dc to dc chargers

[winghead1504]

what is everyones opinion on dc to dc chargers. are they worth it? do they work as well as they say . we have 560 worth of batteries and 6 220 solar panels. just wonder how the dc to dc works. all victron component's

 

[JKJavelin]

Some people like them when they are on the move a lot and don't have any solar, and need to get their lithium batteries back up.
Standard light gauge truck to trailer wiring loses a lot of energy from the truck alternator to the converter/controller. When I had AGM batteries, I would get 6-9 amps from my truck, and now with lithium batteries, I only get about 3 amps from the truck. I'm guessing that's from lithium not have the gradual voltage drop that acid batteries have.
With DC-DC, the package has much heavier wiring along with a unit to control it.
Once in a while I would like one but usually don't need it. I have 1000 watts of solar with 400 amps of lithium.
JK

 

[winghead1504]

yea i watch a utube video installer said you need #4 wire to get full benefit

 

[jarhead-ORO]

when I had my lithium batteries installed I asked the installer how to increase the charge to my 5er. He said a dc to dc charger would due the trick. He installed it with a battery cable from the front truck battery to the back of the bed and put another plug in in the bed. he mounted the dc to dc charger in the front cargo bay near the generator. the ran another battery sized cable from it to the pin box. Problem solved as I am getting about 25 amps straight to my batteries. No more lack of juice when I stop for the night.Dave

 

[winghead1504]

was it worth the price of the dc to dc charger does it keep your lithium batteries charged on travel days when there isnt any sun

 

[JKJavelin]

Well, think about it.
If your 560 amps is down to 60% state of charge, your batteries need 224 amps to get to 100%. That 25 amps that Jarhead gets would take about 9 hours just by themselves. Even on cloudy days you should get some solar power without trees being in the way. And with the system you already have, you could probably get DC-DC with 30 or 40 amps (or more?).

 

[winghead1504]

i guess i will probably see about getting it installed. it seems like it would be worth it

 

[jarhead-ORO]

was it worth the price of the dc to dc charger does it keep your lithium batteries charged on travel days when there isnt any sun

 

[jarhead-ORO]

With the other cable I had added I am pushing 25 to 30 amps constantly while moving. So that is about the power it takes to keep my residential fridge running without drawing the batteries down.

 

[tomkatb]

The answer is it depends.

If you travel a lot and boondock then yes.

When plugged into shore power most 50 ah per hour converters is all you need. So the answer is no.

How similar to the motorhome deal they are i do not know. Motorhomes need a special BIM, I think to prevent cooking the motor home chassis battery and alternator with mixed batteries. I know little about this. Unmodified trailers/fivers use the little wire between the alternator and the rv to limit the amperage. The dc/dc device would make this an issue maybe.

Solar panels are kind of good for 25 ah per day for each 100 watts of panel mounted on the roof. Sometimes better, sometimes not so good.

 

[winghead1504]

i think we may put it on rv we are just getting into boondocking have to see how we do lol