Another Battery Problem

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Another Battery Problem

November 15, 2014, 04:02:12 pm

Any ideas on this one would be appreciated. My 2002 U320 is stored in an enclosed storage facility. It's plugged into just 120 to keep some power into the coach and to keep batteries charged, No 50 amp available. Storage says they start engine every two weeks, but I have my doubts. So a few days ago was loading for next trip and tried to start---nothing out of chassis batteries. Turned booster switch on and coach started. When ignition key is tried, without booster, I get no readings on any of the gauges, nothing. with booster switch on, every gauge registers normally. On the monitor that shows holding tank levels (can't remember what it's called) it shows battery reading of around 14.0 volts. I take it the chassis batteries are DEAD. But why is this happening, all batteries, chassis and house are about 2 years old. If I'm plugged in, wouldn't the inverter keep a charge on the batteries. Any solutions and what am I doing wrong. Any thoughts would be helpful.

Thanks, Ralph

Re: Another Battery Problem

Reply #1 – November 15, 2014, 04:20:14 pm

Ralph, I doubt that your charger charges the engine start batteries. You probably have a parasitic drain that drains the start batteries. That is why so many folks use a battery maintainer on these batteries. Engine batteries are usually only charged with the alternator.
Gary B

Re: Another Battery Problem

Reply #2 – November 15, 2014, 04:22:24 pm

Ralph,

Your cranking batteries are separated from your coach batteries by the battery isolator. With out a trickle charger of some type (which is what we have) or leave your boost switch on (personally not recommended) your crank batteries will not charge from your inverter/converter that charges your house battery. Your cranking batteries are still supplying juice to engine ECM, trans. ECM, and other ghost draws, when your coach is just sitting there. You can install a battery cut off switch on your cranking battery cable, to isolate the batteries but then it would need to be closed to get the engine to start.
Pamela & Mike

Re: Another Battery Problem

Reply #3 – November 15, 2014, 04:44:34 pm

Yes, the inverter-charger charges only the house batteries, not the chassis batteries. There are a number of solutions.

1. Add a trickle charger. I have a maintainer plugged into the block heater outlet and connected to the chassis batteries to keep them charged when plugged in.

2. Add a diode type charger across the isolator to tie the two banks together when the ac charger is running.

3. Add a disconnect switch to the chassis batteries to eliminate the parasitic loads that are discharging it. FT says to disconnect the battery is it is going to sit for two weeks to accomplish the same.

4. Just keep the boost switch on so the ac charger gets to all the batteries. If you already have fully charged batteries when you do this, the current though the boost solenoid will be the small float current. If you do it now to charge dead batteries from the ac charger, it will probably take a full 100A for an hour or so. OK, but not recommended, I have done it when needed.

The best way to bring the fully discharge coach batteries back to full charge would be to use an external charger, preferably one with two or three stages, a smart charger. Then, once it is back, throw the boost switch on and keep it on until you can add item 1 or 2 or 3, or go with 4 as a permanent solution.

Re: Another Battery Problem

Reply #4 – November 15, 2014, 05:32:41 pm

there no need to start the coach until you are ready to use it.

Re: Another Battery Problem

Reply #5 – November 15, 2014, 05:38:39 pm

Quote from: Wayne Macauley – November 15, 2014, 05:32:41 pm

there no need to start the coach until you are ready to use it.

True, but letting the coach batteries self discharge completely is harmful to the batteries. At the very least fully charge them, then disconnect the negative cable. They will still be mostly charged when you come back months later to start the engine.

Re: Another Battery Problem

Reply #6 – November 15, 2014, 06:04:09 pm

Two things:

Make a short jumper with 8 gauge wire between any two convenient places where both batteries or both battery cables are-- like batteries, battery isolator, boost switch, etc. When in storage, keep the jumper wire connected so the inverter/charger charges the house bank and the jumper changes the chassis batteries.

You could also buy an Echo Charger or other bi-directional relay to do this automatically.

A third option would be a small (like 2 amp smart charger (120 VAC powered) exclusively for the chassis batteries.

And, DO NOT START THE ENGINE UNLESS YOU CAN DRIVE A MINIMUM OF 25 HIGHWAY MILES. Unless you can get the OIL, not just coolant up to temperature, all you are doing is adding moisture to the crankcase-- a BAD IDEA.

Re: Another Battery Problem

Reply #7 – November 15, 2014, 06:37:09 pm

Amen to what Brett said about starting the engine every two weeks!!!!

Keith

Re: Another Battery Problem

Reply #8 – November 15, 2014, 08:11:12 pm

Thanks for all your replies. When i bought new batteries, I installed a pos. and neg. cables and posts in my engine compartment. I will hook up a battery maintainer /trickle charger to this to maintain chassis batteries. Since I don't have access to 30 or 50 amp circuit, is normal 120 ok with inverter on to maintain house batteries? Switch at entry door to stay off until I use the coach. This is what I normally do. I really think that someone ,probably me, left the booster switch on which caused the problem. So it's not good to start coach and let it run, didn't realize that ,I just would do it occaisonally to make sure it would start. Won't do that any more. Since I'm not able to get to the coach as often as I would like, I'm always concerned about the batteries. Hope this solves my problem.

Thank you guys for your input.
Ralph

Re: Another Battery Problem

Reply #9 – November 15, 2014, 08:14:17 pm

Is a 2 amp charger enough for an 8D battery?

I never leave my boost solenoid closed when my coach is unattended because if there's a power failure it'll be draining all my batteries instead of just my coach batteries. With the boost solenoid open my cranking battery will still be charged when I come back even if the power failure lasts all day long.

Re: Another Battery Problem

Reply #10 – November 15, 2014, 09:04:02 pm

Yes, a 2 amp charger is enough to maintain (will NOT charge if the battery is discharged).

And indeed 15 amp outlet is enough to keep the batteries and a few other things up. Good idea to reset "power-share/power save" on your inverter. Set it to 5 amps (of 120 VAC) that is plenty.

Re: Another Battery Problem

Reply #11 – November 15, 2014, 10:01:41 pm

Seems that a simple solution would be to connect the inverter/charger output cable to the isolator input terminal. That way, both banks are being charged/maintained separately any time the coach is plugged in to shore power.

The alternator and charger most likely have internal diodes to keep them separate from multiple charging sources.

Re: Another Battery Problem

Reply #12 – November 15, 2014, 10:05:02 pm

I think the best solution would be that relay gizmo that Don found. I might get one and just wire it across the diode isolator.

Re: Another Battery Problem

Reply #13 – November 16, 2014, 08:25:35 am

I think I'm going to install a separate charger for my cranking battery. If / when my main charger fails I should be able to at least maintain both sets of batteries by closing the boost solenoid. Also I should be able to charge all the batteries faster with two chargers when I start the genset, with no need to close the boost solenoid for any reason other than cranking the main engine in cold weather. I think I'll install a charger that's capable of charging an 8D but cuts back to 2 amps after the battery is charged. I'm not real impressed with the Wizbang battery desulfator I installed over a year ago. As near as I can tell the battery it's hitched to (cranking battery) is weakening anyway even though it's less than three years old and has been properly watered and maintained.

Re: Another Battery Problem

Reply #14 – November 16, 2014, 08:34:35 am

One of the extra items I carry is a battery charger, never know when you need one.

Re: Another Battery Problem

Reply #15 – November 16, 2014, 08:42:04 am

They're inexpensive and easy to install. I bought one for my mom's generator the other day at Tractor Supply. I love that store!

As I recall it was a Schumacher (spelling?) and it was designed to be a permanently installed battery maintainer that automatically switched from a 10 amp charge setting to a 2 amp and ultimately to a 1/2 amp I think? It cost about $20 and I permanently installed it in a matter of minutes. I probably should've bought one for my 8D cranking battery but I didn't think it would be big enough to maintain a 150 pound battery! haha ...but I musta been wrong according to this post.

Re: Another Battery Problem

Reply #16 – November 16, 2014, 09:09:42 am

Quote from: Tom Lang – November 15, 2014, 10:05:02 pm

I think the best solution would be that relay gizmo that Don found. I might get one and just wire it across the diode isolator.

NO. There is a .6-.7 VDC drop across the diode-based isolator. This drop would render charging either battery bank poor at best.

Re: Another Battery Problem

Reply #17 – November 16, 2014, 09:51:06 am

I've used a Trik-L-Start for YEARS, with good results. I have one of their new 15A units on order for my NTM (new to me) FT.

Re: Another Battery Problem

Reply #18 – November 16, 2014, 10:12:15 am

Quote from: wolfe10 – November 16, 2014, 09:09:42 am

NO. There is a .6-.7 VDC drop across the diode-based isolator. This drop would render charging either battery bank poor at best.

Good point.

Since I installed a 40 amp smart charger dedicated to the chassis batteries, those batteries are seeing their first full charging voltage.

Now I'm considering the Sterling software based isolator so they can see full charging voltage from the alternator.

Re: Another Battery Problem

Reply #19 – November 16, 2014, 10:25:01 am

Quote from: Ed – November 16, 2014, 10:12:15 am

Good point.

Since I installed a 40 amp smart charger dedicated to the chassis batteries, those batteries are seeing their first full charging voltage.

Now I'm considering the Sterling software based isolator so they can see full charging voltage from the alternator.

I am puzzled. Are you not already seeing full charging voltage to BOTH battery banks from the alternator. With the external sense wire that should be on the chassis battery lug of the battery isolator (unless your 2003 is different than those previous), you ARE seeing full voltage at the batteries.

Said another way, with the external sense wire, the alternator is "fooled" into putting out enough "extra" voltage that you get full voltage on the battery side of the isolator's diodes.

Re: Another Battery Problem

Reply #20 – November 16, 2014, 10:56:08 am

Quote from: wolfe10 – November 16, 2014, 09:09:42 am

NO. There is a .6-.7 VDC drop across the diode-based isolator. This drop would render charging either battery bank poor at best.

wiring the voltage sensing relay across the diode isolator would short out the diode when the relay is active, zeroing out the diode voltage drop. Basically the relay would take over, leaving this isolator and boost solenoid as backups.

Re: Another Battery Problem

Reply #21 – November 16, 2014, 01:29:59 pm

Quote from: wolfe10 – November 16, 2014, 10:25:01 am

I am puzzled. Are you not already seeing full charging voltage to BOTH battery banks from the alternator. With the external sense wire that should be on the chassis battery lug of the battery isolator (unless your 2003 is different than those previous), you ARE seeing full voltage at the batteries.

Said another way, with the external sense wire, the alternator is "fooled" into putting out enough "extra" voltage that you get full voltage on the battery side of the isolator's diodes.

With a digital voltmeter plugged in to the dash chassis battery "cigarette lighter" socket with the engine running at high idle, I never saw more than 13.8 volts. Now with the charger , I'm seeing 14.6 volts on shore or generator power. I attributed the difference to the voltage drop at the isolator.

I've never actually checked the voltage at the alternator lug of the isolator with the engine running. So I don't know what the alternator is actually putting out through the regulator.

Also, I don't know if there is an external sensing wire on the 2003.

I'll check those 2 things next time I'm at the coach.

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