Planning DC charging upgrades- solar and DC-DC

Maxcamp8 · February 20

Jan. 2021 320 boondock. Installed two LiFePo batteries in passsenger wheelwell in 2021 and upgraded the 120v Wefco Controller to Progressive Dynamics PD4135 in early 2022. Link here: https://tab-rv.vanillacommunity.com/discussion/comment/182995/#Comment_182995

Started this discussion under my earlier battery upgrade posting https://tab-rv.vanillacommunity.com/discussion/comment/206156/#Comment_206156
and have continued it under a more appropriate heading here.

After many weeklong boondocks on our son's off-grid farm and far flung trails, we are ready to upgrade our DC charging capabilities to mantain more battery capacity. This time around I've tried my hand at sketching a plan. Surprised at how many bits and pieces are added or changed. Only the batteries and Control dashboard will stay, the rest is new equipment or a heavy-gauge rewire to allow for possible future Inverter and added batteries.

Would welcome any insights or corrections.
Thanks to the many folks who have already provided comment and their own builds.

Specific questions:
1. Is a 30a output DC-DC converter adequate? Truck alternator is 130a output, to single truck battery. 30a calls for 6awg cabling length of vehicle and trailer. 40a calls for 4awg which will be hard to work with and may not fit connectors.

2. Any issue with locating the dual-battery isolation relay in the camper instead of the truck engine compartment?  Keeps me from draining truck battery or back-feeding from camper to truck. It appears the 2023 Tacoma does not have a "smart alternator" and so will keep up full output. I will also have a kill switch on the truck battery.

3. Should I ground the Shunt negative to frame as well on passenger side?
The Wefco/PD converter and ground bus on driver side is grounded to frame.
On AC Voltage systems its contra-indicated to have multiple grounding routes.

4. Does 10ga wiring between Wefco/PD and battery terminal block limit our shore-power charging? May upsize. Too many mornings when on shore power we wake up (8 hours charge...) to find the Wefco/PD has NOT achieved 100% SOC on our batteries. Running overhead fan on low, fridge, everything else is off or on kill switch including displays. On a sunny day rooftop solar takes us to 100%. I do hit the high-charge button on the Wefco/PD repeatedly and have configured systems per Battleborn settings.

5. Can the Victron Blue smart IP65 120v plug-in charger be used on a Parallel Pair of batteries or is it best to isolate each battery separately for charging?
A number of folks have abandoned the Wefco/PD Converter and just use a 120v plug-in battery charger that is better optimized to the Lithiums. I do charge the single detached batteries to 100% between trips, and am going to hardwire a bulkhead plug connection under the seats as per @SLJ and others.
Switchable breakers will let me isolate the batteries for maintenance and separate charging.

6. Recommendations on use of 12v systems while charging with IP65? I think I read somewhere its best to shut battery switch to rest of camper and let the solar or shore power run things. I'm fuzzy on the rationale.

Image: https://us.v-cdn.net/5021717/uploads/editor/g8/2s0geamwa24e.jpg

SLJ · February 21

The only time I charged my two 100AH batteries to 100% separately was when new before the initial installation. Once installed in parallel and given time to balance, I hooked up and calibrated the shunt/monitor. The batteries have been in parallel and charged that way for a year now using either solar or the Victron smart charger when on shore power. I did install a marine switch/breaker on each battery before the +buss bar so I can easily use the monitor to check the voltage of each separately and could charge them one at a time but don't see the need to charge each one separately.

Yoshi_TAB · February 21

Hi,

In regards to #4, I am on the fence to upgrade to a PD 4135 or use a stand alone charger (like Q5). The company (Randy at Bestconverter) I've been talking with to buy the PD 4135 did recommend to upgrade the charge wire to 8 AWG or even 6 AWG, I also asked in a RV electrical forum and the concensus there was also to to upgrade the wire.

The reasons I'm leaning toward a standalone charger is (1) save the hassle of swapping out the WFCO to the PD (you've alread done this); (2) know for sure the charge current would be improved over the PD (along with upgraded wire); (3) bluetooth capability to look at charge data and other charging parameters. I would add a 110 V new outlet and hardwire to busbars to permanently install. You still need to keep the converter/charger to power the 12V side in the WFCO or PD while using shower power.

Also, not saying it's wrong (maybe I need it) , but why are breakers needed on both the negative and positive side of the battery?

Why do you prefer the IP67 over the IP 22?

Maxcamp8 · February 22

@SLJ, helpful feedback. In early discussions with Battleborn they emphasized criticality of Balancing the batteries and that separating them occasionally was strongly urged. Undoubtedly not needed every time.
Decades of expensive failures and issues with PB, Ni-Cad, and standard Li batteries on mining caplamps, rescue headlamps, and our ebike batteries, has left me very cautious about charging and discharging protocols.

@Yoshi_TAB, avoiding the Converter replacement is a worthy goal and may save head and back aches. I don't have data but from the forum it sure sounds like the Victron Multiplus Inverter/Chargers or plug-in chargers provide higher (faster) amp chargers. Mounting close to the batteries is a plus. Wish I'd gone that route initially.

Thanks for flagging unnecessary breakers on negative side. It just looked right at the time. Thinking about it, 120v breakers are only on the hot side too. If I end up with a 3000W inverter at some point will want to isolate both legs for overheat safety.

What are you referring to with IP67 and IP22? Breaker style? Just mimicking what I've seen on forum and other posts, want to manually switch off each battery for maintenance. Do you have an alternate suggestion to the style I list?

On a side note, amazon reviews of quite a few SAE-plug extension cables for solar mention the offshore makers have reversed wiring polarities. Not a nice surprise!

Like to hear as well from someone who's run the DC to DC converter from their truck.....

Yoshi_TAB · February 22

What are you referring to with IP67 and IP22?

oops.. I meant I65 charger vs. IP 22?

SLJ · February 22

Also,
Your drawing shows your batteries in series. 12 volt should be wired in parallel.

Maxcamp8 · February 22

Thanks guys. My drawing is wrong, yes my 2021 batteries are wired in Parallel. Victron IP65 is what they sold me with the batteries. Also use it on portable batteries such as the ebike and leftover nucamp gel cell which I sofar have just used for testing.
In construction I normally send out a RFQ to vendors, going to try same here and see if aggregating parts results in any discounts. Hoping to do the work a little less piecemeal this time around.

Hammick · February 23

Since you are getting all new equipment have you considered doing a 48v system? Will Prowse has some great videos on budget systems 48 systems.

elbolillo · February 23

Hammick said:

Since you are getting all new equipment have you considered doing a 48v system? Will Prowse has some great videos on budget systems 48 systems.

48v system for a Tab 320 would definitely be overkill. A 24v system would be conceivable but also require extra equipment to convert the 24v to 12v to run the systems in the Tab.

MarkAl · February 24

The added complexity of going to 24 or 48 V for charging but have all the components in the trailer at 12V is overkill for my miserly current draw (small but for a long time). Some of you have massive systems for 3+KW I agree that the lower current (with it's losses) would be worth the effort.

DenisP · February 24

I upgraded my 2018 400 to 2 100 ah heated BB, lithium compatible converter and installed 30a DC-DC Victron charger. I tow with a Tundra and ran 6g wire to the bumper use Anderson connectors to make the connection to the Tab. I used 6g wire from the hitch to the charger. The DC-DC charger has worked great on travel days and on the rare occasion the solar doesn’t keep up due to overcast. I have 200 watts of rooftop solar and a 160 watt Zamp portable panel if needed in shady sites. Very happy with the setup.

Maxcamp8 · February 24

Thanks @DenisP! This confirms my plan. Very helpful.

Maxcamp8 · March 4

Started work... crawling round under truck and camper just gets harder each year! Cracked rib isn't helping.
With all this rewiring work, going to order the Inverter and extra batteries now so I don't have to rewire yet again in future.

What size battery and Inverter breakers are other folks using who have a 2000w or 3000w Inverter?
The 30A Glosso style I reflexively ordered are too small.
Rhenology 2000w manual p.29 reads MAX output 166A at 12v DC; 16.6A AC x 120v = 1992 watts.
So a 150A DC breaker could be needed if one were to max out the loads?
I won't come close per spreadsheet below; running either microwave or air conditioner sporadically, plus normal loads.

Battleborn recommends charging the 100ah batteries as up to 50% of capacity or 50A input. The PD4135 puts out up to 35A, the DC to DC charger a bit less, and solar much less.
So 50A Glosso style breakers could be indicated.... but will that prevent the Inverter from drawing enough to run the microwave or A/C?
I'm just not clear on what DC amperage the inverter will draw under load.

Do I need to power the pull-away brake actuator from BOTH vehicle input side and battery output side for safety? Looks like terminal 6 in the front 7-pin box powers the pull away sensor, which then triggers the brakes at pin 1.
I just removed items from behind the front tray box entirely: OEM shutoff switch, and wiring loop to 7-pin box and to.... where? The other end runs through the trailer front side, behind sink cab where I am unable to trace it. Anyone know where it ties into the Wefco/PD fusebox?

Attaching @Bayliss 7-pin diagram for reference.

Image: https://us.v-cdn.net/5021717/uploads/editor/2r/0tsdh9hxd67h.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/4o/win6ml45ppnq.jpg

Yoshi_TAB · March 4

HI,

I followed the guidance here for wire and fuze sizing for my 2000W inverter install:

Calculating Inverter DC Wire & Fuse Size | DIY Solar Power Forum (diysolarforum.com)

I used a 225 amp Class T fuse along with 2/0 AWG wire. I purchased wire from Windy Nation and used Blue Sea brand fuse. It was also recommended to me to put a switch between the Class T and the inverter to be able to isolate the circuit. The fuse should be located as close to the battery as physically possible. The Class T, although more bulky and costly, is recommended for a higher amp fuse and safety.

I hooked up with the author and moderator of this paper and he reviewed my calculations. In my research I did see differences between some folks on the fuse sizing. I follow a couple of other RV electrical forums and this size seems in line with other DIYer installs. The difference is adding in inverter efficiency and a safety factor.

The inverter and battery charge circuits should be seperate circuits with different fuse and wire sizing. The inverter can potentially draw much higher amps than the battery circuit. When using the inverter, the circuit must be seperate so you are not charging the battery in a "deadmans loop" (i.e charging itself)

In my '21, the trailer brakes are only connected to the the #6 space in the trailer junction box. The OEM wiring goes from WFCO>Junction box #6>Battery switch in tub>battery (I moved mine inside). The trailer brakes get connected directly to the Junction box in the #6 position. It's hard, but you can follow the wiring from the brakes into the junction box.

When it's cold and rainy outside, we use a electrical water heater for making coffee with the inverter. It's only used for a short period of time (<5 min), but does draw very high wattage (approx. 1500 W). Just a nice feature to have when camping w/o power.

Maxcamp8 · March 4

@Yoshi_TAB, great information, thank you! Did you connect the inverter 120v output to the Wefco/PD distribution panel? I plan to use it for the microwave and Air Conditioner. Seems like I would need a battery isolation switch on the inverter Output to prevent back-feed from shore power. Or a transfer switch... another complication. Inverter would only be switched on for short term use when boondocking.

Maxcamp8 · March 4

Since the inverter circuit and charging circuit are separately attached to battery terminals, can I confirm a 50A to 60A breaker on the charging circuit is what others are using? I looked at some photos here but the sizes were not legible. The Wefco/PD will push 35A according to Battleborn.

Yoshi_TAB · March 4

Hi, There are a few ways to do it, but here is my install if it's helpful (if you have not seen it).

I used a transfer switch. I was on the fence, it made the install a bit more complicated, but not difficult. In the end I'm glad I did. I can have AC power at all the outlets (even outside) when on battery power. I removed the 110V wires for the battery charger in the WFCO and connected them to the transfer switch shore power leg. The Go Power Transfer switch has connections that make it easy. I did have to add a 15 amp fuse in the transfer switch. The transfer switch wiring diagram shows an optional fuse if you connect a charger. That way, your battery only charges when on shore power. The battery charger 110 AC is on circuit breaker #2 in the WFCO. I removed them and ran the wires to the transfer switch.

I only turn on the inverter when I use it. The inverter has a remote ON/OFF switch and I placed it in the cubby below the Jenson radio control. The inverter does use battery power even in the idle state.

My WFCO does a poor job of charging the battery. I'm getting ready to install a Victron stand alone charger.

Hope this helps...there are other ways to do it.

Image: https://us.v-cdn.net/5021717/uploads/editor/ei/65ehiqlh2go1.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/f5/fyw2mgoelgqi.jpg

Maxcamp8 · March 5

Thank you! It helps to see the separate inverter and charging circuits coming from battery. Mentally I had everything tied to one busbar pair not two.

Maxcamp8 · March 13

The 2000w inverter is huge. Made a rack from angles to site it above batteries in passenger wheelwell cab. Good air circulation. Leaves room in adjacent AC cab for future additional batteries.

Yoshi_TAB · March 13

Hi @Maxcamp8

Looks good. Just a couple of things from my experience in doing a similar project. Not that you have not considered them, but want to pass on as helpful hints.

Not sure what wire size you plan to use, but if it's 2/0 AWG wire for the inverter circuit, it does not bend very easy for shorter lengths (<12-18"). May want to have all your components such as fuses, switches, shunt (if you plan to use one), bus bars, etc and lay all of them in their mounting locations. I used string to measure wire length. I bought premade welding/battery cable from Windy Nation since I did not have a crimper for large AWG wire and there are two common options for wire ends (stud holes) connections. You'll find diameters different on different components. I had to go through a couple of layout iterations to fit everything and exchange wire lengths. Windy Nation has an amazon site that makes exchanges easy.

If I remember, the inverter requires a ground. There is a connection point on the inverter. I connected it to the TAB ground stub up behind the WFCO. The OEM 12V ground busbar (behind the WFCO) is also connected to the stub up (if I remember correctly). You will have to run a wire around to it. There are plenty of cut throughs to get to it.

I'm sure you feel the same way, but I feel obligated to say; do not buy knock off electrical components for fuses and wire. Buy name brand only. Not worth it to save a few cents and risk a fire.

VonAustria · March 13

I have also been working on a battery upgrade on my 2022 320S Boondock and looking forward to heading out for the maiden voyage. Yes, stick with the best grade pure copper welding cables for all the wiring. Not only is it better, but it’s more flexible and easier to work with. It’s a bit more expensive but if you factor in the overall cost of the entire project it’s a very small price to pay.
I hooked up the new battery and fired up the new system 3 days ago and everything is working as I’d hoped. I installed a Renogy 200 amp core battery in the area under the px side seating (a very tight fit but the only place without major mod. 2 each 100 amp batts would have been a better choice) along with the batt cutoff switch, shunt, pos and neg buss bars and fuses. I installed a Renogy 2000 watt inverter just forward of the air cond unit and a Go Power TS-30 automatic transfer switch next to the air cond. where the ducting exits from the a/c. I also installed a 40 amp Renogy dc to dc converter under the driver side couch. I have a couple of items to finish before the camper portion of the project is complete.

The tow vehicle portion is done. This is an area where good quality and flexible copper cable will make that life much easier. I used red and black “InstallGear 4 gauge AWG OFC pure copper” (via Amazon) wire from the tow vehicle through an Anderson connector to the dc to dc converter into the cabin.

When I finish the details I’ll share photos what it looks like.

I also cleaned up the rats nest of wires installed by Nucamp. They should be ashamed. The electrical system installers clearly have zero pride in their workmanship.

tungsten · March 13

Quick heads up, a 30A output DC-DC will draw more than 30A on the input side, due to conversion losses. You risk nuisance fuse blowing if you put a 30A charger on a 30A input.

Victron recommends putting their 30A DC DC charger on a 60A circuit for the input side.

VonAustria · March 14

I have a 75 amp cb on the input to the dc to dc converter/charger. I used a cb so I could easily isolate the tow vehicle battery from the camper when I feel the need. Thank you for the heads up. The camper and all this is new to me. I don’t know anyone other that this forum and a number of reasonable examples on you tube that were helpful as well as the support from renogy and WFCO.

Maxcamp8 · March 14

@Yoshi_TAB et al, some great comments. Members sharing their experiences is how we learn and avoid too much rework. Laying out components and finding working room to be very tight indeed. In a perfect world we'd make up a two-tier skid module with everything prewired, and lower it into the opening. Fat chance.

Received parts today and finished truck battery hookups of my new 6awg DC homerun.
Here's the rats nest Windy Nation sent me. Lots of people report using them for premade cables, however I strongly caution against buying coiled bulk cable from them! Any electrical supply house, or even Home Depot, can coil and tape up a run of wire properly. Exchange of emails with Windy Nation resulted in their writing... "we cannot satisfy your requirements for shipping without violation of manufacturer maximum bend radius limits of 4x to 6x." Even the 2/0 cable was jumbled into a shipping box with nothing to hold the coils without entanglement. Way too expensive to put up with this nonsense.

Image: https://us.v-cdn.net/5021717/uploads/editor/al/3pu2yikgzwk9.jpg

Modified Toyota cable management enclosure to gain battery cable slack: exit to top.
Over an hour to tease apart their (brand new truck!) harnesses and modify. Lots of sealant afterwards.

Image: https://us.v-cdn.net/5021717/uploads/editor/xy/j3eug0r13p4e.jpg

6awg wire, switchable breakers, and battery connections.
These were the only brand of battery terminals I found that have covers. They worked well.

Image: https://us.v-cdn.net/5021717/uploads/editor/ei/6de5zepdpp8o.jpg

Anderson covered receptacle below rear bumper.

Image: https://us.v-cdn.net/5021717/uploads/editor/ql/ufdpe3dmrgwt.jpg

Maxcamp8 · March 15

Started wiring in the T@B wheelwell, very tight quarters.
Attached is an updated diagram.... errors and omissions?
[Diagram does not show the Wefco/PD4135 charging circuit back to batteries.]

Do I need 120v 30A fuses on the 3000w inverter output? I've read it is internally protected.

I opted for a manual rotary transfer switch in blue below. Not sure an automatic transfer switch will kick in during an undervoltage condition we commonly see at shore power sites.

Experimenting with Smartdraw subscription, not too successfully.
It would be nice if I could work off someone's one-line and modify it rather than reinvent the wheel.
Perhaps we could start posting our drawing source file sources under a purpose-made conversation heading.

Image: https://us.v-cdn.net/5021717/uploads/editor/rp/c9ah2qpyl0vi.jpg

elbolillo · March 16

@Maxcamp8 I have never seen fuses on both the negative and positive. You should only need a fuse on the positive between the inverter and the distribution block and between the positive of the battery and distribution block. However, if you have a specific reason for this I would love to learn more.

And are you putting a battery disconnect between the batteries and the 12v system of the trailer?

Any specific reason for connecting the batteries in parallel the way you show on your drawing? I have not seen it done like this before. Not saying it is wrong, but want to learn.

And if you have the DC to DC charger, do you really need the battery isolator?

VonAustria · March 16

There is no need nor is it necessary to install fuses or circuit breakers to the negative side of the camper or tow vehicle batteries or any other ground cables. About all you’ll accomplish is adding resistance into the grounds.

I don’t quite understand how the dc to dc converter is wired as drawn. In my case, I ran cables directly from the tv battery through the Anderson connector to the input of the dc2dc controller. I installed a 75 amp circuit breaker on the positive cable about 12” or so from the tv battery. From there I ran the output of the dc2dc converter to the positive and negative battery buss bars unfused.

I should have my project completed next week. So far everything is functioning as expected. The only part left is to plug the camper into the truck to see if the charging from the tv is working like I think it should.

I’ll post photos after all is done and hopefully they aren’t of charged remains.

Yoshi_TAB · March 16

Hi,

I had the same comments as above and a few others.

-Fuses or circuit breakers on the negative of the circuit is not necessary. The positive side is recomended for safety reasons. I've read that the battery fuse (Class T or other current interupting devices) should be no more than 7 inches away from battery.

-I wired mine a bit differently. I attached inverter circuit directly to battery and made a second circuit for the lower amp (30 amp) rated circuit to the WFCO/PD. Either is fine (I think), but I wanted the fuse protection and switch for the inverter directly in line from the battery. I also had my drawing reviewed in a couple of other electrical forums and that is what they recommended.

-Batteries are not shown wired in parallel as recommended by most battery manufacturers. I would contact your manufacturer for their recommedation.

-Would recommend a battery cut off switch in between positive busbar and PD. You can see in my photo where I added it next to the WFCO.

-I'm probably just not reading it correctly. It looks like from the drawing not all the loads (DC-DC) are on the same side of the shunt. Would it be more efficient to have the battery side of the shunt connected directly to battery? Just something to double check. I don't have one, so maybe it's correct

-Your showing 2/0 wiring from negative busbar back to PD. Is the correct?

-What is the amp output of the victron charger? You are showing 14AWG wire. A larger wire would be better to reduce voltage drop. But don't know capacity of charger.

-Would recommend fuse protection in your solar circuits. Maybe you have it and just not shown on the drawing.

-Re Fuse protection on inverter output. Not sure. I did not put any in mine. Again, had my circuits reviewed by a couple of other electrical forums and it was not mentioned. I also looked at few videos of transfer switch installations and I don't remember seeing fuse protection in that circuit or I probably would have added it. If you need it, would it be required for both shore power AC input and inverter AC power input circuits to your switch? I think the question is, if you had a short by a cut wire in those circuits (before the switch), what would be the fuse protection? After the switch you have the breaker in the PD. But nothing before. Not you have me thinking. I'm going to ask around. If you look here, they do not show one Solar Wiring Diagrams for DIY Campers, Vans & RVs - EXPLORIST.life

-Minor comment. Is your inverter 2000W or 3000W?

Yes, very tight quarters. That's why I split mine up as shown in my pictures. I had to go through a couple of interations to get it to fit.

Not sure it was necessary, but I also bought a small computer fan to cool and move air when the inverter is on. I was concerned with heat build up, especially when the Alde is running and adds heat from the glycol lines. The inverter manual gives space requirements for air cooling/circulation.

I used the drawing tab of MS Word to make my drawing. Power point would also work if you have it.

rfuss928 · March 16

Maxcamp8
It concerns me that the three folks that chose to offer detailed critique of your wiring diagram so far cannot see that the batteries are clearly shown wired in parallel. I would look elsewhere for electrical advise...

Yoshi_TAB · March 16

Your correct, the busbars tie them together in parallel. just not the way most battery manufacturers recommend for best charging and efficiency. That is what the comments probably meant (at least in my case...I did not use the correct choice of words). I updated my comment.

elbolillo · March 16

rfuss928 said:

Maxcamp8
It bothers me that the three folks that chose to offer detailed critique of your wiring diagram so far cannot see that the batteries are clearly shown wired in parallel. I would look elsewhere for electrical advise...

Wired in parallel in a way that is not so common, so yeah, we missed it. Would you have any constructive thoughts on the OP’s wiring diagram that could be of use to all here on the forum?

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