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

[AlumniCU]

On the fence to grab this, was install as straight forward as it looks? Did you get the 40amp one? What kind of charge rates are you getting? I have a 100ah battery charging via cigarette plug power (7amps) and its slow as hell and inconsistent.

It was straight forward to install. I have a dedicated power supply running from the battery back to the charger. It does need to be wired to a 12v source to turn it on. I wired it to the 12v accessory feed in the back of the truck, which presents a unique challenge if I want to park and listen to the radio but not charge the battery without the alternator running. I can simply unplug the wire, but I will probably install a switch in the rear to be able to open that circuit. Or tie it directly to the ignition so it only runs when car is on, and not when car is in accessory mode. Not sure how to do that.

I bought the 20A version. Because my 100Ah AGM has been topped off, I don’t have any experience on how fast it would charge a more depleted battery.




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[RigidYota]

It was straight forward to install. I have a dedicated power supply running from the battery back to the charger. It does need to be wired to a 12v source to turn it on. I wired it to the 12v accessory feed in the back of the truck, which presents a unique challenge if I want to park and listen to the radio but not charge the battery without the alternator running. I can simply unplug the wire, but I will probably install a switch in the rear to be able to open that circuit. Or tie it directly to the ignition so it only runs when car is on, and not when car is in accessory mode. Not sure how to do that.

I bought the 20A version. Because my 100Ah AGM has been topped off, I don’t have any experience on how fast it would charge a more depleted battery.




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Awesome, i think im going to stick with the 40A one. I like the switch idea and i will probably do similar as its nice to have that control. Did you order direct from Renogy? How was shipping?

 

[AlumniCU]

Awesome, i think im going to stick with the 40A one. I like the switch idea and i will probably do similar as its nice to have that control. Did you order direct from Renogy? How was shipping?

Ordered from Renogy through Amazon - came fast.


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[RigidYota]

Ordered from Renogy through Amazon - came fast.


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Went to toss it in my cart and Renogy wants 177$ to ship to my house or 140$ to ship to my mothers in the city. FML

 

[john61ct]

On the fence to grab this, was install as straight forward as it looks? Did you get the 40amp one? What kind of charge rates are you getting? I have a 100ah battery charging via cigarette plug power (7amps) and its slow as hell and inconsistent.

Wut? Lucky you haven't had a melt down at least!

Standard ciggie sockets are IMO a dangerous abortion, avoid like the plague for anything important, or that you use regularly, or for more than a few minutes. inherently poor design

Never more than 5-6A and for short periods, even then they are risky.

Anderson plugs for higher amps is what you need

 

[RigidYota]

Wut? Lucky you haven't had a melt down at least!

Standard ciggie sockets are IMO a dangerous abortion, avoid like the plague for anything important, or that you use regularly, or for more than a few minutes. inherently poor design

Never more than 5-6A and for short periods, even then they are risky.

Anderson plugs for higher amps is what you need

I currently have an arkpak, so not all hot wired with electrical tape haha. But I get you. I want to upgrade as the box is capped at 7a so in reality I probably get around 4-5a.

Hence the shopping around


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[john61ct]

Went to toss it in my cart and Renogy wants 177$ to ship to my house or 140$ to ship to my mothers in the city. FML

Probably classed as Hazmat.

 

[RigidYota]

Probably classed as Hazmat.

Haha I’m up in Canada too. I’m going to be down by LA in September so may swing by renogy then as their office is there. Was hoping for sooner but more chance for reviews and maybe improvements too.


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[dreadlocks]

there's no reason to go for the 40A over the 20A for a single battery setup, that 40A one should be reserved for those of you whom are using lithium or want to be lithium ready.

All that money to save 12 whole minus of charge time is not worth it.

source: https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/

 

[john61ct]

Not just charge time.

Quality AGM reco 0.2C as minimum charge rate available for longevity.

Odyssey / Enersys (inventor of TPPL tech, and Optima spiral) specs 0.4C - again, that's a starting point minimum .

Of course few people coddle their bank well enough to optimize longevity anyway, so if 3-5 years is OK for you, never mind.

Again FLA much easier, even 0.1C's just fine, and 0.2C a maximum practically speaking.

 

[RigidYota]

there's no reason to go for the 40A over the 20A for a single battery setup, that 40A one should be reserved for those of you whom are using lithium or want to be lithium ready.

All that money to save 12 whole minus of charge time is not worth it.

source: https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/

This is a good read, also enjoy the graphs as they paint the picture nicely. I think I’m getting greedy but you got me thinking smarter. Thanks


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[dreadlocks]

I think very few on here can or want to coddle batteries to the point of eeking out maximum lifespan, if your investing many thousands of dollars into a big battery bank of top grade lifeline agm's like on a big boat or remote cabin then of course you'd want to coddle them dearly and never abuse em, spending the money on bigger chargers and keeping everything ideal to get a few more years out of your investment will pay off.. great for those people are relying on em for daily use and trying to hit maximum cycles w/minimal performance loss..

however for recreational use, not living off of you kinda want to do some recreating and not babysitting battery banks, burning fuel and taking night classes in battery chemistry and electrical engineering.. then when your not out adventuring your carrying on with the rest of your life and not thinking about your battery bank parked in the back yard.. the chance for abuse, neglect, and just apathy is high.. so you end up with decisions like, do I wanna spend alot more money and MAYBE get a few extra seasons if nothing ever bad happens and I keep ontop of this for the next 5 years like a fulltimer.. or do you wanna just get the best performance you can for the money and least effort? IMHO Your better off with more capacity of cheap batteries than you are with less capacity of expensive batteries if the costs are the same because with more capacity they suffer less abuse.. on the other side your also likely better off with a cheaper FLA bank at 1/3rd the cost or less that you can go >3x as long with the same money if your not gaining any extra lifespan when a bit of abuse is just naturally baked into your weight/space limitations and you cant carry excess capacity.. when being a part time nomad its takes a whole lot of effort and discipline to reap the rewards AGM offers, I suspect few are up to the challenge..

For small single or dual battery banks two top of the line (LifeLine) 100AH AGM's are already 80% the way to a single 100AH LiFePo4 that has nearly the same usable capacity and will charge in half the time at 40A than AGM will at at its recommended minimum of 80A.. there's not a whole lot of compelling arguments for AGMs for Expo/Overlanding/Camping in the first place once you factor in costs of coddling em and anxiety about abusing em.

just my $0.02 on AGM's and having to pamper em just because they cost more and give you nothing else in return.

 

[john61ct]

The kind of quality LFP I reco (not drop-in) are 4x or more the price of Lifelines, and well over 8x quality FLA here in the NA market.

So not really justified purely on economics, risky long ROI.

For most people the best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH @12V pair from BatteriesPlus or Sam's Club. Deka labeled same batts also sold at Lowes.

Even subpar LFP IMO, go for over $800 per 100Ah and delivery can add another $100 or more

 

[dreadlocks]

4x the cost then yet only half the capacity required, dramatically less weight and what 1/4 of the charging requirements needed to meet spec? top of the line LFP's coddled would go low long you suspect? Decades mebe especially if you had access to cells.. its yet to really be determined but I'd like to think coddled drop in LFP will still end up lasting as long as coddled lifeline agm's so I see no fault in comparing those financially right now unless this is proven wrong.. $800 of AGM or $1000+ of LFP either way is too much money to abuse and neglect, both require hundreds more for tightly controlled charging and monitoring.

but yeah I completely agree neither LFP or AGM are really justified purely on economics.. dunno if I would go as far to say any of this is an investment, its all sunk costs your not getting back.. just which one gets best "fuel economy" and costs less to operate per day you use it.. FLA's are nice reliable economy cars that take a beating and go the distance, AGM's are used high milage luxury cars that seem like a good deal until you sink what you paid for em into keeping it on the road.. Lithiums are like brand new super car that performs like a ************ but makes no sense financially to commute to work or get groceries in and your just hoping one day a lil bit of that that technology and performance makes its way down to the high trim economy level, or you can pick up alot of skills and DIY your own high performance super car, but comes with all the headaches of building a one off with your own blood/sweat/tears and still suck your wallet dry before you know it.

Dual Deka GC Batteries are the best value by a long shot but if you can only do single 12v I'd spend a lil more and get a trojan FLA since getting a real 12v deep cycle thats not marketing mumbo jumbo is already gonna cost yah, they come in automotive friendly form factors and they are still less money than cheap AGMs that are mostly garbage because even coddled they wont outlive a cared for trojan.

 

[john61ct]

Very rare to find 12V FLA automotive form factor with deep-cycle longevity as good as the lower-voltage units, even within the same company.

Rolls and Dyno are the only ones in 4D and 8D for example.

Trojan's J150 and T-1275 are good.

For G24, 27 or 31 the Crown, Trojan and US Battery all deliver their Ah ratings, but will not get the same cycling lifetimes.