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Vantare DC Configuration
Okay, now
that I’ve seen the Vantare schematics, dated 99, I can see where some confusion might come from
and can see a couple of things I would change. As I’ve said before, it was great to see the
use of buss bars for the battery cables.
Why this is not common practice makes no sense. Yes, it will cost an extra $100 in parts and
another hour or so in labor, but with
the initial cost of these coaches, what is a couple hundred bucks.First, the
house bank. Yes, it is in fact one 24V
battery bank made up of batteries numbered one through eight. It may appear to be two banks given the
batteries are split between two locations and there is a 12V and 24V buss bar
and cut-off switches labeled 12V and 24V.The first
house bank change I would make is that both inverter temperature sensors MUST
be on the same battery. The worst case
installation of the temperature sensor is exactly what I see here. That would be one sensor on each 12V half of
the bank. Why this is problematic is
that the current being drawn from each half bank may be very different. The equalizer is responsible for keeping both
halves close, but it has a window of acceptable voltage on each half bank. So, they won’t be exactly the same. I would advocate what I do and that’s
configure your chargers so that only one is ever on and occasionally switch
chargers. Unfortunately, as feature rich
as the Trace inverter/charger is there doesn’t seem to be a mode where you can
have the charger off and still support automatic switching to inverter power
with the loss of commercial and generator power. The next best thing is what some of you have
already done and that’s setting the maximum charge current to the lowest
possible setting on one charger.My biggest
concern, based on this schematic and what some of you have stated, is that I
don’t see adequate circuit protection. I
hope the 12V and 24V cutoff switches are collocated with the left and right
half bank of batteries. This would mean
that the positive battery cables are contained such that they can be adequately
protected against short circuits from cable movement and chafing. If this is where the switches are then I
would have expected to see fuses rated at no more than what the battery cables
or cutoff switches (whichever is less) can handle located immediately on the
output of the switches. The closest protection
(breakers) are at the distribution panel and these don’t protect all loads
directly connected to the 2 buss bars.
There’s no protection on the wires feeding the equalizer, generator
starter, the generator boost connection to the chassis battery, alternator, and
battery monitor. With the smart things I
see done by Vantare, I can’t believe they skimped on circuit protection, which
is what is illustrated. Maybe, in
practice they did install protective devices.
Besides the protection I recommended at the 12V and 24V switches, you
should have protected devices as close to the current generating source as
possible (buss bars, alternator, battery isolator, and chassis battery). The only exception allowed in the automotive
industry is the battery to starter connection.
In your application, you can’t guarantee protection of the physical battery
cable coming from the chassis and house banks to the generator starter, so it
too should be protected at the chassis battery and house battery (at the buss
bar). There is also an exception if the
appliance and current source are collocated such that the cable/wire is totally
protected and that the appliance has circuit protection at its power input.I have three
concerns on the chassis battery system.
One I already mentioned and that’s the lack of protection on the cable
going to the generator boost switch. Another
one is the Guest charger. I tried to
find the manual on the charger, but didn’t find one. I’m confident that the 12V charging circuit
should be disconnected from the chassis battery. It makes no sense and it probably drives the equalizer
and 24V charging circuit nuts. The
chassis battery bank is a single 24V bank.
Yes, it’s half tapped to support 12V loads and the equalizer is there to
ensure each half of the bank is equally drained or charged.The other
chassis battery bank concern is where loads are connected. To get the most out of the batteries they
should be drained and charged as equally as possible. That means all 12V loads should be tapped
from battery #10 and all 24V loads to battery #12. The 12V equalizer connection is correct but
the 12V generator boost connect is not. The 24V charger and 24V chassis connections
are correct, but the 24V equalizer connection is not. You also want to limit the number of physical
connections on any battery terminal, which may have driven why these
connections were done this way. With
this in mind, I would leave the generator boost connection where it is given
how rarely it would be used. I would definitely
move the 24V equalizer connection given its critical function to the entire
bank. I would move and protect the 24V
charger connection to the 24V connection on the equalizer. Although Vanner discourages this, the charger
wire is a relatively small gauge and would be supported over the much larger
equalizer cable to the battery bank.Thanks for
the drawings, -
8 Replies
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I respect Gil’s electrical expertise. However before he convinces all Vantare owners to run out and modify their coach’s systems consider the fact that those coaches were designed and built by some very smart and capable people. None of our coaches are perfect and none cannot be improved, but based on the number of Vantares in the market and the rare number of actual problems reported on this forum and others I have to conclude they are well done, from design to construction.
They are different than most and I know there are some nuamces in their system(s) not widely known so before owners start worrying about safety or performance at least get to do an indepth exploration of the systems to determine if they do need some improvements and how it is best to install them if at all.
Gil mentions circuit protection and if my memory is correct they do have circuit protection for the battery banks in the form of an in-line device.
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I should have been more specific on my findings. They are solely based on the schemetics and not an actual inspection of any coach. How the electrical system, and most importantly circuit protection, was done in practice may be different. There may have been final revisions to the drawing; I just don’t know. So, as Jon said, don’t run out to make make any changes without investigating what you actually have.
Keep in mind that just because no one has reported a problem doesn’t mean one lurks under the covers. How many of your home’s circuit breakers have tripped over your life time. The number is likely very low and in many cases may be zero. That doesn’t mean that we don’t need circuit breakers. What it does mean is that like almost every safety device, when we do need them it’s comforting to know they are there.
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Remember that the Chassis battery wiring was done by Prevost, not Vantare. Only a few connections were added by Vantare:
Gen battery boost, Guest Marine charger (which have fuses at the end of the leads that connect to the chassis batteries), and the alternator charge line to the starter is altered to add the dual battery isolator.Gil is correct, the battery temperature sensors were not originally installed on the same battery, and that is a definite change that should be made. If they are on the same battery, their adjustment to charge voltage for each corresponding inverter will be the same, and will prevent a “conflict” in having both inverters charge the same battery bank. They should not be removed or disconnected, as some technicians baffled by the operation tend to do with or without asking. If they are both installed and operating to adjust inverter charging per unit of temperature, the inverters will not overcharge the batteries. The charging amps settings then do not need to be adjusted from the factory defaults, and all will be well. If one charger is essentially disabled, bare in mind that the recharge time will be SIGNIFICANTLY longer for such a large battery bank like Vantare coaches all have.
As for the circuit protection issues Gil brought up, remember that Vantare’s have the engine battery boost feature, and in cold weather a Series 60 can draw in excess of 500 amps to start, not counting a higher “in-rush” to the series-wound starter motor, plus the current going to the dead starting batteries themselves. Any added fuses should account for this or the risk exists that during a “jump start” exercise the fuse protection would blow, essentially “killing” the house power into the coach altogether.
Also, realize that there were alterations made as time went on and the NEC requirements changed. During that period, there was allowance for the amount of “distance” from the batteries to the circuit protection where required. All the cabling and busbars were in the same area on most coaches (over the passenger-side wheel well on H3-45 slideout coaches), and were made up as an “assembly” in PVC piping off-coach, then installed and connected to the batteries and busbars in the coach. This was done to ensure that chaffing or damage did not occur to the wiring.
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A big thanks to Gill and others for reviewing the Vantare DC configuration.
The line drawing I have for my coach clearly shows one temp sensor sandwiched between battery 1 and 2 of the 12-volt battery bank for inverter #2 and the temp sensor for inverter #1 sandwhiched between battery 1 and 2 of the 24-volt battery bank.
The previous owner of my coach replaced all the bateries just prior to my purchase and the battery tech placed the sensors on the tops of the batteries.
The updated information on the placement of the temp sensors has been much appreciated.
Paul
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As I said and Ben expanded upon, the starter does not have to be fused. The starter connection I said should be fused is that going to the generator starter from both the chassis and house banks. That is because the distance is to great to ensure the cabling is immune from shorting.
It’s good to know the charger lead to the chassis battery is fused, as it should be. I still advocate removing the 12V charge line to the chassis battery. It can’t help and can only drive the equalizer and 24V charger nuts (jon, that’s a technical term).
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Gil, the reason there is a connection to both the “12v” and “24v” potentials of the chassis batteries is that the Guest charger Vantare utilized has two independent, isolated 12v outputs. By connecting them in series to the Ground-and-12v with one output, and then the 12v-and-24v with the other output, they achieved overall 24v chassis battery charging. The outlet for this charger is ignition-switched, and disabled when the key is on, so “fighting” the Vanner equalizer is prevented. This configuration also insures that all the batteries are evenly and completely charged even if the equalizer were to fail. The Guest charger controls the charging outputs separately, but in effect, it is like taking each 12v battery out and fully charging each separately but fully.
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Thanks Ben. That’s why I was looking for the manual. I would throw that charger away given it’s a 12V charger with 2 outputs. Failure of one side, however remote, would only charge half the bank. In my opinion, there’s no reason not to use a 24V intelligent charger.
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Gil,
Your point is very valid, and unfortunately over the years those Guest Chargers have seen a pretty high failure rate as well.
Ben
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