Thanks Sage and Jon, sorry for so many basic questions but I'm trying to get a better understanding of the electrical. If I have the original 10 gauge wire running from my alternator to the truck/ camper plug, I would assume it's safe to upsize that wiring with 6 gauge without overheating the 10 gauge wire beyond the plug?? Also will I need to change out my truck/camper plug to accomidate the larger 6 gauge wire?
Solar replacement and 2 agm batteries
- Thread starter Deancamp
- Start date
pvstoy
Senior Member
Replacing the longer 10 gauge run you will benefit with the 6 gauge.. The short run inside the camper is harder to replace, but easier removing the top cover of the water tank.
Look into Anderson connectors. To replace existing plug. Then just use a separate barrel connector for running lights.
Look into Anderson connectors. To replace existing plug. Then just use a separate barrel connector for running lights.
Last edited:
craig333
Riley's Human
On my camper replacing the interior run to the batteries was pretty simple. Not sure how they do it on the newer campers. I'd definitely do it if you can.
Jon R
Senior Member
You would put a fuse at both ends of the positive battery to battery wire to protect the smallest wire from excessive current. We can talk about sizing that fuse later.
Can you estimate the length of the wire from your truck battery to the camper connector, and estimate the length of the wire from the camper connector to the ACR and then the battery?
Can you estimate the length of the wire from your truck battery to the camper connector, and estimate the length of the wire from the camper connector to the ACR and then the battery?
Thanks to everyone responding. Trying to stay away from the DC to DC charger. I have the Hawk Shell so all wiring inside the camper runs down the driverside in the 2 compartments with the drop down doors and then into the battery compartment on driverside as well. I measure:
16' from battery under the truck hood to plug.
6.5' plug to acr
4' acr to battery bank
This is where my camper wiring runs.
16' from battery under the truck hood to plug.
6.5' plug to acr
4' acr to battery bank
This is where my camper wiring runs.
I normally say "upgrade it all the way" but JonR has a good point. So, if your TOTAL run length is 50' return, then changing the internal wire (not more than 10' worth I would suspect) will result in only 80% of the benefit of upgrading it all. Is that enough?
Using a voltage drop calculator, and assuming your alternator is putting out 15V (that would be very high) I see 31% voltage drop (4.66V) on 14awg. If that's the case, then you will only see a bit less than 10V at the batteries. (15-5=10). Obviously not enough to charge your house/camper batteries.
Just guessing, preventing 80% of that loss might be enough... 10% of 4.66= only about 1/2V drop, = 15-1= 14.
But wait... there is still voltage loss even over 4AWG. 0.37 volts to be exact if we use 40' of 4AWG (ends at the Anderson Power Pole connector).
Plus the loss over 10' (20' return) over the internal 14AWG = 0.93V. Combined voltage loss = 1.3V. leaving 13.7V.
What is the recommended charging voltage for your AGMs? I think 13.7 is too low for most AGM's (never mind LiFePo4 !!!)
The way around this is with fat wires all the way and/or a DCDC charger.
Using a voltage drop calculator, and assuming your alternator is putting out 15V (that would be very high) I see 31% voltage drop (4.66V) on 14awg. If that's the case, then you will only see a bit less than 10V at the batteries. (15-5=10). Obviously not enough to charge your house/camper batteries.
Just guessing, preventing 80% of that loss might be enough... 10% of 4.66= only about 1/2V drop, = 15-1= 14.
But wait... there is still voltage loss even over 4AWG. 0.37 volts to be exact if we use 40' of 4AWG (ends at the Anderson Power Pole connector).
Plus the loss over 10' (20' return) over the internal 14AWG = 0.93V. Combined voltage loss = 1.3V. leaving 13.7V.
What is the recommended charging voltage for your AGMs? I think 13.7 is too low for most AGM's (never mind LiFePo4 !!!)
The way around this is with fat wires all the way and/or a DCDC charger.
ckent323
Senior Member
Vic makes an excellent point. The wire length for voltage drop calculations is the total round trip distance.(positive plus negative wire lengths).
Dean, I just realized I didn’t understand your question about interior wiring. Apologies! From the plug to the batteries, there is gain to be had, I’m just not certain how easy it will be.
I blushingly
admit to thinking you were considering rewiring all internal circuits.
I blushingly
admit to thinking you were considering rewiring all internal circuits.I'm sure it was my fault with a poor explanation. The more I try to understand all the wiring terminology, electrical components of what I need to achieve my goals with my project the more overwhelmed I get. No apology needed and thanks for your help.
ckent323
Senior Member
It has little to do with the Alternator. The resistance in the wire from the truck to the house battery in the camper causes a voltage drop over distance. That drop depends on the gauge of the wire and the distance of the wire (round trip). Larger wire (smaller gauge number) is generally better.
Also the current carrying capacity of the wire is important I do not know how many amps the DC-DC charger can provide but if it is 40 amps then you need a minimum of 8 gauge wire. If more current can be supplied then you need correspondingly bigger wire.
If using a Blue Sea ACR or equivalent instead of a DC-DC charger I recommend a minimum of 4 gauge wire if the total round trip length is over 50 feet.
The details here are important.
It is my understanding you have a lead acid starter battery (FLA or AGM) and Lead Acid house batteries (FLA, AGM or Gel).
What type of alternator is in your truck? That is, is it a smart alternator? (newer trucks since around 2015 tend to have smart alternators),
What is the output voltage of the alternator? as long as we are at it how much current can it supply?
If it is not a smart alternator then you may want to consider using a Blue Sea type ACR.
If it is a smart alternator then you may want to consider using a DC-DC charger. But, because the starting and house batteries have the same chemistry (Lead Acid) then you should be able to use an ACR instead of a DC-DC charger.
If you use an ACR then you may see large current flow (around 80 amps) during periods of recharging. I recommend a minimum of 6 gauge wire for up to 50 feet round trip and 4 gauge wire for up to around 80 or 90 feet round trip.
If DC-DC you need to understand the voltage output and the current capacity before deciding on a wire size.
What is the distance from your truck battery to the house battery (one way)? Multiply that number by 2 and that gives you the total distance to use to put into a voltage drop calculator.
In all events you should put a resettable circuit breaker (or fuse) at each end of the truck to house battery wire (positive side only) as close each battery as practical.
I hope this is helpful
(if I made any any errors here I suspect others will kindly point them out and provide corrections).
Craig
Also the current carrying capacity of the wire is important I do not know how many amps the DC-DC charger can provide but if it is 40 amps then you need a minimum of 8 gauge wire. If more current can be supplied then you need correspondingly bigger wire.
If using a Blue Sea ACR or equivalent instead of a DC-DC charger I recommend a minimum of 4 gauge wire if the total round trip length is over 50 feet.
The details here are important.
It is my understanding you have a lead acid starter battery (FLA or AGM) and Lead Acid house batteries (FLA, AGM or Gel).
What type of alternator is in your truck? That is, is it a smart alternator? (newer trucks since around 2015 tend to have smart alternators),
What is the output voltage of the alternator? as long as we are at it how much current can it supply?
If it is not a smart alternator then you may want to consider using a Blue Sea type ACR.
If it is a smart alternator then you may want to consider using a DC-DC charger. But, because the starting and house batteries have the same chemistry (Lead Acid) then you should be able to use an ACR instead of a DC-DC charger.
If you use an ACR then you may see large current flow (around 80 amps) during periods of recharging. I recommend a minimum of 6 gauge wire for up to 50 feet round trip and 4 gauge wire for up to around 80 or 90 feet round trip.
If DC-DC you need to understand the voltage output and the current capacity before deciding on a wire size.
What is the distance from your truck battery to the house battery (one way)? Multiply that number by 2 and that gives you the total distance to use to put into a voltage drop calculator.
In all events you should put a resettable circuit breaker (or fuse) at each end of the truck to house battery wire (positive side only) as close each battery as practical.
I hope this is helpful
(if I made any any errors here I suspect others will kindly point them out and provide corrections).
Craig
even my 2015 Chevy is not a smart alternator.
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