[Tcaschy021]

For those of you that have a Renogy DC DC charger, do you happen to know if the charger starts charging the house batteries at a certain voltage or percentage?

Reason I ask is, I had this wired in my setup for a few months and used it on a previous trip. At that time the batteries were around 40% according to my shunt-type battery monitor. Worked great, charger charged batteries up no problem. Tonight took the van for a spin, monitor said batteries were at 85% however when I manually turn on the charger, the monitor immediately goes to 100% and doesn't show any current flowing into the batteries. I'm wondering if my monitor is off or if the charger took a dump? Thoughts?

 

[mikeehlert]

What type batteries? Do you have a multimeter? What is the battery voltage?

You need this info to trouble shoot.


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[Tcaschy021]

lithium, 2x100 battleborn
yes I have a multimeter
battery voltage is like 12.8 or so now since its cold here but as soon as I switch on the renogy charger it shows 14.4v

my dip switch settings for the charger are as follows SW1-SW5 Off, On, On, On, Off

Like I said, it worked fine once but that was under different conditions.

 

[mikeehlert]

12.8 for your batteries is fully charged?
14.4 is standard charging voltage, says your charger is charging. Does your monitor show charging current?
IDK the setup on your charger but are the batteries too cold and the BMS preventing charging.


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[Tcaschy021]

12.8 for your batteries is fully charged?
14.4 is standard charging voltage, says your charger is charging. Does your monitor show charging current?
IDK the setup on your charger but are the batteries too cold and the BMS preventing charging.


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Thanks for making me think ...and of course I think I might be dumb here.

No 12.8v is not fully charged. Frankly I'm not 100% sure what voltage is 100%. I even reached out to battleborn to get this info and they said you cant put a measure of battery percentage based upon lithium voltage?
OK I think you are right, i think it is charging and I believe the monitor is messing with me. The monitor has a HIGH voltage setting and I forgot what I set this to when I initially set it up a few months ago. My guess is I set it to 14.2 or something and so that is why its showing 100% when in actuality its actually charging.

 

[JeffWest]

Thanks for making me think ...and of course I think I might be dumb here.

No 12.8v is not fully charged. Frankly I'm not 100% sure what voltage is 100%. I even reached out to battleborn to get this info and they said you cant put a measure of battery percentage based upon lithium voltage?
OK I think you are right, i think it is charging and I believe the monitor is messing with me. The monitor has a HIGH voltage setting and I forgot what I set this to when I initially set it up a few months ago. My guess is I set it to 14.2 or something and so that is why its showing 100% when in actuality its actually charging.

It very well could also be the BMS's of your Battlerborns protecting themselves. They will NOT charge below 25 degrees F internal but will allow passthrough voltage at their 14.4.
I know because I've seen something very similar on my shunts. On mornings cold enough to be below 25 but not cold enough for me to turn on my battery warmer -- I'll get solar generation before my own Battleborn warms up...It'll present as full charge at 14.4v even though I know it isn't. Once the battery warms up the "actual voltage" will return and the battery will start charging.

 

[Tcaschy021]

It very well could also be the BMS's of your Battlerborns protecting themselves. They will NOT charge below 25 degrees F internal but will allow passthrough voltage at their 14.4.
I know because I've seen something very similar on my shunts. On mornings cold enough to be below 25 but not cold enough for me to turn on my battery warmer -- I'll get solar generation before my own Battleborn warms up...It'll present as full charge at 14.4v even though I know it isn't. Once the battery warms up the "actual voltage" will return and the battery will start charging.

Ahhhhhh the bms! Didnt think of that. Thank you

 

[Tcaschy021]

Just an update on this....

Went out today, started the van, flicked on the Renogy charger and voila working fine. Took my laser temperature gun to the batteries and it measured 35°F. So I'm guessing it had to do with the BMS kicking in based upon the cold temps we've been having the past few days vs today's balmy 40°s. Thanks mikeehlert & JeffWest

 

[gypsy brewer]

Sounds like the BMS saved your LiFePO4 batteries!

 

[JeffWest]

Just an update on this....

Went out today, started the van, flicked on the Renogy charger and voila working fine. Took my laser temperature gun to the batteries and it measured 35°F. So I'm guessing it had to do with the BMS kicking in based upon the cold temps we've been having the past few days vs today's balmy 40°s. Thanks mikeehlert & JeffWest

Glad to read it's all working again! The Battleborn BMS's are flipping awesome like that! I made a battery jacket to keep ours warm when winter boondocking but knowing it isn't a crisis to forget is so comforting...given how expensive they are

Cheers,
Jeff

 

[Tcaschy021]

Glad to read it's all working again! The Battleborn BMS's are flipping awesome like that! I made a battery jacket to keep ours warm when winter boondocking but knowing it isn't a crisis to forget is so comforting...given how expensive they are

Cheers,
Jeff

I msgd you about the battery jacket.

 

[gypsy brewer]

I msgd you about the battery jacket.

The DIY Solar Forum has several good discussion threads on battery warmers if you're interested.

 

[JeffWest]

The DIY Solar Forum has several good discussion threads on battery warmers if you're interested.

I had replied to Tchashy021 with a detailed pm about my setup -- but agreed -- diy solar is a good resource.