DC-DC charger as an alternative to generator?
- Thread starter Martinjmpr
- Start date
Martinjmpr
Wiffleball Batter
Sorry, I thought I mentioned that earlier but I guess I wasn't specific enough.
Our recent trip to Oregon is probably a good example of the kind of travel we'll be doing. We left Colorado on a Friday, and spent 3 days traveling to Southern/central Oregon (near Crescent lake.) Our overnights were free boondocking spots, so the only charging the batteries got was from the rooftop 100W solar panel and whatever is pushed through the 7 pin trailer plug. It does have power to the charging circuit but I'd guess it's pretty low amperage just based on the fact that it's running through some pretty small wires. If I was to guess I'd be surprised if it was getting more than 5 amps through the trailer plug.
Once we got to Oregon we were camped there for 5 nights (Sun - Thur) with no hookups. I brought an extra 100W solar panel but that was useless because (a) it was cloudy and overcast the first two days and (b) even when the sun was out, we were beneath a 150' canopy of trees and probably got less than an hour of direct sunlight per day, so solar power was useless to us.
This was when I came up with the idea of just running jumper cables from the truck to the batteries and running the engine for ~ 45 minutes or so. This would give enough of a charge to the 12v FLA batteries to keep things running for a day.
Once we left the campground we stayed overnight with some friends on Medford and they did let us plug into their home so we were able to fully recharge the batteries overnight. Next day we headed home, again it was 3 days/2 nights to get home, boondocking with no hookups and no charging other than what was pushed through the 7 pin.
There were a couple of nights it would have been nice to run the furnace but there wasn't enough power in the batteries to run the fan. We made do but I want to do better for our upcoming trip next month to the Florida Keys.
TL;DR: Would like the ability to be "off grid" for at least 10 days and need the ability to keep batteries (2 x 100AH LiFePo4) at a reasonable SOC for that period.
ETA: Biggest draw is the 12v refrigerator/freezer.
Martinjmpr
Wiffleball Batter
Yes, this is what's making me lean towards alternator charging. Trying to keep things as simple as possible and with as little equipment as possible.
Just went out and started my truck and checked the voltage at idle. Seems to stay right around 14.4v.
Or generator, they are cheaper and output twice the charge
rruff
Explorer
Typically a fridge will use ~300Wh per day, but more if it's hot. Do you ever measure the energy you consume? I have a cheap monitor for this.
A LiFe 100A 12V battery will have at least 1200Wh of capacity, and draining them that low does not hurt them. IOW, there is no reason to charge them unless they are near empty. They weigh about 20 lbs, and I bought one recently with BT and cold temp cut off for $170 shipped. 3 of them should be enough to run your fridge for 10 days. Maybe add a 4th and call it good.
I'm just thinking that a DC-DC charger that you mainly only use while driving would be a good solution. Running your vehicle regularly when parked just to top off batteries, not so much. But having that as a fringe emergency measure would be fine.
Dave in AZ
Well-known member
Which was that, and do you recommend? I was about to buy one Will Prowse just tore apart and liked, WattCycle, but the day after his review price went from $207 to $250. Looking for a decent BT 100Ah mini. Thx
rruff
Explorer
I haven't tested it as a bought it right before a trip, and now that its all snug and cozy I probably never will. It is a mini and the BT works... although it doesn't seem to get the watts right. Supposed to be a JB BMS. I like having BT for trouble shooting bad cells.
It's even cheaper now, $160 shipped with coupon. Since Amazon links are wacky I won't try, but search for this.
It's even cheaper now, $160 shipped with coupon. Since Amazon links are wacky I won't try, but search for this.