New DC to DC Charger From Renogy-20 amps or 40 amps-Flooded/AGM/GEL/Lithium

Just saw a new DC to DC charger from Renogy on Amazon for $129, seems to have quite a few features for a relatively low cost. 40 amp model is $199

For sure beats (in my book) running a solenoid etc which ends up not being much cheaper. Downside of course is charging isn't quite as fast, but should be adequate for most of us I think. This makes it pretty darn easy to add in another battery and even do a quick connect type system where you only install the second battery when you need it as opposed to being installed 24/7. I know a lot of us don't care about having a second battery for self jump etc and mainly for running a fridge/electronics for the weekend.

Hell, I have a dual battery/charger setup and I almost want this for a 3rd battery/box that can easily go in/out of the truck yet still be charged from my existing wiring. Hmm lol.

From Renogy:
Description
This 20A/40A DC to DC Charger is designed to charge secondary batteries while driving using the primary battery connected to the alternator. It is able to charge: Flooded, Gel, AGM, and Lithium batteries using multi-stage charging.
Key Features
  • Multi-Chemistry Battery Types ( Flooded, Gel, AGM, and Lithium )
  • Smart Protection Features ( Battery Isolation, Over-voltage safety, Overheat protection, and Reverse polarity protection)
  • S3-phase Charging (Bulk, Boost, and Float)
  • Built tough for all conditions
  • Able to charge an auxiliary battery to 100% state of charge
  • Increases run time of loads, such as fridges and lights
  • Overcomes voltage drop caused by long cable runs
  • Prolongs Battery Life
renogy-dc-to-dc-charger-on-board-continue-crushing-overland.jpg

renogy-dc-to-dc-charger-on-board-continue-crushing-overland-charging-diagram.jpg


Renogy 20A DC to DC Battery ChargerRenogy 40A DC to DC Battery Charger
Nominal Voltage: 12VNominal Voltage: 12V
Rated Charge Current: 20ARated Charge Current: 40A
Output: 250WOutput: 500W
Idle Power Consumption: <0.4AIdle Power Consumption: <0.4A
Input Voltage Range: 8V-16VInput Voltage Range: 8V-16V
Equalization Voltage: N/AEqualization Voltage: N/A
Float Voltage: 13.2-13.8vFloat Voltage: 13.2-13.8v
Boost Voltage: 14.1-14.7vBoost Voltage: 14.1-14.7v
Operating Temperature: -20°C to +50°COperating Temperature: -20°C to +50°C
Dimensions: 8.31 x 6.89 x 2.68 inchesDimensions: 10.28 x 6.88 x 2.68 inches
Weight: 2.93lbsWeight: 4.14lbs
 
Last edited:

AlumniCU

Member
Saw this from their email announcement. I’m in the middle of building a battery box. I have an AC charger built into it already. Was thinking to add this as well to charge/run from the 4Runner while driving.

Any reason not to do that? Alternative in my mind was to run DC from car through solar charge controller... (is that even a good idea?)


Sent from my iPhone using Tapatalk
 
Saw this from their email announcement. I’m in the middle of building a battery box. I have an AC charger built into it already. Was thinking to add this as well to charge/run from the 4Runner while driving.

Any reason not to do that? Alternative in my mind was to run DC from car through solar charge controller... (is that even a good idea?)


Sent from my iPhone using Tapatalk

I think a box like what you mentioned would be perfect. AC for at the house, DC for on the road. I don't know about DC through charge controller-I mean it should work since the solar is just outputting power, but I'd probably play it safe especially since the car will give way more power to the solar charge controller than a panel would. Most likely would not end well haha.
If I was building (and I'm now thinking about it haha) a battery box, I'm certain I'd be using this. I could just plug it into my plugs that I've got at the back of the truck and unplug it when I'm not using it/it's in the garage.
 

john61ct

Adventurer
good pricing but wish they'd included user-custom setpoints like Sterling and Enersys.

Wonder who the OEM is?
 
The manual also shows a 60A. I don’t see it for sale but maybe it’s coming?
I think they are going to sell a bunch of these.....

I saw the 60a version in the manual too-can't imagine it's too far off? I've seen a lot of, "blah blah brand is better" but for $130 this is awesome. This should help tip the boat for those looking to pick up a battery/box and have a real simple 2nd battery for trips when they need it.
 
Does it charge two battery banks? Sterling b2b does not. You need to buy two.

Another question would be could this run alongside my sterling charger for my second battery bank

It would not charge two batteries separately. If you have your batteries wired together the renogy b2b would see it as one battery.

I think you could run it alongside another charger, not sure if they would confuse each other though.
 

hour

Observer
good pricing but wish they'd included user-custom setpoints like Sterling and Enersys.

Wonder who the OEM is?

Guessing that means you've concluded you can't tell it to stop charging at say... 13.5v or something? That was my plan with my lifepo4 house battery.. figure out what I usually consume in a day, add some breathing room, and then keep it between like 20% and 80% charged. Guess I have a relay gizmo coming from China that could do this if the renogy cannot.
 
Guessing that means you've concluded you can't tell it to stop charging at say... 13.5v or something? That was my plan with my lifepo4 house battery.. figure out what I usually consume in a day, add some breathing room, and then keep it between like 20% and 80% charged. Guess I have a relay gizmo coming from China that could do this if the renogy cannot.

There are dip switches you can set depending on battery type/voltage. I’ll take a look when I’m home to see what exact voltages are listed.
 

john61ct

Adventurer
The Sterling BB series lets you define user-custom setpoints precisely, not just select from their canned choices.
 
Guessing that means you've concluded you can't tell it to stop charging at say... 13.5v or something? That was my plan with my lifepo4 house battery.. figure out what I usually consume in a day, add some breathing room, and then keep it between like 20% and 80% charged. Guess I have a relay gizmo coming from China that could do this if the renogy cannot.

Here are the tables from Renogy. Also, shouldn't you have a BMS or something running/managing the LifepO4? So "end" charge voltage won't matter? Anyway, here they are:
renogy-dc-to-dc-charger-continue-crushing-overland-dip-switch-setting-charged-voltage.jpg

renogy-dc-to-dc-charger-continue-crushing-overland-dip-switch-setting-float-voltage.jpg

renogy-dc-to-dc-charger-continue-crushing-overland-dip-switch-setting-lithium.jpg
 

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