New Battery Purchase

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BUSLIFE

BUSLIFE

New member
Joined
Feb 17, 2014
Posts
2
Location
South Florida
Hello All,

  Wow, where to start.....All three of my Interstate Superstart batteries are due to be replaced. Each are rated at 650 CCA amps and the more I research, the more I am concerned with the wiring job that was done on our bus. Our bus is a 1993 Ford Schoolbus with a 6.6L turbo diesel brazilian Ford.

Questions

1) I currently have three batteries, and a 2000watt inverter, does anyone run just two?

2)How many CCA do you recommend having for two batteries? For three batteries?

3) I made a wiring diagram of how my batteries are wired. Why the hell would you wire batteries like this? Any advice would be wonderful....

4) My new batteries are going to be deep cycle, hopefully two AGM 31D batteries, three if needed. Any feedback on these? Brand recommendations?


Thank you!!

 

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If and that is a big IF you do a lot of boon docking and really need all that much battery capacity, I would for the cost look at maybe 4 or 6 golf cart batteries.  They are plentiful almost anywhere and reasonable priced for decent ones.  They will give you a lot of capacity for boon docking. IF you do not do much boon docking then a couple of decent 12VDC batteries will suffice.
 
Well when it comes to batteries to run an inverter if you are asking about CCAs you are talking about the wrong kind of battery,, WHat you want is Amp hours at the c-20 rate

And you need about 200 amp hours per kilowatt.

So, for a 2000 watt inverter 2 pair of GC-2 Golf Car DEEP CYCLE (All Golf car batteries are DEEP CYCLE) would be a good choice, these are six volt batteries when you buy them so you put them in series in pairs (like this... -{Bat}+t-{ery}+  to make one big 230 amp hour 12 volt battery, 2 pair, 460 amp hours. 

If you want to buy 12 volg boxes.. Well then 4 Group 31's woudl be my recommendation, 3 Group 29's would be the minimum, I think I'm running 3 right now but I do not run long on the inverter (just long enough to notice the park breaker went TRIP) and I will be replacing teh main GC-2's soon
 
We really need to get back to basics here. Do you have separate batteries for starting the engine vs powering the "house" stuff )e.g. the inverter)? If not, you should...  And the batteries that power the house 12v and inverter should be deep cycle batteries with a rating in Amp-Hours (AH) or Reserve Capacity (RC) minutes.  Cold Cranking Amps (CCA) is an engine starting measurement and useless for other purposes.

For the house/inverter, the right number depends on how much load you put on them and for how long, i.e. number of amps used x number of hours needed. If you always use camp sites that have an electricity hook-up, you need very little in the way of batteries - juts enough to keep you alive between campsites. But if you often don't have external electric available, than you need more, and potentially a LOT more. We would need to discuss your power consumption habits before answering the "how many batteries" question.
 
Thank you for the replies. Gary : I do not have separate batteries for starting vs powering the "house". Remember this is a bus, so the wiring comes directly off of the starter motor and wires to the batteries in parallel.

With that being said my plan this far is two Group 31 D batteries(either Optima or Lifeline) wired in parallel to replace my current dead batteries. On the battery (farthest from the starter motor) I want to tie in a 250A in-line fuse and my inverter.  Honestly, I will only use the inverter while driving, and eventually off the grid when I add solar in the future. Because eventually I will be adding solar and currently I have a inverter, I feel like it would be a waste of money to just purchase two new starting batteries. Hence the deep cycle exploration.


                Starter Motor  -------  Battery 1 ------ Battery 2 -------  250A fuse  off of positive battery 2  ----  inverter


When we first designed the bus we wanted our house electrical system completely separate. We have a 50A plug for when we pull into a park and all of our outlets are hot.
 
Gary : I do not have separate batteries for starting vs powering the "house". Remember this is a bus, so the wiring comes directly off of the starter motor and wires to the batteries in parallel.
Click to expand...

Well, right away that says the bus conversion was not well done, since changing the 12v electrical to isolate house from chassis is rather fundamental. If you don't do that, you are very likely to find you can't start the engine one morning becasue the house sucked down too much power.

A pair of 950 CCA batteries are plenty to start the diesel and power the chassis. AGM has no particular advantage for a starting battery, so save your money and get a standard flooded cell. Then install an isolator and one or two batteries dedicated to the inverter and house 12v. A pair of 6v GC2 golf cart batteries in series makes an excellent deep cycle house battery bank. Install a charger for them too, even if just a 120v automotive type charger (but a good three stage from Progressive or Iota is a better choice).

I'm not anti-AGM (I have 4x Group 31 AGMs in my coach), but you are paying top dollar to get the maintenance free feature. You get a lot more battery for your money with a flooded cell and the GC2 batteries are really durable as well as providing a lot of amp-hours (225 AH for a pair in series).
 
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