Amps At 7-Pin Thread?
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Joined: Oct 2015
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From: Wyoming
It seems like a good thing that you saw 16 amps.
Logistics Pro
Joined: Apr 2000
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From: Mills River
Yeah, that may be where I’m headed, something with lug terminals on one end and an Anderson powerpole connector on the other:
https://powerwerx.com/dual-conductor-custom-cable
On our old pop-up camper, I used the truck to run the small 3-way fridge, and PV to separately charge the 2x Group 27 FLA batteries. I could do something similar here, but you can’t always count on nice sunny days here in the Southeast.
I could run the fridge on LP while traveling, but I’ve never been comfortable with the idea, especially when stopping for fuel.
I may bring the camper up a week earlier than planned to give me extra time to measure, order, and install.
Never a dull moment!
Jim / crewzer
P.S. I added some pics to my previous post above.
https://powerwerx.com/dual-conductor-custom-cable
On our old pop-up camper, I used the truck to run the small 3-way fridge, and PV to separately charge the 2x Group 27 FLA batteries. I could do something similar here, but you can’t always count on nice sunny days here in the Southeast.
I could run the fridge on LP while traveling, but I’ve never been comfortable with the idea, especially when stopping for fuel.
I may bring the camper up a week earlier than planned to give me extra time to measure, order, and install.
Never a dull moment!
Jim / crewzer
P.S. I added some pics to my previous post above.
Logistics Pro
Joined: Apr 2000
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From: Mills River
16 A is a good thing, but 11.57 V won’t charge a discharged battery.
Jim / crewzer
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Joined: Jan 2010
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From: Bristol, TN.
Exactly, the same thing I found. If you want to keep the charge lead voltage coming in up, it is best not to put too heavy a load on it. Even just a 3.5 amp load drops the voltage down to under 13.5 VDC in my truck camper.
Steve
Steve
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From: Wyoming
This was posted on the DIYSolarForum today:
Jim, your test wasn't checking to see how hard the alternator was actually working, correct? You were focused on how much current/volts is actually getting to the RV battery. Is it safe to imply that the alternator wasn't doing much? It seems to me that the above statement that I quoted is complete BS, specifically the part in bold.
Normally it is recommended to use a charge booster (battery to battery charger) to charge using the vehicle alternator. If not, your alternator might be using itself 100% to try to charge the battery asap. Therefore they recommend a 30a charge booster (So that the battery charger at maximum 30a and not using the alternator for 100%).
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From: Wyoming
This video has the DIYSolarForum in a bit of a tizzy.
My response was:
My response was:
That wasn't quite a real world test. First, there should have been some air flow over the alternator to assist with cooling. Most vehicles will have some natural air flow at highway speeds and the radiator fan kicks in when needed, also providing air flow. Second, connecting the alternator directly to the battery isn't how the system on my truck works. The 7 pin charge circuit is current limited. It will never exceed 30 amps. Very few owners of 2017+ Ford Super Duty trucks are seeing more than 20 amps.
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Joined: Dec 2019
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The 7 pin does a good maintenance charge for keeping batteries topped off. But you need a lot bigger wire if you plan on actually recharging a bank of batteries on the road.
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Joined: Apr 2000
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From: Mills River
This was posted on the DIYSolarForum today:
Jim, your test wasn't checking to see how hard the alternator was actually working, correct? You were focused on how much current/volts is actually getting to the RV battery. Is it safe to imply that the alternator wasn't doing much? It seems to me that the above statement that I quoted is complete BS, specifically the part in bold.
Jim, your test wasn't checking to see how hard the alternator was actually working, correct? You were focused on how much current/volts is actually getting to the RV battery. Is it safe to imply that the alternator wasn't doing much? It seems to me that the above statement that I quoted is complete BS, specifically the part in bold.
As a practical matter, the fuse in the +12 battery charge circuit (typically 30 A) would blow if there was too much charge current.
Another problem with the video experiment is the missing “pulley ratio”. Alternators are typically pulleyed at an ~3:1 ratio where the alternator spins at ~3x engine speed. The higher alternator speed helps produce more current at low engine speed and the higher internal fan speed improves cooling.
Adding this all up, I can see where trying to charge a 300 Ah lithium battery from an ~100 A alternator operating at low speed could be a problem.
The current specs for our truck’s 240A alternator is inserted below; note the pulley ratio.
HTH,
Jim / crewzer
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From: Wyoming
I don't understand where people are coming up with the conclusion that a LiFePO4 battery is going to kill your alternator, or that the charge from the tow vehicle is going to kill your LiFePO4 battery.
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From: Mills River
I used #2 wire and a 125a switching controller. Our truck has the dual alternators (397a) and 2 batteries, camper has 3 batteries, and we tow a boat with 2 more batteries that is also connected to the truck (7 batteries total). We can run down the camper batteries with the inverter, and the boat batteries while fishing. And the truck will recharge the system during a half day driving.
The 7 pin does a good maintenance charge for keeping batteries topped off. But you need a lot bigger wire if you plan on actually recharging a bank of batteries on the road.
The 7 pin does a good maintenance charge for keeping batteries topped off. But you need a lot bigger wire if you plan on actually recharging a bank of batteries on the road.
Thanks,
Jim / crewzer
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Joined: Apr 2000
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From: Mills River
https://1t1pye1e13di20waq11old70-wpe...n-Manual-1.pdf
However, the recommended bulk/absorption voltage spec is 14.6 V, which is probably not feasible from a stock alternator and trailer wiring harness, especially when accounting for voltage loss in the harness and connectors.
Finally, I suspect someone has figured this out, as Lance is now offering a lithium battery option for their campers.
HTH,
Jim / crewzer
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Joined: Jan 2010
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From: Bristol, TN.
Host has offered a lithium option for a while in their options. I think folks get tangled up in the Li+ battery being able to handle more amps while charging. If running the fridge and wanting to charge the batteries while going down the road, there is a case to be made for AC/DC fridges as they are only cycling the compressor for a portion of the time they are operating and I believe the amp is less than the absorption models.
Steve
Steve
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Joined: Jan 2002
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From: Itinerant
There are more robust alternators out there but come at a hefty price tag.