recharging while driving

[pianotuna]

I'm winding my way south and boondocking.

Last power was in Regina, SK

I used a heating pad and lots of computer time last night, powering them from a 400 watt MSW inverter.

Batteries were at 12.3 in the morning.

I drove for about 8 hours in total.

The first two hours, very little in the way of charging happened as I was using the head lights, running the heater fan on high and running the laptop with Microsoft Streets and trips. In fact, at first I was concerned that the alternator was not sending any energy to the house bank.

I stopped about 5 p.m. in Fargo, ND and voltage was back up to 12.9 (under load from the fridge and attempting to recharge a tablet, using a 12 volt adapter.)

I will be using the heating pad and perhaps the tablet tonight. The Tablet is supposed to be able to tether--but it won't. Nor will it do a hotspot. I'm too exhausted to deal with this tonight.

I may or may not have power tomorrow night.

[MEXICOWANDERER]

I am certainly in agreement with the position that no matter how large the relay (my old-fashioned terminology has a solenoid as being a mechanical actuator) the release of the disc will cause arcing. Just as a note mercury-filled power relays almost completely eliminate the phenomenon. But the media is not friendly. My eight + pound relay has had it's disc flipped then refurbished with opper/tin bronze.

Be that as it may if that Ford chassis is wired so that power to the house batteries is tapped mid-harness it is severely limited. On cruising sailboats the where of the tap is so critical that the alternator feeds the house battery and from there a controller manages the engine starting battery. Exhale. That was not a suggestion. There is nothing sadder than seeing a 140 amp alternator limited to 60-70 anperes charge because ALL POWER has to pass through a length of 12-gauge fusible link. The last F450 I oversaw had headlight voltage increased from 12.8 during heavy charging to 13.9. The effect was notable. Ford apparently went hog-wild with newest dual alternator vehicles and harness amperage restrictions were corrected to an extreme degree. Yay Ford! But from what I have been able to trickle the hairpin NDs are very hard to retrofit.

Advice: Assume nothing. With discharged batteries measure amperage or voltage drop if on-the-road-recharging is important to you.

[MrWizard]

IIRC
his batteries are divided into (2) banks
one relay and one 8ga wire for each bank
he can flip switches and choose which bank OR both OR none gets charged

[landyacht318]

MEXICOWANDERER wrote:
Your charge path is defective.

Why continue guessing, or denying this very strong possibility?

17$ hall effect ammeter

[pnichols]

pianotuna wrote:
Hi Phil,

I have two solenoids, each with a 200 amp rating. It would seem doubtful to me that both had failed at the same time.

pnichols wrote:

Don,

Does you RV connect the alternator to the coach batteries with just a 12 V high current solenoid like in my Class C?

If so, you might want to measure the voltage on both the input and output side of the solenoid when the coach batteries are low and the engine is running?

Obviously those voltages should be identical. If not, the solenoid contacts have turned resistive, which could explain why your RV battery bank isn't getting charged as it should be with several hours of driving.

I've had this happen twice in the 10 1/2 years we have had our Class C.

Don,

I guess you mean that you have two 200 amp solenoids in parallel with each other ... so that the chance of both having resistive contacts at the same time is (near or at) zero? If that's the case, good for you, as redundancy is the ultimate way to achieve solenoid reliability over the long haul!

For what it's worth, the single Trombetta silver contact solenoid I'm using in our RV's system is rated at 225 amps continuous current and 600 amps peak inductive inrush current ... and still my first Trombetta developed contact voltage transfer loss after 7-8 years. So ... either I have to believe that the Trombetta I'm using is fluvey-dust spec'd ... or I have to believe that one can't assume that contact corrosion/erosion is not going to detrimentally occur in any solenoid regardless of how over-spec'd it is or how much it costs. 😉

[pianotuna]

I finally have some shore power.

After 5 hours of driving (2 with headlights) the battery bank only wanted 10 amps.

It is currently charging at 9 amps--but drops to zero when both the oil filled heaters and fridge happen to be "on" at the same time. Current weather conditions are 7 C (44 f).

I'm using a current tap from a porch light. I don't feel that using more than 11 amps is safe (and even that may be pushing it).

I'll see what it says in the morning.

[pianotuna]

Hi Phil,

I have two solenoids, each with a 200 amp rating. It would seem doubtful to me that both had failed at the same time.

pnichols wrote:
Don,

Does you RV connect the alternator to the coach batteries with just a 12 V high current solenoid like in my Class C?

If so, you might want to measure the voltage on both the input and output side of the solenoid when the coach batteries are low and the engine is running?

Obviously those voltages should be identical. If not, the solenoid contacts have turned resistive, which could explain why your RV battery bank isn't getting charged as it should be with several hours of driving.

I've had this happen twice in the 10 1/2 years we have had our Class C.

[MEXICOWANDERER]

C'mon Don!

May the spirits of Burma Shave signs protect you. I moved out of that misery "Sierra Nevada Mountains" and when living there frequently had a bad storm chasing behind. I do not miss it. As long as 100,0000,00,000 indocumentos are being hugged and kissed in the USA now's your chance! Waiting to help with that charging issue 🙂

[westend]

pianotuna wrote:
Hi all,

I'm currently staying ahead of the snow! In fact, if I'm lucky I won't see it at all.

Overnighting at Harmony, MN or possibly farther south.

You're on US 52? OK, just beat it South below Dubuque, IA and you should be OK. It's raining and cold up near the Twin Cities, today. Expecting rain, freezing rain, and then wet snow, all capped off by sub freezing temps, tonight. Roads tomorrow AM will be miserable. Western part of MN will be impassable except for local trips on well maintained roads (and maybe not even then). The bad part of these first storms is that the rain cleans the surface, snow packs, and THEN salt gets put down. If they pre-salted the surfaces, we'd be better off but that's a budget-buster.

Yes, a larger wire and maybe, even, an external rectifier would be advantageous for your alternator charging. I guess I'd listen to Mex. He has forgotten more about this (and not much) than I'll ever know. Good luck with the charging. Hopefully, you'll hit open sky and sun as you slip South.

[MEXICOWANDERER]

Such is why I have not recommemded anything but 200-ampere rated charge dividers. Quicksilver has a massive 600 ampere amplified relay driven relay driven by a rectified stator signal. The Monmouth relay is rebuildable utilizing a 2.75" x 3/8" copper disc and 1/2" copper bolts. The contacts do indeed get pitted and black. I rehab with copper-tin bronze.

Regardless every inch of charge path must be proofed including the coach AGM battery - alt/reg. Can be done easily. Process of elimination. If everything checks out but the battery. Oops let's not go there...

[landyacht318]

Bet the solenoid is getting smoking hot quickly when batteries are depleted. Soon the contacts will fuse together.

It will likely still sound nearly the same when fed 12v to activate or deactivate.

They are like brake pads. They do wear out, even if top of the line and the buyer puts complete faith in them.

[pnichols]

Don,

Does you RV connect the alternator to the coach batteries with just a 12 V high current solenoid like in my Class C?

If so, you might want to measure the voltage on both the input and output side of the solenoid when the coach batteries are low and the engine is running. Obviously those voltages should be identical. If not, the solenoid contacts have turned resistive, which could explain why your RV battery bank isn't getting charged as it should be with several hours of driving.

I've had this happen twice in the 10 1/2 years we have had our Class C.

[MEXICOWANDERER]

If you recall there is no way on earth a bad battery can consume inapprpriate levels of amperage without getting hot - ain't gonna happen.

You are relying on a single (?) Or multiple AGM batteries for how many amp hours of nightly duty?

Doubling of wire = 3 steps down in gage. 7-6-5. So your equivalence is 5-gauge. So ampacity is not a question. But measure volt drop between the altetnator output stud and house battery lead post and steel yourself for a shock.

With that alternator your headlights wiper and heater on high should slam 70+ amps into multiple AGM house batteries. Daylight should see close to 100 amperes potential. Your charge path is defective.

[time2roll]

mchero wrote:
Just like the guy that was speculating my isolator relay was getting 16 volts!
LOL

That was yourself....

mchero wrote:
You think I should also be equalizing the chassis batteries at 16.2 as well?

Another reason I'd like to disable that solenoid.

http://forums.woodalls.com/index.cfm/fuseaction/thread/tid/29090644/gotomsg/29099355.cfm#29099355

[pianotuna]

Hi BFL13,

Yes the voltage is higher. About 12.87 volts after sitting for one month in the summer. Nominally 13 volts. I have to say I was impressed.

[BFL13]

pianotuna wrote:
The only change was to the AGM jars for the house. I noticed lower charging immediately--but put it down to the old tired Marine jars (9 years old).

What about the supposed higher standing voltages of AGMs compared with Wets? Less voltage diff between batts and alternator = fewer amps?