Coach Batteries and Storage

[HoosierB]

I believe you're correct on my extra pos cables. According the electrical diagram in the manual, I think this is what my situation should look like...?

[Blue~Go]

I believe you're correct on my extra pos cables. According the electrical diagram in the manual, I think this is what my situation should look like...?

I wouldn't expect it to be quite that way. I re-drew it how I would expect to see it. To explain the negative wires: on my Chinook (and most RV's that I know of), they use a chassis ground for the negative. In other words, the frame (chassis) of the vehicle becomes a huge negative "wire," and all you need to do then is make little leads from various things to the chassis. Saves on wire. I'm not saying this is how I would wire up a boat or even an RV from scratch, but this is usually how RV's are done (and it mostly works fine).

Hence the black wires are all short leads that go to the chassis and ground there. They typically look like this in real life. Sorry this is a bit off center!

This is the original chassis ground on my rig that was the one leading from the house battery to the frame. But they usually look similar. On my rig there is one by the start battery, the one shown in the photo (main house battery ground), and then a group of them at the rear end of the frame on either side of the rig (underneath the shower and the closet). The latter groups are, on the passenger side: the refrigerator negative wire, the bunch of wires from all the small stuff on the passenger side, and the generator start ground. On the driver's side, the ground from the "brown box," the ground from all the small stuff on the driver's side, and....I can't remember if there is a third one there right now.

One exception is that Chinook may have taken the small negative solar wire straight to the house negative post, IIRC (I re-did mine, but this is what I remember). Everything else is chassis grounds.


Then here is the drawing I re-drew.

So here is what I would expect to see. Sorry about the dotted lines, but I can't make a long solid line with my annotation program

The black round circles are "chassis grounds," but I don't have a good way to make the usual ground symbol so they are circles. In reality, most (all?) of the ground wires on the Chinook are white, but I drew them black.

See how now all the negative wires come off of one of the batteries, and all the positive wires come off the other one? That balances the load on the two batteries. Also, there is just the one big negative wire coming off going to the chassis ground (that's a photo of my original one up above - it's on the frame just inboard of the battery box under the rig). Then the small solar negative wire (IIRC).

Then all the positives come off the other battery. One to the generator to start it, one to the LVD (and thence to brown box), and one to the Surepower separator under the hood (and thence to Ford start battery positive post).

The ground wires from gen start, the brown box, and the start battery go to the chassis (the start one is in the front/right corner sort of between the headlight and the start battery).

How does this strike you?

[HoosierB]

I think I get it now. The only wire I don't see in my photos, is the ground coming off the neg post. Maybe it Y's off inside the rig, before the solar panels? Worst case is just do the couple of redirections for balancing it out like you suggested. Anyway, I'll crawl around and scope it out... after the big snow blows out of here.
As far as locating a disconnect switch, the rule in the "car world" was always connect it to the negative post, never the pos. Still hold true here?
Thank you!

[Blue~Go]

I think I get it now. The only wire I don't see in my photos, is the ground coming off the neg post. Maybe it Y's off inside the rig, before the solar panels?

I believe it is this one, which I have marked in green.

As far as locating a disconnect switch, the rule in the "car world" was always connect it to the negative post, never the pos. Still hold true here?
Thank you!

In boat/RV world, the switch is generally on the positive wire. Reason is, I believe, because otherwise a given circuit could be completed (ground) through another piece of gear, another battery, etc. I may not have the reason exactly right, but switches definitely go on the positive in boats, and I would say RV's too (I'll have to refresh my memory as to the whys and wherefores).

ABYC excerpt
11.6.1.2.1. A battery switch shall be installed in the positive conductor(s) from each battery or battery bank with a CCA rating greater than 800 Amperes.

[kdarling]

You know, I was just sitting here scratching my head wondering why you have three large positive cables on your house bank, whereas I only had two (one from start battery; one leading to LVD and thence brown box). But, Aha!, I bet the third one is your generator starter supply wire (which on my era rig, went to the start battery).

The Chinook generator is powered from the engine starter battery, at least going back to the early 90s.

This makes sense, as the generator is used to charge the house battery(ies), so if they're dead, hopefully the starter battery is not and can start the generator.

Moreover, the starter battery is designed for, well, starting loads

Reference: the wiring diagrams I recently uploaded to the forum reference section. Hmm. The later one shows three + cables from the house battery: one to the starter battery separator, and two to the LVD.

--

Another common wiring factor is that the emergency start solenoid is usually enabled by power from the house battery system. This also makes sense, because if the house batteries don't have enough power to flip the solenoid, then there's no reason to tie them in with the starter battery and drag it down.

[Blue~Go]

You know, I was just sitting here scratching my head wondering why you have three large positive cables on your house bank, whereas I only had two (one from start battery; one leading to LVD and thence brown box). But, Aha!, I bet the third one is your generator starter supply wire (which on my era rig, went to the start battery).

The Chinook generator is powered from the engine starter battery, at least going back to the early 90s.

Well, it was. My 1999 came with the generator wired to the starting battery, as shown in the wiring diagram in the 1999 manual. However, Chinook changed this in 2000 and wired the generator start to the house battery bank from year 2000 onward (as shown in that manual). Here is an excerpt from the 2000 Chinook manual showing the change. I highlighted it with a red arrow.

I understand the logic of starting it from the starting battery, but I can think of a few reasons they changed it. The main one is that, as my rig was wired (from starter battery), there was something like a 100' round trip circuit, and they had used #6 wire. This was WAY below the recommendation listed in the Onan manual, and could cause problems trying to start the generator in cold weather (huge voltage drop).

In the circa 1995 and older Chinooks, the house and starter battery were both under the hood, so the lengths would have been the same from either bank.

However in (I think) 1997 (maybe 1996), the house bank was moved to a position just under the water heater. This meant that the wire run would be something like 50' less (round trip). So for the same wire size (#6 is still technically a bit small, but much less so) there would be much, much less voltage drop when trying to start the generator. It's a lot closer to Onan's specs.

I moved mine this summer, simply cutting off the excess #6 wire that "went on" to the start bank. I think I eliminated a bit over 25' (one way). I'd still prefer it to be #2, but at least for now the #6 is less over-taxed.

I do see the logic in using start bank (if house bank is depleted and you want to start generator), but I can also see a danger in it. Say I run my house bank down to the point where it won't start the generator (one should not do this anyway, as it greatly reduces the life of the house bank, but let's say I did). Now I use my start battery to try to start the generator. With the voltage drop of a super long #6 wire, this takes a lot of oomph out of the start battery. And darn, this generator is balky today. I'll try a couple more times. Hmm, now the start battery sounds bad. Well, time to leave. Uh-oh, now how do I start my Ford engine?

So, I think on balance, I prefer to keep my start battery "untouched" by anything but starting my Ford engine. And since I don't let my house bank go below around 50% charged (for longevity reasons), it shouldn't be a problem. But even if I didn't want it starting from the house bank (because I can see your argument too), the much (much!) longer run to the start battery (in circa 1997 and newer Chinooks) makes the house battery a better choice, I think. That super long, scraggly #6 was very far out of spec (Onan spec, generator takes about 60 amps to start).

One option I did not explore (and maybe there is a good reason Chinook did not do it) is to run the start cable from the start battery, down the *passenger side* frame rail to the generator (1997 and later the start battery is on the passenger side of the engine compartment). Maybe it was just by habit that they went over to the driver's side, down under, along the driver's side frame rail, and then across again to the generator (habit from when the start battery was on the driver's side, as I think it was prior to 1997). Or maybe there is some other good reason not to go down the passenger side - maybe the heat from the exhaust is too close to that side - that'd be my guess.

At any rate, given all the givens, I decided I prefer to keep the start battery "sacred," and have the much shorter run to the house bank (1997-and-later). Chinook started doing it this way in 2000, and I think Hoosier's rig is a 2001. Hence the third "big" cable on the house positive.

As a side note, the few other RV's I have seen also have the generator starting from the house bank.

PS: Here is the 1998 diagram for comparison, showing the generator start still connected to the Ford start battery. My 1999 shows (and was) the same, but I don't have that manual digitized. So the change was for the year 2000 and onward (gen start to house bank).

[kdarling]

Well, it was. My 1999 came with the generator wired to the starting battery, as shown in the wiring diagram in the 1999 manual. However, Chinook changed this in 2000 and wired the generator start to the house battery bank from year 2000 onward (as shown in that manual). Here is an excerpt from the 2000 Chinook manual showing the change. I highlighted it with a red arrow.

Thanks for the update and correction! Very interesting!

However in (I think) 1997 (maybe 1996), the house bank was moved to a position just under the water heater. This meant that the wire run would be something like 50' less (round trip). So for the same wire size (#6 is still technically a bit small, but much less so) there would be much, much less voltage drop when trying to start the generator. It's a lot closer to Onan's specs.

That makes sense.

And yes, as far as I can tell, it seems that the change to dual batteries happened during the 1996 model year.

[Blue~Go]

It's kind of fun to see how things evolved, isn't it?

And yes, as far as I can tell, it seems that the change to dual batteries happened during the 1996 model year.

It looks like there used to be a small "outside" compartment just aft of the water heater, but it was basically contained within non-rounded shell body space. At least that's the idea I'm getting in photos.

Then it looks like in 1997 they enlarged and lengthened the compartment (dropping into the lower, more tucked in part of the body line) and thus were able to make the outside compartment larger, PLUS have it run underneath the water heater. This is how my 1999 is, but I have seen a 1997 that was the same. So in this iteration the pair of house batteries is in the outside compartment just below the water heater, and the rest of the compartment (aft of that) is free storage space.

So I guess in 1996 they had the house battery (batteries?) in that little mini compartment aft of the water heater? I don't have a 1996 manual so have no idea. But I do know how it was as of 1997-onward (I have a 1999 Concourse and looked at a 1997 Premier when shopping).

Here is a photo of a 1996 - you can see the "small" outside compartment that is within the non-tucked body line and only starts aft of the water heater.

And here is the change. This is a 1998 as I don't have a good photo of a 1997, but I did look at a 1997 in person when I was shopping, and they are the same as the 1998. The compartment has been lengthened to include the area under the water heater, and the batteries occupy only the forward 1/3 of it (beneath the water heater).

This shows what's inside on a Concourse. The Premier was the same but without the slide-out battery tray.

[Blue~Go]

Here is a 1997 Premier. Kind of cluttered, but shows the battery portion of the above arrangement without the slide-out tray that was added on the Concourse (the open storage area is to the right/aft):

This continued the same until 2005/2006 (after which there were no more). In 2005/2006 the batteries were still in the same place, but the area aft of them was given over to the propane tank, and the area on the passenger side where the propane tank used to be, was made into a free space locker. Also the locker doors were improved and made more like Class A type. Integrated with the body and with a single center handle/lock that operated side locks via bars on the inside. Nice doors.

Here's the driver's side of the new arrangement (on a 2006 Concourse):

And the passenger side:

Okay, Hoosier, are you still here? I hope you don't mind the tangent.

[HoosierB]

Still here. So, it looks like if I were to mount a busbar on the inside aft wall of the battery compartment for the positive cable hookups and the Blue Sea transfer switch on the other side of that wall (sort of a cable pass-thru), that would make for a tidy and secure install (Blue-Go ?). I would be curious to see any other 2001+ Chinook owner's battery cable hook ups. As Blue-Go observed, mine seems to have been not so well re-connected. This most likely happened during the last few months when the rig was being upgraded at Duncan RV Center... AND when the new coach batteries were installed (sigh).