Carbon Foam AGM Batteries

[Scalf77]

Originally Posted by Klompen

Scalf77 - It was not my intention to imply that Battleborn is making claims that their Lithium batteries are a "drop-in" replacement. I only meant that Battleborn's protection circuitry means that I can mount their batteries in the same external rack where my 200Ah AGM battery is currently located. There is a lot more to consider before I would pull the trigger on such a system change.

I got "Drop in Replacement for Lead Acid Batteries" from their web page, about 8th bullet down, not your post. I apologize for the confusion.

-greg

[Klompen]

Originally Posted by Scalf77

I got "Drop in Replacement for Lead Acid Batteries" from their web page, about 8th bullet down, not your post. I apologize for the confusion.

-greg

That's cool, Greg. I haven't looked at their page much. I know Battleborn mostly from discussions with Northern Arizona Wind & Sun about the power system in my SMB. They are local to me and very highly regarded by the build-your-own conversion community. NAWS thinks very highly of Battleborn.

[1der]

My only issue with lithium batteries is usage and charging below freezing. This is important to us because we do lots of winter camping. The copy below is from a post by a Battle Born engineer on airforums.com -
Link: Battle Born LiFePO4 batteries - Page 3 - Airstream Forums

Note: I also spoke to Dennis at B.B. today about the below freezing issues, very helpful and straight forward discussion. They have some ideas in the works for battery cases which incorporate heating elements into the BMS. External heating pads are 15w draw from the battery itself to keep the battery above 30 deg. It will be interesting to see what they come up with.

In the meantime, below floor rack mounted Li batteries will be challenged with below 30 temps.

Below is mentioned post from AirStream forum:
“Li-ion batteries operate based on the diffusion of Li-ion through an electrolyte. Since diffusion slows down in cold temperatures, there are some general limitations when it gets cold. When the internal battery temperature is freezing (32F) battery capacity falls to around 80-85% of full capacity. The capacity continues to fall to around 60% when the temperature falls to 0F. HOWEVER, the bigger problem occurs when you charge a Li-ion battery below freezing. The slow Li-ion transfer into the anode during charging could cause Li metal to plate the anode, and this could cause an internal short. The Battle Born battery has an internal protection mechanism that prevents charging when the internal temp falls below 25F, and reconnects when the temp rises above 30F. Discharge is always allowed at low temp.

The high temperature operation is not as restrictive. As long as the internal battery temperature stays below 170F (that is when the battery separator begins to melt), then you are OK. The Battle Born battery prevents charge and discharge when the internal battery temperature rises above 140F.

For long-term storage, the main thing is to avoid freezing of the electrolyte (sub-zero) and melting of the separator or thermal degradation of the MOSFETs on the battery management board at high temps. The acceptable temperature range is very wide. 0F to 100F is fine.”

[Klompen]

Very interesting stuff about the BB Lithium Ion batteries and freezing temps. I knew about the BMS preventing charging when it isn't safe, but I'm wondering if having your rig plugged in to shore power will maintain battery temp because it applies a float charge as needed. That's my situation - I don't camp when it's that cold, but my rig is parked at my house at 7,000 feet where it snows regularly in winter. I wouldn't want to damage the batteries during winter storage.

[1der]

My semi-educated guess is “float” will do nothing to maintain battery temperature. Your scenario would point to an insulated box and external heating elements to warm the batteries enough to get them above 30 degrees. Then any needed charging would be accepted by the BMS.

Plugged in you have an acceptable scenario since the ~1.5Ah draw can be compensated for. The NOT plugged in, or solar is unavailable scenario starts to create a potentially untenable condition because the ~1.5Ah draw means the batteries will be depleting themselves to stay warm and “be ready” to accept a charge. So, perhaps 36 Ah are drawn down per 24hrs to keep the batteries warm and ready if the sun comes out. Add whatever other draws are present and 60Ah can be used on a day of no sun and freezing temps. In two days 100Ah of capacity is depleted.

Dennis described an internal / integrated heating system they are hoping to achieve which would have a 5w draw vs 15 to 18w for the external pads. Hope they figure it out.

[r27d]

It seems these are great tech but impossible to get. I've called the manufacturer and they only have voicemail. I also called two distributors who stated that they have lots of backorders for $$$$ yachts and that orders for one or two batteries is likely not possible but they're hoping to start filling their backorders at the end of August.

[Twoxentrix]

Originally Posted by r27d

It seems these are great tech but impossible to get. I've called the manufacturer and they only have voicemail. I also called two distributors who stated that they have lots of backorders for $$$$ yachts and that orders for one or two batteries is likely not possible but they're hoping to start filling their backorders at the end of August.

This issue in itself speaks for the product, they have become very popular with the Boating community. No idea where you are located, but I have 8 Marinas within 2 blocks of me and many of these facilities carry the batteries (on the East Coast unfortunately). If you're close to the Coast, have you tried contacting Battery Shops near Marinas (as well as full serve Marina's themselves)? ...you may have better luck.

[r27d]

Originally Posted by Twoxentrix

This issue in itself speaks for the product, they have become very popular with the Boating community. No idea where you are located, but I have 8 Marinas within 2 blocks of me and many of these facilities carry the batteries (on the East Coast unfortunately). If you're close to the Coast, have you tried contacting Battery Shops near Marinas (as well as full serve Marina's themselves)? ...you may have better luck.

I'm in Minnesota for the summer but we have some ok marinas on Lake Minnetonka and the St Croix river. I'm also heading to Oshkosh WI for EAA next week so perhaps I can find them near Lake Michigan and there are yacht builders up by Green Bay. I'll make some more calls. Thanks for the suggestion!