Forum Discussion
27 Replies
FWC wrote:
In many cases there will be no issue with the alternator. I have had various LiFePO4 setups over the past 10 year, and never had an issue with overloading the alternator. The wiring, breakers and ACR between the alternator and batteries provides plenty of resistance to limit the current to the battery bank.
In specific cases with higher voltage alternators and very large gauge wiring, there could be an issue, but it is easy enough to try a direct connection and see how much current flows before adding a DC-DC charger.CharlesinGA wrote:
Do it right and install a DC to DC charger between the vehicle charging system and the Lithium batteries, and your problems are solved. that is what they are designed for. Lithium connected directly to a alternator charging system will fry the alternator.
The video linked to in the first post is a very good one and while one way (usually on boats) of controlling the charge, the DC/DC works well without messing with hugely expensive alternators custom fitted to a vehicle. New vehicles have computer controlled alternators and none of this plays well with lithium in the house battery box.
Charles
I've put over 6,000 trouble free miles on a standard MB Bosch 220A smart (internal fan, internal regulator) alternator charging 2 X 100Ah Relion RB100-LT batteries, with no additional hardware to do anything in between the charging source and the lithium targets. In varied ambient temperatures and at varied engine RPMs, at varied SoC, including some idling.time2roll wrote:
Most any RV situation the amps will be limited by the wire connecting the alternator and battery.
Yep, unless you do an upgrade like this- In many cases there will be no issue with the alternator. I have had various LiFePO4 setups over the past 10 year, and never had an issue with overloading the alternator. The wiring, breakers and ACR between the alternator and batteries provides plenty of resistance to limit the current to the battery bank.
In specific cases with higher voltage alternators and very large gauge wiring, there could be an issue, but it is easy enough to try a direct connection and see how much current flows before adding a DC-DC charger.CharlesinGA wrote:
Do it right and install a DC to DC charger between the vehicle charging system and the Lithium batteries, and your problems are solved. that is what they are designed for. Lithium connected directly to a alternator charging system will fry the alternator.
The video linked to in the first post is a very good one and while one way (usually on boats) of controlling the charge, the DC/DC works well without messing with hugely expensive alternators custom fitted to a vehicle. New vehicles have computer controlled alternators and none of this plays well with lithium in the house battery box.
Charles - My alternator goes through 2 40 amp breakers and then to the battery isolator before going to the batteries so it should be OK.
- Do it right and install a DC to DC charger between the vehicle charging system and the Lithium batteries, and your problems are solved. that is what they are designed for. Lithium connected directly to a alternator charging system will fry the alternator.
The video linked to in the first post is a very good one and while one way (usually on boats) of controlling the charge, the DC/DC works well without messing with hugely expensive alternators custom fitted to a vehicle. New vehicles have computer controlled alternators and none of this plays well with lithium in the house battery box.
Charles - The dummies today use Ford alternator fans on all early GM AND ford small case ALTS. I'm glad to be retired. Today, use the wrong part # reg and the ECU faults limp home.
- Seeing that alternator smoke reminded me, about 40 years ago I cobbled a Delco 10si alternator to a chainsaw engine to power 6 automotive high beam headlights to night fish at the Texas City Dike. That alternator lasted about 15 minutes before it smoked.
- Look at the wiring in newer vehicles and it is a full 3 AWG larger than those ten years older. A 120 amp genuine not a toy breaker is less than .2 volt at full load. BMS are dedicated to lithium technology.
Nippensenso ND is said to be hot on the trail of Silicon Carbide rectifiers controlled by a processor unit. For use on electric cargo trucks used on regenerative braking which is a huge stumbling block because of engine exhaust brake elimination.
Any voltage loss in excess of a half volt at full alternator output is considered by me to be a design failure. I have had to use full 4/0 charging cable on several motorhomes with rear engines and front mounted batteries. My bus has 4/0, the gen shed uses 330MCM cables which are almost twice the diameter of 4/0. I used split 3/4" garden hose to pass the cables within the frame rails of pusher motor homes. There are button end cable ties with the once inch diameter button to secure stuff to the channel of a frame rail that has a hole. time2roll wrote:
Most any RV situation the amps will be limited by the wire connecting the alternator and battery.
Exactly! This is yet another instance of an edge case being way overblown on internet forums. The setup in the video is not representative of a real world vehicular application.
It is true that a lithium battery can draw more current than an alternator can supply (it is also true for lead acid) but in most situations it is not a problem due to the resistance of the wires, breakers, relays and BMS.- Seems the easy way is to separate the Li and lead acid banks. Have the alternator charge the lead acid bank then use a dc to dc charger to charge the Li bank
