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Old 11-23-2020, 09:26 PM   #1
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Default 2015 Roadtrek Adventurous CS with 10 AGM Batteries

I recently purchased one of the Roadtreks that was made just before the switch from AGM to Ecotrek Lithiums. It has 600+ watts of solar and 10 AGM batteries. There are two under the hood as a 12V series and eight(!) under the chassis in two 24V series.

The battery balancer/equalizer had already been installed.

I'm concerned about the electrical layout from what I've read here (https://www.classbforum.com/forums/f...ment-6802.html) and also because of the fact that the two batteries under the hood were dead on arrival. The dealer replaced those two batteries, once we convinced them that they wouldn't hold a charge.

I'd really like to install a battery monitor, like the Victron BMV-712 but I am not sure which battery bank to monitor and which to set up as a secondary battery, or do I need get two battery monitors?

Second question, can the Victron shunt be installed at the battery equalizer? That would be sooooo much easier than installing it under the hood or under the chassis.

Thanks!
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Old 11-23-2020, 10:52 PM   #2
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I recently purchased one of the Roadtreks that was made just before the switch from AGM to Ecotrek Lithiums. It has 600+ watts of solar and 10 AGM batteries. There are two under the hood as a 12V series and eight(!) under the chassis in two 24V series.

The battery balancer/equalizer had already been installed.

I'm concerned about the electrical layout from what I've read here (https://www.classbforum.com/forums/f...ment-6802.html) and also because of the fact that the two batteries under the hood were dead on arrival. The dealer replaced those two batteries, once we convinced them that they wouldn't hold a charge.

I'd really like to install a battery monitor, like the Victron BMV-712 but I am not sure which battery bank to monitor and which to set up as a secondary battery, or do I need get two battery monitors?

Second question, can the Victron shunt be installed at the battery equalizer? That would be sooooo much easier than installing it under the hood or under the chassis.

Thanks!
Are you sure you have 10 AGMís? Normally there are the two under the hood and 6 more under the van. They are wired as a 24v battery bank and you have a 24v solar controller and inverter and under hood generator.
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Old 11-23-2020, 10:58 PM   #3
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Yup. I traced the layout today just to be sure. It is a crazy setup with a rack of 6 batteries and another rack of 2 batteries under the back and the 2 batteries up front under the hood. There are two solar controllers too - one at 24V and the other at 12V.
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Old 11-24-2020, 04:09 PM   #4
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I wonder if the extra AGMs were added by a previous owner or maybe you just got an odd build by Roadtrek, the old company was famous for endless variations in their builds for the same model.

Since you want to install a shunt based battery monitor, I would consider ditching the two underhood batteries and rewiring the rear 8 batteries as the 24 volt bank with a common ground to make it easy to install the shunt.

What is the 12v solar controller connected to? Must be the extra two 6 volt batteries that are separate from the 24 volt bank. How is this separate 12v battery pair connected into the rest of the electrical system?
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Old 11-24-2020, 07:31 PM   #5
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Since you want to install a shunt based battery monitor, I would consider ditching the two underhood batteries and rewiring the rear 8 batteries as the 24 volt bank with a common ground to make it easy to install the shunt.
The typical SOC meter requires installing the shunt in the path of a common ground which in this case might require quite a bit of rewiring of beefy ground cables. However, Blue Sea offers a model 1830 SoC meter with a shunt that can be located on the positive battery bus which would simplify the shunt installation by eliminating the necessity for a common battery ground. Their engineers reported that it results in a reading error of less than 4% which I would consider acceptable.


https://www.bluesea.com/products/183...meter_with_SoC
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Old 11-24-2020, 07:51 PM   #6
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The typical SOC meter requires installing the shunt in the path of a common ground which in this case might require quite a bit of rewiring of beefy ground cables. However, Blue Sea offers a model 1830 SoC meter with a shunt that can be located on the positive battery bus which would simplify the shunt installation by eliminating the necessity for a common battery ground. Their engineers reported that it results in a reading error of less than 4% which I would consider acceptable.


https://www.bluesea.com/products/183...meter_with_SoC
The problem here is that there are two power taps on the battery bank, one at 24v and one at 12v. There is no single point on the positive side to install a shunt.
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Old 11-24-2020, 07:55 PM   #7
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The problem here is that there are two power taps on the battery bank, one at 24v and one at 12v. There is no single point on the positive side to install a shunt.

Yep, I think the only way to do it would be to ditch the balancer and add a 24 to 12 converter, which would give a much better system in general, especially if you get rid of the front two batteries and the horrible cable runs.
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Old 11-24-2020, 08:00 PM   #8
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Yep, I think the only way to do it would be to ditch the balancer and add a 24 to 12 converter, which would give a much better system in general, especially if you get rid of the front two batteries and the horrible cable runs.
A good option, depending on which model battery equalizer was used, it may be able to function as a straight 24v to 12v converter. Get the model number of the battery equalizer and look it up at Cooper Busman. Or simply buy an adequate size converter for the 12v loads.
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Old 11-24-2020, 08:27 PM   #9
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The problem here is that there are two power taps on the battery bank, one at 24v and one at 12v. There is no single point on the positive side to install a shunt.
You're right of course. I keep forgetting that. When did they discontinue this kluge?
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Old 11-24-2020, 08:34 PM   #10
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You're right of course. I keep forgetting that. When did they discontinue this kluge?
The 8 AGM eTrek was discontinued when the lithium battery option came out. Your van with 10 AGMs is a real oddity, never heard of one before...

As Booster noted above, the best solution is to switch to a 24v to 12v DC to DC converter connected to the 24v battery side and remove the 12v tap in the middle of the battery bank and move it to the converter. See notes above.
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Old 11-25-2020, 02:20 AM   #11
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Just a thought. How would you wire 10 six volt batteries for 24v?
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Old 11-25-2020, 02:27 AM   #12
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Just a thought. How would you wire 10 six volt batteries for 24v?
My point above in another comment, you canít. They must be separate with their own 12v solar controller and no other charger or maybe tied into the chassis battery with a separator. But what do they power? Another Roadtrek Frankenvan...
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Old 11-25-2020, 10:24 AM   #13
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It's possible that the 10 AGM unit is this one: https://www.classbforum.com/forums/f...tml#post114524

DC description: https://www.classbforum.com/forums/f...tml#post116514


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Old 11-25-2020, 11:41 AM   #14
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It's possible that the 10 AGM unit is this one: https://www.classbforum.com/forums/f...tml#post114524

DC description: https://www.classbforum.com/forums/f...tml#post116514


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A one of a kind Frankenvan it seems...

I suppose, if you are trying to maximize battery powered air conditioning runtime before restarting the engine you could get some added time with moving some 12v loads to the two added 6v AGMs. Wouldnít make sense to have them under the van and keep the long cables to the underhood pair wired into the 24 volt bank but maybe they just did the expedient thing for a show vehicle and didnít redo the wiring.
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Old 11-25-2020, 02:00 PM   #15
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...I'd really like to install a battery monitor, like the Victron BMV-712 but I am not sure which battery bank to monitor and which to set up as a secondary battery, or do I need get two battery monitors?...
I believe Victron makes a model that can monitor two separate battery banks.
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Old 11-25-2020, 03:19 PM   #16
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It's possible that the 10 AGM unit is this one: https://www.classbforum.com/forums/f...tml#post114524

DC description: https://www.classbforum.com/forums/f...tml#post116514


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I also kind of vaguely remembering a home drawn wiring diagram that showed a separator going from the engine to the front batteries and maybe with a statement that the 12v loads were pulled off there in the front. That was an 8 battery setup, though, I think.


Here is a discussion for 2015 that seems to show in some of the wiring diagrams posted for the stock and potentially changed wiring that the the stock alternator was putting 12v charge to the center tap of the battery. If the 12v loads were there also, as it is would be the center tap, perhaps that was to give the batteries that would be lower from running the loads more charge than they would from being in the24v string? I didn't reread the whole 8 pages, though, as it is very long.


https://www.classbforum.com/forums/f...tall-3984.html
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Old 11-25-2020, 06:06 PM   #17
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Whatever it is at the moment, I would think the best long term solution is to wire the 8 batteries under the van as the 24 v bank with a 24v to 12v converter to power the 12v loads. You could keep the battery equalizer to try to promote even charging and prolong the life of the battery bank.

I would be tempted to just jettison the two batteries under the hood and tie the loads into the converter. If there are solar panels on a 12v controller you could possibly add them to the others if feasible or use that controller to keep the chassis battery charged when parked.

All the added complexity in this build seems to me to just add the potential for future problems...
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Old 11-25-2020, 08:41 PM   #18
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I think in the other thread the solar controller was 24v from the factory, but this is certainly different so that may not be the same either.
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Old 11-25-2020, 11:04 PM   #19
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I think in the other thread the solar controller was 24v from the factory, but this is certainly different so that may not be the same either.
I think he mentioned that this one had two solar controllers, one 12 and one 24. What happens if you connect two controllers to the same panels?
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Old 11-25-2020, 11:16 PM   #20
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I think he mentioned that this one had two solar controllers, one 12 and one 24. What happens if you connect two controllers to the same panels?

Magic smoke?


You might be OK for damage if you hooked up the 12v controller in the middle of the 24v string of panels, but I can't understand why you would do that.


I wonder if they are using an MPPT solar charger like a 24 to 12v converter to charge the the two front batteries at 12v from either the solar or the shore charger or 24v bank. There may be some switching going on between the chargers depending on shore power, engine running, only solar times. Roadtrek did so many silly a$$ things with the etrek design, I would not rule anything out.
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