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Old 09-26-2017, 08:38 AM   #21
Half a Rivet Short
 
2017 30' Classic
Carlisle , Pennsylvania
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Hi

Dropping the starter across the house batteries sort of makes the chassis battery redundant. Put another way, if the house batteries are always used for starting, why have the chassis battery at all? Deep cycle batteries are ideal for the house batteries. They generally do not like high discharge currents.

Manual switches work fine for the rare case that the chassis battery has died. They also can be rigged for the case of house dead and chassis still live. Dirt cheap and very reliable. Yes you see MH setups with the magic relay, that still does not make it the best solution.

If you have a pair of group 27 batteries for the house batteries, that gets you to around 180AH. Discharging at C/1 type currents (so 180A) will take the battery voltage down quite a bit. Your "normal" 12.6V is 11.4V or less at these levels. As the battery ages, you might be at 10.5V on an otherwise fairly good battery.

A proper design for deep cycle house batteries (as opposed to starter batteries) is to keep the max discharge around C/4. If you anticipate a typical 180A of discharge, you need around 700 AH of battery. Worst case should be C/2, that would get you to 350 AH of battery. These are still not "healthy" rates for the battery, they just are the levels you can run without shortening the life a whole lot.

You might say, let's go with starter batteries. That's fine. They are designed for a few seconds of operation at their maximum load. Their voltage will hold up a little better, they will not do well in a deep cycle application. There's always a gotcha ...

Lots of details ....

Bob
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Old 09-26-2017, 12:30 PM   #22
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Well the bridging solenoid came stock back in 84.
The attached photo shows it and a Kill switch, but mine did not have that, so I added one that connects one, two or both batteries to the circuit.
I assume the original intent of bridging batteries was to give the starter a boost, which with the old carb, was needed when starting hot.
I added the toggle switch to enable bridging manually.
I had used it to start the generator when the chassis battery "chit the bed" this spring.
The setup also allows me to use my solar gear to charge all batteries if needed.
True it aint perfect, but it is nice to have options.

Right now I am stripping out my last wiring method and prepping to make the installation more efficient.
With my inverter, converter and solar controller under the front dinette seat, I pulled the entire seat assembly to have more elbow room to do it right this time.
I will start documenting it soon and add it to my web pages.
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Old 09-26-2017, 12:43 PM   #23
Half a Rivet Short
 
2017 30' Classic
Carlisle , Pennsylvania
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Quote:
Originally Posted by WayneG View Post
Well the bridging solenoid came stock back in 84.
The attached photo shows it and a Kill switch, but mine did not have that, so I added one that connects one, two or both batteries to the circuit.
I assume the original intent of bridging batteries was to give the starter a boost, which with the old carb, was needed when starting hot.
......
Hi

Like a lot of fine old ideas (Univolts ...) time has marched on a bit. With a proper chassis battery it should not be something you need to do. Back in the same era, fusing things like starter cables was sometimes a "why do that?" item. Don't ask how I know this ..... Back then, you also did not have the sort of sensitive electronics running around on the house circuit you do today. Starter motors and alternators can put some massive spikes on the 12V line.

Bob
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Old 09-26-2017, 01:00 PM   #24
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I guess if I wanted to remove the bridging solenoid, and if I had a problem starting the engine or generator, I keep jumper cables with me and I could just jump the house and chassis batteries.
For now, the solenoid is there and has not caused me a problem (So far), so it will stay.

Speaking of sensitive electronics, on my last run I had the inverter on to run my laptop taking data from the ALDL port.
While driving, I keep my rear view camera on to monitor idiots behind me. The NTSC video goes to a in dash DVD/Radio player
(Made by Pyle, I call it a Pile of chit)

Anyway, with the inverter on, there was horizontal banding on the video screen, I can only assume it is high frequency feedback getting into the 12VDC lines getting back into the Pyle DVD player.
]
On my rig I run everything except essential chassis specific electrical/electronic on the house batteries.
If I leave the radio or auxiliary lighting on, it will kill the house battery and not the chassis battery so I can still get home or run the generator.
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Old 09-27-2017, 08:57 AM   #25
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Hi

Simple answer is to replace the solenoid with one of the marine battery switches. They are cheap and this is one of the things they typically are used for. No muss, no fuss with cables. Just throw the switch and away you go.

Some of the subtle issues with the solenoid - giant house batteries are dead (like 2V) due to Uncle Bob leaving your lights on for you Solenoid pulls in, chassis battery tries to charge the house batteries. They are big so there's a lot of current. Now you have a dead-er chassis battery. Other way around: Chassis battery is dead. Turn the key, nothing happens. Solenoid needs power from the chassis battery to pull in .... Hopefully none of this ever happens. If it did happen, that switch is your friend. In the mean time keep that drunk Bob guy away from the light switch

Bob
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Old 09-27-2017, 09:57 AM   #26
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Quote:
Originally Posted by uncle_bob View Post
Hi

Simple answer is to replace the solenoid with one of the marine battery switches. They are cheap and this is one of the things they typically are used for. No muss, no fuss with cables. Just throw the switch and away you go.

Some of the subtle issues with the solenoid - giant house batteries are dead (like 2V) due to Uncle Bob leaving your lights on for you Solenoid pulls in, chassis battery tries to charge the house batteries. They are big so there's a lot of current. Now you have a dead-er chassis battery. Other way around: Chassis battery is dead. Turn the key, nothing happens. Solenoid needs power from the chassis battery to pull in .... Hopefully none of this ever happens. If it did happen, that switch is your friend. In the mean time keep that drunk Bob guy away from the light switch

Bob
Ultimate solution for those drunken daZe...
Install pull starter on Onan 4.0BFA generator
Better yet, hand crank on the 454
Finally, while waiting the the hangover to dissipate, I could let the solar panels do their thing, if it is not sunny out, work on hangover part II
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Old 10-02-2017, 03:53 PM   #27
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The parts came in today.
Not a bad buy, they are a little odd on how they isolate the cable lug from the battery fuse post. They use a plastic T washer that keeps the lock nut and threaded shaft from contacting the cable lug.
If you order these, beware that unless you get a longer T washer, you can only put one lug on the terminal post.
Also, the covers I order were mostly a waste of money. The cable lugs would not fit through the opening and if they did, it would be a pain to fasten them to the fuse post. I decided to aim the cable down anyway and since I bought them, I just put the covers on to of the whole assembly for added short protection.
It does look like the fuses are identical to the Buss fuses available in the US.
It will be a few daZe before I can finish the install and test the voltage to the inverter at full load.
Edit to add; I guess the design is good in case you are stuck with a blown fuse, (and whatever shorted it is repaired), you can just leave off the plastic T washer and you are connected again, at least until you have a new fuse!
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Old 10-08-2017, 12:29 PM   #28
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The new gear is installed and it looks like the current capacity between the batteries and the inverter will handle the full wattage. This link is to the updated page of my solar project:

http://theouterlimits.ws/projects/ai...ar/Page2a.html



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Old 10-22-2017, 01:15 PM   #29
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I did some testing with the new wiring and a fairly heavy load on the inverter.
I used a quartz heater on high power, drawing 10.4 amps at 109 volts for a total of 1165 watts on shore power.

Using my 1800 watt pure sign wave inverter the ac output values were similar.
Here are the DC numbers from a clamp on ammeter and TM2030 readout:
Battery...Ammeter...TM2030
Both.........143...........135 ..(Clamp on DC ammeter accuracy is questionable with zero offset)
Front........90.............134.. (Front battery is a few months old)
Rear.........67.............134.. (Rear battery is over a year old)

Those tests were done with both front & rear batteries in the circuit, the battery voltage was drooping to about 11.? volts (at the battery, not the inverter)
I did a second test using my battery switch with only the front or rear battery powering the inverter alone.
The voltage droop was too much and the inverter shuts down at about 10.5 volts.
I switched the heater to low power and I could get the newer front battery to run 75 amps and keep running.
The rear battery got up to 85 amps and the inverter shut down in a few seconds before I could get a stable reading.
I assume the higher amps on the rear battery is due to its lower voltage output.

So I dont think my wiring is the major problem.
The sizes are more than adequate for the run length.
I think the older Exide battery could be to blame, or that the inverter may be too fussy shutting down at 10.5 volts, but that is their design, and I dont think it would be wise to mess with its internal settings.
I may also be at the limits of two 100AH batteries trying to power over 1000 watts through this inverter.

I dont think I will ever run anything at 1000 watts, (10 amps), my biggest load is the morning coffee pot at 7 amps for 15 min, so I guess I can live with the results.
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Old 10-23-2017, 08:31 AM   #30
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Carlisle , Pennsylvania
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Quote:
Originally Posted by WayneG View Post
I did some testing with the new wiring and a fairly heavy load on the inverter.
I used a quartz heater on high power, drawing 10.4 amps at 109 volts for a total of 1165 watts on shore power.

Using my 1800 watt pure sign wave inverter the ac output values were similar.
Here are the DC numbers from a clamp on ammeter and TM2030 readout:
Battery...Ammeter...TM2030
Both.........143...........135 ..(Clamp on DC ammeter accuracy is questionable with zero offset)
Front........90.............134.. (Front battery is a few months old)
Rear.........67.............134.. (Rear battery is over a year old)

Those tests were done with both front & rear batteries in the circuit, the battery voltage was drooping to about 11.? volts (at the battery, not the inverter)
I did a second test using my battery switch with only the front or rear battery powering the inverter alone.
The voltage droop was too much and the inverter shuts down at about 10.5 volts.
I switched the heater to low power and I could get the newer front battery to run 75 amps and keep running.
The rear battery got up to 85 amps and the inverter shut down in a few seconds before I could get a stable reading.
I assume the higher amps on the rear battery is due to its lower voltage output.

So I dont think my wiring is the major problem.
The sizes are more than adequate for the run length.
I think the older Exide battery could be to blame, or that the inverter may be too fussy shutting down at 10.5 volts, but that is their design, and I dont think it would be wise to mess with its internal settings.
I may also be at the limits of two 100AH batteries trying to power over 1000 watts through this inverter.

I dont think I will ever run anything at 1000 watts, (10 amps), my biggest load is the morning coffee pot at 7 amps for 15 min, so I guess I can live with the results.
Hi

As you have found, "deep cycle" batteries are not real happy with major current loads. Major is normally defined as a current > 1/2 the capacity of the battery. They don't just sag voltage, the discharge rate also wears them out a bit faster.

The unequal discharge capability you noted between your batteries is not unusual. The net effect is that on a given load, the newer battery is doing more work than the older battery. That puts more wear on the newer one.

Since things like idle current scale with the total size of the inverter, in some cases it's better to simply go with a smaller inverter. It also keeps you from getting into weird shutdown situations.

Bob
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