2015 CS Adventurous 8 battery schematic

[cowxie]

Became an owner of a 2015 RT CS Adventurous earlier this year, and have gradually become more acquainted with the house electricals, and its idiosyncracies. The content and schematic below is the result of my findings of the wiring as purchased (but not necessarily as shipped from the factory due to other owners possibly mod'ing over the last 10 years). I've also included my changes to that wiring to address some points of weakness/concern.

Our RT CS uses 8 lead-acid batteries at 6Vdc for house load. Batteries 1 thru 6 are located in the rear battery tray under the fold out bed behind the rear axle. Batteries 7 & 8 are in the engine bay, on a tray on the right hand side when looking into the engine bay. This battery numbering scheme is used on the attached schematic.

Given that the 12Vdc fuse panel above the driver's head is fed seemingly predominantly by batteries 7 & 8 (due to cabling proximity from this circuit's feeder connection on battery 7), I felt these two batteries were somewhat more 'vulnerable' as they are heavily relied upon to feed all 12 Vdc load. As can be seen, the devices used for charging batteries (i.e. the 'UHG' under hood alternator, the PV system and the 5kW rated inverter/charger) all did so at 24 Vdc without regard to state of charge of any battery. It is my belief that this lack of state charge consideration results in under charging some AND over charging other batteries. The net effect of that is having to replace batteries much earlier than necessary. If the system can be configured to better use all batteries on board, and not just draw from 7 & 8, then this premature battery replacement issue is hoped to go away.

So I set about re-wiring, to as much as possible turn this into a 24 Vdc system...
All 12 Vdc load previously fed from the overhead fuse panel is now being fed from a newly installed 24 to 12 Vdc converter, with one exception - the fridge. The fridge is now wired to directly take 24 Vdc (via twisted pair conductors per Norcold's recommendation). We were seeing rapid compressor cycling when the fridge was on 12Vdc (this did not occur when on 120Vac), maybe because of the low voltage detection threshold kicking in when the Norcold fridge compressor was starting. Initial sentiment on this 12 to 24Vdc fridge feeder change is positive so far, but will have to wait until next RV season to ultimately be proven.

Other 12Vdc load fed from the incoming side of the Intellitec isolation relay (MCR) under the driver's seat remains unchanged. Thus, the fold out bed, the power step and the power step override continue to draw from batteries 7 & 8. The use of these 3 devices/circuits is very intermittent in our case and as such, I decided to leave the circuits 'as is' rather than go through an extensive re-wiring exercise for minimal gain.

Removed the 8 neg to chassis ground conductor in the engine bay and ran a new 1/0 cable between 8 neg and 3 neg. Done to help facilitate the install of a battery monitor system.

What's next...?
Looking to add a battery isolator switch and battery monitor. Leaning towards the isolator switch being installed on the conductor between 3 neg and NEG post, in a new, up-sized enclosure that will replace the existing (rusted) enclosure near the driver's side rear wheel well. Also looking to install the battery monitor shunt in this same new enclosure.

As an aside...
This 8 battery config can, without a lot of work be turned into a 4 battery system (either 1, 2, 7 & 8 OR 3, 4, 5 & 6). Yes, this sheds some boon-docking capacity, but it also sheds a couple of hundred pounds of weight that gets hauled around all the time. Guess that decision will come down to how long we want to stay off-grid...

Sharing this with the group in hopes that it might help even one sole to sort their own RT house electrical system. I'll try to answer any questions that may cross your minds, And I'm open to suggestions and critique (because I know that there's always more to learn).

Wishing you all the best and the safest of travels.
Cheers
/paul

Please do note that this schematic may inadvertently be missing some details (e.g. like the C.Brkr in the engine bay on the conductor between 7 plus and the MCR)

 

[booster]

I think that I am missing some of what you are saying. With 8 AGM 6v batteries this would be an Etrek or equivalent and they were a 24v system so don't need to change to 24v?

The did not use a a 24 to 12v converter and instead used a center tap on the series parallel battery string to get 12v to run the 12v coach stuff.

They did have severe issues for most users as the center tapped batteries would get way out of balance and fail early and the front batteries which had their out setup and ground in place and IIRC wired to the alternator would fail early because of the under hood high temps.

The long cable to the front gave a very large voltage drop and messed up charging balance in general.

There were numerous suggestions of possible fixes, changes, updates and some were done. Adding a battery balancer to the center tapped string was one that Roadtrek also started doing. The long cable was always an issues as was the double grounding.

It is really simple to change and 8 battery 24v center tapped system to 4 batteries, just cable them in series instead of series/parallel.

If you are using a B to B for your charging and a 24 to 12 converter to supply 12v that will help, but I think the best solutions got rid of the front batteries and turned it into a 400ah bank with just the rear batteries. No center tap with the converter and better charging from the alternator and current limiting by the B to B.

With just the six batteries you can more easily even out the cable resistance to each of them so charge gets to all of them the same. The single ground lets you use a battery monitor like you intend to.

At the time I think it was proposed to use 8v batteries to get the 24v which would work fine with no center tap, and IIRC they would fit the battery case better also. At the time they were available and used in some higher powered gold carts I think. You might even by able to find some large 12v or 24v batteries that fit the case.

Of course now you could swap to lithium also but that will take more work if they go underbody to handle the heat and cold times plus all the control stuff.

What inverter/charger is in it? The originals were said to be very unreliable.

 

[cowxie]

@booster - you're correct... the original configuration was a 24Vdc system, with the center tap 12Vdc powering the majority of house load.

Most of the time, I've seen 'E-trek' refer to lithium battery systems. This 2015 CS Adventurous has a pre-lithium era battery system made up of the 8 x 6Vdc lead acid batteries. Note that these batteries are not AGM lead acid, but simple flooded cell lead acid batteries (like these ones from Canada Energy)

The center tap the you noted is what I wished to get rid of, or at least minimize, because of the issues you mention. Except for the intermittent loads of the fold out bed, the powered step and the step override, all devices now use, store or generate at 24Vdc as applicable to each connected device.

All existing 12Vdc house load has been been moved over to a 24V to 12V dc-dc converter (probably oversized at 70amp capacity). And the Norcold fridge was moved to a 24Vdc feed to hopefully stop it from (low-voltage?) cutting out when on 12Vdc and to get it off of the dc-dc converter load.

Thanks for the suggestions on alternate batteries and configurations. I'm going to let the piggy bank fill back up for a while before attempting any more major circuitry and device changes.

The 24Vdc inverter/charger is a model LW5000W-24-C. I think it is original equipment, but I have no proof of that. So far, it has been good to us, other than a lot of fan noise. I've replaced the fan on one end with a quieter, but lower air flow rate fan. Sounds much better, but I'll have to wait until next season to see if there's any internal heating consequences of using this new fan.

Another item on my list this off-season is to get the 24Vdc UHG alternator sorted. I do wish to ensure that it is appropriately configured for these lead-acid batteries...

Cheers,
/paul

 

[booster]

I just took a quick look and everything I could find said that the original batteries were AGM. The Roadtrek brochure for 2015 is non committal by just saying 6v batteries.

I think I would carefully look for corrosion issues with the wet cells as the system may not be set up to ventilate well and/or corrosion proofed.

I can't say offhand if the 24v alternator would have had a remote programmable regulator on it or if it went with an internal regulator back then.

The Balmar regulator was the norm later on and can be set for different profiles, but if it was my system I would leave an internal regulator if it has one and run a b to b charger so the charge rate can also be set. 8 AGMS, and to some extent even wet cells, can pull to much power for the alternator to handle. If you eventually go to lithium batteries they will take too much for certain so a b to b would be necessary, so maybe best to do that now.

Especially with making changes, you probably should replace all the batteries and I would not go with wet cells because of the corrosion and voltage drop on heavy loads issues. AGM or Lithium depending on preference and budget would be better. The bet would be somebody put in wet cells to save money as 8 good AGMs are expensive.

The configurations probably weren't changed with the batteries and probably would have been OK. Possibly no AGM setting anyway in some of the parts used then.

Be sure to check the AC inlet connections to that inverter/charger as that era has some that overheated the terminals and melted it down, risking a fire. If it has bare stranded wires connected, put ferrules on wiring is the connector will be OK with them.

 

[cowxie]

Really appreciate hearing your thoughts @booster

Corrosion issues found, and plans have been made to coat all battery terminals with some sort of protector/sealer when the batteries go back in this coming Spring.

I am fortunate to have worked in industries where re-torquing electrical connections when the opportunity arose to safely do so was SOP. I have unfortunately seen the results of not doing so. But fortunately these instances have not resulted in personnel injury, just major equipment damage.

I'm (re-)torquing the battery connections, and other major electrical connections on the RT CS the same way, specially given your comment about the inverter/charger 120Vac connection history.

Note that I have found one of the cable lugs loose to the point that it slid off the conductor with a very mild tug! This occurence has only firmed my resolve to check all connections on a regular basis.

Would recommend to others to do the same checks, as I have a suspicion that this loose connection had been that way since the day it was made. But regardless of this connector's history, it just makes sense to check connections on a regular basis because electrical connections can come loose when they go through repeated, cyclic usage and the consequent lug expansion & contraction of usage heat cycles.

Speaking of the inverter/charger, there is a rotary switch on that unit that sets the battery charging profile (I'm going to double check the setting, but I believe it is now set to 14.1 Fast V, 13.6 Float V).

Similarly, the MPPT solar charger can be configured to charge various types of cells, and it is now set to 'Flooded' to match the existing batteries.

The only 'charger' that hasn't yet been checked in the UHG, which is why it's on my off-season list. If there's personal experience with a particular battery to battery charger (like Sterling, for example), I invite you to share as I'll add that to my research and reading list. Many thanks!

Cheers,
/paul

 

[booster]

It sounds like you on the right track in many ways.

What brand/model are they. With most of them under the floor it must be difficult to keep up with checking the water levels, if it is even checkable.

Our power system changes go back to only a couple years after we got our 07 Chevy Roadtrek 190P in the fall of 2008 when it was still new on the lot. I am now retired but then I was still working as a manufacturing and process engineer and that means my job was to do things to make our products faster, better quality, safer, and more reliably to improve profitability and competitive edge. It is baked in how I do stuff.

We have gone through quite a few incremental changes in wet cells, AGS, larger single alternator, second alternator, solar, different shore chargers, etc, so have seen a lot of it all.

B to B chargers weren't really around much at the beginning so nothing with them as we have gone a different path for our systems based around remote regulators and cutoff switches at full charge. I concentrated on settable parameter regulators for the alternators that also could limit charge rate.

When we had AGM it was a Charles private label unit that is no longer produced and when we went to lithium we went to a Wakespeed regulator. Both needed a lot of tweaking to do what I wanted, so hard to recommend to most folks.

When we had wet cells we used a larger than stock alternator with an internal regulator with cockpit controllable separator that I could activate when the amps dropped down to full charge spec.

I have no idea what your budget and available time is, but if you intend to continue for a while with the existing wet cells you might want to use a very simple setup like we did early on, and forego the more modern stuff until you decide on a final battery type and bank size.

Such a system would just be an internally regulated second alternator that will give something in the about 29v initially and then taper to maybe 27v . Cheap and easy and may be what your alternator already is. You have mentioned adding a battery monitor which I totally support for every system and Victron has models that are inexpensive and have a relay that can be set to trip based on SOC, voltage, current, etc. Put the monitor in the cockpit and put in a manually controllable charge relay so you can shut off the engine charging when full and monitor tells you that. This would also work for AGM so that switch later would be pretty easy. You would need to see how many amps your batteries will accept as you will have nearly 3X the capacity that we did and that might need to be addressed. If current limiting is needed, it gets more complicated and 1/0 cable will be too small, I think. Systems with that much capacity and a dedicated alternator would be 4/0 so can handle the full output of the alternator. This is why B to B chargers have come into play with lithium systems that almost all will accept large charge amounts. The mentioned system would be easy to just add a B to B to reduce the charge current. Sterling, I think, is the only ones that make a high amp B to B as they have a 120 amp one and a 180 amp one that I think you can order from Europe. For reference we charge our 648ah at 12 lithium bank at 120 amps of the second alternator.

Where are you in Canada and how is the van winter stored? That can make a huge difference when lithium gets into the picture.

We are in the NW exurbs of the Minneapolis area so not far from Canada.

 

[cowxie]

It was easy to check all wet cells, as I had removed all batteries to clean up and both the front and rear battery trays (and paint the rear tray).

Even when installed, it looks to be relatively easy to check water levels in all batteries. Hope that these aren't famous last words when next season comes around and I actually have to do this...

Van is stored in an unheated garage. So weather protected, but not temperature controlled.

Location is eastern Ontario near the outlet of Lake Ontario. Hope you're staying warm eh.

Cheers,
/paul

 

[booster]

Does the garage have power in it so you can charge the wet cells regularly? They lose charge quickly, often well over 10% a month so a winter top offs are a good thing for them.

 

[cowxie]

The RV storage area has 120Vac power when I literally pull the extension cord in.

Since I'm currently working under the RV on the rear battery tray, the spare tire carrier and the factory electrical enclosure behind the rear axle, my plan this year is to remove at least the 6 rear batteries and store them indoors. These batteries will occasionally be put on battery minder(s) during the off-season.

Any remaining battery (or batteries as the case may be) in the unheated RV will also occasionally be put on a battery minder.

Over the off-season, the new larger electrical enclosure c/w the Victron battery minder and the battery isolator switch will be installed back on to the RV. I mention this as I may re-connect a total of 4 house batteries and see if and how well the solar MPPT system helps to keep these 4 batteries 'topped-up' (yes, there is sufficient ambient light for the MPPT to show that it is 'awake', will it charge however?). The single 12Vdc battery for the engine will continue to be connected to a minder.

Again, many thanks for sharing your thoughts. All to the best to you.

Cheers,
/paul

 

[peteco]

These batteries will occasionally be put on battery minder(s) during the off-season.

Any remaining battery (or batteries as the case may be) in the unheated RV will also occasionally be put on a battery minder.

... The single 12Vdc battery for the engine will continue to be connected to a minder.

/paul

What BatteryMinder model(s) do you use?

 

[cowxie]

What BatteryMinder model(s) do you use?

I've got 2 of them - a factory BMW one and one from a Canadian auto parts store. I guess what I'm trying to say is that they're nothing special, and were originally intended to be used on our daily drivers during the winter season.
Both are rated for use on 12Vdc batteries, so it'll be interested to see if and how well they perform on pairs of series connected 6Vdc FLA batteries...

Cheers,
/paul