower output. Don't recall if it was something someone said or if it was manufacturer thing.

[gregmchugh]

Not relevant to this exactly but in an effort to get at least one of the 24v lithium battery Etreks working Roadtrek removed the 12v tap that supplies the 12v loads and replaced it with a 24v to 12v DC converter. Not sure that helped getting them working in any cases, did not work in that case, or what configuration they are now delivering with the 24v lithium sysytems.

[markopolo]

Originally Posted by booster

The C+ to G+ is what I also saw as missing in the diagram compared to the other systems.

http://www.classbforum.com/forums/f5...html#post35756

It doesn't appear to be an important connection though, and would do the same function as the big 6v connection from front to back on B+ and E+.

I seem to remember something about the balancers being either the only source of 12v power (large capacity ones), or that the 12v power would come from the batteries and then the balancer would rebalance the string in time at a lower output. Don't recall if it was something someone said or if it was manufacturer thing.

I was more or less just curious about that wire. It just seemed odd to just have that one long 6v+ to 6v+ in the schematic so I was wonder if easier to remove wires had been taken out when the balancer was installed.

I like the idea of using the equalizer or converter to directly supply 12v loads. This pdf shows it installed either way: http://www.cooperindustries.com/cont...ST_180156a.pdf