Odd battery behavior???

I recently acquired a 2013 Winnebago Era 70a. 2012 Sprinter. Living in Michigan I put her bed till spring. I went out to start her up after about a month and the battery was dead. After reading a few forum posts I learned this is very common and that I should disconnect the battery at the connection by the accelerator. I charged the battery up and did the disconnect. I noticed the cluster still lit up when I opened the door. I thought maybe a capacitor somewhere had a little charge left and was lighting it up. Went out today and the cluster was still lighting when I opened the door. I opened the hood and put a meter across the jumper studs and it read 11.6v. The disconnected battery read 12.7. With the battery still disconnected I put the key in the ignition and was able to start her right up without the boost switch being depressed. When I do press and release the boost switch I can hear the solenoid under the passenger seat click. So… are the house batteries supposed to automatically connect? If so what’s the point of the switch? Or is there something wrong?

Solved see post #11

Yes, something is wrong. When you pull the disconnect by the accelerator pedal that should disconnect the primary ground of the Sprinter chassis battery. Whenever I have done it the chassis electrics have gone totally dark.

Try pulling the negative from the "house" batteries to confirm the power is coming from them and if so look for the place when the systems are cross connected.

Maybe a TrikLStart has been installed?

If the chassis battery negative (near the accelerator pedal) is truly disconnected, I don't think a Trik-L-Start could cause this. Possibly an additional ground has been added directly to the chassis battery. This would circumvent the chassis battery disconnect stud.

At a specced maximum output of 5A from the TrikLStart when it's doing it's (normal) thing, I would agree, but based on the wiring diagram at the TKS website, (some) current could be flowing from the house to the starter motor. If there were residual cranking amps present in the chassis battery, it might be the bridge that's allowing the starter to turn over. Maybe? The TKS is (supposed to be) grounded, as well as the coach battery(ies).
http://www.lslproducts.net/UTLS_FAQs.html
Or not, I'm not an engineer, electrical or otherwise. Just trying to understand it all.

TJLee089 said:

If the chassis battery negative (near the accelerator pedal) is truly disconnected, I don't think a Trik-L-Start could cause this. Possibly an additional ground has been added directly to the chassis battery. This would circumvent the chassis battery disconnect stud.

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It is disconnected and nothing else is connected to the neg. post. I thinking now that maybe the boost relay is stuck closed. I'll have to get a torx socket and take the seat off to check it out. It's clicking but maybe the contacts are stuck??

rvdan said:

It is disconnected and nothing else is connected to the neg. post. I thinking now that maybe the boost relay is stuck closed. I'll have to get a torx socket and take the seat off to check it out. It's clicking but maybe the contacts are stuck??

Click to expand...

Any chance there's a break/wear/cut in the negative cable insulation, and it's shorting to the frame somewhere along the wire run between the battery terminal and the disconnect post by the accelerator?

TJLee089 said:

If the chassis battery negative (near the accelerator pedal) is truly disconnected, I don't think a Trik-L-Start could cause this

Click to expand...

I guess I don't understand the workings of a Tril-L-Start as well as I thought - It connects the RV battery to the starting battery anytime it detects the RV battery is at a higher voltage than the starting battery . . . . right? Now, if you remove the ground from the starting battery, that connection would then power everything the starting battery used to power before it was removed . . . . or, am I missing something obvious . . . . again!??

Don

The boost relay is fried under the passenger seat and is connected directly to the house batteries. The house battery negative is connected to the MB chassis and this is draining your cab battery. This is a well known issue with the Winnebago electrical design and is the main reason you should keep your house battery separate from the cab and only use a dc to dc charger between cab and house.
I myself removed this in my View. Now i have a 24 volt house system separate from the 12 volt cab system.

Alphacarina said:

I guess I don't understand the workings of a Tril-L-Start as well as I thought - It connects the RV battery to the starting battery anytime it detects the RV battery is at a higher voltage than the starting battery . . . . right? Now, if you remove the ground from the starting battery, that connection would then power everything the starting battery used to power before it was removed . . . . or, am I missing something obvious . . . . again!??

Don

Click to expand...

Yes, that is exactly right, assuming that the coach and the chassis share a ground, which most do. It is a real "gotcha", discussed elsewhere on the list. I am pretty sure I once fried a Trik-L-Start by attempting to start the vehicle under these conditions.

You should be careful to disconnect the Trik-L-Start before taking your Sprinter in for repair--the tech will assume that removing the ground shuts everything down.

Solved I took the seat out and checked the voltage on both sides of the solenoid and found them to be the same. I removed it and opened it up to indeed find the contact plate stuck down to the posts. The plate connects to the plunger with a spring in between. This allows the plunger to up and down and produce a “click” while the contact plate remains stuck down. I have a replacement ordered. I ordered the more robust model mentioned elsewhere on the forum (Cole Hersee 24213). No Trik-L-Start involved ...yet. Thanks to all for looking and chiming in. Dan

You're not the first to discover that the original isolation relay wasn't up to the job.

--dick

Not quite. The Trik-L-Start only connects the house battery to the chassis when the house is being charged, i.e. house connected to 120v. I suspect the TLS detects a voltage in the 14v+ range for this to happen. If as you described the house battery would continue to drain into the chassis battery.

Alphacarina said:

I guess I don't understand the workings of a Tril-L-Start as well as I thought - It connects the RV battery to the starting battery anytime it detects the RV battery is at a higher voltage than the starting battery . . . . right? Now, if you remove the ground from the starting battery, that connection would then power everything the starting battery used to power before it was removed . . . . or, am I missing something obvious . . . . again!??

Don

Click to expand...

autostaretx said:

You're not the first to discover that the original isolation relay wasn't up to the job.

Click to expand...

It's not really a 'relay' - It's a heavy duty starter solenoid. If you don't have some way to keep your chassis battery charged, I doubt any solenoid will prove 'up to the job' because when you connect a couple hundred amp hours of fully charged house batteries directly to a dead starter battery, the initial current could be several hundred amps and that's enough to weld the contacts closed no matter how good the solenoid is - They just weren't designed for that type service

Don

Alphacarina said:

It's not really a 'relay' - It's a heavy duty starter solenoid.

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The starter solenoid engages the gear on the starter with the flywheel. That's not what this solenoid does.

Alphacarina said:

If you don't have some way to keep your chassis battery charged, I doubt any solenoid will prove 'up to the job'

Click to expand...

But that is exactly what the battery boost switch is intended to do.

TJLee089 said:

The starter solenoid engages the gear on the starter with the flywheel. That's not what this solenoid does.



But that is exactly what the battery boost switch is intended to do.

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Many starter solenoids simple control power to the starter. A starter with a "Bendix" drive does not need a magnet to pull the drive gear into the flywheel.
So what amounts to a momentary starter solenoid is what we are discussing.
The more proper way to use the momentary boost switch from the house to the chassis battery is to hold the switch for a minute or so to cut down on the voltage difference between the two sets of batteries. Better yet, don't use the switch at all if the chassis battery is completely dead. Charge the battery instead. Bad things can happen to electronics if you have a completely dead battery in the running system.
The combiner switch is best used only when the chassis battery is weak, not completely dead.

Alphacarina said:

It's not really a 'relay' - It's a heavy duty starter solenoid. If you don't have some way to keep your chassis battery charged, I doubt any solenoid will prove 'up to the job' because when you connect a couple hundred amp hours of fully charged house batteries directly to a dead starter battery, the initial current could be several hundred amps and that's enough to weld the contacts closed no matter how good the solenoid is - They just weren't designed for that type service

Click to expand...

Any electromagnetic device that uses an energized magnet to pull a moving piece of metal to close an electric circuit is a "relay".
The design may vary (typical single moving contact versus copper plate clanged against two non-moving contacts), but it's still generically a "relay".

Old-style starter solenoids bolted to the side of the starter used to have a pivoted fork-arm that also pushed the starter gear into mesh with the flywheel gear, but inside there was still a "relay" (at least in the 1950's). The extended motion and mechanical work performed by the magnetically-pulled core is why they gained the name "solenoid".

Starter motors can draw 500 amps when stalled, so the contacts in a true starter solenoid are beefy ... but the unit may not be designed for continuous operation ... the T1N Sprinter's solenoid has two coils, one of which is taken out-of-service once the starter motor is energized ... thus high magnetism to close the circuit quickly and firmly, then lower current in the relay coil during the extended "hold during cranking" phase.

--dick

autostaretx said:

Any electromagnetic device that uses an energized magnet to pull a moving piece of metal to close an electric circuit is a "relay".

Click to expand...

Six of one, half dozen of another - Technically, if the iron core of the electromagnet doesn't move, it's a relay - If the iron core does move, it's a linear actuator . . . . and if that moving core pulls electrical contacts together, it's properly called a solenoid, very different from the operation of a relay

Not all starter solenoids have anything to do with engaging the starter gear to the flywheel. Many are mounted on the firewall or a fender well and just supply high energy power to the starter. The starter *could* draw hundreds of amps if the armature was locked, but in actual use, as soon as the power is applied, the armature turns and the current draw is instantly reduced. Standalone starter solenoids last for many thousands of starts, whereas when used as a battery combiner like we have in our rigs, the very first use *could* weld the contacts together

Don

Thanks ...
I'd forgotten the "moving core" portion of the description... and the "round disk" style of relay (like the Cole Hersee) does have a moving core. So you're correct in that it is a "solenoid" (but i still prefer "relay" if it's closing a circuit).

That said, a "linear actuator" (with no electrical contacts) is called a solenoid. Linear Actuators tend to be other styles of motion-production (at least by my memory) ... either motor-driven screw devices, or piezoelectric (sometimes direct, sometimes as jittery little feet walking the linear portion through a housing)

Solenoid examples:
https://www.digikey.com/product-detail/en/delta-electronics/DSOS-0416-05D/1144-1397-ND/6599945
https://www.digikey.com/product-detail/en/sparkfun-electronics/ROB-11015/1568-1592-ND/6163694
https://www.digikey.com/product-detail/en/delta-electronics/DSOL-0630-12C/1144-1404-ND/6599952

... all identified by their manufacturer as "solenoids" (http://www.deltaww.com/filecenter/Products/download/04/0409/DSOS-0416-D.pdf)

--dick

THREAD HIJACK..

Wow.. deja vu all over again... After getting out of the Army in 1972 I spent 1-1/2 years working for an amusement machine company, repairing pinball machines & juke boxes. Talk about your relays & solenoids!! Those pics above brought back a lot of memories.

Got out of it just as the new solid state pinballs and cocktail table video games were beginning to show up. Terrible working environment (bars, combined with a lot of driving ), but a great education in reading wiring schematics & early electronics.

OK, back to topic....