Excellent write up on the basics of automotive/RV batteries:
The 12volt Side of Life (Part 1) (http://www.marxrv.com/12volt/12volt.htm)
That is one of the sites I found that listed 40% charge as being acceptable. Others list 50% as minimum. Looks like this is a Ford vs. Chevy opinion type issue.
OK Sven, you opened the door for me--I just have to ask.
Can I have a 12V engine start battery and two 6V golf cart batteries and still use the same charging system?
What problems might I have?
Kind of been thinking about this for a couple years but not sure.
Currently have an 8D wet cell and a 12V--1000CCA truck battery.
New 125A Leece-Neville alternator.
Two 6V golf cart batteries are wired in series. If you have more than one 12v battery, they are wired in parallel. Using the isolator, you should have no troubles.
Pierce
I used four 6 volt golf cart batteries for the coach and two Costco 12 volt batteries for the start system on the Monaco I had and had no issues, Monaco uses an isolator system also.
Thank you, good article, once I aquire a coach I will probably swap the 8ds for the golf cart batteries out of my boat. Also have access to scissor lift batteries at work, since they change the entire set if they have any issues. Bought one of the schuamaker smart chargers a few years back that has the desulfication mode, and have been able to successfully revive about 2/3 of "dead" batteries. Until a inexpensive lithium set appears on the horizon. Next step is building/modifying the roof A/C to inverter drive compressors, with ECM fan motors that use only 900 watts per 12,000 btuh, with so little inrush current that you could start a pair with a 2 kW generator or alternater.
Sure, charging system won't know if all the cell's are wired in series inside one case(12v) or inside two cases (6v)
Pierce, Craneman and Phred answered the question. The charging system will read the 6volts in series as 12v. Same thing with two sets of 6v (in series), wired in parallel with two more 6v batteries. Same pressure (voltage) with more storage capacity.
Thanks, Pierce. Now, next question: Does our 1989 have an isolator and where might it be?
Also, will batteries charge equally?
Our isolator shares an under the coach electrical panel with the boost solenoid, etc. On the driver's side not far from the house batteries. It isolates the two battery systems so the coach battery can't drain the engine battery when the inverter is on, etc. The engine alternator charges both when running.
Pierce
Easy to trace. Raise the bed and follow the large gauge red wire from the alternator B+ terminal. Should lead you right to the battery isolator. It will be between the alternator and batteries.
On the 89 the isolator should be mounted on the left frame rail behind the left rear wheel
Yes, a common (and IMO not very good) location on many Foretravels. Electrical components outside and right behind the two rear tires???
Many of us have moved it "indoors".
Hey!! I think I remember where it is!! And what it looks like!!
A red "thing" with fins and cables. When I opened the engine access door on the driver's side I could see it--almost straight down from the inside wall at the foot of the bed. (this is using memory recall, seeing as how the coach is 18 miles away)
Often wondered what its function was.
Now I have got another thing to worry about--vulnerable position behind the wheels!! Thanks a lot, Brett!!!! :)) :)) :))
I guess I will have to add moving the isolator to my spring list.
Norm,
If on an inside wall in the engine compartment, you should be OK. Many were mounted on a separate metal piece right behind the driver's side rear wheel (not on engine room wall).
Thanks, Brett. Forgot to mention that our isolator is mounted (if it is the one I saw) on the outside of the frame and kind of behind the inside dual. Vulnerable position if an inside dual tire blows up.