Looking for good DCBC+solar setup.

[tincan]

Hello all,

New guy here. Forgive me if this has been covered already, but I just purchased an Engel fridge and I'm trying to put together a solid charging system for my new rig. Here's where I am so far (please feel free to correct me if something doesn't seem right):

- New truck so I want to avoid interfacing with the factory power systems (Lead Acid) except to charge.
- I have a 240ah LiFePo4 house battery pack mounted in the rear.
- 80W solar panel

I'd like to charge both batteries via alternator when I can, but I'd also like to take advantage of the solar charging with as little effort as possible. So far, I've only found two solutions:

Redarc
https://redarcelectronics.com/products/dual_input_25a_in-vehicle_dc_battery_charger.
Redarc seems to check all the boxes, but I'm not familiar with the product. I've love to hear from someone with "real world" experience.

Ctek
https://www.ctek.com/products/vehicle/20a-off-grid
This one also seems do what I want, but I'm afraid it might not handle the Lithium pack well.
I like the simplicity of this setup w/o the need for an ignition wire.
The controller looks huge though!

Both of these options seem to be on the high end. Are there other options?

 

[john61ct]

For LFP I would only buy a unit with full profile customability.

Check out Sterling BB series.

 

[tincan]

Interesting. Looks like I could run one of these B2B and use a separate MPPT charge controller for the solar. I assume the BBW1212 would be a good fit.

For the money, the Redarc still seems like a better option. Are you running the sterling?

 

[DiploStrat]

Each product has different advantages/features. Only you can decide which is best for your purposes.

CTEK recommends their product only for lead acid. 20A is not a lot of charge, hence their recommendation of adding the SmartPass, an intelligent relay, to boost the charge rate.

Sterling makes a wide range of B2B products, most have many useful adjustments, none AFAIK, have an integrated solar controller.

I have a REDARC BCDC 1240D which works as advertised. I have it connected to the starter battery and to a 160w solar panel.

In my case, I went with the REDARC because:

-- I could use it step down from my 24v vehicle system to my 12v camper system.
-- 40A is on the larger side of B2B. (Sterling makes even larger models.)
-- I could use it to handle an addition solar panel, my main solar controller was maxed out.
-- The REDARC could be used with LiFePO4 batteries in the future.
-- The unit is physically small and does not require a fan, etc.

As always, YMMV.

 

[Bayou Boy]

I would ask your battery manufacturer what they recommend. A lot of people use Lithium batteries as house and trolling motor batteries on boats and integrate charge on the run capability so they should be familiar with it. Odds are they will suggest something from the marine world.

 

[tincan]

Each product has different advantages/features. Only you can decide which is best for your purposes.

CTEK recommends their product only for lead acid. 20A is not a lot of charge, hence their recommendation of adding the SmartPass, an intelligent relay, to boost the charge rate.

Sterling makes a wide range of B2B products, most have many useful adjustments, none AFAIK, have an integrated solar controller.

I have a REDARC BCDC 1240D which works as advertised. I have it connected to the starter battery and to a 160w solar panel.

In my case, I went with the REDARC because:

-- I could use it step down from my 24v vehicle system to my 12v camper system.
-- 40A is on the larger side of B2B. (Sterling makes even larger models.)
-- I could use it to handle an addition solar panel, my main solar controller was maxed out.
-- The REDARC could be used with LiFePO4 batteries in the future.
-- The unit is physically small and does not require a fan, etc.

As always, YMMV.

Thanks! That's +2 for Redarc.

....On a side note, Your avatar caught my eye. My very first "rig" was a '72 K5 Blazer. Baby poop yellow. Bought it for $400 and explored nearly every fire trail southern Utah...great memories.

 

[john61ct]

Industry reco voltages for LFP are way too high for House bank usage longevity, based on use for propulsion.

I never go past 3.45Vpc in daily use.

I would not usually want a SC as part of my DCDC charger, great Victron unit for 200+W is maybe $100, can use in 1:1 ratio with a well matched panel.

 

[tincan]

Industry reco voltages for LFP are way too high for House bank usage longevity, based on use for propulsion.

I never go past 3.45Vpc in daily use.

I would not usually want a SC as part of my DCDC charger, great Victron unit for 200+W is maybe $100, can use in 1:1 ratio with a well matched panel.

Hi John,

Thanks for the input. Depends on how you run LFP I guess. 3.40-3.45 is what I was thinking, so that's encouraging. I will primarily be running the engel with the LFP. My goal to the run the fridge full time and never think about it. That's the main reason I wanted to incorporate SC and DCBC. The SC won't need to do much, just maintain the bank when the sun is out. With an average load of maybe 1-2 amps, and 160ah "real world" storage I should be able to run for several days even w/o sun. I guess the other side of that is to forget about SC and make sure I'm pushing as many amps a possible while the vehicle is running. The 25A redarc may not be the best option there. I'd probably be looking at a much bigger unit.

Keep in mind, I'm cramming this in the back of a Tacoma so I'm trying to simplify as much a possible. That's why I've decided on LFP. Compact, safe, and won't suffer extreme climates (much) in the cab. If it were something bigger I'd more than likely be looking at separate systems.