'02 E450 Diesel House/ Battery

[Low594]

I have a 2002 Ford E450 based Short Bus w/ 7.3L SuperDuty Turbo Diesel
So, I am planning to upgrade my Bus with House Battery system and after contacting Sterling about their BBW2412 and my bus specs, they told me that was the correct unit. At the time, the wiring seemed very simple, just connect the Sterling inputs to the factory batteries and the Sterling outputs to the House Batteries. But the batteries are 12v each and the Sterling is a 24v input. So now, as my brain does, I am probably overthinking things.
Option:
1) connect to 12v frame mount battery
2) connect to starter positive & ??? ground
3) ????

Im not going to do alot with the power. Just my Engel MT60 fridge, laptop, 12vdc monitor, thats about it.
I havent gotten batteries yet, but I bought (2) Ford frame mount battery boxes to house them.
I might add a Solar panel & charger to aid the House batteries, one day.

Ive tried alot of searches here and via google, vague info at best. Hoping to find some experience out there!

 

[dwh]

Judging by the electrical mods you list in the first post of your build thread, I'm thinking your bus has 12v chassis wiring. If so, then you've got the wrong charger. You'd need 12v input.

I don't recall the amp rating of that unit, but for a couple of big house batteries, you'd probably be better off with a bigger unit like the BB1250.

 

[Low594]

Hmm, well that definitely throws a hitch... I did send Sterling USA another email, asking for more info on recommended hookup, maybe I will get the info I need from them. The unit is still in shipping, so I should be able to send it back and have them send me the correct unit. And I am in no rush at this point.

What do I need to look at to determine if I need a 24vdc input or 12vdc? As you said, the items I have worked with, horns, stereo, lighting has all been 12v. I suspect the system is really 12vdc, with a second battery that only comes into play for starting the engine via some form of controller.

Thank you for the help!

 

[luthj]

The two chassis batteries could be in parallel. This is not uncommon for large diesels which need lots of cranking amps. Less common, but still possible, is that your two batteries are 6V units wired in series for 12V.

Putting a volt meter between the alternator output and ground with the engine running will tell you right away what voltage your system is running (12v/24V). I am betting 12V.

 

[dwh]

Most likely just two batteries paralled full time. School bus doesn't need any kind of battery backup since the engine would normally be running whenever the bus is in use.

The two batteries give plenty of oomph for cranking and also enough reserve capacity to run the flashers for a while with the engine off...which would rarely ever happen anyway.

 

[DiploStrat]

Yell At Charlie, Jr.

IF you need a B2B, then this is the model you want: http://www.sterling-power-usa.com/SterlingPower12volt-12volt45ampbatterytobatterycharger.aspx

If your Ford charges at 14v+, and it probably does, then this is what you want to read: http://www.expeditionportal.com/for...ke-a-cheap-isolated-dual-battery-setup-for-50

I prefer an automatic relay if you have solar, but that is another issue.

Finally, if you REALLY need a voltage boost and you want a minimal solar kit, consider the CTEK D250S/SmartPass combo: http://smartercharger.com/products/dcdc/ctek-d250s-dual/

Don't pay a lot of money for things you don't need.

 

[luthj]

What voltage does your alternator run at? If its 14.2+ then you might be able to get by with direct alternator charging. If you are relying on your alternator exclusively for charging AND you drive enough, a sterling charger is a great way to keep your house/aux battery charged.

Otherwise the alternator is great for free/easy charging, but its not going to keep your house battery fully charged (unless you are very light user). If you drive a lot and use the sterling charger you would probably be okay.

A small solar array to get your batteries fully charged, and simple separator relay for bulk charging is my preferred method. Mostly due to the value/cost judgement. A proper charging regime for lead acid batteries has them being topped off (14.4+ V depending on type) on a regular basis. Without this absorb stage the batteries will sulfate and fail prematurely.

If you size your solar array correctly, you can run the fridge indefinitely as long as you park in the sun! In california you might get by with 100W, but 150-200W of solar will usually be enough for a fridge, lights, and laptop.

I have seen some interesting things done with the CTEK and smartpass systems. It seems to be a very flexible DC-DC charger that can use source voltages higher and lower than the output.