Originally Posted by folivier
Here is a picture of the installed cells in the compartment where there was a rack with 4 8D size lead acid batteries.
Im detailing the install on this forum: Lithium battery install
For balancing the best tool I have found is a bench top power supply. The Mastech EX series is about the best value. I have a Mastech 3030EX and a 3050EX..
For balancing in a motor
home I would think you would be similar to a boat and would want to top balance.
A trick I use is to wire the pack in series
then charge until the highest cell hits 3.8V then STOP.
Now break them out of series and wire them in parallel
. Let them sit for a day or two and then charge the entire pack to 3.8V as measured at the battery terminals. When in parallel they will self balance but this takes TIME. As the cells balance become closer and closer less and less current flows between cells and it can take time for them to become balanced.. Allow the current to stop dropping, or moving downward, at 3.8V but do not go above 3.8V as a parallel
I honestly don't know how anyone could own Li cells and not own a bench top power supply but folks do. They just make life so much easier. Once you own one you will like never use a standard charger
again for tinkering, set up and testing.......
The reason to charge in series
first, until the highest cell hits 3.8V, is because you will only be charging a 1000Ah pack. It will still take a LONG while. While below 14.4V or so you can parallel all the chargers you want to get more current and speed the process. But do watch the individual cell voltages because when they hit the upper knee they can hockey stick, and it happens rather suddenly..
When you break them down and wire them in parallel
you are now charging a 3.2V 4000Ah pack and even "finish balancing" the pack can take days, even with a 50A power supply....
Set the max current of your power supply to about 10% less than its rating. For a 50A supply they run well at 45A etc.. It will run cool and can do this for days on end.
Originally Posted by Foliver
On gel setting now. That is what Balqon recommended.
Good point! I'll set it for lead acid (only have LA or gel settings) then I can use the ambient temp setting to bring it down a bit if it's too high.
I think part of my problem is the inverter is reading 0.4 volts higher than the Victron monitor and battery.
Where is the link sensing voltage? This is CRITICAL! If it voltage senses anywhere other than the positive battery & negative terminals, and the shunt should be VERY close to the neg terminal, than you will get inaccurate readings especially when pushing the inverter hard.
The Link 2K's are also now VERY, VERY old and have a tendency to drift...
One thing I have learned is that voltage sensing is critical in Li batteries. Voltage must be sensed at the battery terminals or a risk of over charge or poor charge performance is possible.
You are going to want a LARGE alternator and MC-614 regulator. This regulator has a dedicated voltage sense wire that carries nothing but voltage and it also allows current limiting of the alternator to protect it.. The v-sense wire on the 614 does not power the reg or do anything but sense voltage, thus accurate readings. The ARS 5 uses the power wire to power the reg and sense....
For most chargers they have no means of sensing voltage other than through the cables
you are pushing 100A through, and this results in INACCURATE readings to the charger. If you go all the way to full the batt term voltage and charger voltage will eventually match up, you need current for voltage drop, but when in bulk, which you are most of the time, the voltage will usually be off.
As an example if your inverter is pushing 100A and you have it set for 14V but the actual battery terminal voltage is 13.7V the charger will begin limiting current because it is technically limiting the voltage to 14.0V and that is what the charger is seeing
. The batteries can
take the full amount but the charger thinks they are at absorption voltage thus starts cutting back current to maintain the voltage. You will still get decent output but usually not full output....
For the fastest charging of Li it is critical that you are properly sensing voltage. I am going to guess your alt is suffering from the same problem?