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pnichols

The Other California

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Posted: 08/02/20 10:29am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

pnichols wrote:



I think that my coach battery interconnect solenoid connects the chassis battery in direct parallel with the coach batteries, so there's nothing to protect the alternator (?) from getting really hit with high initial inrush charging current if I were to drop in Battle Born Li batteries, from what I read about them


I think your inrush argument doesn't hold water for several reasons.

1. my class c had an oem 60 fuse--so if inrush exceeded that, it would blow.

2. my class C had #8 wire for the oem charging path. That limits it to about 50 amps.

I did replace the OEM fuse with a 50 amp automatic circuit breaker. I also added a 2nd charging path with #8 wire, switchable solenoid, and automatic circuit breaker.

Anecdotally, my alternator is still OEM and I do push it hard--even so far as running the 1400 watt water heater via the inverter. I use a 1/3 duty cycle--20 minutes of heating and 40 minutes off. That lets me arrive at the boondocking site with hot water and lots of battery power.

There is an excellent article on inrush at the smartgauge site.


When I said "direct parallel" that wasn't including any OEM fuses that might be in place. For what it's worth, my 2005 Itasca (also on a model year 2005 E450 chassis) has at times shown over 70 amps going into my coach batteries, for a bit, when I first start idling the V10 to charge up ~50% discharged coach batteries.

So if my chassis has OEM fuses somewhere after the 130 amp Ford alternator, then they're larger than 50 amp. Winnebago may have gotten involved in all this someway when they built the coach, but so far I can't find out how - with cursory poking around the chassis and from looking at the Winnie electrical schematics for the coach. [emoticon]


Phil, 2005 E450 Itasca Spirit 24V

pianotuna

Regina, SK, Canada

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Posted: 08/02/20 11:14am Link  |  Quote  |  Print  |  Notify Moderator

Hi Phil,

My oem fuse was in a box inside the engine compartment, more or less straight in front of the driver, and 1/3rd of the way back from the grill. It is right on top allowing easy access. My unit is also an E-450 so yours may be quite similar.

I do see over 70 amps--but because of the circuit breakers which I deliberately got at 50 amps the current is interrupted.

When I first heated water, I kept the power on until the chassis battery was at 12.3. Then I cut it off until it had recovered.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

pnichols

The Other California

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Posted: 08/02/20 12:25pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Hi Phil,

My oem fuse was in a box inside the engine compartment, more or less straight in front of the driver, and 1/3rd of the way back from the grill. It is right on top allowing easy access. My unit is also an E-450 so yours may be quite similar.

I do see over 70 amps--but because of the circuit breakers which I deliberately got at 50 amps the current is interrupted.

When I first heated water, I kept the power on until the chassis battery was at 12.3. Then I cut it off until it had recovered.


Hmmm ... my high initial charging currents from the alternator to a ~50% discharged coach battery bank don't suddenly stop as if cut off by a fuse. These initial currents merely taper down as the coach batteries charge up. There doesn't appear to be anything drastic happening like a fuse or circuit breaker opening up. [emoticon]

P.S. Recall that I know actually what current is going into or out of my coach battery bank at all times via a shunt I installed in the battery bank's negative lead. The shunt voltage feeds an ammeter on the cab dash (actually a voltmeter interpreting voltage values from the shunt) - so I can see coach battery bank current flow at all times. I've never seen the coach battery bank's charging current make a sudden step-function change, as it probably would if a fuse inline from the alternator opened.

pnichols

The Other California

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Posted: 08/02/20 02:03pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

My next set will be SiO2. They can withstand 620 cycles to stone bone dead. Self discharge rate is 1.6% per month.


Don ... I just spent some time studying SiO2 12V batteries for drop-in RV use.

They look ideal ... and less $$$$ and less "tricky" than using Li batteries in an RV.

I may seriously consider them whenever I replace my two AGM RV batteries.

Thanks for bringing this type battery to my attention! [emoticon]

Gjac

Milford, CT

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Posted: 08/02/20 07:28pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote: What I would love to know is, after those 1500 deep cycles, is there still 80% of the capacity left? (I'm using that number as it is where electric vehicle batteries are considered "done in".) This is a good question. I have a nickel hydride battery in my hybrid Rav 4. It operates best between 20%- 80% SOC (it never fully charges except on long down hills , much different than Li or SiO2 or wet cell. These are cheaper than Li and last 15 years in a car that is a DD, don’t know what they would last in a MH used 3 months a year.

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