Amps Rating 1991 Ford E350 Solenoid and CB Question UPDATE

The wire is maybe #8 at most but could be #10. I didn't look for AWG. The CBs are the little box ones with rounded corners but do not have any black button.

I get about 25 amps at the battery bank from the "alternator" with low house batteries. I have the lower amp rated 2G alternator, not the newer better 3G that came along with the 92s.

Thanks all, I will try to find a part number on them which would then perhaps lead to the specs.

It could well be an add- on by the RV builder and not Ford. Good point. The regular E350 van seems to have an aux battery over on the driver's side that uses a similar set -up, but my RV does not have any aux batt, just the house battery bank farther back in the Rv part.

The whole thing starts with a pos wire ring terminal on the starting battery (passenger side) post clamp, then to the solenoid near that. The solenoid has the wire from ignition via EEC relay to power it.

It all works the way it is supposed to thank goodness, but more amps could be useful at times depending on the scenario.

I have not yet tried the trick with an inverter on the starting battery powering a battery charger on the house batts. That method is available if parked and the engine is idling and means no change to OEM set-up. But not possible while driving so upgrading the OEM set-up would be needed for more amps that way.

What size is the wire between them? That might give some clue as to how large the breakers are, or would reasonably be. Also, are these the little rectangular self-resetting shortstop breakers, or some other style? The shortstop ones I think only go up to 50A.

Typical solenoids I've seen available (for this general use) are often rated in the vicinity of 100A.

Doubtful about your alternator style, thus it's potential. EVERYTHING is predicated on that. The IAR 75-amp, the 7074 70 or 100 amp, and 3G small and large frame alternators (95 or 130 amp) were used in those models.

If you cannot take a picture and post it, stare at the alternator then compare with individual online google images.

FORD 2G IAR alternator

Ford large frame 100 amp alternator

Ford 3G 95 amp alternator

Ford 3G 130 amp alternator

That'll make a good start

Example this is the 100 amp large frame

Unless you've got a huge battery bank I doubt the current thru the solenoid will change much. Current will be mostly determined by: charge voltage, wiring resistance, and battery internal resistance. Alternator current rating won't change any of those things.

With that gauge of wire the solenoid is not in any jeopardy.

BFL has the...





Ford version...

Yes, Mex, you warned me about that before. I have not forgotten.

Right now I am just trying to "learn my rig" and will decide what to do about what later. I am still pondering this info:

http://www.fourwheeler.com/how-to/electrical/1612-ford-alternator-upgrade-for-more-battery-charging-power/

One thing there is that he is going to use the alternator as a power supply for more lights etc, not for faster battery charging (although he thinks maybe, that they are the same thing) As we know, your converter can do its full rated amps as a power supply backing up a battery being drawn down by an inverter, but it most likely cannot provide the same amps when charging a battery with its high R.

While one still at the mercy of the alternator's voltage regulator, as to how many amps could flow, I recommend one go fat on the cabling and oversized on the Solenoid.

I've read that when the solenoids fail, they fail with the contacts seized together, meaning NO isolation with engine off, and a deep cycled starting battery along with the house.

Also ideally, the solenoid trigger circuit would only become live after the engine is actually running, not with the Key to ON. An illuminated toggle switch would be employed if I could not find such a circuit to act as the trigger.

I would not want my house batteries contributing to starter motor current. This also beats up the solenoid contacts more.

Cole-Hersee-24213
200 amp continuous
Silver Tungsten carbide contacts.

Step up to 4awg minimum.

Be aware that some solenoids are latching, and should not be fed a continuous 12v, just a momentary 12v pulse to latch or unlatch.

I was unaware of this one one vehicle I was trying to troubleshoot, and apparently so was the person who tried to install it originally.

Even with the 2G, I don't know if I only change up to #4 wire, whether the amps will then be too much for the CBs and solenoid.

Really want the ratings of those so I know where I am starting from. I have not dived into Google and waded through all the Ford stuff, but hoping somebody here might know before I head into that wilderness :(