How to bypass batteries and go on shore power?

[eldin]

Want to remove my two batteries and go on strictly shore power. Can I tape up battery cable after removal of batteries?

[xrvr]

I think if you do that all your twelve volt stuff will be running off the converter? Not the optimum deal.

[mandolindave]

Originally Posted by eldin

Want to remove my two batteries and go on strictly shore power. Can I tape up battery cable after removal of batteries?

Why do you want to remove the batteries?

[55AS]

Originally Posted by avionstream

I think if you do that all your twelve volt stuff will be running off the converter? Not the optimum deal.

When I got my Bambi II it had no battery. Ran fine on Univolt until I replaced it with a modern converter.

[HowieE]

The converter is not intended to be the main power source for the 12 system. The batteries are that main power source. The converter is a battery charger.

yes under light loads the converter will supply 12 volts but it is not intended to be the only source of 12 volt power.

Leave the batteries in. If you do not have a smart converter, one designed for constant use, get one you will be a happy camper.

[alano]

Originally Posted by HowieE

The converter is not intended to be the main power source for the 12 system. The batteries are that main power source. The converter is a battery charger.

yes under light loads the converter will supply 12 volts but it is not intended to be the only source of 12 volt power.

Leave the batteries in. If you do not have a smart converter, one designed for constant use, get one you will be a happy camper.

It's perfectly fine to disconnect the batteries and let your converter supply 12 V while connected to shore power. In fact, while I'm connected to shore power I always leave my Use/Store switch in the Store position so that the converter does not charge my batteries with its single stage charger.

Good practice says to remove the negative connections from the batteries first. It's safer in case you accidentally touch ground while removing the positive terminal.

[jdalrymple]

Yes, one can simply remove the batteries and tape, or otherwise protect, the positive cable from shorting to the frame.

The original converters charge the batteries and use them as regulators to some degree. Voltage supplied by the converter alone will move around some as load increases, if the batteries are not in the circuit.

However, I have switch the batteries on and off when on long term shore power to keep them from being over charged without issues.


Regards,

JD

[crisen]

Are you planning to tow the trailer without the batteries in place? If so, I think I'd be a little concerned about the proper operation of the trailer brakes without a battery, especially in an emergency where the breakaway switch is triggered.

[Bill M.]

Yes to the above. You have to have a working battery while towing the trailer it that is a consideration. I worry about the voltage regulation so I keep a batteries connected in mine. I also worry about power failures and like having some battery backup.
Would like to hear more about this. I am a little afraid of frying something that is voltage sensitive due to the lack of regulation

[lewster]

Modern switch mode power converters (like what you have in an Airstream) serve 2 functions:

• provide sufficient 12VDC (nominal) for the operational requirements of the DC loads of the RV; things like control voltage for appliances like A/C, control boards, furnace fan, igniter boards, lights, etc.
• they also provide power used to charge the batteries.

We all know how bad the Parallax units are for battery charging, but they actually make a pretty good power source for operational DC in an RV.

This is great IF you don't intend to use your trailer on the road. Once you hitch up, both RVIA specifications AND most if not all local laws require that any trailer that is heavy enough to require trailer brakes MUST have an operational battery with sufficient capacity to engage the trailer's braking system in the event of a disconnect (activation of the break-away switch).

[xrvr]

I think there are self contained breakaway switches with their own power source,.

[lewster]

Trailers that don't have internal battery systems USA a small tongue-mounted battery for break away operation of the trailer brakes.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
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Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters
541-490-6357

[HowieE]

Originally Posted by lewster

Trailers that don't have internal battery systems USA a small tongue-mounted battery for break away operation of the trailer brakes.

That system would cost about the same as trailer mounted batteries and create a new maintenance problem that most likely would be forgotten.

Why are you considering removing the batteries, weight?

[AnnArborBob]

In summary:

If you don't plan to move the trailer, then taking out the batteries is fine. Despite some earlier comments to the contrary, the stock converter is perfectly capable of providing you with all the 12 volts power you will need when plugged in to shore power without any ill effects. However, DO NOT attempt to tow your trailer without a properly charged battery as you will not have trailer brakes and will not only be operating your set up illegally but will also have a lot of trouble controlling the rig on the road.

Also, unless you make some changes to the stock Airstream wiring, I suspect that your tongue jack will not operate without the battery as I believe that the jack is wired directly to the battery and not to the breaker panel which is powered by the converter when on shore power.

[kdickinson]

for my trailer no battery no 12v power, it's part of the circuit

[Wingeezer]

It may vary with age and design of the trailer, I'm not sure,

But with our 2005, It can be done just fine - in fact If I recall correctly, my manual even states that you can power all the 12v stuff in the trailer from the converter without any battery in place.

You do need at least one battery in place though to move the trailer in order that the
breakaway switch could do its job.


You are correct though that if you have one or both batteries out, you should protect the bare 12v + connector(s) from accidentally grounding because they will be live from your converter/charger.

Being inherently lazy, I generally just stick the positive connector into a heavy rubber glove that I carry for trailer washing! Not the best but it works!

I also have quick disconnect knobs on my battery connectors. I installed them because we just have the original (Not smart!) charger in our trailer and I am afraid of cooking the batteries if it remains connected too long.

If we are going to be on shore power for more than just a couple of days I disconnect the batteries - and try not to forget to put them back on line when we are ready to move!

Brian.

[xrvr]

Aren't the trailer brakes actuated by the tv? It just the breakaway switch that needs its own battery, either on the switch itself or the one in the trailer.

[HowieE]

Originally Posted by avionstream

Aren't the trailer brakes actuated by the tv? It just the breakaway switch that needs its own battery, either on the switch itself or the one in the trailer.

Under normal operation, traveling down the road, the brakes are powered by the TV. However if the trailer separates from the TV while on the road the brake-away switch closes and supplies power to the brakes assuming there is a battery to draw that power from. Keep in mind that current will be 6,12, or 18 amps, depending on your axle count. That requires a good size battery, like those normally in the trailer.

Noone has yet said why the OPer wants to remove the batteries.

[AnnArborBob]

Originally Posted by HowieE

Under normal operation, traveling down the road, the brakes are powered by the TV. However if the trailer separates from the TV while on the road the brake-away switch closes and supplies power to the brakes assuming there is a battery to draw that power from. Keep in mind that current will be 6,12, or 18 amps, depending on your axle count. That requires a good size battery, like those normally in the trailer.

Noone has yet said why the OPer wants to remove the batteries.

I'm not so sure that you get enough amps via the umbilical cord to power the trailer brakes.

[HowieE]

Originally Posted by AnnArborBob

I'm not so sure that you get enough amps via the umbilical cord to power the trailer brakes.

Your suspicion is correct but has nothing to do with the breakaway switch and the current that would flow to the brakes when the switch is closed.

They are 2 different systems. The current supplied to the brakes from the TV is limited by the length and size of the wiring, all to often undersized.
The current flowing to the brakes when the breakaway switch is closed is only slightly limited by the wiring in the trailer, but very close to the max. This system is designed to come as close as possible to locking the trailer brakes and thus stopping the trailer ASAP.