Non-traditional DC power system build

tincan45

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Hi Folks,

With a nice long weekend and no real plans, I was able to start on my DC charging and power system. I'll start with the disclaimer that this is a work in progress, and while it all works "in my head", I'm sure I'll encounter a few surprises along the way. This is a bit of a departure from the usual dual-battery or Redarc BCDC install. I wanted something with a little more flexibility in design and future upgrades. I also don't want to touch the factory power system. The result was a child born of two inspirations. The first was the Victron Van and second @Eric Sarjeant's recent dissent build. The real challenge was to boil all these components (charging/switching/protection) into a small package like the dissent build without a dissent budget (although none of this stuff is cheap).

Goals:

Simple single Power cable from engine bay to DC system
All aux DC devices will run on house LifePo4 battery in the drawers
Handle draw of 100+ amp when needed
Be compact (Needs to fit behind trekboxx)
Be hidden (No clutter)
Be serviceable

1 - DC design (This is a rip-off the Victron van plans provided online)

Power Design.JPG


2 - Form Factor (Making it all fit behind the second row) ...and yes, I used pipe cleaner to layout my cable runs.

IMG_8582.jpg


3 - Assembly (As of 5/24/20...will update when finished)

IMG_8588.jpg


So far it all seems to be working out. The hardest part was arranging everything so they fit behind the seats. There is very little room. The Victron lynx distributor is HUGE! I was expecting something half the size. I wish they made a baby 500 amp version. It's complete overkill, but I really like the distribution design and it will make it extremely easy to add solar and inverter at a later date. I fused my charging system at 60 amps even though it's a 25 amp charger. Originally I wanted a 50 amp charger, but after a lot of research, 50 amp charging was going to be too hard on the alternator at idle and a fairly significant cost increase.

Enjoy! I'll try to update the first post as it evolves.
 

TeCKis300

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Interesting.

I've rarely seen a lynx distribution system used. What was the particular need?
 

tincan45

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@TeCKis300 - Need is always subjective! :) In this case I needed a serviceable back plane that was compact and insulated. While it's just a glorified bus bar and completely overbuilt for this purpose, it does offer a very nice way of combining all my sources and loads. I still have two feeds available for solar (if needed) and inversion (which I have). I worked out a few home brew bus bars on paper and had trouble engineering an equivalent solution with my limited resources/skills. I don't know who @benc has doing his power systems at dissent, but the one they built was a work of art. I consider the lynx a ($180) commodity equivalent. I also feel I have the advantage of serviceability and upgrades.

 

Sandroad

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Nice work. I'm about to install a Lynx as a bus bar in my off-grid solar system that charges my Q5e plug-in hybrid. The company helping me is sold on the versatility and quality. It's good to see one open and installed in your set up. Everything about your setup looks up good all around. Are you going to use the Victron monitor too, running off that shunt? My only concern is your plan to put the battery in the drawers. Inside the drawers could get hot and the battery will get hot too when it's working hard. In wonder if the battery management system will limit use? In know the Battle Born batteries I'm considering have a BMS that shuts off charge and discharge at 135F (and charge at 25F)
 

TeCKis300

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Car interiors are not unknown to go into 170*+ in the summer. Hot enough for phones and tablets that run on li-ion to shut down if left in the car. If the goal is to run a fridge, I'd try to make sure a battery is compatible with the environmental requirements of the install. I do believe Battle Borns, being LiFePO4 will go to 160*. Cracking a sunroof or window should help dampen peak temps.
 

tincan45

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Nice work. I'm about to install a Lynx as a bus bar in my off-grid solar system that charges my Q5e plug-in hybrid. The company helping me is sold on the versatility and quality. It's good to see one open and installed in your set up. Everything about your setup looks up good all around. Are you going to use the Victron monitor too, running off that shunt? My only concern is your plan to put the battery in the drawers. Inside the drawers could get hot and the battery will get hot too when it's working hard. In wonder if the battery management system will limit use? In know the Battle Born batteries I'm considering have a BMS that shuts off charge and discharge at 135F (and charge at 25F)
Yes - the shunt came with the battery monitor. I'll be adding the temperature sensor as well. I've had a smaller LiPo batteries in my rigs (freestanding) to power my old Engel on camping trips and never had a problem even in some hot environments. Granted, keeping the fridge cold was it's only purpose. I feel much better about LiPo than I do Lithium-ion in over temp situations. It's just a much safer battery all around. Good advise though, I'm going to take a wait and see approach. Technically, a larger battery won't need to work as hard at lighter loads. I may even play with the idea an auto exhaust fan if things get too hot. The cabin vents are right there in the back...who knows?
 

tincan45

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Got the power cable run today. Having a factory grommet made this about as easy as it could be.

TIP-1 : After you snip the end of the spare grommet on the firewall, I found a small length of CAT5 cable will push though easily and provide a great pull cable through the firewall.

TIP-2: Dip the battery cable in soapy water while you are pulling through the firewall. It will make the pull quite easy. I had no problems squeezing a 6 AWG cable through the grommet. I imagine you could get a 4 AWG, but it's going to be SNUG!

IMG_8590.jpg
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IMG_8595.jpg
 
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Got the power cable run today. Having a factory grommet made this about as easy as it could be.

TIP-1 : After you snip the end of the spare grommet on the firewall, I found a small length of CAT5 cable will push though easily and provide a great pull cable through the firewall.

TIP-2: Dip the battery cable in soapy water while you are pulling through the firewall. It will make the pull quite easy. I had no problems squeezing a 6 AWG cable through the grommet. I imagine you could get a 4 AWG, but it's going to be SNUG!

View attachment 2318659View attachment 2318660View attachment 2318661View attachment 2318662View attachment 2318665
Thank goodness you posted this - it saved me from having to find out the size limitation by "accident". I decided to have a professional shop put a 6GA line in for me while they're in there doing a Redarc trailer brake controller install, hopefully this week. I will be doing something a little different. I'll be having an Anderson SB50 fastened under the driver's area up behind the dash - accessible with just a bit of contortion.
I have a question - where did you place/attach your ground? Any hints on making a good electrical connection? I'm asking because I want to check the shop's work.
Thanks!
 

tincan45

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I have a question - where did you place/attach your ground? Any hints on making a good electrical connection? I'm asking because I want to check the shop's work.
Thanks!
I'll let you know when I have it all hooked up. Unfortunately, I haven't had time to work on this the last two weekends. I plan on using one of the available bolt locations from the third row seats (now removed). Lots of threads and direct to the body.
 
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Thank goodness you posted this - it saved me from having to find out the size limitation by "accident". I decided to have a professional shop put a 6GA line in for me while they're in there doing a Redarc trailer brake controller install, hopefully this week. I will be doing something a little different. I'll be having an Anderson SB50 fastened under the driver's area up behind the dash - accessible with just a bit of contortion.
I have a question - where did you place/attach your ground? Any hints on making a good electrical connection? I'm asking because I want to check the shop's work.
Thanks!
This might help. I mounted a grounding bar to the side of my ARB drawer and ran a cable to the rear-most third row seat bolt. You can just see the lug in the photo where the carpet is cut out. Here's a link to the ground bar I used:

Amazon product
IMG_0358.JPG
 
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This might help. I mounted a grounding bar to the side of my ARB drawer and ran a cable to the rear-most third row seat bolt. You can just see the lug in the photo where the carpet is cut out. Here's a link to the ground bar I used:

Amazon product
View attachment 2332372
Very interesting - I wouldn't have thought of that. I'm not sure what the shop plans - I'm assuming either drilling somewhere and attaching a grounding nut/bolt or adding onto something existing. I'm not sure which method I'd prefer. I'd kind of lilke to not mess with any existing grounds on the other hand I'd kind of like to not drill any new holes. I'll have that discussion with them this week. Thanks for the info.!
 
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I'll let you know when I have it all hooked up. Unfortunately, I haven't had time to work on this the last two weekends. I plan on using one of the available bolt locations from the third row seats (now removed). Lots of threads and direct to the body.
Thanks! The shop will either add onto a current grounding lug or make a new one. I'd prefer not to make a new hole anywhere on the other hand I'd also like to leave Mr. T's electrical system as pristine as possible. The shop does lots of audio installs so I I assume they know what they're doing. Thanks again for the reply.
 

tincan45

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Put the finishing touches on the home-brew battery (100Ah). I had a bunch of headway LFP cells in the shop and decided to put them to use on my new power system. I will probably build a smaller version next but this was a fun proof-of-concept to build a fully serviceable "off-road ready" battery. Tried to match the Trekboxx with some bed liner. Color is not right but close enough.

IMG-8663.jpg

IMG-8664.jpg
 

sdnative

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Put the finishing touches on the home-brew battery (100Ah). I had a bunch of headway LFP cells in the shop and decided to put them to use on my new power system. I will probably build a smaller version next but this was a fun proof-of-concept to build a fully serviceable "off-road ready" battery. Tried to match the Trekboxx with some bed liner. Color is not right but close enough.
Neat! Details? Pics of the inside? What BMS did you use?
 

tincan45

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Neat! Details? Pics of the inside? What BMS did you use?
I'll have to take some pictures next time I open it up. My tinker time has been fairly limited lately, so I keep forgetting to stop and take pictures. With LCDC coming up my list of things to get done is getting longer too!

This is going to ruffle some feathers, but I do not have a BMS in this one. I've found that simple voltage monitoring of the cells is much more efficient for my purposes. I have no problem manually top or bottom balancing if one of the cells get out of whack. BMS is great idiot proofing, but when you are dealing with higher current and older cells (which these are) they tend to create more problems than they solve. Once I figured they make self powered volt meters that work at 2.5+ volts, I have been using them and haven't really looked back. Super simple, cheap way to monitor cells and not worry about some no-name Chinese BMS starting a fire because of cheap mosfets.
 
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