Good Sam Club Open Roads Forum: Here we go again yet another Trombetta "Big Boy" failure!
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 > Here we go again yet another Trombetta "Big Boy" failure!

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maillemaker

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Posted: 02/27/20 08:18am Link  |  Quote  |  Print  |  Notify Moderator

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If its purpose is to isolate the house batteries from the starting batteries during cranking and when the engine is OFF, it will only be ON when the engine is running and you are trying to charge the house batteries from the engine. I am certain that your engine alternator can not generate anything near 300A !


In my RV, there is a momentary switch option to gang the house batteries to the engine batteries during cranking, so that the house batteries provide an emergency jump start if the engine battery is dead.

I think engine starters can pull 200-500A if I'm googling correctly.


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BFL13

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Posted: 02/27/20 08:31am Link  |  Quote  |  Print  |  Notify Moderator

You can also choose to leave it disconnected. The wire from the house side of the isolator is not that fat, and likely has a fuse at each end. Likely 50a DC circuit breakers. You could pick whichever end that is easier to get at, by the house batts or by the engine batt, and swap that CB for a fuse you can pull.

Chev trucks have the 7-pin always live and nobody dies or anything. If you want to keep the engine battery isolated you just pull the 40a Stud 1 fuse or else pull the 7-pin.

No reason you can't do the same thing with a MH set-up.


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mchero

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Posted: 02/27/20 08:37am Link  |  Quote  |  Print  |  Notify Moderator

maillemaker wrote:

Quote:

If its purpose is to isolate the house batteries from the starting batteries during cranking and when the engine is OFF, it will only be ON when the engine is running and you are trying to charge the house batteries from the engine. I am certain that your engine alternator can not generate anything near 300A !


In my RV, there is a momentary switch option to gang the house batteries to the engine batteries during cranking, so that the house batteries provide an emergency jump start if the engine battery is dead.

I think engine starters can pull 200-500A if I'm googling correctly.

Most all RV's have what's called an "Auxiliary Start Switch". Energizes the isolator solenoid thus connecting both banks so you can start the rig. It can EASILY pull 200+ amps and can easily blow the house battery fuse! I have done it myself once.
I was at a state beach, a new Discovery pulled in and the owner was walking around scratching his head. I asked him what the issue was. He told me he had no interior lights, every 12v item was dead.
First thing I looked at was his house battery fuse and sure enough, it was blown. He had a low chassis battery and tried to use the Aux Start Switch.
If I ever run into a dead or low chassis battery I'm going to hold that Aux Start Switch for about 3 to 5 minutes to get some juice into the coach batteries B$ trying to crank her over.


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markchengr

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Posted: 02/27/20 09:45am Link  |  Quote  |  Print  |  Notify Moderator

I had 3 different brands of so called smart relays to charge my truckcamper house batteries from my truck only when the engine was running. They all failed in different ways The last one was a Cole-Hersey which failed closed while the truck was shut down with the camper off the truck. It drained both chassis batteries and the solenoid was smoking hot. Fortunately this happened while I was home. No more automatic (smart??) relays for me. I'll use a manual disconnect from now on. My solar will keep the house batteries charged up most of the time anyway.

fourthclassC

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Posted: 02/28/20 11:36am Link  |  Quote  |  Print  |  Notify Moderator

Been through this one each rv I have owned. Trombetta is worthless in my opinion. I suggest 2 possibilities. NAPA continuous duty solenoid. Need a good counter person to help look it up.... or how about a properly rated solid state isolator? no moving parts and they worked good for me.

Chum lee

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Posted: 02/28/20 12:38pm Link  |  Quote  |  Print  |  Notify Moderator

Just a question. Where does this 300 amps (charging) come from for continuous use? Very few automotive type alternators will produce 300 amps, (@14 volts) continuous, for battery charging purposes. IME, when solenoids/relays regularly fail, it's because they get too hot. That can be a result of small wire size on the signal circuit, or, too much resistance on the main load (switched/charging) circuit.

When you say the solenoid is warm, . . . . . how warm is it? Too hot to touch?

Chum lee

mchero

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Posted: 02/28/20 12:46pm Link  |  Quote  |  Print  |  Notify Moderator

fourthclassC wrote:

Been through this one each rv I have owned. Trombetta is worthless in my opinion. I suggest 2 possibilities. NAPA continuous duty solenoid. Need a good counter person to help look it up.... or how about a properly rated solid state isolator? no moving parts and they worked good for me.


I was looking into a solid state solution but I'm not sure how it will play with my "Intellitec BCC - Diesel w/AUTO IGN RECONNET 00-00886-100"
Not sure what the auto reconnect means. The BCC is functioning properly other that the main battery disconnect latching relay not disconnecting. I'll go over the diagnostic routine outlined in the PDF I found on the web. I also need to monitor the voltage to the Trombetta. Not sure if the voltage drops to hold the solenoid. I have a cheapo VOM from HF that is not as reliable as I would like. Need to find another.

Last week we had a scheduled power outage, the inverter took over but the house battery volts started dropping like a rock. Yesterday I took the battery hydrometer out and found one pair of the 6 volt batteries fully charged but the 2nd pair was low! Both showed 6VDC.
I watered the charged pair but the low pair I want to fully charge B4 I water them. No cells were dry, the water was above the plates in all cells.
Cleaned tatterp posts and replaced a questionable battery cable on the low pair.

I ordered this charger from Amazon;

Going to charge/desulfate the pair on the low side then top off with distilled. Just not sure if I should charge as a pair or individually.

Will keep you all posted on my progress.

mchero

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Posted: 02/28/20 01:02pm Link  |  Quote  |  Print  |  Notify Moderator

Chum lee wrote:

Just a question. Where does this 300 amps (charging) come from for continuous use? Very few automotive type alternators will produce 300 amps, (@14 volts) continuous, for battery charging purposes. IME, when solenoids/relays regularly fail, it's because they get too hot. That can be a result of small wire size on the signal circuit, or, too much resistance on the main load (switched/charging) circuit.

When you say the solenoid is warm, . . . . . how warm is it? Too hot to touch?

Chum lee


If your referring to one of my posts. I don't believe I stated anything about an alternator putting out 300 amps. Although if you Google "dual extra heavy duty alternator" I see 320 amp alternators.

IF the isolator solenoid is used to assist starting I would assume it would have to carry a large load. Have yet to clamp my VOM to the starter cables to see how many amps the starter draws. I'm thinking the beefier the solenoid the longer it will last.

My current trombetta is warm to the touch, not hot as in burn.

BFL13

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Posted: 02/28/20 02:30pm Link  |  Quote  |  Print  |  Notify Moderator

You can get one battery down more than another if they are not balanced for load/charging. Be sure your load/charging wires go one to each pair in the series/parallel pair. Try not to have a "downstream" pair of 6s that does less of the work.

It can be difficult to do that if the rig's wires are too short so they won't reach the back pair in a battery tray. You can extend those wires to make it work

MEXICOWANDERER

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Posted: 02/28/20 02:33pm Link  |  Quote  |  Print  |  Notify Moderator

I was asked to comment on this. One condition was not mentioned. And it is a condition that will burn any solenoid. If the test is not verified then solenoid burnout is assured -- even 300 amp modeks.

The solenoid must not remain engaged as the engine is cranked. Check that the small ignition post goes dead as a doornail as the engine starter motor is cranked.

A five dollar fender mounted plastic body solenoid is more resistant to burnout at 700 amps rating than a hundred dollar 300 amp continuous duty solenoid. Why? Because when the engine is being cranked that so I avoid no longer utilizes 12 volts. Try 10 volts. Weak pull in, chatter and contact arcing.

Putting in a flywheel diode reverse orientation will help correctly connected solenoids live longer. More info about flywheel diodes on the web.

Verify correct connection to ignition B Instead of Ignition A

I am minus a laptop so no more posts

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