Battery: Series+Parallel & Monitor

[stevanpierce@gmail.com]

I was reading a few of the threads on here, of which got me to thinking of extending my off-grid action. I am sure there are a lot of other factors I have yet to think of when it comes the idea I had.

So, I let my deep cycle batteries die a sloooow death. I suspect that something was left on or had a phantom power leak somewhere, more than likely first one.

I have a stock 2010 Roadtrek 210. The batteries that were for the coach are Napa 8144's and battery monitoring system is what came with the coach. Since the batteries are dead and Napa has been anything but helpful, have decided to take my money elsewhere....another story another time tbh.

After running some calculations, I found with the basics running in the rig would eat up 30A, with 230AH, equates to ~7.5 hr of power. Using the following for calc, https://power-calculation.com/battery-storage-calculator.php

I was thinking of getting two (2) Duracell Ultra 6V Deeps (SLIGC125), run a series. https://www.batteriesplus.com/productdetails/sligc125 which would add 0.25hr for total of ~7.75hr of off grid since I would achieve.

However, I ran across a site that talked about a battery bank in a series and parallel. So, if I had four (4) SLIGC125's configured in this manner, I would in effect end up w ~15.5 hr of off grid.

Then I was thinking of getting the Victron Energy BMV-712 to remotely monitor the system, https://www.victronenergy.com/battery-monitors/bmv-712-smart

For the location of the additional two (2) batteries, I was thinking of placing them on the opposite side of where the coach batteries are located, in the long pull-out draw. (The same drawer/storage that the hose from the macerator is stored.)

Now the cost: (Batteries $700) + (Battery Monitor $200) + (Cables $100) + (Misc $50) = $1050 * (110% because it usually ends up being at least that much more) = $1175

This does not account for me driving the rig and charging the batteries. Nor does it account for me running the generator to charge them. I'd also hasten to say that all 30A would be run all the time for ~15.5hr. (Just thought I would head those questions off at the pass )

Would a solar setup be a better idea given the above? (If I went solar then would just keep a pair of the Duracell flooded SLIGC125's.) I am not really looking to spend all that much $ tbh....just want something practical. I am okay running just the fridge and using a headlamp at night and occasional tv/dvd action.

 

[booster]

30 amps for the basics would be considered way high unless you are running the absorption frig on DC all the time and lots of other stuff. A normal Roadtrek would be about .5 amps for the detectors plus what ever else is running. If you leave the inverter on all the time, that would 1.5-3 amps approximately with no load on it.


What are running that takes so much power?

 

[markopolo-ClassB]

If the energy use calculation result was 30Ah per day and not 30A then:

230Ah batteries x 80% depth of discharge = approx 180Ah / 30Ah = 6 days


Edit to add: Pending more details ......... I'd say definitely consider adding solar. 100W or 200W would make a big difference and help keep the new batteries in good condition.

 

[booster]

If the energy use calculation result was 30Ah per day and not 30A then:

230Ah batteries x 80% depth of discharge = approx 180Ah / 30Ah = 6 days

I think you are probably right that it should have been 30AH per day. Just another case of the hazard of using wrong units and mixing them besides, if that is the case.


Agree on the solar. If it is 30AH per day, then 200 watts of solar would be enough except under extreme bad sun to keep the OP running off grid essentially indefinitely. We ran 260ah of wet cells with 200 watts of solar and had no real issues even with the compressor frig except when we got many days of no decent sun, and then we still were not totally to 20% SOC.

 

[GeorgeRad]

.........................
After running some calculations, I found with the basics running in the rig would eat up 30A, ...............

30A draw is a lot, can you share your calculations? - perhaps you meant 30Ah pointed earlier. Did you figured out why your previous batteries died? Did you add water on regular basis?

 

[stevanpierce@gmail.com]

30A draw is a lot, can you share your calculations? - perhaps you meant 30Ah pointed earlier. Did you figured out why your previous batteries died? Did you add water on regular basis?

Yeah...learning curve on electricity. 15ish for fridge, 6 led tv+stereo, + 2 for safety items + 1 for water pump + 2 lights + 1 fan + 3 misc stuff i've overlooked

The previous batteries died because i more than likely left something on, suspect the inverter. I did check the water on a regular basis. It was an expensive lessen. Also had the rig battery died two. I'll perform a power audit next time I am in the rig.

 

[booster]

Yeah...learning curve on electricity. 15ish for fridge, 6 led tv+stereo, + 2 for safety items + 1 for water pump + 2 lights + 1 fan + 3 misc stuff i've overlooked

The previous batteries died because i more than likely left something on, suspect the inverter. I did check the water on a regular basis. It was an expensive lessen. Also had the rig battery died two. I'll perform a power audit next time I am in the rig.

You should never be running the 3way frig on DC when on batteries and only on 12v while driving. Exception would be a quick stop on a long driving day. You would want to be on propane. The rest of the items would intermittent use so need to figure out how many hours per day each is running. The water pump won't run more than a few minutes per day, TV a few hours, etc. Inverter normally off unless needed for TV and using a small inverter for that is very common to reduce power use. Many with a similar setup would be using in the 30AH per day most of the time, maybe a bit more or less, not anywhere near the 720AH per day you would calculate by using 30 amps all the time. At night, inverter off, you would use maybe 1/2 amp unless the fan is running. We ran that system with a compressor frig and would use only 40-50 amp hours per day in our Roadtrek. Your frig should use near zero power and I think it even has an auto switching to go to propane.


Most folks will get at at least 2-3 days on a two battery setup with propane frig and some can get quite a bit more than that even without solar. Your battery monitor, once setup properly will quickly show you how much actual power you use in a day so you have a real world answer. Put a couple of hundred watts of solar on and you can normally go a long time.


4 battery setups are nice, we have such a setup so we can go for over a week without sun if we need to, but most don't need the capability, and we have a compressor frig. We also have less penalty to the system because the batteries are underbody so don't use up all the storage space. Going four batteries is normally also done with charger and inverter upgrade to take advantage of the extra capacity for running the microwave, etc, and many of us also added big second alternators. Doing such a conversion is not cheap or for the non DIY types unless they are willing to spend a lot of cash and finding a good shop is very difficult for this kind of stuff.


I think you would be best to start off with getting a monitor in place and properly setup to find out how much you really need for power. A bit of money spent on power use improvements would likely be much less than adding two more batteries. You also have to consider that you have a 210, which is going to likely be very short of weight capacity capability. Putting another 150# of batteries could use up a big chunk of the capacity you have.

 

[avanti]

I would also consider installing a convenient master battery switch. The BlueSea remote ones are very nice. Lets you reliably shut down the whole coach with one button press.

 

[hbn7hj]

I think you should add just one lithium battery at 29lbs.

https://www.classbforum.com/forums/f23/2003-roadtrek-hybrid-battery-system-8526.html

No one else has done it that I know of but it works so very well you don’t need solar. You will have to install it yourself. You will still need two new FLAs for your battery tray.

Your first purchase needs to be a shunt based battery monitor in any case.

Edit. Another install was done. I don’t have the link. It seemed more complex than mine with five battery switches rather than one. I think it works well, too, and better documented.

Found it: https://www.classbforum.com/forums/f23/yet-another-hybrid-lithium-install-9904.html

 

[markopolo-ClassB]

Stevan - are you able to keep your 210 plugged into grid power when not using it?

If not, then solar is almost a necessity for keeping the batteries in good condition (assuming RV parked outside and not in under shelter). Lead acid batteries last longer when fully recharged regularly.

As a suggestion, I think I'd spend $1,200 as follows:

2 new AGM batteries for the coach. $600 no more adding water.
200W solar with PWM controller that displays voltage. $400 DIY - Renogy https://www.renogy.com/200-watt-12-volt-solar-rv-kit/ (check for space on roof & fitment etc)
Bi-directional automatic charge relay (Blue Sea) to replace the battery separator under the hood. That will keep the chassis battery topped & always ready to go. $100
$1,100 total so far so a bit leftover for incidentals.

 

[booster]

Stevan - are you able to keep your 210 plugged into grid power when not using it?

If not, then solar is almost a necessity for keeping the batteries in good condition (assuming RV parked outside and not in under shelter). Lead acid batteries last longer when fully recharged regularly.

As a suggestion, I think I'd spend $1,200 as follows:

2 new AGM batteries for the coach. $600 no more adding water.
200W solar with PWM controller that displays voltage. $400 DIY - Renogy https://www.renogy.com/200-watt-12-volt-solar-rv-kit/ (check for space on roof & fitment etc)
Bi-directional automatic charge relay (Blue Sea) to replace the battery separator under the hood. That will keep the chassis battery topped & always ready to go. $100
$1,100 total so far so a bit leftover for incidentals.

The $1200 price point gets a bit tough to cover everything, and Marko has hit most of them.



I would add that IMO a battery monitor is nearly a necessity in a case like this, where there is no history or knowledge of how much total power is being used and where it is being used. Without it, it would still be flying blind and not knowing if you charged batteries fully, or not, if you have enough capacity of battery, charger, solar, if the alternator is doing a good job, etc. Even experienced RVers are often surprised at what they find out once the put in a monitor.


One possibility to consider would be to use the Bogart solar controller and monitor combination. It would be the PWM style controller but is linked to the monitor to precisely control the charging. IIRC they are a bit over $300 for the controller, monitor and shunt combo.



Also of concern, but a bit expensive to update (would go over the $1200 unless it replaced the solar, which is not a good idea) would be to get a better shore charger, if shore charging is for important charging which is likely. We had a Tripplite like is probably what is in the OP's van, and it did a very poor job of getting a two battery bank full charged, usually stopping at about 85% full. A Progressive Dynamics with Charge Wizard pendant is a good choice for well under $500. I think Marko has used some other units lately that do decent accuracy charging also if it is in the budget that are also reasonable. If a new charger is in installed, it would then be of need for an inverter for whatever load you would use it for. If it is just TV and audio stuff, a small standalone pure sine wave inverter is relatively cheap and much better than the modified sine wave one in the Tripplite.

 

[engnrsrule]

I have a 2006 RT (Sprinter). The original battery configuration was one 12v at 90 Ah. I upgraded to the optional setup of two 6v in series at 235 Ah and it has made a world of difference. The battery space accommodates 2 of the duracels just fine. Finding space for 2 more would be a challenge, or cost valuable and scarce storage space.

It is important to understand off grid limiting factors. For us it is the 10 gallon black tank. 3 or 4 days and we need to get to a dump station. We also have generator to give a boost if needed.

We also added the Victron 712 and that has been a big help in understanding loads. Lastly I reset the combined charger/inverter (750w, modified sine wave) to charge only and added a 1500w pure sine wave inverter. Can now make coffee and run other items off the inverter that were not possible before. Now feel much more secure in boondocking.

One last point, a refrigerator is a big drain on 12v. We run it on 12v when rolling, propane when stopped, or 110 when we have shore tie.

I have other threads up about these mods if you care to see them. I incorporated the Victron meter and the new inverter controls/readout into the factory control station. The inverter just fits in the existing charger and electrical compartment.

 

[stevanpierce@gmail.com]

Thanks everyone for really great info! When we're done with shelter in place, I'm taking this baby on an extended road trip. Luckily I'm able to wfh wherever as long as I have a solid internet connection and/or cell coverage.

I'll definitely get two things to start off with, battery monitor and coach disconnect. My current disconnect for rig and coach is unplugging the batteries.

 

[stevanpierce@gmail.com]

I have a 2006 RT (Sprinter). The original battery configuration was one 12v at 90 Ah. I upgraded to the optional setup of two 6v in series at 235 Ah and it has made a world of difference. The battery space accommodates 2 of the duracels just fine. Finding space for 2 more would be a challenge, or cost valuable and scarce storage space.

It is important to understand off grid limiting factors. For us it is the 10 gallon black tank. 3 or 4 days and we need to get to a dump station. We also have generator to give a boost if needed.

We also added the Victron 712 and that has been a big help in understanding loads. Lastly I reset the combined charger/inverter (750w, modified sine wave) to charge only and added a 1500w pure sine wave inverter. Can now make coffee and run other items off the inverter that were not possible before. Now feel much more secure in boondocking.

One last point, a refrigerator is a big drain on 12v. We run it on 12v when rolling, propane when stopped, or 110 when we have shore tie.

I have other threads up about these mods if you care to see them. I incorporated the Victron meter and the new inverter controls/readout into the factory control station. The inverter just fits in the existing charger and electrical compartment.

I checked out your mods, victron and fridge. I'll definitely tackle the victron this summer and wait a tad on the fridge, but will do that not too far down the line. GREAT ALBUMS!