Switch to Lithium Batteries

[TaxWonk]

Originally Posted by jakegw2

TaxWonk - thank you for this writeup, your system is very thorough.

Two items that I thought of when reading:

Your DC-DC charger might not be doing any limiting of current since 60A is probably more current than your alternator has to spare, after feeding the chassis load, much of the time when you are driving. Your alternator (probably a 160A unit?) may be running flat-out when you are charging. My 220A alternator supplies between 65A and 85A when driving, depending on what else is running (it supplies as much as 120A at startup for a few minutes). I do not use a DC-DC charger. I don't know if the Sterling device lets you set a max current, but if it does you might consider dropping it to 30-40A so that the alternator does not run at max load.

The charger will still raise the charge voltage slightly to accommodate the LiFEPo chemistry, which can be important if you seldom charge off of other sources (LiFEPo needs the higher voltage to balance the cells - not all the time, but periodically to protect the battery).

You have capacity to power the AC if you wish. Based on my experience with two Battleborn batteries and a slightly more powerful AC I estimate you could get 2.5 to 2.75 hours of AC off your setup. You may not need it, but in FL it is really nice to be able to go shopping or in to eat at a restaurant and come out to a comfortable vehicle. Also great for rest breaks without having to idle the van.

Hi Jakegw2,
According to the RoadTrek owners manual I have a 150amp alternator. The charger does have a half power mode and I think if you want to really get into the coding you can set the max charge amperage. Interesting that you say to cut the charging amperage back to 30A. So far I have not seen it charge any higher than 30A according to my battery monitor. But you make a good point and I think I will set it to half power just to make everything last longer.

As for the AC, I had not originally intended to install a mciroaire soft start and I knew that the Mutliplus could not handle the starting amps so I wired it to not run the AC on battery. I thought it was a good feature for someone using my wife's van that did not understand the system. But now that I have the soft start I might go back to having the AC supply back in the main panel.

Thanks!

[Nic7320]

Originally Posted by TaxWonk

3. Maxxair Fan - Maxxair fans do not like anything over 13.9 volts and we would be charging at 14.6 volts so I installed a voltage regulator on the 12v supply to keep the fan control board from burning out.

Hope this helps someone.

A silicon diode in series with your fan will drop the voltage about 0.65 Volts. While it's not a regulator, it's easier to install and probably more reliable. Just make sure the diode has a current rating greater than the maximum current of the fan, and make sure it's not a schottky diode (they have a lower forward voltage drop).

[Rlum]

Originally Posted by jakegw2

I found at least one person on the Promaster forum that swapped the factory 180A for a factory 220A and says it is working fine.

https://www.promasterforum.com/threa...od-idea.83639/

Thanks for information!

[midi459]

if u want ur batterys to last dont slam them at 14.6 try 14.4 lower is longer life
u dont need to boil them .thats why they swell ...over charging and they heat up

[Rlum]

Originally Posted by midi459

if u want ur batterys to last dont slam them at 14.6 try 14.4 lower is longer life
u dont need to boil them .thats why they swell ...over charging and they heat up

I have heard this also. Too increase the longevity of LifePo batteries. Do not overcharge and over discharge. Keep between 90 to 35 percent. The life of these things will dramatically increase.

[midi459]

yes this is true for most batterys lifep04 is whats used in the mercedes sprinter sieres campers .with a 160 amp alternator direct to the batterys .using a balmoar regulator we had to throttle the voltage 14.8 to 14.4 it was over charging and cooking the batterys .. these camper battery systems are designed for fast as possable charge not longevity of the batterys ..ok so the batterys dont run the ac for 4 hrs u get 3 hrs 45 min .2 v or .4 isnt that much but now the batterys will have a 6-10 yr life insted of cooked at 2 yrs

[midi459]

https://batteryuniversity.com/
read read read .........verry interesting exspecialy for us on the road trying to live off a battery ...lifep04 are exspensive be nice to them

[TaxWonk]

Originally Posted by midi459

if u want ur batterys to last dont slam them at 14.6 try 14.4 lower is longer life
u dont need to boil them .thats why they swell ...over charging and they heat up

Right, but the Tripp Lite does not have a voltage setting available. It does have a high (45 amps) and low 11(11 amps) charge setting. Also when the battery separator kicks in you are at the mercy of the Sprinter alternator. My flooded lead acid were inexpensive batteries from Costco and lasted 4 years so not terrible.

[midi459]

ur running lead acid not lifep04 and ur charger is set for lead acid or agm some batterys like 14.6

[TaxWonk]

Just a follow up. Almost three years and no issues. Yes, the alternater seems fine. Just opened everything up to check all my connections everything looks good. Also just installed a 12volt refrigerator Isotherm Cruise 130 Elegance. Averages 36 watts an hour under ideal conditions of 76 degrees in the shade. Still no solar, but with the new electric frig I am thinking the time is right. Maybe just a folding panel that I can use for the van as well as Ham Radio.