Battery Draw

[jkbriggs]

It seems like my chasis batts "discharge" pretty quick when the bus is just sitting. If I turn charger off, within a few days, the voltage drops from 14 to 12.5. I noticed several small indicator lights that remain on all the time (trailer brake unit, 12 volt master, spot light pad, etc.) that would draw some power. But, is there something else I should look for?

Also, if batt disconnects are off, will the chargers still charge the batts? Thanks for any info - Jody

[Joe Cannarozzi]

Hey Jody a little late but I was happy to here your winter trip went well. Best thing you can do for that webasto is to work it like that. Especially a southern bus that normally doesn't exercise that feature.

You should be shutting off your master every time you store the bus. Parasitic draws are common and often numerous so what you are experiencing is common.

Unless you have added an additional chassis battery charger the one for the house does not even charge the chassis.

When we have landed for more than a couple of days, even with power at a campsite I have to shut the chassis off for the bay doors being open often will run them down to the point that the bus hasn't started.

If you are plugged in when stored put some battery tenders on the chassis batts and plug them into the outlet in the engine compartment.

[Joe Cannarozzi]

Jody it just occurred to me that your chassis is 24 volt and the readings you are seeing are definitely house batteries and if you are shutting off your house batteries no they will not charge.

That is still a little odd cause if you are disconnecting them it should eliminate the parasitic draws.

If I had to guess someone has hooked up things to the house batteries at the wrong point.

If you have power in storage leave the house batts on and the charger or inverter on.

[ronwalker]

I haven't searched the archives, but aren't we supposed to keep the transmission memory alive at all times? I keep my chassis batteries topped off from my house batteries by using a Xantrex echo~charge http://www.xantrex.com/web/id/103/p/1/pt/8/product.asp, but then my house battery bank is 24 volt like the chassis.

It only takes one wire to swap the bay lights to house power... 'don't know why the converters don't do it for all motorhomes. You'll need to change bulbs if the house is 12 volt.

Regardless of voltage, old wooden clothespins put out the bay lights for open door times. Just push in the door switch and you'll see where the clothespin goes. 'Works for me!

[Joe Cannarozzi]

That's all great stuff Ron.

[gmcbuffalo]

It seems to me that a drop from 14 to 12.5 volts would be normal. Since the reading is only 14 because of the charger and after surface charge has been depleted isn't 12.5 around 70% of full charge?
GregM

[Joe Cannarozzi]

Greg agreed but that is still a little much. Either one or some of those batteries are going south or there is some draw.

12.7 maybe.

[truk4u]

This topic is getting a little confusing.. If Jody is referring to the house batteries, there's no way the voltage should be at 14 unless the chargers are being shut off while in Bulk or Absorbtion mode. Float should be around 13.2 - 13.4 and the house lasting a few days would be real good with few loads running. If your using the bus, overnight is about all you can expect with the usual AC loads.

If Jody is talking about chassis, if they're Liberty is like mine, they have gauges for both 12 and 24 on the dash. If there is no external charger, then the only way to charge is by running the engine. That 12 volt voltage would be about 14 while running and after shutting down and setting for a few days, a voltage of 12.5 would be normal.

Jody - You mention chassis and (chargers). The chassis generally only has one external charger, but the house would have two through the inverters. Maybe you could clarify which you are talking about.

[JIM CHALOUPKA]

Jody, some draws (parasitic loads) are necessary for proper maintenance of the overall bus operating system.
You have indicated you are aware of them even if you don't know exactly what they are.
You also indicate you have the ability of measuring your battery condition (voltage).
IMHO it would not be wise to disconnect the batteries until you know exactly what parasitics you are eliminating.
Your best bet is to continue to monitor your batteries and run your charger when their voltages gets too low.

JIM

[jkbriggs]

Yes, I do have a 24v system. But my concern is w/the chasis batts. I do have an on-board charger (in other words, not a portable one) for the chasis. I have in-dash gauges that read voltage for both 12 & 24v. I'm going to put the bus in storage w/o hook-ups and will shut off my disconnects. But I didn't want to have something drawing that shouldn't be even when in use. Do I understand you to say that the batt charger does NOT charge if the disconnects are off?

[jimshoen]

Jody,
Here is what I have been doing and it works. This came from another POG'er somewhere in this site.
Purchase a common 120 Volt timer like is used for lights or christmas lights. Get the most basic 24 hour unit, Intermatic etc.
Then get a 24 Volt battery charger/maintainer. The little units that put out very low AMPS and has an automatic shut off. I think mine is a GUEST brand. Paid about 60/70 dollars for it.
Using a very short extension cord plugged into the block heater outlet (disclaimer:coach is plugged into shore power) plug the timer into the extension cord and the battery charger into the timer.
Through trial and error I determined that running the charger about 1.5 hours per day keeps everything OK. I do turn off the 12 volt and 24 volt Prevost Chassis disconnects. Everything else I leave on.
My charger is set to run from noon to 1:30 each day.
I made a quick disconnect for the charging leads from the battery charger to the chassis batteries so I do not have to access the battery terminals each time I want to connect or disconnect the charger.
When it is time to go I put the cord, timer, and charger in the bus tool box.
Last Spring when I went to start my coach the chassis batteries had died.
After paying for the new set I got motivated to take care of them.

[jkbriggs]

Good idea Jim, I'll look into that. How/what kind of batt disconnects are you talking about? Like another set of cable-ends? I don't understand...

[Darrell McCarley]

JODY.......WEST MARINE sells the 24V charger that you need.

[truk4u]

Jim,

Why would you unhook your Guest charger or put it on a timer? The Guest is a 3 stage that goes to float, just like your inverter chargers. Many of us have hard wired them.

Jody - If there is no shore power, there is no charging! Turn off the dis-connects and leave it. It you leave it for an extended period of time, it will go dead.

[jkbriggs]

I think I'm going to be putting the bus in covered storage, but the only available power is a 20amp, 110/120v plug-in. I guess I can go by regularly to start & charge batts. Trust trying to avoid trouble.

[tdelorme]

Jody, the 20 amp hookup is plenty to keep your batteries charged and even run your block heater if we get some real cold weather. Plug your 50 amp plug into a 50amp to 30amp step down adaptor. Then plug the 30 amp into a 30 amp to 20 amp adaptor and plug it into the 20 amp receptacle. Even if it's a 15 amp receptacle, it will keep your batteries topped off. Any RV place will have what you need or you can order from these folks.http://www.pplmotorhomes.com/parts/adapter-rv-power-cords-outlets-adapters.htm?source=google&gclid=CILhhaenpZgCFQVuswodTzM0mQ

[jimshoen]

Tom, You are right. I originally had mine hard wired it. However, for some reason I switched it over to the timer. I like the timer and the charger is only getting power when the timer is on. Somewhere there was a comment on a charger wearing out attempting to keep up a set of questionable batteries? Just the quirky way I do it.

[Jeff Bayley]

Regarding the first post for the thread and the parasite draws, the inverters themselves use power when they are on even if your not running anything. If I'm boon docking, I turn off the inverter at the remote that isn't running the fridge and the batteries last longer and don't discharge as much.

What is the main reason for flipping the 24 volt and 12 volt switches in the engine bay area off when parked besides security ? Are we saving wear and tear on anything or just keeps the batteries from discharging ?

[Steve Bennett]

Jeff, the coach draws both 12V & 24V from these batteries. Shutting off the switches will eliminate most of the draws to keep them up longer. It also prevents a battery imbalance, that can shorten battery life.

[Jeff Bayley]

Thanks Steve- I know the 24 volt switch kills the chassis batteries since the coach won't start but if you turn the 12 volt switch off, the house stuff still runs so I presume this is just related to 12volt systems on the chassis like dash lights, radio, etc ? Since the house batteries are still running the inverters, there's not helping battery life there. I wonder if you mean to say that shutting these off is just related to the chassis batteries. Is there a step down converter or is is wired back there to let the chassis batteries work for 24 volt and 12 volt ?

[jkbriggs]

As far as setting up disconnects to hook in another charger, could the charger just be connected to the batt booster terminals in the r/hand engine compartment?

[Joe Cannarozzi]

I suppose you could but it is better hooked directly to the batteries.

If dead with no chassis charger and only a 12 volt portable charger you can remove the short jumper that connects the two sets of parallel batteries, together in series to create 24 from 12. It is 1 6 or 8 inch cable often of a different color, mine is red.

All of the shorter cables on the chassis batteries connect pos to pos posts or neg to neg posts. There is only one that connects pos to neg that is the one to disconnect.

Then you can charge two 12 volt batteries at a time, parallel, at 12 volts.

Be sure your master disconnect is off.

We have no chassis charger built in.

I went to leave a spot after our first long stay and had drained the chassis with all the bay doors open all the time and the master on. Charged one set for 1/2hr and then the other set for the same and she fired right up.

[truk4u]

Get somebody that know's what they're doing. I see a potential disaster here messing with batteries that are hooked in series/parallel if you don't fully understand the connections and how to charge both 12 and/or 24.

[Joe Cannarozzi]

Take a chill pill. I'm sure anyone not comfortable with doing that will not. I was just putting that out there for those who might benifit from it.

On a complicated scale of 1 to 10 I give it a 2.

[Joe Cannarozzi]

You might be able to take two 12 volt trickle chargers or battery tenders and simultaneously hook them up, one into each set of parallelled chassis batteries without disconnecting anything.

I think a CC I worked on was set up like that. I am going to check it out and see if it works on ours.

This alternative would be much less expensive than the 24 volt charger.

[truk4u]

Easy for you to say Joe, it's not your money if someone makes a huge mistake!

I'll give you an example.. When I bought my CC, some nimrod had improperly hooked the chassis battery cables up wrong after changing out batteries. The jump lugs where both cabled for ground. Anyone hooking 24V to the Red positive lug would have his day ruined.

My post wasn't directed at you, but anyone in general. There are just some things that should be handled by experienced people. There's nothing wrong with helping out, I do it all the time, but sometimes it's clear that folks are getting in over their heads.

[Denny]

You can buy a 24 volt Battery Tender from Blue Spruce Aircraft (and other suppliers) for about $80. I recently bought one from Blue Spruce. Two 12 volt Battery Tenders will cost that much and one 24 volt is much easier to use than two 12's.
__________________

[dale farley]

I've got a 24V 3-stage charger on my 4 engine batteries and a 12V 3-stage charger on my 6 house batteries. I paid a little less than $100 for each, and have had no problem with them. They stay in float mode most of the time since I have very little drain on the batteries.

This configuration allows me to keep my inverters off except when I really need them. I keep the bus plugged in all the time (using a Progressive Industry EMS), and the bus normally draws 3 amps from the 240V power source. Anytime I walk in the bus, I still have all my 120V circuits, even if I have my "Domestic Battery Disconnect" engaged, and if I have my 12V and 24V switches turned off in the engine compartment. My computer memory, etc. is not affected. I am not sure how many other conversions are wired this way, but it works fine with Country Coach.

I run the bus every few weeks until it reaches normal operating temperature, and during that time, I run the inverters (giving a charge to the batteris),, refrigerator, AC units, and I exercise my air system up and down. I also go through each gear in the transmission.

[Steve Bennett]

Jeff, you are correct. The 2 chassis disconnects 24V & 12V, are only for your chassis. Most converters will have a provision to run things that would typically be on the chassis side (dash radio, GPS, spot lights) off of the chassis batteries. Shutting off the 2 chassis disconnects anytime the coach will not be operated (driven) in the next 8 hours or so will go a long way towards protecting the batteries. Typically a good set of chassis batteries will stay up for at least 30 days without any external charging.