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Improvements to our Start Battery Bank

Wanting to improve our start battery bank for our Cummins C-8.3 engine, we made several changes:

Replaced original two batteries with three batteries.  Our battery tray had space for three.  Bought Red-Tops at Sam's Club.

Replaced the short inter-battery connector cables with two aluminum home-made bus bars.  Bars are ¼" x 1" with two bars each for negative & positive, cut from metal purchased from Lowe's.  Bars were installed parallel to each other without any air space between.

Used Belden heavy-duty battery terminal connectors purchased from NAPA for about $9 each.

Separated original motorhome 4/0 battery cables, so that positive is bolted at one end of the three batteries and negative is connected to a battery at the other end of the parallel battery bank.

Added a new 4/0 ground cable from start battery bank to motorhome frame.

Re: Improvements to our Start Battery Bank

Reply #1 –
i did the samething with 31 stud batterys
Mike
1990 GV 36'

Re: Improvements to our Start Battery Bank

Reply #2 –
Nice job. Looks good.

Just curious - were two batteries not enough? I'm running a single Optima yellow top 27F in my U225, and it seems to be adequate. I think I would run two, if the space were available, but going with what I got.

Steve
1991 U225 Grand Villa

Re: Improvements to our Start Battery Bank

Reply #3 –
 ^.^d

Thanks for sharing the project. Our two Red-Tops turn our C8.3 reasonably well at temperatures above 32F. They failed to turn the engine when I tested them one time at 25F.

We usually use the boost switch when starting. The engine turns over faster with the boost switch engaged. Three batteries with a robust cabling system seems to be a good plan.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Improvements to our Start Battery Bank

Reply #4 –
Your engine block heater is your best friend when temperatures drop below freezing on a diesel engine. We have several diesel vehicles and keep them plugged in all winter long. It also greatly decreases the time it takes for the heater to start heating up the cab, too. :)

I really do like the bus-bar idea for a battery bank. It certainly helps cut out the cable-crowding problem in so many battery boxes. I plan to explore this idea for our "hotel" bank.

Thanks for the idea. :)

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Improvements to our Start Battery Bank

Reply #5 –
We have had some engine start 'hesitation' on turning the ignition key to start and we had room for a third 1,000-amp battery, and Sam's was willing to take back our two older start batteries, so we bought three new batteries at the same time.

The number and capacity of batteries is dictated by engine starter amp requirements.  In our model years, Foretravel used two 1,000 amp Optima Red Tops for C-8.3 engines and three of the same batteries for M-11 engines.

The Optima battery line is a bit confusing between Red & Yellow, as to which is best for starting. So sticking with what is in the coach may be the best path.

Re: Improvements to our Start Battery Bank

Reply #6 –
Our coach is 1997 model and engine is C8.3-325. Starting response is similar. Two Optima Red Top batteries will do the job most of the time, but I would rather have three. The "bus bar" solution looks good. The cabling appears to balance the load as much as possible.

If temperatures will be below 32-40F at "start time" I engage the block heater. If we are "on the grid," I turn on the block heater before we retire for the night. If we are on generator power, I turn on the block heater when we rise and start the generator. Keeping the batteries on some kind of charger in cold weather will help also. The charger will warm them, allowing them to deliver more power.

I reviewed the Optima web site and concluded that Red Top was their best solution for start batteries. My recollection is that our coach had Red Top batteries when we bought it.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Improvements to our Start Battery Bank

Reply #7 –
I found that a new starter was a big improvement after I recalled and installed new batteries. Turned over way faster.  Also ran a second cable directly to the starter avoiding a black junction box.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Improvements to our Start Battery Bank

Reply #8 –
Quote from: Barry & Cindy –
Separated original motorhome 4/0 battery cables, so that positive is bolted at ONE END of the three batteries and negative is connected to a battery at the OTHER END of the parallel battery bank.
Very smartly done.  Very impressive job.
Audrey & Harvey Nelson
2000 U-320, 40' towing 2014 Jeep Grand Cherokee
nelsonah@ieee.org

Re: Improvements to our Start Battery Bank

Reply #9 –
Very nicely done Berry. Up to your usual high standards. Thanks for sharing.

see ya
ken
The selected media item is not currently available.ken & dori hathaway & Big Agnes
🍺1992 U300 GrandVilla WTBI #4150 FOT FBP 2011
✨6V-92TA DDEC Parlor Coach 350HP Series 92
🏁2011 Nissan XTerra Pro-4X

Re: Improvements to our Start Battery Bank

Reply #10 –
We had a SUCCESSFUL test of our new battery connector bars.  Today we took Homer for a warm-up run and we had back the strong quick engine start that we used to have.  This is our first engine cranking since installing the battery bars.

In trying to diagnose our starter hesitation,
1)  I have also learned about how start battery bank flows current through a 30-amp (which I replaced) and a 10-amp circuit breaker to the Allison computer.
2)  When ignition key is on and the transmission is in neutral, the Allison computer sends power to the coil on the Neutral Start Relay located on the circuit breaker panel by the front door. 
3)  When ignition key is turned to start position, current flows through normally-open Neutral Start Relay points,
4)  to close the Auxiliary Start Solenoid located on the isolator panel,
5)  which sends power to the Starter's Solenoid,
6)  which allows start battery current to flow to the engine starter.
7)  The big 4/0 start battery positive cable is directly connected to the Starter's Solenoid.

We also tribute our clean start to our new BlueSea ACR relay-based battery combiner that keeps our start battery bank fully charged. 

Our previous diode-based combiner (like Trick-L_Start) charged our start battery bank at a lower voltage due to voltage drop across diodes.  The ACR is working quite well and will really pay off when batteries are around 100 degrees from being enclosed or on a hot day.  In hot weather diode-based combiners may not work due to battery charger's lower temperature compensated voltages.

Re: Improvements to our Start Battery Bank

Reply #11 –
Hmmmm...Just reading this post and it triggered an observation I have not checked out yet.  Not sure if the systems are the same, but I've had weird no crank issues on the 02 while in storage.  Almost as if there was no voltage in the batts, but the TrikLStart is on all the time.  But, you reset the key, attempt start again and it cranks right up.  A tired circuit breaker makes sense.   

I also want to hear more about this ACR... I havent been too impressed with the Trik L Start.   

I certainly hope that your new red tops work out;  through the ownership changes, cost reductions, etc., IMO the Optima brand product is not the same as it was 10 yrs ago.  I've been very happy with the flooded Cat brand group 31s from EastPenn. 
Mike
2002 U270 36'

Re: Improvements to our Start Battery Bank

Reply #12 –
Quote from: jrdrag6396 –
... I also want to hear more about this ACR... I havent been too impressed with the Trik L Start. ...
I chose to install a Battery Tender as a maintenance charger for the start batteries on our coach. It is plugged to an outlet that is live when the 120VAC outlet has power from shore, generator, or inverter. I have been pleased with the results. The batteries have been at appropriate floating voltage levels when I checked them.

The Battery Tender is a five amp charger that has a microprocessor programmed for an appropriate charge/maintenance profile. It can be left connected and turned on all the time. I have used a Battery Tender on my 2006 Goldwing since the motorcycle was new. The original battery is still working well.

I expect the relay that Barry installed would provide excellent maintenance conditions for the start battery, also. I chose not to use a Trik-L-Start because of the 0.5 volt drop from house batteries to the start batteries. It seems to me that the float voltage on the start batteries would be a bit too low. Your choices and results may vary. ;)
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX
 

Re: Improvements to our Start Battery Bank

Reply #13 –
RE: I also want to hear more about this ACR...

Last summer, we were in 100 degree temps while hanging out in Texas making changes and putting our roof solar back together after our big paint job. I noticed that our temperature compensated Xantrex Prosine 2.0 inverter/charger was float charging around 13.0 volts which is exactly correct on for MK Gel batteries which have a stated optimum float charge voltage of 13.0 when batteries are 100 degrees.

Our house battery bank was very happy with 13.0 volts, but our diode-based battery combiner, by design lowers output voltage by about 6/10ths of a volt, so at about 12.4 - 12.6 volts, we were not charging our start battery bank at all.

After weeks of not charging our start battery bank, I went looking for a relay-based battery combiner, which automatically connect house & start banks when house battery is being charged and disconnect when charger is turned off, with no diode voltage drop.

I first purchased Magnum Energy ME-SBC Battery Combiner relay, which kept our start battery charged. But when I started the engine a month later, with start and house banks automatically tied together, Magnum had to deal with the instantaneous very high current demand the start bank had from the engine starter. Magnum caused a very bad new big multiple starter hesitation problem while the ignition key was in start position. This was an O' S-- t moment as a month ago we started ok. Adding to our situation was that I had such confidence in Magnum, I didn't think it was the cause.

I changed several things over the next weeks, but the problem did not go away until I disconnected our new Magnum Combiner and instantly we were better but not back to perfect. Magnum has a plug on its battery cables, so for a while we manually unplugged Magnum before start and re-plugged after turning engine off. Magnum technical support was no help. I am not sure, but I think Magnum current limiting logic quickly cycled and it caused a voltage drop on the Allison battery connection, which caused the Neutral Start Relay to cycle causing starter pauses.

After that new start problem, I found that this is not an isolated problem in that combined batteries can cause 12-volt devices to malfunction due high starter current voltage drops on house battery loads. The marine market has more info on this sort of stuff as boats with multiple engines and multiple battery banks use intelligent relay-based combiners. I found a very interesting BlueSea combiner that has additional logic to turn off combining when ignition is turned to start position, preventing all the problems we found.

We now have installed a well-designed BlueSea model 7610 SI-ACR (Start Isolation - Automatic Charging Relay) that works great. I wired the Start Isolation sense to a circuit that is hot when ignition is on, not just when starter is on. We only need automatic combining when engine is off. Our new ACR has kept our start bank charged and it automatically stepped out of the way when ignition was turned on during our half-hour warm-up run today.

Our BlueSea ACR also has a remote LED connection that I wired into our motorhome at our battery monitor panel. LED is on when combining, flashing when Start Isolation is active and off when not combining.

ACR combines house & start battery banks and can handle 120-amps. Automatic combining starts when battery bank is being charged at 13.0 volts and disconnects at 12.7 volts

Detailed Specifications for SI-Series Automatic Charging Relay - Blue Sea