DC-DC battery charger under hood?
- Thread starter msand1977
- Start date
restorationrides
Member
So I did a quick review of Ctek's Catalog online, not having heard of them before.
The idea of having a DC/DC device charge your battery from another battery source such as your alternator is an interesting application. I need to do a little further research on Ctek for my own edification before I can weigh in knowlegably on their application and benefits.
Just keep in mind, that any device that consumes energy is going to dissipate some of that as waste (in this case HEAT) so you want to minimize the number of devices that you use to convert/transfer energy from one form to another or from one place to another...
Usually I use isolators to direct the charge supply (from the alternator while the engine is running) to one battery at a time depending on the needs. One by one each battery gets charged to its full capacity, without directly bridging the batteries together. Isolators are inexpensive and rugged and can fit in a tight space like under your hood.
I use battery switches to keep the batteries separated. Then when I need to tie the batteries together, I simply select the proper combination on the switch(s). By good circuit design, I can call on any (or all) of the batteries to provide starting power for my engine even if the starting battery is flat, or one or more of the batteries (including the starting battery) together perhaps to power some other device like an inverter when mandated by the situation...
Sometimes there is a need to use a DC-DC charger because the batteries are of different voltage's such as 6 vs 12 or 12 vs 24...
I would like to hear about your particular application and all the batteries and how you have them tied together or not. And can you tell me why you feel the need to use a DC-DC charger?
Regards,
RestorationRides
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DiploStrat
Expedition Leader
FWIW: Redarc on where to mount their toys. https://www.redarc.com.au/Content/Images/uploaded/Handy Hints/Mounting the BCDC.pdf
You can put them under the hood, but, as with all discussions of B2B, be sure that you really need one first.
You can put them under the hood, but, as with all discussions of B2B, be sure that you really need one first.
mike morrison
Observer
We have a Cetek 250 dual mounted in the engine compartment and on our Botswana trip external temperatures reached 42 deg C and the charger was fine even though the specs state a max operating temperature of 50 deg C. Another option is the Projecta IDC25 Projecta.com.au that is designed for under bonnet installations with a max operating temperature of 80 deg C
MANUCHAO
Aventurero
kevman
Observer
Why not?
Serious question though. For the price they seem like a no brainer. The Redarc Dual Input 1240 is ~$400US or so. Since voltage drop isn't a big issue anymore with cabin mounted batteries you don't need huge wires (~$100 saving), you no longer need a starter isolator (~$100 savings) and finally it's an MPPT controller for a solar set up (~$200 savings). I guess if you're putting your house battery in the engine bay, don't have solar, and have a strong alternator you don't need it. However most rigs on this site seem to have a cabin mounted house battery and a solar set up so wouldn't that make a DC-DC charger a simple no brainer?
Unless I'm missing something - which I might be - I'm still learning.
Hillbilly Heaven
Explorer
The only real reason I could see having a DC-DC charger would be if your house battery chemistry is different than your vehicle battery.
DiploStrat
Expedition Leader
Two comments, or maybe more:
-- A B2B still requires the same size wiring. Amps is amps. A B2B will help with voltage drop, but you still need properly sized wires.
-- The most common purpose of a B2B is to raise the charging voltage to the secondary battery, a problem with some Toyotas and Mercedes.
-- A B2B may also be useful in dropping the voltage and controlling the amp draw with a LiFePO4 battery. Also serving as an isolator when the voltage settings for an intelligent relay won't work.
Bonus points:
-- Some B2B also include a solar controller which can be useful in small setup.
-- Some B2B (e.g. CTEK) also include a trickle charge function for your starter batteries. This feature may be coming to others.
-- A B2B still requires the same size wiring. Amps is amps. A B2B will help with voltage drop, but you still need properly sized wires.
-- The most common purpose of a B2B is to raise the charging voltage to the secondary battery, a problem with some Toyotas and Mercedes.
-- A B2B may also be useful in dropping the voltage and controlling the amp draw with a LiFePO4 battery. Also serving as an isolator when the voltage settings for an intelligent relay won't work.
Bonus points:
-- Some B2B also include a solar controller which can be useful in small setup.
-- Some B2B (e.g. CTEK) also include a trickle charge function for your starter batteries. This feature may be coming to others.
The redarc you want to buy is a little baby
Which one you wanna buy? 20a? 25a? Or just 15a.
The alternator outputs 165amps
A commercial DC DC charger can output 100amps, but not the "hobby" dc-dc you want to buy.
And this is my advice. If you don't have a smart alternator, then dc-dc charge maybe even give you a faster charger to your battery. I understand you are under the impression that dc-dc charge will charge battery faster
And this is all marketing ****************...
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They are sometimes necessary. See how you go charging directly off the alt first.
If 'smart alt' is the cause of the problem, see if the problem can be switched off.
Actually measure / log volts and amps into the batt while driving, $30 inline ammeter.
If you need a DCDC charger, then get one.
I prefer Sterling.
If 'smart alt' is the cause of the problem, see if the problem can be switched off.
Actually measure / log volts and amps into the batt while driving, $30 inline ammeter.
If you need a DCDC charger, then get one.
I prefer Sterling.