External Li Battery Upgrade Install Concept

[K7MDL]

I finally made some decisions and started working on my Li conversion. I diverge from most installs here by mounting the DC-DC charger under the back of the cab. It is IP67 rated with BT control and configurable up to 50A with MPPT solar built in. It replaced the ACR I had mounted there. The existing output wiring goes to 2 locations:
1. Back of the cab interior where my radio gear is (6AWG)
2. Normal camper Attwood connector mounted in my truck bed which is 6AWG down stepped down to the 10AWG of the connector and the stock 10AWG camper wiring.

My radio gear draws high current and does not tolerate much voltage drop. Nothing in the camper draws much current or cares too much about a little voltage drop except for battery charging current. On Li the furnace should be happy at all times.

My existing AGM batteries are near my rear bumper and will be removed saving a lot of rear axle weight. The Li battery will be tested in 2 locations, both up forward cutting the total wire length to 2/3rds reducing voltage drop

Location 1: The Li battery will reside under my back seat about 4 wire feet to the DC-DC charger and 1-2ft to my fused distribution panel. All the high charge and discharge currents are within the 4 feet of wire in my cab and the total charging wire length is shorter and larger gauge than if located in the camper. I should be able to see 40-50A charge rates. The appliance and lighting loads of the camper are relatively low so the 10AWG stock camper wiring is suitable, there is no battery charge current. I would want to run the solar panel (PV) wiring to the under-cab DC-DC charger MPPT input (deferring for now pending the location testing below). That will also trickle charge the starting battery. Other than the solar wire routing outside, the camper stays all stock.

Location 2: Place the Li battery in the front corner of my front dinette camper under the driver side seat and test the voltage drop to the radio gear into the cab. Given the higher voltage of Li and the now shorter total wire length compared to the rear located AGMs, it may overcome the V-drop of the mixed 10/6AWG cable run and keep my radio gear happy. The charge rate will be reduced relative to the cab location (configured to 20 to 30A max) but I can keep the solar charging wire completely within the camper. The existing Overland Solar MTTP 100|15 charger, which appears to be a rebranded Victron, is supposed to have a Li preset as noted in the Victron version manual (and User defined also). Upsizing the camper wiring would be a last step on this if needed, not sure it is needed so far.

Waiting for the right size crimp ring terminals to arrive to begin testing Location 1. Camper will come out of the garage and onto the truck in a month and can then test location 2 then.

- Mike K7MDL

 

[K7MDL]

Got it wired up today and tested with a 50Ah LiFePO4 battery in the cab.

6AWG from the starter battery (via 60A breaker) to the IP67 rated DC-DC charger under the right rear of the truck.

Output is 4ft 6AWG to a 75A Anderson splitter then 18" 8AWG to the fused battery. The splitter also feeds though 6" 10AWG SuperPowerGate battery isolator/charger for a 7Ah AGM (decided to leave it in place) and its output feeds a PowerPole distribution fuse panel and my radio gear with peak loads up to 32A total. That wiring is 12AWG and varies from inches to 2.5ft.

I set the charger output for 50A max charge limit and started the truck up to measure voltage drop and see what charge rate I could get. The battery is partially discharged for storage.

Answer is 32A charge rate with 0.9V drop between the starter battery and the charger. 13.7V input to the charger, 14.6 output from the charger. I suspect the alternator was the limiting factor but not sure yet since the voltage did not drop. Was hoping to see a higher charge rate. Battery can accept up to 50A. I decided to set the charge rate limit to 30A anyway.

I did not measure the voltage at the radio gear but there was only 2A load so would not be much drop. When I install the high-power VHF amps then I will get a measurement. They do not like low voltage but are happy on the Li battery alone.

In a month I will put the camper on the truck and 2 things.

1. Set the charger for AGM and see what the charge rate and voltage is at the existing pair AGMs now in the back of the camper. Lots of 10AWG wire. I have seen 19A max with previous standard setup.

2. Disconnect the AGMs and relocated the Li battery from the cab into the camper front driver side under dinette seat box and tap into the existing ACR and see what the total voltage drop and charge rate the stock 10AWG camper wiring can yield. Additionally measure the voltage at the radio gear.

Based on the above can leave it as is, upgrade the camper side wiring size, or put the battery back in the cab and call it done. Probably put a 100Ah battery in as I use the 50Ah for my microwave radio field work.

If the battery stays in the camper I can use the existing solar charger set to LI profile. If it goes in the cab then I will run the solar panel output wiring outside the camper and down under the truck to the charger MPPT input. That has the advantage of trickle charging my starter battery. I have a high parasitic starter battery drain, 2 weeks and I have a dead battery, so this solution is most desirable from that perspective.

 

[K7MDL]

I have identified a problem with keeping the battery in the cab. Condensation.

It is on the floor under my rear seat. I checked the battery in the morning and it was very wet. When the daylight hits the battery does not worm up as fast as the rest of the truck, it has also been humid here. Could wrap it in foam.

I think I will wait until I put the camper back on and install the battery in the front corner near the cable entrance and see how it does with the stock camper wiring. Can also upgrade the wiring. Putting it outside in front of the wheel well also remains an option but is more work accommodating the connectors needed.

 

[K7MDL]

I went looking for panel mount Anderson high current connector products. Started with the usual SB50/PP75/SB120 and SB175 models. Examining the detailed specs, the SB50 and PP75 are more than enough to handle worst case charge/discharge rates possible in my truck and camper with 6AWG cable. The full load break (pull apart under load) rating is 50A. Continuous current is higher, 62 to 90 depending on the rating agency.

I wanted, at minimum, to have just one connector to handle 3 wires. Battery pos/neg at 50A, 60A surge, and the low current marker light which is < 5A. This is what most people here need.

In my own case, I need a 4th wire good for up to 25A to feed the solar charging input on my DC-DC converter located under my rear truck cab. The Camper battery system also feeds my radio gear in the truck cab as noted in earlier posts.

I searched around for panel mount options to mount a receptacle on the side of my truck bed, replacing the standard 3 wire Attwood trolling motor connector. I did not want a free hanging wire in, though, or over the truck bed.

There are some 3rd party solutions, some 3D printed. None that were waterproof, most are not covered. There are some boots and plugs around. Many are surface mounted. I found some 3D print files for free and for a few bucks.

I discovered the Anderson SBSX75-A series IP68 connectors. These have 2 high current pins like the standard SB50/SB120 but in the middle fits a separate housing for aux contacts. One option has a single green color center housing with a large current grounding pin for 3 large wires. I needed a 4+ wires. The other options for the center housing are 4 or 6 aux contacts. For the 4 aux contacts they are rated at 10A each. I can wire 3 in parallel for 30A for the solar. The 4th pin is for the marker light. Went through the data sheets and composed a bill of materials - covers, connector housing, and crimp pins.

If you only need 2 battery wires plus the marker light wire, then you can use the version with 4 aux contacts as listed in my attached BOM and just buy 1 aux pin contact and 1 aux socket contact. The power contacts come in pairs, so 2 pair are needed. That gives you 6 crimp contacts total, 3 for each connector.

I shopped DigiKey, Mouser, and Newark. DigiKey and Mouser were about the same price, around $120 shipped (with extra crimp pins). Depending on the color, some parts were out of stock at all places. Mouser had the best in-stock selection and they (only) have a new part, a spring-loaded flip-top panel mount cover. Newark had the best prices by far as they have promo price thing going on. Total bill minus the flip top cover at Newark was $85.20 shipped, also with extra small crimp pins. So I ordered from Newark. I can get the flip-top cover later bundled with a future order from Mouser. Maybe others will stock it later.

I noted in another post someone found a 3-pin 75A trolling motor connector, that is a decent option too.

I attached a PDF of a Mouser shopping cart where you can see the part numbers and details.

- Mike

 

[K7MDL]

Panel receptacle and plug came today, now mounted in the truck bed.

Removed the Attwood connector, cut the hole square, wired up the receptacle. 6AWG on the battery connectors. In the center a 4 pin connector snaps in place. It has 3x #16 in parallel for 25A max solar input to the under-cab DC-DC converter, and 1x #16 for the marker light power. It has metal latches with a receptable cover installed for now (not shown).

Next up is to upsize the wiring into the camper. The existing 10AWG white will become unregulated solar panel power to the 50A DC-DC converter under the cab. The 10AWG black will be capped off. Marker light wire is reused.

New 6AWG wires will run from the plug into the front corner of the camper to the existing ACR. The ACR is bypassed and just used as a terminal post. A 100A Li battery is due to arrive soon. It will start off in place of the pair of AGMs in the back. IF the voltage drop is too much I will move the battery under the front dinette next to the ACR and new cable entrance.

There is not enough room between the camper and truck bed wall to put the battery outside. It will not go inside the cab due to condensation and resulting mold issues that will cause. So it stays in the camper after all.

My cab wiring has a battery isolator/charger that I can add in one of the AGMS or my 50Ah Li battery for running high power radio gear, some of the amps will be on a 12V to 28V inverter drawing up to 45A at 12V.

 

[K7MDL]

Ran 6AWG from the camper ACR and GND bus through 2x 5/16" holes between the ACR and battery breaker under my front dinette seat. Connected to the plug. The old 10AWG battery + and marker light wires still need to be terminated in the new plug.

The wires size is 8AWG from the ACR in the front of the camper to batteries in the back of the camper which is not bad. Only the external connection cable segment is 10AWG.

Tested things out quickly. With the engine running, DC converter set to AGM and a charge rate of 7A, seeing between 0.1-0.2V drop between the charger under my cab and the batteries in the back. Need to run down the batteries and see what the max charge rate achievable is, and the voltage drop for that rate.

I am using a Renogy One Core monitor mounted in front of the sink, replacing the original Overland Solar controller, they use the same mounting hole size. Under the truck cab is a RBC2125DS-21W-G2 50A DC-DC Converter which has built in BT (LE and BLE MESH) and 2x LP16 7-pin IP68 connectors for a wired CAN bus. It is around 4-5ft straight line distance for BT connection. While there is plenty of aluminum in the way, I was hoping for better results.

I found I am having a tough time connecting the charger to the monitor via BT. I used a BT dev app on my phone to measure BT signal levels. Standing 2ft away from the charger on the side of the truck, the signal levels are very weak. By the time I get to the rear axle, or around the monitor area inside the camper, same distance, the BT signal is mostly non-existent. I can use direct BT connection from my phone but sort of defeats the purpose of the monitor. So I am going to wire the charger to the monitor using the CAN cable option.

I ordered a 20ft 7 wire cable with RJ45 to LP16 connectors installed. Also ordered a pair of LP16 plugs with matching panel receptacles. One receptacle will mount on the truck bed wall, the other near the front left area plywood. An external plug to plug jumper cable connects the camper to the truck.

My Renogy One Core monitor is a G2 version. Renogy is now selling a G3 version. It adds 5Ghz Wifi band capability. They also released new firmware and updated DC Home app in the last couple days. Now my Shunt 300 battery monitor connects but cannot get any data ;-(. Got it working via BT direct 1 time.

- Mike K7MDL

 

[K7MDL]

Camper side cable completed. #6 power, #14 marker and 3x#14 for 25A max solar panel input.

Here it is covered and fastened back in place. The #6 enters the camper next to the ACR and connects to one ACR stud. The ACR is not used, just acts as a positive battery terminal post.

In the original wiring, the external #10 Attwood connector cable enters the camper then runs forward to the ACR. There is a short #8 jumper between the ACR and battery breaker. Then #8 runs to the back of the camper to the battery. Also on the camper side of the ACR is the #12 feed to the Battery switch where it connects to the distribution panel and the IOTA charger/power supply. I disconnected the external #10 white wire and put the new #6 red wire in its place.

The old white #10 (was battery charge input from truck) is now wired to the truck charger's solar input. To use it, I will disconnect the solar panel input + wire on the existing Overland MPT100/15 in the back of the camper above my battery area and extend the solar panel side + wire though the cabinetry 6ft to the old #10 white wire. I plan to leave thedMPPT100/15 in place in case I want a separate solar charger or when the camper is sold, it can be returned to use. with just 1 connection. The round meter face is now stowed under the sink still connected. I can open the door to see it today.

You can see the old #10 white wire to the right of the ACR. WiIl now be solar panel power. The #6 black and red come in through holes drilled in the plywood sized for a snug fit so that no sealant is required. It is held in place securely on the outside. The #6 black runs up to the GND bus stud on the far right.

This close up you can see the 2n white wire with a tag on it. It says 'Kill Switch'. Disconnect it and there is no battery power to the camper. The Iota charger (AC to DC converter) is on the load side of the kill switch so that works, battery or not. The battery side breaker is the small part with 2 studs with purple colored crimp terminals. ACR on one side, battery on the other. I am going to put plastic covers over those exposed breaker studs.

The solar charger in the back of the camper. I still need to make this change as described above, pulling a new #8 wire into this area.

An alternative that might make pulling in the new wire easier is disconnect the solar charger output from the battery and connect it to the new #8 wire running forward. Then disconnect both red wires from the solar charger and connect them together to bypass the charger.

 

[K7MDL]

It occurred to me that since I plan to replace the AGMs with a Li battery soon and fit that Li battery up front under the dinette seat. Connect it to the battery breaker with a short 18" cable, reducing voltage drop more and removing a lot of rearward weight. I can reuse the old #8 battery cable described earlier to run the solar up forward, no new wire pull required. I will move the Battery Shunt 300 up forward as well. The old battery cabinet space will be completely available for storage and is much easier to access than under the seat. Probably put a shelf in there.

 

[PaulT]

Mike,
I passed on using the Victron solar modules due to reported RFI noise, (largely from OH8STN & others). Have you found that a problem in your situation? Perhaps, not as your QRZ page indicates you are primarily interested in VHF, UHF, & higher frequencies.
Paul kc7pmu

 

[Vic Harder]

Camper side cable completed. #6 power, #14 marker and 3x#14 for 25A max solar panel input.

View attachment 1110024

Here it is covered and fastened back in place. The #6 enters the camper next to the ACR and connects to one ACR stud. The ACR is not used, just acts as a positive battery terminal post.

View attachment 1110025

In the original wiring, the external #10 Attwood connector cable enters the camper then runs forward to the ACR. There is a short #8 jumper between the ACR and battery breaker. Then #8 runs to the back of the camper to the battery. Also on the camper side of the ACR is the #12 feed to the Battery switch where it connects to the distribution panel and the IOTA charger/power supply. I disconnected the external #10 white wire and put the new #6 red wire in its place.

The old white #10 (was battery charge input from truck) is now wired to the truck charger's solar input. To use it, I will disconnect the solar panel input + wire on the existing Overland MPT100/15 in the back of the camper above my battery area and extend the solar panel side + wire though the cabinetry 6ft to the old #10 white wire. I plan to leave thedMPPT100/15 in place in case I want a separate solar charger or when the camper is sold, it can be returned to use. with just 1 connection. The round meter face is now stowed under the sink still connected. I can open the door to see it today.

You can see the old #10 white wire to the right of the ACR. WiIl now be solar panel power. The #6 black and red come in through holes drilled in the plywood sized for a snug fit so that no sealant is required. It is held in place securely on the outside. The #6 black runs up to the GND bus stud on the far right.

View attachment 1110033

This close up you can see the 2n white wire with a tag on it. It says 'Kill Switch'. Disconnect it and there is no battery power to the camper. The Iota charger (AC to DC converter) is on the load side of the kill switch so that works, battery or not. The battery side breaker is the small part with 2 studs with purple colored crimp terminals. ACR on one side, battery on the other. I am going to put plastic covers over those exposed breaker studs.
View attachment 1110035

The solar charger in the back of the camper. I still need to make this change as described above, pulling a new #8 wire into this area.

An alternative that might make pulling in the new wire easier is disconnect the solar charger output from the battery and connect it to the new #8 wire running forward. Then disconnect both red wires from the solar charger and connect them together to bypass the charger.

View attachment 1110037

Super clean. Nice work!

 

[K7MDL]

Mike,
I passed on using the Victron solar modules due to reported RFI noise, (largely from OH8STN & others). Have you found that a problem in your situation? Perhaps, not as your QRZ page indicates you are primarily interested in VHF, UHF, & higher frequencies.
Paul kc7pmu

I have not tried HF. I pretty much only work 6M and up. The 222 and 903 transverter IF is 28MHz and nothing heard there.

I built a 3-band transverter box and an ESP32 based controller that lets the IC-705 act as an IF rig, recalling stored radio parameters for each band. A PC can connect and get the transverter frequency. Digital mode programs and loggers have no idea what band the 705 is really on.

I am soon to install it into the truck, found a bug in the N3FJP AC Log rig driver (ie HamLib) in WSJTX for bands 1Ghz and higher and found a solution. after it gets fixed I think I have a complete integrated solution for all bands HF through 1296 with 1 IF rig, something only my K3 could do before. I use a IC-905 for 2.3, 5.7 and 10G bands. Likely out on Salish Overlook next weekend for microwave activity day so trying to wrap this up before then.

 

[K7MDL]

Super clean. Nice work!

Thaks Vic. Several of my various careers wiring and install were part of the job description from nuclear power plants, telecom and telecom power to marine power and control. Now doing anything less than professional quality seems wrong . Now days I think about solutions a few days or weeks longer than when I used to have to crank out a solution for a paycheck.

 

[K7MDL]

Removed the 2 AGM batteries. Reminded me just how heavy these things are, and sitting next to my bumper reducing my hitch load capacity.

Removed and bypassed the solar controller. Extended the solar panels in the back through the now unused #8 battery cable that runs up to the breaker in front. Disconnected it from the breaker, tied it to the former external #10 charging wire, now have solar charging and trickle charging to the starting battery.

New Renogy Mini-100Ah self heating battery arrived this afternoon. It fits crosswise in the storage under the left dinette seat with 1/2" to spare, perfect. Cut a 3/4" spacer for the bottom inside end to level it out, and cut another piece of wood, 5/8" thick, sandwiching the 2" nylon web strap with Fastex buckle to the floor. Stuck on some 1/2" dense rubber weatherstripping to acts as ventilation and rub spacers on the 3 sides of possible contact.

Mounted the Renogy Shunt300 above the battery and cabled it up along with the 24" positive #6 that runs to the breaker where the old #8 wire used to go. So now have #6 from starter all the way to the battery with the shortest possible cable lengths.

Items left to do are to tidy up the old rearward area solar cabling, support the new red battery cable, and make a shelf for the old battery compartment, now fully available for storage. Also find out why my truck backyup camera stopped working. Verified it is not the camera after trying the original tailgate camera. Have to check fuses, measure connector pin voltages.

Here is the nearly finished battery install under the front left dinette seat. Added post covers. It fits so nice I am tempted to install a 2nd battery in parallel sooner than later, it will be super easy to do. Maybe make a partition to keep junk away from the battery so it has ventilation.

The battery support and web strap hold down with rubber spacers.



The recently released Renogy Mini-Core 100A self-heating battery. Rated for 5,000 cycles. I have a smart shunt so skipped a battery with internal BT BMS and saved some $$.

Old solar charger now removed and the solar panels wires extended to the truck DC-DC charger/Solar charger under the truck cab.

Got about 36A charge rate, about the same as when I had a battery in the truck cab, so cable length is not the limiting factor. The most I have ever seen out of my alternator in my F-150 is 39A. I can watch the voltage drop real time with the charger at the source and the shunt at the battery. At 36A it was about 0.9V.

I have a support case open with Renogy to get the DC DC charger CAN bus plug, the terminating resistor plug part numbers, and the wiring diagram from the round 7 pin charger receptable to the Renogy One Core RJ connector. None of that stuff is in the manuals and no parts were found online. They were all bare wire or LP16 type. Once I have that I can monitor the charger from the One Core unit and over the internet. Right now I am connecting direct from my phone over BT and have to be position at the front of the camper or in the truck cab to get a strong enough BT signal.


- Mike K7MDL

 

[K7MDL]

Found a longer piece of #6 red for the battery jumper and routed it along the bundle with the black GND bus wiring, much cleaner. Updated the photo in the above post.

Tied up the old solar and battery wiring in the rear battery compartment, removed the battery hold down straps and positioning blocks and false floor. Now ready for general storage use. Maybe build a shelf.

Other than the CAN bus wire between the Montor and the DC-DC charger, the electrical work is now done, seems to be working as designed, today the new battery reached full charge for the first time with a mix of engine and solar charging.

 

[Vic Harder]

saweeet!

 

[K7MDL]

My RBC2125DS-21W-G2 50amp IP67 DC-DC Charger is mounted under the truck cab and the BT signal is very marginal at the Renogy One Core monitor mounted in place of the old Overland Solar controller in front of my sink. So I will wire up the controller to the charger.

The manuals do not specify the charger side CAN bus connector part number or wiring diagram and I could not find a cable part number from Renogy online. I opened a support case with Renogy to get the CAN bus wiring and connector part number. They sent me the info including a picture of the cable. They confirmed they do not produce this cable.

The connector is a 7-pin bayonet version PY07 Z108 and looks like it should match the actual charger I have. It comes with a screw-on version so choose wisely when shopping. I could not find a source in the US but they are around $1 each and plentiful on sites like AliExpress. I ordered 4 for about $5. Due to shipping and tariffs, the total was $25.78!

Here is the detail. I am awaiting the connector arrival in the next or 2 hopefully. Note that you would want 2 connectors, one for a 120ohm terminating resistor, the other for the cable. There are 2 receptables on the charger. The CAN bus electrically loops though the charger potentially onward to other equipment on a bus such as the "RV-C" bus. I just have a point to point connection.

 

[pawleyk]

Overall sounds like a good approach, at least for when the camper is installed to conceal and protect the battery boxes.

There was a thread once that described removing the Iota charger by taking off the black vent grille on the front of the cabinet that ventilates the compartment and using a stubby screw driver or 1/4 ratchet with the correct driver. I have not done it myself, but I’ve had that grille off to install wiring and it appeared doable.

This is the way. It's entirely doable.