Charging Lithium batteries with non lithium charger (my experience)

Yoshi_TAB

Hi,

Just want to pass on some info. that may or may not be helpful for those moving over to Lithium batteries and are considering not changing out the non lithium  charger /converter.  I have two  lithium batteries and did not change out the WFCO 8735P (stock for lead acid) in a 2021/320.  I always read that the WFCO will not charge the lithium batteries to 100%.  I have found that my WFCO 8735P does consistantly charge my two x 105 Ah lithium batteries back to 100%, every time although slow.  This is measured with a shunt.  But I have to “fake it” into charge mode by turning off and  on both the battery switch and shore power at the same time.  When that is done, it always starts the charger and takes the batteries to 100%, every time. If only one is turned off, it does not kick on the charger.    Without turning both off/on, the charger will never go into charging mode I think because the voltage of a discharged lithium battery is still higher than a discharged lead acid battery and the WFCO does not detect a low enough voltage to go into charge mode.    Here is the charging data I've seen on a multiple occasions.  This is with the solar charger turned off.  So, after boondocking and back home you may be able to get your lithium batteries back to 100%  and you are not in a hurry.  It maybe worth checking before changing out your equipment and slow charging works for you.  I understand that solar and/or an external charger gets you to the same place…maybe faster.  Just another option that may work for others. And occasionally charging with a lithium designed charger helps to balance the cells.  Below is some data, but I’ve had the same success start at 60% SOC.  The voltage was measured at the converter output on the WFCO (the vcc connection point). The 13.67 is at the resting stage.

Happy charging.... 

Time                    SOC (%)     Current (A)     Voltage (V)
T0                        80            0                     13.27
T  1 hr 15 min.     83            5.85                13.49
T  2 hr                  85            6.26                13.50
T  4 hr  30 min     92             6.00                13.51
T 5 hr   30 min     94             5.82                13.51
T 6 hr   30 min.    97             5.14                13.51
T7 hr    30 min.    99             4.43                13.53
T 7 hr    45 min   100            4.34                13.55
T  8 hr                 100           2.91                 13.58
T 8 hr   15 min     100           0                     13.67

AnOldUR

If you turn off the battery switch and solar charging overnight, does the voltage stay at 13.67 or settle to a lower number?

Yoshi_TAB

Hi @AnOldUR

Update;

GM ; After 24 hrs with battery switch off (and solar off) it remained  at 13.68




I believe it does, but I will double check.  Just posted to let others know it may work for them.  I know the WFCOs can be finicky.  My WFCO will never start a charging cycle (for the lithiums)  no matter how low the SOC is.  It worked fine for LA.  I’ve emailed WFCO but never get a direct answer (other than to switch out chargers which I do not plan to do) to as why it won’t start a charge cycle …as I said I’m guessing because the lithium does not get below the threshold voltage to kick on the charger.  

SLJ

I didn't change out the converter on my 2021. Instead I added a Victron smart charger and put the batteries on a switch to turn them off when using shore power. The Victron charges them to 100% and then floats correctly. Cheaper, easier, and a better charger than the WFCO. https://amzn.to/3EkOZ63

GregChris

There a couple you-tubes on this, sorry I can't link them, but a search will find them. One is from wfco and is about auto detect, and why it does work eventually. The other is changing the wfco to an auto detect unit in a 320s. The 8735-ad is an exact replacement and doesn't seem impossible with a little patience. Maybe a couple of hours  and some before photos for correct wire placement. The WFCO 8735-AD is around $170  on Amazon.

dsfdogs

@Yoshi_TAB You would still want to use a lithium compatible charger like a Noco Genius 10 to periodically charge your batteries with 14.4-6 volts to rebalance your batteries. The easiest way was to buy the adaptors and plug it into the solar port.

Yoshi_TAB

@dsfdogs,

Understood…Tks Buried in my original post I  mentioned that.  I have a lithium charger…I just posted some results I stumbled on ..for some reason my WFCO will charge the batteries to 100% where I never see that mentioned, always just 80-85 percent or there abouts…happy charging.

dsfdogs

@Yoshi_TAB I was able to charge mine single Battle Born to 95% over night, but didn't do to unplug/turn off method you do. Thanks for posting your results.

N7SHG_Ham

Did you reprogram the shunt for lithium to properly display the correct SOC?

Yoshi_TAB

N7SHG_Ham said:

Did you reprogram the shunt for lithium to properly display the correct SOC?

Hi, Yes I did.  Both the shunt and solar.  I’ve verified with a  multimeter 

tombeaux

I installed a WFCO 8740AD and had nothing but trouble getting it to switch to lithium mode and then stay in lithium mode. I have seen all the videos produced by WFCO and others on the tricks to make it work and they have not been successful. I worked with WFCO technical support and sent the unit back to them for a firmware update (it takes time to remove and reinstall, of course). Counting ground shipping each way, I was without the unit for 3.5 weeks. They would not just send me a new one with current firmware with a return label for the faulty one. The new firmware did not fix my issues. I tried using battery cables to see if my wiring was an issue. Didn’t work. I finally just ordered a Victron IP22 charger (as others here and in other forums have suggested). You physically select lithium mode through either the mode button on the charger or the App and it does a beautiful job. You can even select “night” mode while you are sleeping to reduce the charge power to no more than 50%, which keeps the fan off. I know the auto detect works for many, but there are also plenty who have had issues. If I was starting again with the switch to lithium, I would keep my old controller and take care of the charging with the Victron unit. My second choice would be a controller with a switch for lithium mode rather than auto detect.