DC-DC battery charger - Is the Grail hunt over ?

[theoldwizard1]

While "wandering around" the internet, I found a relatively new product. It is a DC-DC battery charger, designed SPECIFICALLY for charging a "house" battery from your vehicle charging system while driving ! In theory THE GRAIL QUEST IS OVER !!
'
The CTEK D250SA takes current from your vehicle charging system as low as 11.5V and boost it up to the appropriate level for doing a multi-step charge on your house battery ! Additional features:

• Isolation between vehicle battery and house battery when the ignition is OFF
• Input from solar array (up to 23V and 300W) and does propper MPPT charging
• Different charge profile for AGM house batteries
• Back "trickle charge" vehicle battery if it is low and there is adequate solar power

The downside is, it is limited to 20A, but you are not likely going to be able to push more than 20A through a typical 7 pin trailer connector anyway. (They do make an option that will do 120A but now you are likely going to need ZERO gauge wire !)

EDIT - The older D250S does not have the capability to properly charge AGM batteries, but it does cost less.

[SoundGuy]

Dropped by my dealer and borrowed a G24 to see if it would fit the spare tray in my Silvy and indeed it does - perfectly. :B Discussing this project with the service manager we both came to the same conclusion that I'd be best to stick to my original plan of installing a single G31 AGM in the front pass through close to the inverter. If I find the single G31 isn't sufficient for the way in which we use the camper I can then always go on to Step 2 which is to buy a G24 AGM and park it on the Silvy's spare battery tray. I'd always leave home with both the G31 and G24 fully charged so if I draw the G31 down before we're done camping I'll have a fully charged G24 sitting there as a spare. If I find I frequently use the reserve provided by both batteries and would like a means of recharging while still camping I can then move on to Step 3 which is to invest in this new CTEK DC > DC charger. The biggest advantage is that spreading the costs over time will make the entire project a lot easier to justify. :B

[SoundGuy]

theoldwizard1 wrote:
It has been covered MANY TIMES before, that simply connecting your RV battery in parallel with the TV battery, even using LARGE cable will not fully charge your RV battery !

mike-s wrote:
No, but it can get it to 90%, and that's only an issue if your bank is underrated for the need, or you don't have any opportunity to fully top off every week or two via other methods.

theoldwizard1 wrote:
I don't think I would want to go "a week or two" without properly FULLY recharging my battery bank.

People who boondock would still be better off with a generator and a good charger and/or solar. This would be good for folks who "dry camp" for one night (Walmart, rest stop) and are going to get on the road first thing and want there battery bank topped off by the time they get to their next destination.

We don't "WalMart" but we do seem to use our truck daily while camping for moving about the campground, going out to sight see, get groceries, etc, so the ability to properly charge a trailer battery with this CTEK DC charger while driving around is really an attractive solution for me. Here's my dilemma though - for whatever reason GM designed in this empty space & tray for an auxiliary battery but it's only big enough for a G24. :S



I just tried dropping in my dead G27 and no way will it fit, largely because that large rad hose is blocking access. :M However, if I just wedge the battery in at an angle it will fit and since a G31 is the same width & height but just a bit longer I think it would wedge in as well. I'd have secure it of course but for a few times each season this just may work. 🙂



I suppose the alternate argument in favour of two G24s is that this size would not only fit in this space but the trailer would still always be powered by one battery while I'm charging the other, whereas if I pull the one G31 to charge it the trailer would be dead. 😞 I'll have to muse on this a bit more but I sure like the idea that this new CTEK DC charger could in fact be the Holy Grail for some of us. :B

[theoldwizard1]

mike-s wrote:

theoldwizard1 wrote:
It has been covered MANY TIMES before, that simply connecting your RV battery in parallel with the TV battery, even using LARGE cable will not fully charge your RV battery !

No, but it can get it to 90%, and that's only an issue if your bank is underrated for the need, or you don't have any opportunity to fully top off every week or two via other methods.

I don't think I would want to go "a week or two" without properly FULLY recharging my battery bank.

People who boondock would still be better off with a generator and a good charger and/or solar. This would be good for folks who "dry camp" for one night (Walmart, rest stop) and are going to get on the road first thing and want there battery bank topped off by the time they get to their next destination.

[SoundGuy]

SoundGuy wrote:
I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery.

theoldwizard1 wrote:
Do NOT replace the flooded lead acid battery in your truck with an AGM battery ! Your trucks charging system will NOT properly charge it, leading to a short life.

SoundGuy wrote:
Where did I say anything about replacing the truck starting battery? :h

theoldwizard1 wrote:
My apologies.

No worries, I re-read my post yet again to make sure I was clear in how I thought I could take advantage of this new CTEK DC charger, and I think I was. 🙂 Over the winter I've been considering upgrading from my current CTEK Multi US 7002 7 amp charger to a CTEK 25000 Multi US 25 amp charger featuring temp compensated charging that would be more suitable for maintaining a costly AGM battery. However, now that you've brought this new CTEK DC charger to our attention I'm thinking this may be a better option, even if it means removing the battery from the trailer to the truck those few times each season I may need to recharge it before we get home. It's a conundrum - I really don't need the reserve capacity of dual G24a on a regular basis, yet that space GM provided in my Silverado for an auxiliary battery isn't big enough for a G31 ... arrghhh. :M I'm going to have to take another look to see if there isn't some way I could squeeze a G31 in there ... if so, I'd buy this new DC charger instead of the 120 vac CTEK 25000 so I could recharge the G31 while driving. Anyway, thanks for the heads up on this new charger. 🙂

[mike-s]

theoldwizard1 wrote:
It has been covered MANY TIMES before, that simply connecting your RV battery in parallel with the TV battery, even using LARGE cable will not fully charge your RV battery !

No, but it can get it to 90%, and that's only an issue if your bank is underrated for the need, or you don't have any opportunity to fully top off every week or two via other methods.

[richconn]

Check out lslproducts.com Using trickle start on my Itasca. Works great.

[theoldwizard1]

SoundGuy wrote:

Where did I say anything about replacing the truck starting battery? :h If you believe I did you should re-read my post ...

My apologies.

[SoundGuy]

SoundGuy wrote:
I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery.

theoldwizard1 wrote:
Do NOT replace the flooded lead acid battery in your truck with an AGM battery ! Your trucks charging system will NOT properly charge it, leading to a short life.

Where did I say anything about replacing the truck starting battery? :h If you believe I did you should re-read my post so you understand I'm talking about putting one G24 AGM in the trailer, a second in the currently empty spot in the truck designed for an aux battery, and investing in this CTEK DC charger to maintain that aux battery. How has this got anything at all to do with the truck's starting battery? :@

[theoldwizard1]

time2roll wrote:
$300 is a bit much unless there is a serious issue to resolve or have extraordinary needs.

It has been covered MANY TIMES before, that simply connecting your RV battery in parallel with the TV battery, even using LARGE cable will not fully charge your RV battery !

If you want to charge while you are driving, you need something like this. Period. End of discussion.

[time2roll]

$300 is a bit much unless there is a serious issue to resolve or have extraordinary needs.

[theoldwizard1]

SoundGuy wrote:
I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery.

Do NOT replace the flooded lead acid battery in your truck with an AGM battery ! Your trucks charging system will NOT properly charge it, leading to a short life.

[SoundGuy]

theoldwizard1 wrote:
While "wandering around" the internet, I found a relatively new product. It is a DC-DC battery charger, designed SPECIFICALLY for charging a "house" battery from your vehicle charging system while driving ! In theory THE GRAIL QUEST IS OVER !!
'
The CTEK D250SA takes current from your vehicle charging system as low as 11.5V and boost it up to the appropriate level for doing a multi-step charge on your house battery ! Additional features:

• Isolation between vehicle battery and house battery when the ignition is OFF
• Input from solar array (up to 23V and 300W) and does propper MPPT charging
• Different charge profile for AGM house batteries
• Back "trickle charge" vehicle battery if it is low and there is adequate solar power

INTERESTING! :B

I recently ordered a Deka G31 AGM to replace my aged tongue mounted flooded G27. This new G31 is going in the trailer's front pass through cargo compartment so I can use short 18" 1 or 2 gauge cables to connect to my 1000 watt PSW inverter. I already own a CTEK Multi US 7002 that properly bulk charges at 14.4 volts and will use it instead of the trailer's WFCO which never charges beyond ~ 13.7 volts. Yes, it's only a 7 amp charger and no it doesn't offer temp compensated charging but since we normally camp on electric sites I don't significantly draw the battery down more than a few times each season and therefore don't often have the need for significant recharging.

As such, I only use the inverter a few times each season when shore power fails or isn't available and because of this I've been reluctant to invest in two batteries when I otherwise have no need for that much reserve. Those few times each season I do use the inverter I've found that load supporting the one battery with the truck (running) by connecting to it with heavy gauge booster cables is sufficient to prevent excessive voltage drop when the inverter is under brief but heavy load measuring up to ~ 60 amps from the toaster or coffee maker. Now here's the interesting part - my 2012 Silverado has an empty spot next to the under hood fuse box that's designed to hold a second battery up to G24 size, but no larger ... for what reason this space is there I don't know, it just is. :h I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery. The one G24 in the trailer would certainly serve our normal needs yet still get us through one night of camping without shore power. On those few occasions when I do use the inverter I could load support the trailer battery with the second auxiliary battery in the truck, knowing it would always be maintained at a 100% SOC. It therefore seems to me the only drawback is that on occasion I might have to swap out the trailer battery with the truck aux battery for recharging with the DC charger ... OTOH that certainly would be convenient to be able to recharge while just driving around in the truck! Hmmmm, maybe this new CTEK DC charger is indeed the Holy Grail for those of us with limited battery requirements, who don't want to drag along a genset, or aren't really all that interested in solar that only works when the sun is out anyway. Hmmmmm.

Thoughts anyone? :@