battery discharge

[pacesetter]

Can some one tell me why mycranking battery discharges after a few days.
I have a pace arrow 1983 29 ft 454 engine, battery charges up but discharges after a few days. Thanks for any help

[RJay]

Hi pacesetter, Welcome.
On my 2000 suncruiser I had to install one of these. It seems the chassis battery isn't charged when connected to shore power and this device solves that problem. However you don't say your connected to shore power so I'm assuming that it loses charge after it just sits a few days after use. You may have some parasitic discharge going on, something wired directly to the battery system instead of thru the ignition. It could also be a short somewhere.

[Petro]

Quote:

Originally Posted by pacesetter Can some one tell me why mycranking battery discharges after a few days. I have a pace arrow 1983 29 ft 454 engine, battery charges up but discharges after a few days. Thanks for any help

First I would like to welcome you to iRV2. We are glad you joined us. You could have several problems causing your battery drain. I would encourage you to visit our MH - Problems, Solutions, & After Market forum HERE You should receive more replies there.

Don

[Gary RVRoamer]

His Pace does indeed charge the chassis battery while on shore power, so that's not it.

The parasitic drain on a old Pace Arrow ought not to drain the battery that quickly - should last for weeks. How old is this battery? Have you had it load-tested? Most auto parts stores will do that for free.

[TQ60]

Get a volt meter that also has an amp meter function, one that will measure 10 amps, money well spent.

Now make the following measurements
1. Voltage before starting, should be 12.6 volts or better.
2. Voltage while cranking, should NOT be below 10 volts or so.
3. While engine is running at fast idle voltage should be between 13.6 and 14.6 volts, any higher is over charged and lower is not charging enough.
If above 12.8 and below 13.6, turn on lights, if drops down shut off engine and verify alternator belt is tight, try to turn pully, if pully turns or slips in belt it is too loose, if old replace belt, if not old tighten until pully does not slip, then re-test.

If all above passes turn EVERYTHING off...EVERY switch.

Remove the negative wire from the post, count to 10 and touch it back, if large spark then large load, if small spark it could be filter cap in stereo.

Now switch meter to measure amps, place black lead on battery and red lead on wire, this is the amount of parasitic load, depending on what you have connected this may vary from zero to about an amp or so.

Remember you should have everythig turned off so only memory loads should be present.

You may want to add an additional small battery specific for your alarm, stereo and other MBS or add a trickle charger to the starting battery to supply the loads and maintain the charge.

A normal car battery is in the range of 70 to 90 amp hour capacity, is we assume it takes only 25% of the charge to start the vehicle, and the battery is GREAT, then using a 90 amp battery you have about 65 amp hours of capacity.

Multiply the amps you measure by the amount of time between when the engine is running and that is the capacity of the battery that is consumed by the parisitic loads.

Also consider the alternator takes many hours to fully charge the battery, it must return the capacity consumed by starting as well as the parisitic loads, and given the nature of how a battery works, the charging current of the alternator will go down as the charge in the battery rises, so if ne has a 100 amp alternator it is only putting out 100 amps when the battery is near dead, as the battery charges the current is much less, it could take many hours to fully charge a dead battery.

One could place a trickle charger on the battery for a few days, disconnect the charge and after about 2 hours the float charge should be gone, the voltage should be 12.8 or so indicaing a FULL CHARGE.

If the battery has bad plates but the cells are not shorted it still can indicate a full charge, but with bad plates the capacity is greatly reduced.

So if the batteyr is over a couple years old and the measurements above do not indicate too high of a parasitic load while everything else looks ok (charging voltage etc) it might be a good idea to just change out the battery and be done.

[pacesetter]

I have a new battery,when I camp for a couple of weeks my cranking battery goes down to where it will not start the motor without help from the coach battery's. Every thing is off from the cranking battery, we don't play the radio.
I have a clock that runs all the time could this be running down the battery, the battery is a 1000 am cranking battery that I just replaced new.
I usually disconnect the positive cable but I would like to know what is causeing my problem. Thank all of you for your help

[pacesetter]

When I am camping I am hooked to the campsites electric which keeps the coach battery's charged but does not charge my cranking battery.

[bigskymt]

I don't believe your converter is set up to charge the chassis battery on that model coach. As TQ60 suggested you should remove a battery cable and install an ammeter between the cable and battery post.............a test light will also indicate a draw.......the brighter the light the more draw.
It's possible someone connected something from the house to the chassis battery via the fused battery terminals on the fuse block.
Is your step electric or vacuum?
It's also possible the alternator has a shorted diode that could be drawing current. On your model I believe the alternator output runs to the battery isolator on the firewall, if you disconnect that wire from the isolator you should eliminate the alternator from the circuit.