Deep cycle or starter battery charging issues
I recenty moved from a class B to a small fiver. My old van had one deep cycle battery and I installed an isolator. This set up was good for several nights of light usage before I had to run the van t...
Forum Discussion
Hi Turnkey,
Part of the difference is that you moved from a B which opportunity charges every time the vehicle is driven to a trailer.
The seven pin connector is essentially useless for actually charging the battery bank.
Do you know what converter is in the trailer?
I suspect that the battery bank is not being fully charged before you leave on trips. It can take up to 168 hours to get to 100%.
My first step if I were in your shoes would be to beef up the charging path from the tow vehicle to the trailer battery bank #4 wire would do wonders for that.
In my RV, I "cheated" and used a marine cycle battery for the starter. That means all of my batteries are identical chemistry. I also doubled up on the charging path.
Even small solar (12.5 watts per 100 amp-hours) may make a big difference because the battery bank will be bursting full at the start of any trip.
Charge acceptance rates above 85% state of charge may be around c/10. At 95% that may be c/20. Flooded batteries need equalization from time to time. c/20 is about the minimum capacity for equalization to work well. For those reasons I'd size a solar system between 150 and 60 watts per 100 amp-hours of storage. The smaller the battery bank the more I'd lean to 150 watts. If you wish to eliminate generator use entirely I'd also lean to the 150 watts. Costs are about $2.00 per watt for a system. I don't include battery bank costs, nor inverter costs--because most folks who boondock have both already.
It is not uncommon for me to see just 1 amp flowing into the 875 amp-hour battery bank.
Here is a simple flow chart.
Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT.
Here is a link to the rather special spreadsheet that N8GS has created to help size solar battery charging systems!
Solar Spread Sheet N8GS
Part of the difference is that you moved from a B which opportunity charges every time the vehicle is driven to a trailer.
The seven pin connector is essentially useless for actually charging the battery bank.
Do you know what converter is in the trailer?
I suspect that the battery bank is not being fully charged before you leave on trips. It can take up to 168 hours to get to 100%.
My first step if I were in your shoes would be to beef up the charging path from the tow vehicle to the trailer battery bank #4 wire would do wonders for that.
In my RV, I "cheated" and used a marine cycle battery for the starter. That means all of my batteries are identical chemistry. I also doubled up on the charging path.
Even small solar (12.5 watts per 100 amp-hours) may make a big difference because the battery bank will be bursting full at the start of any trip.
Charge acceptance rates above 85% state of charge may be around c/10. At 95% that may be c/20. Flooded batteries need equalization from time to time. c/20 is about the minimum capacity for equalization to work well. For those reasons I'd size a solar system between 150 and 60 watts per 100 amp-hours of storage. The smaller the battery bank the more I'd lean to 150 watts. If you wish to eliminate generator use entirely I'd also lean to the 150 watts. Costs are about $2.00 per watt for a system. I don't include battery bank costs, nor inverter costs--because most folks who boondock have both already.
It is not uncommon for me to see just 1 amp flowing into the 875 amp-hour battery bank.
Here is a simple flow chart.
Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT.
Here is a link to the rather special spreadsheet that N8GS has created to help size solar battery charging systems!
Solar Spread Sheet N8GS
