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Old 07-17-2015, 11:03 PM   #1
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Default The E-trek Blog

I've been reading the posts on The E-trek Blog with interest. After 2 1/2 years or so I still don't know much about the E-Trek so it's nice to finally see someone talking about voltages and state of charge etc.

Here's a link to the well written blog: www.theetrekblog.com

They even kept an Etrek Battery Log that is posted on the site.

Their E-trek battery bank is connected so that it is (or at least part of it is) 24 volts. Divide posted voltages in half for comparison if you are used to 12 volt battery systems.

One post mentions
Quote:
Adequately charged…..23.5 volts and above
- that's like 11.75V on a 12v system.

If you Google "12v SOC chart" you'll find many charts that indicate 11.75v at rest indicates a state of charge of 30%. You'll often see references that suggest limiting the depth of discharge to 50% to prolong the calendar life of a lead acid AGM battery. Those same charts indicate that 12.0 volts measured while the batteries are at rest indicates 50% SOC (state of charge).

Hopefully we'll see more technical type of discussions about the E-trek emerge. It will be good info to refer back to as these rigs get older and pass onto 2nd and 3rd owners etc.
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Old 07-17-2015, 11:34 PM   #2
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That is pretty interesting stuff, and really nice to see folks putting the data out there.

We have always kind of wondered how they worked, and suspected that the only way they could get enough charge back fast enough to use again, would be if they were operating in the middle of the SOC most of the time. This would indicate that might be true, but more information is needed.

It will be fun to follow the reports and see how they shake out.
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Old 07-17-2015, 11:37 PM   #3
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Hmmm. I've looked at the blog, read some of it.

A bit odd that someone with no RV experience would jump into perhaps the most technologically advanced RV available (outside of custom-builds!).

I did look a bit at their voltage charts, as most of us with an ETrek have likely tried to do something similar. I think they are vastly overthinking the issues, though their numbers are interesting.

For me, using the ETrek as it was proposed, driving most, but not all, days while out on a trip, the rig has performed flawlessly. No alarms. No shutdowns. Plenty of use of the 120 volt devices.

I did recently pick up the Innova 12 volt meter discussed by others, and find that it does give me a better indication of the SOC by far than the 4-idiot-lights box. Just how that 12 volt reading correlates to the ETrek's 24 volt system is something I've yet to understand.

I'll continue to read that blog. Even though their problems are not my problems.
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Old 07-17-2015, 11:59 PM   #4
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the next issues will be on the ECOTREK blog.

th thing i got from this is what mark pointed out when i asked my voltrek/inverter questions.

12 volt inverter charger-10.5 volt warning 10 volt shuttdown

24 volt inverter charger 21 volt shut down.

i think many e-treks suffer from not having battery balancer.

Mary Ellen Stagg Capek has a post today about e-trek charging issues on the roadtrekking facebook page
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Old 07-18-2015, 12:23 AM   #5
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This topic could go in many directions. The whole add a balancer or not discussion would be very interesting I think. I read a bit about the balancers on the Roadtrek forum before it was shut down.

And, let's keep this topic positive. There are lots of happy E-trek owners out there.
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Old 07-18-2015, 12:26 AM   #6
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there are many e-trek owners. the battery balancer thing seems to come up regularly though.

i have no idea why it happens to some but not to others.
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Old 07-18-2015, 01:25 AM   #7
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Quote: "A bit odd that someone with no RV experience would jump into perhaps the most technologically advanced RV available (outside of custom-builds!)."
==================
Not odd to me. That's exactly what we did. The more technologically advanced, the fewer things a newbie needs to learn and keep straight. We eliminated the entire propane sub-system and any attendant learning curve, for example.
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Old 07-18-2015, 02:07 AM   #8
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That is why they are taking the approach of the system being automatic and not requiring any real user intervention. They want to dumb it down and make it appeal to the ordinary user, not the tinkerer's we have on this forum.
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Old 07-18-2015, 02:09 AM   #9
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I don't really understand the discussion of adding a balancer. The BMS should do cell balancing. The Smart Battery has this built in. They claim that since they match cells very closely, that this function would rarely engage. But these are "toy" cells I guess, so who knows what Jim's need.
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Old 07-18-2015, 02:20 AM   #10
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The balancer / equalizer mentioned here is used when you have both 12 volt and 24 volt systems. It maintains battery balance so you can draw 12 volts from some of the batteries without drawing those batteries down disproportionately.
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Old 07-18-2015, 03:31 PM   #11
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Quote:
Originally Posted by obgraham View Post
I did recently pick up the Innova 12 volt meter discussed by others, and find that it does give me a better indication of the SOC by far than the 4-idiot-lights box. Just how that 12 volt reading correlates to the ETrek's 24 volt system is something I've yet to understand.
Is the 4 light panel all you get in an etrek package for monitoring battery state of charge? That seems pretty odd for a rig that is so heavily electric.
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Old 07-18-2015, 03:38 PM   #12
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E-Trek is my first RV (May 2013 build). The electrical system has performed flawlessly, as obgraham states. I monitor both 24v (via solar controller) and 12v (via Innova meter) SOC regularly after resting the batteries overnight. (Inverter shows only integer volts so not very useful.) My observation is that the 24v side is a bit greater than double the 12v side. A few minutes ago 12.55v vs. 25.3v. Full charge will show about 12.7v and 25.6v so I'm not seeing battery degradation so far, and most charging is via "engine generator". It sure looks like all charging is on the 24v side and then a balancer or DC/DC converter is powering the 12v outlets. RT, of course, is not saying. It does work, but would be more fun if I knew how.

I lurk, I learn, I marvel at those of you who have the skill and patience to undertake complex modifications.
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Old 07-18-2015, 03:38 PM   #13
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If you have a balancer of equalizer installed then the 12V reading should be half of the 24 volt system. If you don't have a balancer of equalizer installed then I would expect the 12v reading to indicate a lower voltage most of the time.
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Old 07-18-2015, 03:43 PM   #14
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Here's a link to the Facebook discussion Gerry referenced yesterday: https://www.facebook.com/groups/road...7160028109648/

It seems to indicate that adding a balancer or equalizer is recommended at least on some units.
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Old 07-18-2015, 04:53 PM   #15
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Quote:
Originally Posted by booster View Post
Is the 4 light panel all you get in an etrek package for monitoring battery state of charge? That seems pretty odd for a rig that is so heavily electric.

Not sure about the new ones, but mine has only the 4 lights that are easily viewed. The solar controller has a volt meter but is tucked away in a cabinet so not easily viewed (and requires selecting this function). Inverter has % number (calibration unclear) and volt meter, but can only be viewed with rear doors open.
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Old 07-18-2015, 05:35 PM   #16
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Quote:
Originally Posted by wincrasher View Post
I don't really understand the discussion of adding a balancer. The BMS should do cell balancing. The Smart Battery has this built in. They claim that since they match cells very closely, that this function would rarely engage. But these are "toy" cells I guess, so who knows what Jim's need.
Ron-this is with e-trek agm's not the lithiums; having said that i suppose it could also be an ecotrek issue in the future
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Old 07-22-2015, 02:30 AM   #17
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I'm the new kid on the block with a 2015 TS E-Trek (Coach Connect and all, for whatever it's supposedly worth). This thread got my attention regarding the BMS. I understand it stands for Battery Management System, I know where the switch is to turn it off, and can view it on the attached and detached tablet that came with my unit. Supposedly I can even watch it from my smart phone (but that's a whole other gripe). Beyond that, I have no idea what it is. Can any of you give me a short description of what it does? For instance, it only shows two 6 volt batteries for a system that supposedly is a 24 volt system. What exactly am I monitoring here and what exactly is the system doing for me?
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Old 07-22-2015, 03:08 AM   #18
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Quote:
Originally Posted by gerrym51 View Post
your mixing 2 different things, the BMS we are discussing is for lithium batteries. thats one thing.

the battery balancer being discussed is for the AGM's in your e-trek package.
the etreks wire the batteries as 2 4 packs to make in effect 2 24 volt batteries to feed your 24 volt inverter. if you only used the inverter for everything there would never be battery charging issues,

however you have many 12 volt devices. so 2 batteries out of the 4 packs are also wired together to create a 12 volt battery. because these batteries are being discharged at a different rate than the 4 pks when the batteries are charging sometime they charge unevenly. that is why some e-trek owners need a battery balancer to balance charging to ALL batteries
Actually 4 of the 6 volt batteries(2 ea in series and then in parallel) are for the 12v system and the other 4, in series, are for the 24v inverter. Originally RT did not engineer a proper balancing between the 24v and 12v system, but they claim to have that resolved and will modify the balancing process under warranty. Contact RT direct for resolution.
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Old 07-22-2015, 03:16 AM   #19
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i deleted my post since i only know based on what i have read i just have a single battery in my roadtrek
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Old 07-22-2015, 03:22 AM   #20
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xroadtrek. i have a question. if what you say is true and there is only one 4 pack feeding the inverter-doesn't that greatly cut down on air conditioner run time.

50 percent of 4 6 volt batteries would only be 220 amps i see people running the air condioners in e-treks 2-3 hours. i would not think 220 amps would do that.

using 4 6 volt for just the 12 volt seems like overkill on 12 volt and underkill on the 120 volt inverter,

just wondering
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