Roadtrek E-Trek Battery Replacement

[booster]

Originally Posted by markopolo

To keep track of topics - the other current e-trek topic is here: http://www.classbforum.com/forums/f5...tall-3984.html

In other models Roadtrek used Sure Power 12V separators that activate at 13.2v and disconnect at 12.8. It's likely the same in this unit but confirmation would be useful.

Both the Separator and the Equalizer provide 12V+ to the FE/AB group (in the design below). I added the Cooper equalizer chassis ground: (it could be routed to the front)

Attachment 2978

It makes no sense to have separator in the circuit from all I can think of. It is going to put two 12v charging systems, at likely different voltages, on the 12v set of 4 batteries, and is probably going to confuse the Mercedes computer controlled alternator in the van. The only time it would be needed would be to charge the starting battery when on shore power, I think, as the engine generator does all the rest.

If the shore power charging is what they were trying to do, then it would have to be a unit that did an "ignition interrupt" to open it whenever the engine was running. Even a one direction separator wouldn't work because there is charge voltage on both side when the engine is running.

[gregmchugh]

I guess you need to decide if you want the starter battery to be charged from shore power, one typical way to handle this is to put a small 120v battery tender charger in the system connected to the starter battery powered from the shore 120v circuit. Isolates the two systems and keeps the starter battery topped off.

[avanti]

Originally Posted by gregmchugh

I guess you need to decide if you want the starter battery to be charged from shore power, one typical way to handle this is to put a small 120v battery tender charger in the system connected to the starter battery powered from the shore 120v circuit. Isolates the two systems and keeps the starter battery topped off.

...or a Trik-L-Start.

[gregmchugh]

Won't the Trik-L-Start activate when you are driving and the aux generator is charging the house batteries? I was referring to a way to only have the starter battery charge when connected to shore power. There seemed to be a concern with running a charger in parallel with the van alternator while driving.

[avanti]

Originally Posted by gregmchugh

Won't the Trik-L-Start activate when you are driving and the aux generator is charging the house batteries? I was referring to a way to only have the starter battery charge when connected to shore power. There seemed to be a concern with running a charger in parallel with the van alternator while driving.

I'm pretty sure that this is not an issue. The Trik-L-Start sees the chassis alternator voltage and shuts down. From the Trik-L-Start FAQ:

WHAT HAPPENS WHEN THE ENGINE IS RUNNING? TRIK-L-START™ is effectively disconnected from both sets of batteries whenever the engine is running, and will not affect your alternator's normal operation.

[gregmchugh]

Originally Posted by avanti

I'm pretty sure that this is not an issue. The Trik-L-Start sees the chassis alternator voltage and shuts down. From the Trik-L-Start FAQ:

Very good, sounds like it is the way to go. As I recall, these might be standard in Advanced RV vans.

[gsm]

Booster and All

The Curious Finding on Your New Battery Installation

1 -The experience you describe in the first five paragraphs of your post # 38 is indeed very intriguing. Unfortunately I do not have a definitive answer. I wonder if there are differences in your batteries even if the they are from what is normally considered the same batch.

2 - If one narrows it down there is always some element of the production process that changes as the day goes by. For example the generally insignificant effect of exposure to air, light, temperature as the sun goes around the building, material set out before lunch for the afternoon's production, etc. .

3 – These variable may only show up in a higher order impact such on the tapering-off of the charging process. Something that might not be controlled as tightly as other parameters. I am no expert on this.

4 - Furthermore, and this is only my impression, batteries like most other physical/chemical systems attain/retain a signature from past environments, cycle-experiences, etc..

5 - If one simplifies your battery situation as two from before, and two from after lunch one gets the following idea. I am just throwing out to stimulate other thoughts.

6 – Re-using the battery-nomenclature from this E-Trek discussion, we have four batteries A & B, (morning) and E & F (afternoon). We no longer know which is which. Your first setup might have been A in series with B paralleled with E in series with F. Whereas in the second setup (parallel first) you configured AB in series with EF. Perhaps you marked your batteries and can verify if that happened.

7 -To be absolutely sure you would need to put each battery through the same charge-discharge cycle at the same temperature. Look specifically at the first cycle and compare the data to later cycles. Perhaps going through several cycles in an attempt to find if the results on the batteries start to lineup more closely as the number of cycles increases.

8 - With respect ending your charging process, if I understand your dilemma correctly, you might switch in a resister that takes say 0.5 Amp, and fool the threshold. The resistor drops out once charging ends.

AGM E-Trek

9 - With respect to paragraph six and seven of your post #38. I completely agree that my proposal of paralleling the A and B battery and keeping them under the hood is less than ideal. And I made that clear in my posts under Photolimo's thread titled “E-Trek Battery Monitor Install” (#141 and # 150). I also made it clear that for better results the batteries A and B should be moved to the rear. I suggested an installation set into the floor behind the wheel-well like Great West Vans has done.

10 - I have given up on RT doing anything useful for customers. I felt that leaving the A and B battery up front would make a good compromise solution that could be undertaken with a bit of care and guidance, even by DIY challenged owners.

11 – After re-configuration, overcharging of batteries A and B is exclusively caused by the higher charging-efficiency at the higher temperature. It is no longer worsened by unbalance. As I stated in my earlier posts, I estimate that for AB the charging-efficiency rises only five to ten percent as result of temperature. To allow full charging of the cooler battery-pairs I would allow AB to overcharge by five to ten percent. I do not believe that the amount of overcharge is significantly harmful, and might even be good for the batteries.

12 -The rest is up to the qualities and setting of the regulator used with the high-current-alternator. The voltage Delta from the hot batteries A and B seen by the alternator/regulator is no longer comes from 50 percent of the battery bank, it now comes from only 25 percent of that voltage, viewed in comparison to the Delta of a tack four pairs of hot batteries. After allowing for the Delta it is now safe to sense temperature at the six upper batteries.
It might be possible as booster suggested to direct cooler air around the under-hood battery-pair.

13 - Overall not and ideal situation, but definitely much better, than RT's configuration, and I think workable as an intermediate DIY solution accessible to most owners.

NOTE-1: - I gather that everybody agrees that separator and connection to the starter battery is both undesirable/harmful and not installed on AGM E-Treks. We also settled on a converter to derive 12-volt dc.

Best Regards

GerryM

[gregmchugh]

If it was my van I would pick a configuration that is relatively easy to implement, provides reasonable performance, avoids the pitfalls of the current Roadtrek approaches for getting around 400 amp hours at 24 volts, and tries to minimize your cost as much as possible. I would go with the six 8 volt battery configuration and ask Roadtrek to foot the bill for the new batteries. If they agree to provide some level of covering the cost then I would go for it. Even if they don't cover the cost, I would eat the cost since it seems like a reasonable approach to get a reliable system. If you already have the Cooper equalizer from Roadtrek use it as a converter and if not I would get them to provide one at their cost. Just the way I would go based on all of the analysis I have seen here.

[booster]

Besides the 6 eight volt batteries, it might very well be possible to fit two of the 4D or 8D twelve volt batteries in the rear box. Just looking at the layout and battery dimensions off of the specs, it might just work, and those series of batteries are usually designed to work in this kind of application.

[gregmchugh]

Are there any 12v batteries in that size with 400 amp hours, they seem to be about 255 max at least at Lifeline? You would need 4 of them, not two to get 400 amp hours or more at 24v...

[booster]

Originally Posted by gregmchugh

Are there any 12v batteries in that size with 400 amp hours, they seem to be about 255 max at least at Lifeline? You would need 4 of them, not two to get 400 amp hours or more at 24v...

You are correct. I just looked at the AH and forgot the 24 volt system. Outside chance the 4 would fit, but would definitely need to measure the box.

It is interesting that the pix in Hal's link show the batteries from the top, but it also looks like they are just on an open tray under the van as I think you can see the ground around the batteries. I assumed they were in a box based on the pix Roadtrek had of them on the bench in what I thought was box.

[gregmchugh]

Originally Posted by booster

You are correct. I just looked at the AH and forgot the 24 volt system. Outside chance the 4 would fit, but would definitely need to measure the box.

It is interesting that the pix in Hal's link show the batteries from the top, but it also looks like they are just on an open tray under the van as I think you can see the ground around the batteries. I assumed they were in a box based on the pix Roadtrek had of them on the bench in what I thought was box.

Yes, clearly there is not an enclosed box just a support structure for the batteries. Any idea what brand AGM batteries those are in Hal's picture, I don't recall any AGM batteries with caps like that on the cells?

[gsm]

Winston Battery - Lithiums


In five years time when batteries need to be replaced this is what should be heading our way.

It make one dream?

Thunder Sky Winston Energy Group Limited

Perhaps six of these
WB-LP12V300AHA

300 Amp-Hr, 12 volt
Temperature Range - Charging/Discharging
- 45 to + 85 degrees Celsius
Or
Just two of these
TS-LTHP2000AH12V

2000 Amp-Hr, 12 volt
Temperature range – Charging/Discharging
- 45 to +85 degrees Celsius
Imagine the high current alternator system needed to do justice to the 2000 Amp-Hre beasts.

Regards All

GerryM

[booster]

I wonder how they are doing the cold weather charging? All we have seen says you can't charge below freezing without doing damage.

[gregmchugh]

They do seem to be just bare cells with no way to keep them warm...

[Davydd]

I checked the 200ah batteries. They are not much different than what I have in size and weight. I think they may be a tad optimistic about performance on the temperature range. I am not sure they really mean you can charge at -45C. The range is quite a range. My batteries can be discharged at any conceivable temperature I will encounter and are safe to about 145F. As far as charging I supposedly can charge down to 30F. My DOD at 80% with 5,000 cycles is in line with their claims. That's 13+ years of daily use. I'll never see that. There is a physical and practical limit as to how much you can put in a van. Advanced RV is topping out at 1200ah with their present 12v design of 24 3.2v-200ah cells in one contiguous block of cells. Anyways, I don't have 5 years to wait and dream. That's why I went with now.

[markopolo]

GerryM's design (previously posted) is so simple and effective. Here it is again:

E-Trek Battery balanced layout converter.jpg

- Minimal rewiring.
- Minimal expense. Two new 6V replacement batteries could be enough to demonstrate the design.
- 12v loads are drawn from the entire 24v battery bank - no mid bank tap in.
- A&B will trail the rest because of the long wire run but could catch up because of daily solar charging and touring usage expected with most Class B's. There's the under the hood heat issue with A&B but some of the batteries in the rear might be affect by exhaust heat or radiant asphalt heat.
- Should be able to add a state of charge monitor.

General questions:
Is the solar controller output 24V?
Where does the solar controller connect to the battery system?
Does the coach rely of the wattage potential of combined 12V and 24V alternators?
Any other questions / concerns?

If I think in terms of good, better, best then this would be in the better category.

I think it's worth submitting it to RT to get feedback and get warranty approval. There may be parts of the coach we are not aware of.

[gsm]

Markopolo and All

Question On AGM E-Trek Charging System

Up to now we all assumed that the second alternator of the AGM E-Trek is a high current 24-volt model.

What if we are wrong? Could the second alternator be a 12-volt model with negative and positive terminals isolated from chassis ground? RT might have stacked the floating output of this second alternator on the 12-volts of the Sprinter alternator? That would explain the need for the separator connection to the starter battery, and all else that flows from this configuration.

If this is the approach RT used, it would be a real Rube Goldberg design. I would really like to know. So AGM E-Trek owners please check this out.


Best Regards
GerryM

[photolimo]

Originally Posted by gsm

I would use a clamp-on Ammeter to check currents and balance among all eight batteries.

In a similar way I would check the charging-currents and determine balanced charging.

I would also make sure that terminals are all torqued properly.

Thanks for the tips GaryM. I am currently working on cleaning and checking all the terminals as the E-Trek was returned from service with all the battery posts still extremely dirty. I was hoping when they installed the balancer and new batteries a few weeks ago that they would clean the posts but that was hopeful thinking.

Do you have a DC Ammeter you would recommend?

[gsm]

photolimo

I use a reasonably priced Uni-Trend Group Ltd. clamp-on Ammeter UNI-T Model UT203, I bought some years ago for around US $70. It has all the normal multimeter functions except the AC and DC current ranges are 40A and 400A and only available via the clamp-on jaws. I bought it at the local Active Electronics outlet about 10 years ago. Wallmart may have a similar product. A US $400 Fluke clamp-on Ammeter with remote reading capability is nice but unnecessary. You might also check if the meter is powered by standard readily available cells, which is preferable.

When clamping the meter onto a rigid battery-cable make sure that the jaws close completely. You might finesse jaw-closure and use the highest reading. You may also need to hold onto the meter so that its weight does not open the jaws.

In your setup you could find a battery without suitable jumper to clamp onto, while its mate has two. This is a wiring-balance error you will need to correct. I suggest that you first check all wiring for correct configuration, to give you the necessary access points.

Since you will likely have to bend/lever jumpers clear of the battery cases, you should take the opportunity to ascertain that jumper-terminals are securely crimped/soldered. This will be indicated if the ammeter-reading is unsteady as you flex the jumper. Of course terminal-nuts could also be loose. All this will need to be corrected to get meaningful measurements.

The time to make measurements is during the high current phase of the charging cycle. Since you will be focusing on comparing current through battery pairs measurements will only be a few moments apart. A gradual downward drift of the charging current while you proceed from pair to pair is not significant as you are looking for balance only. However I suggest that charging-current should be at least 50 Amperes. Personally I would prefer 100 Amperes.

I would allow the batteries to charge completely and then repeat the measurements with constant load of at least a couple of kilowatts applied to the inverter. Using a heater is best as is is easy to set it to draw a continuous current. Besides it will keep you warm while you make the measurements.

In Post # 58 I tried to make AGM E-Trek owners aware that RT might have several substantially different alternator-configurations out there. Some variants would work better than others. By talking about the possibility of stacked alternators, I wanted to indicate how extremely different the variants might be. I should have worded my Post much better.


Best Regards
GerryM