There are 8ea 6v AGM batteries with the non Lith E-trek's. 4 of those are in series to create 24v for the 5000w inverter. The other 4 are split into two series of 12v that are then paralleled into the 12v system.
Given there are 8ea 6v coach batteries, and given the inverter is 24v, there is no other way to split the 8 batteries that I know of to have both a 24 and 12 volt set up. My diagnosis also confirms this set up.
Not commenting on whether or not this make sense, but there is an issue on my soon to be former unit with the balancing of the two setups while charging with the solar and engine "generator". RT claims to have a warranty fix for this and I trust that is true.
Here's why I don't think XRoady is correct in his description:
There are indeed 2 banks of 4 6-volts each. And the voltage in those two banks' individual batteries differs by roughly .3 volts. That was what got Hal D involved with adding a battery balancer.
However, If I turn on my inverter, and run 110-v equipment for a long while but little or no 12-v stuff, eventually the percentage charge remaining will drop (of course). But all 8 batteries show a voltage drop, and the .3 volt differential remains.
So to me the inverter is drawing from all 8 batteries. Whether the 12-v stuff draws from all 8 is a different question.
One thing we have all learned, though: the RT dealers know little to nothing about these matters. I'm not convinced that everyone at RT is clear on it either. If they would just publish the wiring diagram, all this speculating could be cleared up!
What part of the description was not correct? I have diagnosed the wiring and RT HQ has confirmed findings.
There is a factory installed balancer that is not properly working between the 12 and 24 while charging, at least on my unit. You are discussing discharge.
No need to debate, the factory has confirmed an issue and has agreed to install an electronic balancer under warranty. Speak with Peter in service if you have questions or do not agree. Dan Neeley, mobile service provider, was at the factory last week being trained on the repair and will be out in the field making the repairs.
up until xroadtreks post i though that the 8 6 volt batteries were made into 2 battery packs of 24 volts. i also thought that these packs both fed the inverter.
I also though additionnal wiring had been put on these batteries to create 12 volt battery packs to feed 12 volt appliances.
this is what i thought caused the need for the battery balancing device,
using 4 6 volt batteries exclusively for 12 volt in the e-trek
seems as i said overkill for 12 volt and underkill for the inverter use for air conditioner. i can't see how 1/2 a 24 volt pack(220amps) could run the air condtioner for the times people are seeing.
There was a wiring diagram shown somewhere that showed 6v batteries in series to get the 24v, with a center tap to get the 12v out. This will discharge 1/2 of the batteries more than the others based on the 12v loads and time. It will also reduce the output of the bank to the inverter because of the battery mismatch. It will also make the batteries recharge unevenly, overcharging some, and undercharging others. The balancer is just a controlled "leak" to put power into the lower batteries from more full ones, to even things back out.
This is certainly not anything that is proprietary, or innovative, or probably even the best way to do it, but it has been a way to get 12 and 24 volts out of a system for many years on boats. To build a system like this without the balancer is just plain not right.
There was a wiring diagram shown somewhere that showed 6v batteries in series to get the 24v, with a center tap to get the 12v out. This will discharge 1/2 of the batteries more than the others based on the 12v loads and time. It will also reduce the output of the bank to the inverter because of the battery mismatch. It will also make the batteries recharge unevenly, overcharging some, and undercharging others. The balancer is just a controlled "leak" to put power into the lower batteries from more full ones, to even things back out.
This is certainly not anything that is proprietary, or innovative, or probably even the best way to do it, but it has been a way to get 12 and 24 volts out of a system for many years on boats. To build a system like this without the balancer is just plain not right.
Booster-xroadtreks says differently. i am not sure who is correct
Not sure I am saying completely different than others. Per my experience, as obraham points out, the draw is on all batteries and as booster notes the draw is not equal. As booster further notes, the recharge is uneven.
During a recent long trip without shore power, I experienced uneven charge between the 24v and 12v systems, where the 12v system was quite a bit under the 24v. Speaking with the factory, they were aware of this occurring due to the current balancer configuration, and I was told they have a fix using an electronic balancer.
I really am not claiming to be an expert and will defer to others with more knowledge, but I did experience issues with the 12v system, discussed these issues with the factory, and was told there was a fix for the issue. The fix has been scheduled.
As referenced in an above post, I would recommend speaking with the factory if you have an E-trek and have experienced charging issues with your 12v system while untethered. Other than that, best I remain silent so as not to muddy waters further.
I hope you don't stay silent! Expert, or not, you have lived with how the systems worked in the real world, which is vital information to a lot of folks, and has been very rare to see.
The tech geeks will discuss, guess, and analyze what you have seen, and will greatly appreciate the information.
xroadtrek- you said in one of your first posts that one 4 pack was configured as 24 volt for inverter and one 4 pack configured for 12 volt for 12 volt devices.
you said it with such conviction that because you actually owned one i assumed you were correct.
did roadtrek specifically tell you this configuration.
as i said in this configuration power for 12 volt devices is overkill and inverter power is underkill.
however i do not have e-trek and can only really on others to illuminate me-lol
as for the roadtrek balancing-when this issue first started roadtrek was denouncing people like Hal Devera for saying it needed battery balancer. I like roadtrek and it's people but sometimes they put their heads in the sand when questioned about things then look even worse when they turn out to be true.
If I were designing such a system, I would give serious consideration to a completely separate 12V battery, rather than trying to keep such a complex setup balanced. It could be kept charged with a separate small converter, powered from the inverter, or else a DC-DC charger driven from the 24V system. For that matter, maybe a 24V->12V DC-DC converter alone would suffice--they can be pretty efficient.
__________________
Now: 2022 Fully-custom buildout (Ford Transit EcoBoost AWD)
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
IMO, with the current stuff you can get off the shelf (of course Roadtrek could design much better stuff in house ), I think just making the 8 batteries two strings of 4, then parallel them for an all 24v system.
Put in a 24v to 12v DC power supply to run the 12v stuff (otherwise you might need a reference battery for a DC charger) and you should be done and balanced.
IIRC, Hal Devera was really close to getting booted from the Facebook group, but he turned out to be the one who was correct.
Getting Hal's tale in complete form would be very informational, I think, including how he got the information about needing a balancer. I assume he must of had a well qualified tech, or equivalent, map the system and diagnose it, as there are no schematics available. Wouldn't be inexpensive if it were hired work, though.
One thing that Hal's situation makes me wonder about is back to the Roadtrek secrecy and "proprietary" discussion. It always seemed to be put out that the lack of information published about how the systems worked was because they were highly advanced, innovative, designs and Roadtrek didn't want the competition to catch up by copying.
That logic made little sense to me because truly advanced stuff would be patented and non copyable, and if competition wanted to know what was going on, all they needed to do was find a Roadtrek and examine it, which would be relatively easy to do.
Could it be that Roadtrek doesn't want to publish what is being built because it is not all that special? I can (somewhat) understand not wanting to have to deal with a lot of questions from the public about how it worked if the information was provided, but that is part of selling technology products. What could turn out to be a big problem for Roadtrek would be if the schematics were out there and folks who have issues go to a knowledgeable tech or engineer and get told that the system was poorly designed. That would remove the "armchair engineer" argument and make it very easy for other "real" experts to also give their opinions, in ensuing discussions. Evaluating a design from drawings can be done easily by lots of folks, from nearly anywhere, very easily, where if they have to take apart a van to do it, you may not get anyone doing it, which may be what we are seeing now.
The etrek blog stuff was pretty interesting, especially the run time and recharge time and accuracy stuff. I think there may be some issues with the belts on the engine generators, though. It appears theirs has popped off several times, and Campskunk even wrote up a procedure for replacing the belt. It may be because of the high loads it sees the belt could need to be a yearly maintenance item. I think Roadtrek even sent a spare belt with some units.
One thing that Hal's situation makes me wonder about is back to the Roadtrek secrecy and "proprietary" discussion. It always seemed to be put out that the lack of information published about how the systems worked was because they were highly advanced, innovative, designs and Roadtrek didn't want the competition to catch up by copying.
That logic made little sense to me because truly advanced stuff would be patented and non copyable, and if competition wanted to know what was going on, all they needed to do was find a Roadtrek and examine it, which would be relatively easy to do.
Could it be that Roadtrek doesn't want to publish what is being built because it is not all that special? I can (somewhat) understand not wanting to have to deal with a lot of questions from the public about how it worked if the information was provided, but that is part of selling technology products. What could turn out to be a big problem for Roadtrek would be if the schematics were out there and folks who have issues go to a knowledgeable tech or engineer and get told that the system was poorly designed. That would remove the "armchair engineer" argument and make it very easy for other "real" experts to also give their opinions, in ensuing discussions. Evaluating a design from drawings can be done easily by lots of folks, from nearly anywhere, very easily, where if they have to take apart a van to do it, you may not get anyone doing it, which may be what we are seeing now.
I did draw a battery and associated wiring schematic before selling my 2015 CS E-trek, and snapped some photos of the rear batteries, under hood batteries, and under mount junction box. Hopefully I can figure out how to attach them here, and if so, possibly people more knowledgeable then myself can determine how advanced, innovative, etc. the system is. And please lay off the critique of my drawing and handwriting skills! http://www.classbforum.com/forums/im...cons/icon7.gif
It looks like they have a setup of parallel pairs of batteries, put into a single string of 4 pairs in series to get 24v.
They are pulling the 12v off the first 2 pair of batteries, so only those 4 will discharge from 12v loads. All 8 would discharge at 24v loads to the inverter. All 8 would be charged at 24v, but the first 4 batteries would need more charge than the second 4 batteries. They can't charge that way accurately, so you will have mismatched charging, and the discharging at 24v will also be uneven if the batteries groups are not at the same state of charge.
The line marked "balancer" is just one of the cables to parallel one of the pairs of batteries, just like on the other 3 pairs. This must be what they call their "mechanical" balancer. It really doesn't do much of anything except put the middle of a series pair at the same voltage. You still have 4 pairs that can be different. Another thing is the very long length of cable to the front of the van batteries is going to cause a bigger voltage drop between them and their series cousins than the others and further mess up the charging and discharging balance.
If this is all there is, IMO there is nothing remotely high tech or proprietary. There is absolutely no way anybody who knew what they were doing would copy it anyway.
It has to have some sort of 12-24 volt balancing system to work properly, again IMO.
I think this completely backs up what Hal found out with his.
Here is a very crude sketch of what the battery layout would look like more in schematic form. It looks much simpler and easy to understand this way, I think.
I did draw a battery and associated wiring schematic before selling my 2015 CS E-trek, and snapped some photos of the rear batteries, under hood batteries, and under mount junction box.
That was a great idea.
Re: the balancer / equalizer - Here's a repost of a link from the early E-trek discussions on this forum:
It's a good read about why to use an actual balancer or equalizer instead of just center tapping with a wire.
That was a very interesting article, I must have missed it earlier.
The system he shows with the 24 to 12v converter sure does look like it would work very well, but of course, so does the one with the electronic equalizer.
This information from xroadtrek is the best we have seen, I think, and it is also from a current model so it is even more valuable. thanks to him
I wish Roadtrek would tell us what the proprietary part of it is I also hope they did a better job on lithium, which is very possible because it sounds like a lot of it was done out of house.
This higher voltage option will get more interesting in the future. Right now it looks like 48 volt start-stop systems will be in many vehicles starting in 2017 when the next level of new emissions standards in the EU and USA will take effect.
At the recent ARV Fest a rep from Mercedes vans confirmed that the new Sprinter in 2017 would have the 48 volt star-stop system. Some Mercedes car models in USA already have a system known as ECO Start/Stop, which is only 12volt.
In the telecommunications world 48 volt inverters are the norm for max efficiency.
I wish Roadtrek would tell us what the proprietary part of it is :confused
I did spend some time crawling underneath looking at the set up, and, solely based on what I could see, IMO the only thing proprietary appeared to be the unique handwriting of some factory worker who wrote "balancer" on a piece of masking tape and wrapped it around one of the cables.
will discuss, guess, and analyze what you have seen, and will greatly appreciate the information.
), I think just making the 8 batteries two strings of 4, then parallel them for an all 24v system.
I also hope they did a better job on lithium, which is very possible because it sounds like a lot of it was done out of house.
Linear Mode
