Has anyone done any dc to dc charging for lithium batteries. How does it work with the DD alternator?
Quote from: Fred Mc on July 08, 2026, 08:10:22 PMHas anyone done any dc to dc charging for lithium batteries. How does it work with the DD alternator?
Basically, in layman's terms they are step-up pulse charger to increase the voltage needed for Lithium batteries in stages to protect the alternator, I installed a Renogy on my daughters RV after replacing the alternator twice,if you have solar hers takes the solar out of the loop to keep from over charging while driving
I use a Victron unit, the "Orion-Tr Smart DC-DC Charger non-isolated". https://www.victronenergy.com/dc-dc-converters/orion-tr-smart-non-isolated (https://www.victronenergy.com/dc-dc-converters/orion-tr-smart-non-isolated)
It is programmable through a phone app and bluetooth, where you tell it what kind of battery you have so it can adjust the voltages. It then behaves like a multi-stage charger. You an also tweak the charge voltages individually in great detail if you want.
This non-isolated version requires that your house battery and chassis battery (and alternator) share a negative. For me, it's all bonded to the body. This same unit can be had in an 'isolated' version where the negatives don't have to be in common at all.
I picked up 24 volts from the OTR air conditioning junction box near the front driver's side; through a quality 50-amp breaker; to the Orion; then the Orion's 12 volt output gets another breaker before hitting the house battery bank.
Works like a charm. It auto-senses whether the bus is running and shuts itself down when you are parked so it won't drain the chassis batteries. Mine does 30 amps into the house battery but they come in other smaller amperages also.
They also have a new "XS" version that does 50 amps even though it is physically smaller. The original Orions can be had in combinations of 24 or 12 volts in, and 24 or 12 out; but they are fixed at the factory and cannot change. The XS has a version that can change both input and output voltage by programming. It looks like the XS only comes in a non-isolated (common negative) version.
I don't remember whether mine can be programmed with current limits, but it wasn't an issue for me since mine can only put out 30 amps (so it is probably pulling 15-20 amps).
Hope that helps. I've been 100% happy with it.
Quote from: KF6-BusFan on August 27, 2026, 06:54:59 AMI use a Victron unit, the "Orion-Tr Smart DC-DC Charger non-isolated". https://www.victronenergy.com/dc-dc-converters/orion-tr-smart-non-isolated (https://www.victronenergy.com/dc-dc-converters/orion-tr-smart-non-isolated)
It is programmable through a phone app and bluetooth, where you tell it what kind of battery you have so it can adjust the voltages. It then behaves like a multi-stage charger. You an also tweak the charge voltages individually in great detail if you want.
This non-isolated version requires that your house battery and chassis battery (and alternator) share a negative. For me, it's all bonded to the body. This same unit can be had in an 'isolated' version where the negatives don't have to be in common at all.
I picked up 24 volts from the OTR air conditioning junction box near the front driver's side; through a quality 50-amp breaker; to the Orion; then the Orion's 12 volt output gets another breaker before hitting the house battery bank.
Works like a charm. It auto-senses whether the bus is running and shuts itself down when you are parked so it won't drain the chassis batteries. Mine does 30 amps into the house battery but they come in other smaller amperages also.
They also have a new "XS" version that does 50 amps even though it is physically smaller. The original Orions can be had in combinations of 24 or 12 volts in, and 24 or 12 out; but they are fixed at the factory and cannot change. The XS has a version that can change both input and output voltage by programming. It looks like the XS only comes in a non-isolated (common negative) version.
I don't remember whether mine can be programmed with current limits, but it wasn't an issue for me since mine can only put out 30 amps (so it is probably pulling 15-20 amps).
Hope that helps. I've been 100% happy with it.
While it is helpful to have a DC to DC converter. I tend to use mine the other way to maintain the start batteries.
Given that it costs us over a dollar a mile in fuel to drive in our bus we tend to have short bursts of travel verses being on the road daily. So drawing 30 amps off of the vehicle is not much in relation to the house battery pack size.
Just food for thought...
Quote from: freds on August 27, 2026, 10:18:07 AMWhile it is helpful to have a DC to DC converter. I tend to use mine the other way to maintain the start batteries.
And if you have solar charging the house batteries, then this is even better! Now the solar is charging both house and start batteries. Nice.
Quote from: KF6-BusFan on August 27, 2026, 11:50:07 AMAnd if you have solar charging the house batteries, then this is even better! Now the solar is charging both house and start batteries. Nice.
That's exactly what my bus does. My rooftop solar charges the house batteries that in turn charge the start batteries through a pair of LSL Products Ultra Trik-L-Start battery maintainers. I got over eight years from my previous set of Group 31s, so I'm happy!
John
I didn't have solar panels ,I used the inverter with a Echo charger to charge the batteries, when the house batteries were charging the Echo charge would direct a small amount of the current to my starting batteries to. I did it on a 15amp service by reducing the charging amps on the inverter high amp charging would trip the breaker for me it was a good setup ,never had dead batteries on either side
Quote from: luvrbus on August 27, 2026, 04:52:53 PMI didn't have solar panels ,I used the inverter with a Echo charger to charge the batteries, when the house batteries were charging the Echo charge would direct a small amount of the current to my starting batteries to. I did it on a 15amp service by reducing the charging amps on the inverter high amp charging would trip the breaker for me it was a good setup ,never had dead batteries on either side
Well get busy mounting some LOL!!!
Quote from: freds on August 29, 2026, 12:11:28 PMWell get busy mounting some LOL!!!
Never needed panels with a total electric coach wasn't much happening without a power pole or the generator, my house batteries did charge off the engine alternator while driving through isolators