Batteries Dying on New Prism 24G

falcon50 · 04-02-2015, 04:11 PM

I picked up a new Prism 24G from MHS 2 weeks ago and the batteries keep going dead when it sits for more than a day with the battery switch off.
Are the batteries bad or are there parasitic drains causing the issue or ???

Happy Vibe · 04-02-2015, 04:19 PM

How long are you charging it for? Would take a good 24 hours or more with the onboard charger, the battery should not be going dead if the battery disconnect is really disconnecting the battery. You will need to find out what is still connected with the disconnect on.

camaraderie · 04-02-2015, 09:26 PM

Parasitic loads won't drain a battery THAT fast. Was the battery first fully charged?? If so...prolly dead lead.
If not...do so... Put it on a real charger overnite then see how long it lasts with the electric off. At least a week would be normal.... mine last over 3 weeks on a class A. and that is just to 50%.

falcon50 · 04-03-2015, 08:22 AM

I assume since I had been driving the RV for a couple of days straight, the batteries were fully charged.
As far as I understand, the only things still connected with the switch shut off were the safety sensors, carbon monoxide, etc.
If the batteries prove to be bad, any idea if they are covered under warranty?

Duckogram · 04-03-2015, 08:46 AM

Quote:

Originally Posted by falcon50

I assume since I had been driving the RV for a couple of days straight, the batteries were fully charged.
As far as I understand, the only things still connected with the switch shut off were the safety sensors, carbon monoxide, etc.
If the batteries prove to be bad, any idea if they are covered under warranty?

Driving does not normally charge the house batteries. They charge off of your converter which has a built in charger. So you need to be plugged into shore power or running your generator to charge the house batteries. Or, you can get a solar charger $$$.
With your battery disconnect switch "shut off", your CO & gas detector is off as is everything else that is wired thru the converter. Only things that are wired directly to the battery will function... like a remote control receiver and steps. Some things, like your radio clock and such are powered by your chassis battery and remain on.

falcon50 · 04-03-2015, 09:19 AM

Great information, thanks.
I'm new to RVs.
There are 2 batteries under the step, are they just house batteries?
Do they also start and run the motor?
If not, is there a 3rd battery somewhere?

camaraderie · 04-03-2015, 09:29 AM

Batteries should be covered if the unit is new... but they probably can be charged and "rescued". ThePrism has a built in 55 amp CONVERTER... a converter supplies 12V to stuff when you are plugged in...AND...charges your house batts. Procedure:
1. Get yourself a cheap multimeter that will allow you to read voltage at the battery posts. DIGITAL readout needed. 10 bucks.
2. With everything unplugged...take a voltage reading at the battery posts. Anything less than 11.5 volts is seriously flat! Assuming you are seriously flat...fill battery water levels if needed and plug in your coach somewhere...household current is fine if you have the right adapters.
3. With the coach plugged in...turn ON your 12V switch and you should be able to turn on your overhead 12V lights. Take another reading after waiting 5 minutes or so. You should be getting somewhere in the 14V range at the battery terminals.
4. If you aren't seeing ANY change to your original reading...there's a problem with your converter... it may be as simple as a blown fuse...back to dealer. If you are seeing well over 13V...then leave the coach plugged in for 24 hours.
5. Unplug and Remove the NEGATIVE wire (black) and wait 24 hours. Then take a new reading at the posts. You should see 12.6 or 12.7 Volts. Anything less than 12.4 indicates significant loss of capacity (damage) and I'd talk to your dealer about a replacement. Get a new TRUE deep cycle in any event.

Note... don't know about yours but MANY benz chassis models do NOT provide for alternator charging underway except to engine batt...to charge House batts you must either plug in or use your generator. Easy to check what YOURS does.
With 12V turned on take a battery reading for voltage at the house batt terminals.
Then turn engine on and take a new reading after a few minutes. Should be somewhere over 13V if engine DOES charge the house batteries. If no change...plug in.

Hope this helps...good luck.

Witch Doctor · 04-03-2015, 09:30 AM

Quote:

Originally Posted by Duckogram

Driving does not normally charge the house batteries. They charge off of your converter which has a built in charger. So you need to be plugged into shore power or running your generator to charge the house batteries. Or, you can get a solar charger $$$.
With your battery disconnect switch "shut off", your CO & gas detector is off as is everything else that is wired thru the converter. Only things that are wired directly to the battery will function... like a remote control receiver and steps. Some things, like your radio clock and such are powered by your chassis battery and remain on.

My CO / gas detector is wired directly to the battery, had to put in SPST switch in line with another for the clock radio. Just remember to turn them back on when you use the unit. No more parasites. There is not one unit wired the same, you just need to find them...

falcon50 · 04-03-2015, 09:32 AM

Thanks for the very useful information.

Duckogram · 04-03-2015, 09:55 AM

Quote:

Originally Posted by falcon50

Great information, thanks.
I'm new to RVs.
There are 2 batteries under the step, are they just house batteries?
Do they also start and run the motor?
If not, is there a 3rd battery somewhere?

Your chassis is a Mercedes Benz Sprinter 3.0 Diesel that came with a battery. I know that my baby benz has the battery under the floor of the passenger foot well. I do not know where MB hides your chassis battery if it is not stuffed under the hood someplace. It is likely to be in a box so it may not look like a battery. Just follow the cables and you will find it. Or you can just call your deslership service dept and they will tell you.
Also, I have an emergency switch that will start the coach engine from the house batteries. That was a coachmen factory install. If you kill your house batteries you will not he able to start your generator without a jump.
Since you bought new, you must have the Chassis owners manual. That is a good reference for your question as well.

bubbles · 04-03-2015, 10:11 AM

Quote:

Originally Posted by Duckogram

Your chassis is a Mercedes Benz Sprinter 3.0 Diesel that came with a battery. I know that my baby benz has the battery under the floor of the passenger foot well. I do not know where MB hides your chassis battery if it is not stuffed under the hood someplace. It is likely to be in a box so it may not look like a battery. Just follow the cables and you will find it. Or you can just call your deslership service dept and they will tell you.
Also, I have an emergency switch that will start the coach engine from the house batteries. That was a coachmen factory install. If you kill your house batteries you will not he able to start your generator without a jump.
Since you bought new, you must have the Chassis owners manual. That is a good reference for your question as well.

But can't you use the emergency start (es) to also start the genny since the es ties the 2 systems together unless of course the chassis battery supplies the 12 volts to the switching circuitry? This is the way my GT Georgetown will function. Maybe not yours.

camaraderie · 04-03-2015, 10:31 AM

Ducko... most of the Sprinters use propane generators. I would think that jump starting the generator would not work IF the propane solenoid has been closed due to flat batts and a dead lp gas detector. Am I wrong about this? Seems like you need to get a green light on the lp detector then you should be good to go.

falcon50 · 04-03-2015, 10:33 AM

I found the 3rd battery under the drivers side floor mat.
If this battery is dying and it is not connected to the house stuff maybe, as suggested, it has gone bad.
I'll pull it out and get it checked and replace it if necessary.
Thanks.

camaraderie · 04-03-2015, 10:53 AM

NO....wrong. If your engine starts that battery is fine. The other batts are dead because your engine alternator does NOT charge them as you thought. That is NOT a feature of your coach. The ONLY ways to charge your house batteries are the coach plug & converter OR the generator (but you can't start that with dead house batteries).
PLUG IN THE COACH AND TAKE A BATTERY READING WITH A VOLTMETER AT THE STEP BATTERY TERMINALS

falcon50 · 04-03-2015, 11:01 AM

That's the problem the engine does not start.

camaraderie · 04-03-2015, 11:18 AM

Ahhh...so all batteries dead. Just jump the engine battery from your car and let it run for a couple of hours to get a bit of a charge on it. This will not cure your other battery problems. And you may have damaged the engine batt.
To future proof the engine bat starting problems you have TWO choices:
1. A trickle charger when not in use like the battery tender:Battery Tender Plus 021-0128 12V Battery Charger - Walmart.com
2. Remove the negative wire from the batt OR install a disconnect switch like this:
Everstart 936W Positive and Negative Terminal Disconnect for 12-or-24-Vehicle Dynamic Control Systems - Walmart.com

mdf123 · 04-03-2015, 01:06 PM

To clarify an issue raised on this post: I have a Prism 24g and the House batteries are charged whenever the coach is running as long as the system is otherwise working correctly.

jeffrapp · 04-03-2015, 01:17 PM

I also have a 2015 Prism 24G. Great coach!
I have some slightly different opinions.
Regarding charging the house batteries from the engine alternator, I'm not 100% certain, but I believe it does. A few days ago I discovered that I had stupidly left the porch lights on, and forgotten to turn off the battery switch. Although the battery charge indicator (otherwise known as idiot lights) showed "2", the generator wouldn't start. I didn't know about, or don't have, the emergency switch mentioned by Duckogram, so I simply started the engine, which then allowed the generator to start up. I assume that was because the alternator was providing additional charge.
Also, I note that after driving, the battery status indicator shows more lights.
Duckogram, where is your emergency switch located? I thought the Prism came with one, but I can't find it. A picture would help.

camaraderie · 04-03-2015, 01:25 PM

More confusion! Well....easy to check. Put a multimeter on the house battery terminals when the engine is running AND the 12V lights are turned on & working (i.e. cutoff switch is disengaged). If it is over 13V then the alternator charges the house batts as well.

Duckogram · 04-03-2015, 01:28 PM

Quote:

Originally Posted by falcon50

That's the problem the engine does not start.

Ahh. The coach does not start. You drove for days and it did not charge. The house batts did not charge. You did not run the generator and you did not plug into shore power.
If all the above is correct and assuming mdf123 post is applicable to your unit as well, it would appear that your coach has an electrical problem...

If any of the above is not true, you may have more than one problem.

My best advice is to take it to the dealer, its under warranty.

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