House Batteries

Richard,

Many of us are in Southern CA, maybe 30 minutes away. Would love to connect some evening and get together for dinner. Maybe we could get a group to meet half-way?

Ray

Joe, I will look this weekend but memory says that it kicks on at 11.8 - at least thats when the Techlink system says the batteries are depleted.

Jon,

Good idea, where are we going to find the electrical wizard to help with this problem?

I was incorrect when I stated my auto-start activated at 11.5, it's actually 11.15 according to the Liberty Manual, that's even worse. It also states that the gen will run until 13.6 volts are achieved.:eek: My bulk and absorbtion charge is 14.2 and float is 13.1. So in theory, the gen would shut off during the bulk/absorbtion cycle. My float will never get it to 13.6, so what were they thinking!:confused: I do know that it will not shut off and continues to run indefinitely.

This Watch Dog thing must be some dark, secret, hidden for Liberty Eyes only since there is no way to make any adjustments.

Truk,

I based my idea on Jack's 6 hour generator run time.

If the generator run time is not based on hours in the Watchdog, but on house battery voltage then the idea of using a resistor in the sense line is invalid. A resistor will make it start sooner, but since the voltage will read lower than actual it will never be seen by the Watchdog as being at a high enough value. To address that would require the addition of a relay and some additional wiring.

The Watchdog is a deep dark secret and if there were any single lousy feature on a Liberty this feature has to be near the top of the list, if not at the top of the list. If I were not content to manually start my generator and to monitor my voltages that alone would put me in another coach.

Even if the Watchdog is solely dependent upon battery voltage for starting and stopping I think a modification to the sense wire circuit could be implemented. The first step would be to install a resistor in the sense wire circuit so the generator would start at some new higher value such as 12.25 volts. As soon as the generator started, use a relay with a 120 volt coil that is closed upon generator start to bypass the resistor and allow the Watchdog to "read" actual voltage in the sense wire while the generator was running.

I could easily create the circuit, all I would need would be someone to get me the correct resistor value to change 12.25 actual volts into 11.15 volts to fool the Watchdog into starting prematurely.

Jon,I don't think that the watchdog shuts the generator off based on voltage but shuts down only on time.I think your resistor method would work fine except I would like to reduce the run time to possibly 3-4 hours which should fully charge the batteries.I will be dry camping in 2 weeks and I will verify how long it takes to fully charge the gels from 12 volts to 14.1 volts.When the batteries reach 14.1 volts should I maintain the bulk charge for some period of time to fully charge the batteries?

My Magnum is like Jack's it goes on with voltage but then I can adjust that easily but once it starts it will run for a 3 hr period and that is not adjustable. That is just about perfect timing to get us from 12.2 to 13.1. They get there around 2&1/2 hr+.

I have found I do not need it. I will run the gen when I get up 3hr and before bed 3 hr unless it is warm the gen runs as long as it needs to to keep comfortable.

I do not like to let the gen run when I am not there even though it could, why invite potential problems.

Right now 8 hrs of gen time is 20 bucks, a small price to pay for comfort and convenience where there would be none.

Jon when the charge starts and the charger is giving them 30amp they are at 14.1 almost immediately and as the charge rate goes down so does the battery voltages till the charger drops off to 10 amp then float and the batteries follow at 13+ to 13 even or so.

That would mean you would be trying to sense getting back to 13.1 to get it to shut down at the right time?

I think 3 hrs is a pretty close universal time frame to get from 12.2 to 13.1 on most coaches who else can add data here?

Jack,

I don't think you get the batteries 100% charged until float is achieved. Also, on mine, bulk and absorbtion are the same charging voltage 14.2.

Just call Nick Hessler and see if he has any ideas on the subject.
I think he would like to have a product of his own for the RV market.
He sure is knowledgeable enough. If he wanted to do it I think he could!
His old cell number is 541.321.2545.
If that's not current I think Ray has his number.
He could probably make a kit to add or a whole new watchdog type gizmo from scratch to do what is necessary!

JIM

The charge rate of the batteries is dependent upon how the inverters are set up.

I have my inverters set up for the lowest charge rate because we rarely dry camp. You will go into float a whole lot faster if you set the inverters up for maximum charge rate. Then when you are on shore power trying to manage loads you have to remember how you have the inverters set up so you do not trip the power outlet relay.

For example, on a hot night with a heavy load on the 50 amp power outlet turning on a lot of coach lighting such as the Tivolis the inverters will ramp up the power to keep the batteries charged possibly tripping the power outlet breaker.

If you find out exactly how the logic is on the Watchdog (time or voltage?) pass it on and I will try to experiment on my caoch to develop a way to start with a higher voltage so the batteries have a longer life.

One thing everyone needs to consider. I don't know the answer, but it is one that can probably be plotted.

A 50% maximum discharge may give the batteries a life of 5000 charge / discharge cycles. A discharge down to 10% remaining life may cut the number of cycles to 1000. The question I have is how many hours of use before the batteries reach 50% versus 10%, and does the number of life cycles match the number of times the generator will start regardless of which rate of discharge is selected? Obviously starting the generator at 50% means it is going to start more often than if the batteries are allowed to go down to 11.15 volts before recharging.

Jon,You are right about the AC current draw and tripping the breaker,I can adjust the outback inverter/charger down to 5 AC amps.Liberty wants them set up on 50 amp service at 18 and 10 amps,and this will almost always cause a problem with current draw.The other thing that I don't like is the chargers are set up for 4 hours of bulk charge and 2 hours of float charging,this is a problem because whenever a current source is changed it goes into bulk charge for 4 hours.I adjust mine based on the needs of the batteries.If I plug in after driving it will go to bulk charge even though the batteries are fully charged.My Marathon with the trace inverters would do the same thing.This can not be good for any type of batteries,and I think that this would help sell more batteries.The systems that we have for charging are not smart therefore we must adjust and monitor the chargers to deliver the correct voltage and current based on the condition of the batteries.