House battery charging

Precept14 · 10-17-2018, 09:12 PM

2014 Jayco Precept...I’m struggling to figure out why my alternator won’t charge my house batteries. I found a diagram for a 2016 Jayco but can’t see how the house batteries charge. My generator and shore power both work fine. Any thoughts? Thanks

Precept14 · 10-17-2018, 09:33 PM

Im thinking I might have found my problem...The Battery Isolation Manager (BIM) monitors the battery voltage of both the chassis and coach batteries over long periods of time. If it senses a charging voltage, it connects the two batteries together. If the charging system is drastically overburdened, the batteries will be isolated. However, if the BIM sees a long term charging of both batteries it will allow the batteries to remain connected and allow the charging system to do its job. Once the batteries have reached a float charge state for one hour, the BIM will isolate the batteries to prevent overcharging, and will only reconnect the batteries for charging if one of the battery drops to approximately 80% charge, and the other is being charged. This long term monitoring of the batteries prevents the annoying relay clicking that exists in simpler isolation modules today. So...once my house batteries get to full charge, I won’t see any voltage out of the isolator until the batteries drop to about 80%? I guess I will try this out tomorrow.

NickM · 10-18-2018, 05:19 AM

Good work on isolating your problem. I had no idea that the Precept had a battery isolation manager. Where is it located?

My dealer service measured .26 amps drain on the house batteries when off shore power in storage mode. That doesn't seem like enough to drain the house batteries when the coach is in storage.

I'm thinking a small solar panel would be helpful during storage, 10 to 15 watts should overcome the coach residual drain.

RVspeedster · 10-20-2018, 07:22 PM

My problem is that coach batteries aren’t getting enough charge to turn the generator. Low amp shore power isn’t changing enough or at all. Engine idle alternator jucice isn’t getting me there either. Thoughts.

**Mustang65** · 10-20-2018, 07:46 PM

Quote:

Originally Posted by NickM

My dealer service measured .26 amps drain on the house batteries when off shore power in storage mode. That doesn't seem like enough to drain the house batteries when the coach is in storage.

I'm thinking a small solar panel would be helpful during storage, 10 to 15 watts should overcome the coach residual drain.

.26 watts drain will kill a battery in a week or 2, without any type of charger. When you mention 10 to 15 watts of SOLAR, is .8 amps and 1.2Amps. You will get these outputs for less than 2 hours in a day, and that is under FULL Sunlight. If there are any clouds, cloudy/rainy days or partial/full shading, you will not even come close. I do not recommend anything less than 50 watts , about 4 amps and a SOLAR charge controller to insure there is no overcharging, to keep the battery(s) topped off. You will still get enough energy to keep your batteries topped off even on cloudy days.

Don
My Registry

RVing with SOLAR

NickM · 10-20-2018, 08:15 PM

Quote:

Originally Posted by RVspeedster

My problem is that coach batteries aren’t getting enough charge to turn the generator. Low amp shore power isn’t changing enough or at all. Engine idle alternator jucice isn’t getting me there either. Thoughts.

You have a serious problem RVspeedster. On shore power the house batteries are charged by your converter under your bed. On shore power you can test your converter by putting a digital volt meter across the positive and negative terminals, you should see something greater than 13.8 volts DC. If your house batteries are pretty low you may see something greater than 14.2.

When running your V10 engine the Ford alternator adds some charge to the house batteries, I'm not sure how large the alternator is but it seems to bring the batteries up enough to start the generator in 30 minutes or less. Disconnect from shore power and measure the voltage on your house batteries with the engine running. I would expect more than 14 volts, likely 14.6 or 14.8 if the batteries are pretty low.

If your house batteries are not holding a charge they could be like my el cheapo original dealer installed batteries and refuse to maintain a charge after 12 months.

Good luck on your search for a solution.

NickM · 10-20-2018, 08:21 PM

Quote:

Originally Posted by Mustang65

.26 watts drain will kill a battery in a week or 2, without any type of charger. When you mention 10 to 15 watts of SOLAR, is .8 amps and 1.2Amps. You will get these outputs for less than 2 hours in a day, and that is under FULL Sunlight. If there are any clouds, cloudy/rainy days or partial/full shading, you will not even come close. I do not recommend anything less than 50 watts , about 4 amps and a SOLAR charge controller to insure there is no overcharging, to keep the battery(s) topped off. You will still get enough energy to keep your batteries topped off even on cloudy days.

Don

Thanks Don, I didn't do the math, just pulled those numbers out of thin air. I have a battery isolator that will be installed just as soon as I get our Precept back from the dealer.

After that I'll look for a 50 watt solar panel with charge controller. It will not be a permanent installation, just for the time when we will be off shore power for more that a few weeks. Usually this only occurs in November and December.

RVspeedster · 10-21-2018, 01:10 PM

Off engine, volts show 14.5v. So there pretty low. May be time for new batteries. These are somewhere between 1 1/2 - 2 yrs old.

NickM · 10-21-2018, 01:17 PM

Quote:

Originally Posted by RVspeedster

Off engine, volts show 14.5v. So there pretty low. May be time for new batteries. These are somewhere between 1 1/2 - 2 yrs old.

IF the engine is running 14.5 is a good charging voltage. What do you get with the engine off?

Let the batteries sit without charging for 24 hours and read the voltage. Should be 12V min up to about 12.6 for a fresh charge. Anything under 12 and they are not holding the charge.

My house batteries were 18 months old and quit holding a charge so I replaced them with some Energizer Group 31 AGM batteries. I'm trying now to get Jayco to reimburse me.

JDooley · 10-19-2020, 09:42 PM

Good luck on getting reimbursed...
I have a 2020 precept 34g and found the BIM on the left of the batteries I assume that that is where I need to go to stop alternator charging of the house batteries.

RetiredOne · 10-19-2020, 09:55 PM

Quote:

Originally Posted by JDooley

I have a 2020 precept 34g and found the BIM on the left of the batteries I assume that that is where I need to go to stop alternator charging of the house batteries.

Why would you not want the alternator to charge the house batteries?

JDooley · 10-19-2020, 10:35 PM

With lithium I dont want the alternator to charge the house batteries.
Currently as provided by jayco I have two agm 6v which I'm replacing.
The alternater most likely would overheat as it is not meant for 14.4_6 continuous charge..
I have 120 via home 120 when plugged in and generator to get batteries to 14.4-6 and 600w 24v solar when not plugged in

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