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Old 02-21-2016, 09:44 AM   #21
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Sure you can. Both positive are usable. Just remember if your connecting a positive and a negative wire from the same accessory you would connect positive to one battery and use the negative connection from the other battery.
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Old 02-21-2016, 09:51 AM   #22
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Quote:
Originally Posted by fastwilly View Post
forgive my ignorance, but with the shunt wire (the wire between the two batteries) does that make both terminals in effect the same? could you not connect a couple of your reds to the other terminal? Maybe I'm not understanding the problem. If so, please ignore.
I think you understand it well. Once the two +to+ and -to- jumpers are connected then you effectively have one big battery and any external needs can be connected to any +/- terminal.
If you are dealing with a larger bank for charging...it is a good idea to connect to the + of the first battery and the - of the last battery in line to insure a full charge is reflected when all batteries are 100%.
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Old 02-21-2016, 09:56 AM   #23
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Quote:
Originally Posted by fastwilly View Post
forgive my ignorance, but with the shunt wire (the wire between the two batteries) does that make both terminals in effect the same? could you not connect a couple of your reds to the other terminal? Maybe I'm not understanding the problem. If so, please ignore.
The short answer is no.

The long answer involves some math (providing both are 12 volt batteries as it appears).

In order to balance the charge and discharge rates of the batteries the total resistance between the charge/discharge points must be equal. That resistance includes the resistance internal to the battery(s) and the interconnecting cable system. Read the attached article and examine the attached graphics.
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Old 02-21-2016, 10:15 AM   #24
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Thank you camaraderie and Herk7769 for your answer. And I totally agree with your explanation of the charging circuit. I was looking at supply of 12 volts only, rather then charging.
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Old 02-21-2016, 10:38 AM   #25
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Great info Herk.
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Old 02-21-2016, 11:04 AM   #26
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Thank you Herk7769, that's why I moved the alternator/Leveler cable over to the other battery. Good explanation!
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Old 02-21-2016, 11:39 AM   #27
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Just so we are clear; the charge AND LOAD must be on the same (opposite) terminals of a battery stack; no matter how many batteries make up the stack.

Putting anything (load or charger) "in the middle" is a mistake that will result in unbalanced charge rates and discharge levels.

This will eventually cause one battery to fail before the other(s) due to one "aging out" before the other battery.
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Old 02-21-2016, 11:55 AM   #28
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In some motorhomes (I have seen) the inverter (not converter) is wired to a positive terminal other than the one with the converter charge/coach load wire.

This may make the wiring much simpler for the installer/manufacturer, but will cost you money in batteries in the long run. Better to have it rewired so the batteries "see" an equal amount of the total load and get their "fair share" of the recharge when you get connected to AC again.
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Old 02-21-2016, 04:38 PM   #29
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Question for Herk7769

After all this, I discovered that after switching the battery cut-off to OFF, there is still a -2ahr draw showing on both my battery monitor and clamp-on amp meter. That's almost 5 amps per day and half the capacity in 2 weeks. A disconnect on the negative or just replacing the nut with a wing nut should allow complete disconnect, right?
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Old 02-21-2016, 04:47 PM   #30
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Originally Posted by Sagecoachdriver View Post
After all this, I discovered that after switching the battery cut-off to OFF, there is still a -2ahr draw showing on both my battery monitor and clamp-on amp meter. That's almost 5 amps per day and half the capacity in 2 weeks. A disconnect on the negative or just replacing the nut with a wing nut should allow complete disconnect, right?
That sounds a lot like the fridge climate control.

2 amps DC (24 Watts) is not a lot of power. (does not point to a DC tank heater)

Parasite draws (clock in the radio or Propane detector) should be no more than 6 or 700 milliamps.

A SINGLE RV incandescent lamp left on in is 1.2 amps though, just to give you an idea of what you are looking for.

Want model is your fridge? If there is no switch to turn it off, there is a mod to the fridge light (power source for the defroster - climate control) that you might want to investigate.
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Old 02-21-2016, 05:18 PM   #31
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Quote:
Originally Posted by Sagecoachdriver View Post
After all this, I discovered that after switching the battery cut-off to OFF, there is still a -2ahr draw showing on both my battery monitor and clamp-on amp meter. That's almost 5 amps per day and half the capacity in 2 weeks. A disconnect on the negative or just replacing the nut with a wing nut should allow complete disconnect, right?
From the context of your note, I think you meant you had a .2 amp draw rather than a -2 amp draw. Correct??
And yes...assuming there are no other "black wires" other than the main one, then a cut off switch at the terminal will kill that parasitic load. It there are other ground wires, then just move them to a buss bar or other connection that the cut off switch can kill as well.
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Old 02-21-2016, 06:56 PM   #32
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OOOOpppps!

OOOOpppps! Sorry, it's .2 ahr not 2 ahr. See what happens when you don't go back a proof read!

Everything appears to be off even the dash radio and 12v power plugs???
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Old 02-22-2016, 12:10 AM   #33
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OOOOpppps! Sorry, it's .2 ahr not 2 ahr. See what happens when you don't go back a proof read!

Everything appears to be off even the dash radio and 12v power plugs???

Sage, mine has a .1 ahr draw when disconnect is off. I was told this was the big foot system and that was normal . They have to be wired directly and not thru the disconnect because of how many amps they draw when in use.
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Old 02-22-2016, 02:39 AM   #34
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Sage, mine has a .1 ahr draw when disconnect is off. I was told this was the big foot system and that was normal . They have to be wired directly and not thru the disconnect because of how many amps they draw when in use.
That makes sense Ben.
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Old 02-22-2016, 07:31 AM   #35
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Several hundred ma is normal parasite draw for a camper.

There are a few things that bypass normal battery cut off systems; some required by law.

The propane leak detector has no way of "knowing" that the propane valves are on, so that must be powered. The radio internal clock would need to be reset every time you used the cut off so, by convention, it also is bypassed.

As camper systems become more computer controlled, these systems also need continuous power to maintain settings and correct operation.

If you will be storing your camper and will not be using the propane gas at all (valves closed) you can easily add a switch at the positive terminal of your battery for storage (in a heated area).

Obviously you never want to store a battery without trickle charging current where the battery will freeze. While a fully charged battery will not freeze, a partially discharged one WILL; breaking the lead plates and ruining the battery(s).

Batteries will "self discharge" over time due to the small, but real, losses from internal resistance using up the plate charge.
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Old 02-22-2016, 08:24 AM   #36
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There is some good conversation on this battery thread and a few of my questions actually got answered with out lifting a finger, although it take take a few clicks.

Just a footnote for FR, it may beneficial to route the inter battery cable connections in a fashion that does not block the battery caps. I have been wanting to check the water level in the batteries and cannot until I take some time to redo the cables. In a few weeks the weather should be warm enough to complete this job.
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