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Topic: Coach battery charges, engine battery doesn't. (Read 603 times) previous topic - next topic

Coach battery charges, engine battery doesn't.

Coach is plugged in the S&B. Boost switch is in center switch position.
When I check on the batteries the coach battery is at 13.9 and the engine battery is down to 12.5.
These voltages are verified in two different places.
The coach battery also has a 100A solar hookup.
When I move the boost toggle to the "charge" position the monitor immediately shows 13.7 or same as the coach battery. Switch back to center position and engine battery drops down to 12.5V
Both batteries are about 15 months old. I did take the engine battery and had it checked professionally a month ago and results showed 14.3 volts.
House battery is a big 8D and the engine battery is a 1000 CCA truck battery.

Re: Coach battery charges, engine battery doesn't.

Reply #1 –
That would suggest the engine battery has lost capacity to me

Re: Coach battery charges, engine battery doesn't.

Reply #2 –
Refresh me on S&B. Don't know about yours but our engine batteries don't charge when on shore power. I have to use a jumper I made or you can put a trickle charger on the engine batteries. This is the way our coach is designed.

You can put a charger on the engine batteries, charge overnight and then check voltage.

When on shore power, don't use the boost switch to charge the engine batteries.

Pierce

Re: Coach battery charges, engine battery doesn't.

Reply #3 –
Our engine batteries are maintained by a separate charger that gets power from the coach batteries as needed.  I can't remember the name of it to send a link.  It works very well.  Maybe someone with a similar setup can chime in. 

Re: Coach battery charges, engine battery doesn't.

Reply #4 –
OK Pierce. I am doing just what you said.
I've got a trickle/maintainer charger on the engine battery while plugged in to the house (S&B).
Just thought there might be something wrong with my system.
Just wondered why I couldn't run jumpers from the coach battery to the engine battery and take advantage of the solar.

Re: Coach battery charges, engine battery doesn't.

Reply #5 –
You are misunderstanding your batteries or I am misunderstanding you. A fully charged battery is 12.6 not 14+. Your house batteries are charging correctly both by the solar and the charger. When you switch on the boost switch, both the start and the house batteries SHOULD read the same. That means both banks are charging with both the solar and the charger. Idle at 12.5 makes me happy. The 14.3 volts you saw is CHARGE RATE. I ALWAYS use the boost switch to charge the start batteries.

While plugged in and with solar your start batteries do not charge unless you turn on the boost switch.

Re: Coach battery charges, engine battery doesn't.

Reply #6 –
Quote from: Johnstons –
Our engine batteries are maintained by a separate charger that gets power from the coach batteries as needed.  I can't remember the name of it to send a link.  It works very well.  Maybe someone with a similar setup can chime in. 

Just installed Amp-L-Start on ours after killing the start batteries last month.
Sends a charge from the house batteries over to the start batteries when plugged into shore power.
Separates the two when shore power removed.
Seems to be working well, both sitting at 13.2v
Boost switch off.

Re: Coach battery charges, engine battery doesn't.

Reply #7 –
Quote from: nitehawk –
OK Pierce. I am doing just what you said.
I've got a trickle/maintainer charger on the engine battery while plugged in to the house (S&B).
Just thought there might be something wrong with my system.
Just wondered why I couldn't run jumpers from the coach battery to the engine battery and take advantage of the solar.
I do run jumpers from my AGM house to conventional engine batteries. Not a problem mixiing types as our house AGM are eleven years old and doing fine.

The reason I don't use the boost switch is that it has a pretty good current draw and gets hot to the touch after 30 minutes or so. While it is continuous duty, it takes a constant supply of juice to stay activated. The solenoids that don't use any current while in operation are called "latching solenoids" but keep reading. 

So what is the problem using the boost switch and boost solenoid? Who cares if it uses juice as the shore power has an unlimited supply, right? In the event of a power outage, because of a squirrel in the power lines, a hurricane or here in California with PG&E as the utility, is that when the electricity is no longer supplying the coach, the boost solenoid will continue to suck power out of both batteries until the voltage drops way down. Last year, because of high winds, PG&E turned off our power for days. And they don't turn it back on when the wind dies down, they have to inspect all the lines for trees, etc. This takes more days. By this time, engine and house batteries are ready for recycle. In language some might use, "boost switch is very bad, evil, corrupt."

So, best of all worlds is solar to charge both sets of batteries and if the coach is at a distance, a possible internet connection may allow remote sensing of the battery condition for both banks. There are other options available but I like to keep it as simple as possible.

Pierce

Re: Coach battery charges, engine battery doesn't.

Reply #8 –
A combiner auto disconnects under no charge  conditions.  Either bank getting a charge they are combined.  100% reliable

Re: Coach battery charges, engine battery doesn't.

Reply #9 –
Quote from: Pierce & Gaylie Stewart –
So what is the problem using the boost switch and boost solenoid? Who cares if it uses juice as the shore power has an unlimited supply, right? In the event of a power outage, because of a squirrel in the power lines, a hurricane or here in California with PG&E as the utility, is that when the electricity is no longer supplying the coach, the boost solenoid will continue to suck power out of both batteries until the voltage drops way down. Last year, because of high winds, PG&E turned off our power for days. And they don't turn it back on when the wind dies down, they have to inspect all the lines for trees, etc. This takes more days. By this time, engine and house batteries are ready for recycle. In language some might use, "boost switch is very bad, evil, corrupt."
Pierce
Normally, most of us would go turn the boost switch off. I suppose a plane could fall on my coach as well. But hasn't yet.

Sorry. I keep editing. Also, as an aside, I have an MPPT controller so when I'm in the sun it charges both banks and they still discharge separately.

More than one way to keep your batteries up. I just find the boost switch best.

Re: Coach battery charges, engine battery doesn't.

Reply #10 –
Quote from: Caflashbob –
A combiner auto disconnects under no charge  conditions.  Either bank getting a charge they are combined.  100% reliable
Yes, they are a good alternative that may fill the bill. But nothing in electronics is 100% reliable I've found. I just prefer KISS.

P

Re: Coach battery charges, engine battery doesn't.

Reply #11 –
The blue seas combiner is 500 amp rated and 100,000 cycles and magnetically engaged after switching,  no power to hold it open or closed.  Marine unit

Vs 3 amp continuous load physically heating the boost solenoid and its switch.

Original gas FTX's had momentary on boost switches to prevent continuous use.

Had to jam a toothpick in a 79's boost switch to hold it closed  after the alternator failed on a trip through Oregon so as to power the engines ignition from the gen side

Re: Coach battery charges, engine battery doesn't.

Reply #12 –
Installing a Trick-L-Charge is a way to keep your start batteries charged when on shore power, if the coach batteries are fully charged , it will send a small charge to the start batteries, takes about 10 minutes to install

Re: Coach battery charges, engine battery doesn't.

Reply #13 –
Quote from: Caflashbob –
The blue seas combiner is 500 amp rated and 100,000 cycles and magnetically engaged after switching,  no power to hold it open or closed.  Marine unit Vs 3 amp continuous load physically heating the boost solenoid and its switch.
My thought: Boost solenoid is already there...so....free. No need to buy anything. The ignition solenoid is identical to the boost solenoid. So.....why do you not worry about the ignition solenoid heating up while you drive for 8-10 hrs a day? They both do the same thing. I'm all for free. I did have to replace the light bulb in the switch once, though. Keep in mind I only turn it on to charge the start battery as needed.

Re: Coach battery charges, engine battery doesn't.

Reply #14 –
I assume that a solenoid that requires power to hold it closed has a higher failure rate than a magnetically held together later design.  It just came to my memory's that my guru buddy replaced the std starter solenoids with blue seas units.  Highly recommended I replace mine. Now that you mention it.

Re: Coach battery charges, engine battery doesn't.

Reply #15 –
Quote from: Caflashbob –
I assume that a solenoid that requires power to hold it closed has a higher failure rate than a magnetically held together later design.  It just came to my memory's that my guru buddy replaced the std starter solenoids with blue seas units.  Highly recommended I replace mine. Now that you mention it.
No doubt your Blue Seas are much better and will live a lot longer. Cole-Hersee has changed the points material in theirs but they still fail. On the good side, you can pry them apart, sand the contacts and they usually work again. But you probably will never have to replace the Blue Seas. They just cost more but in this case, you get what you pay for.

Pierce
 

Re: Coach battery charges, engine battery doesn't.

Reply #16 –
Mark Crick wrote an article on this subject in the Spring 2020 issue of Motorcader.  Based on your replies, I would suggest that you guys read it.

Larry