DC to DC Charge Controller for Lithium Batteries

[cadillackid]

Originally Posted by Rock-N-Ruth

We have considered the diesel heater and it's not completely of the table. This winter was the first with under battery heat and that was a game changer.

does battery heat allow the packs to reach a higher SOC? or gives you more useable Watt hours if they are tempered?



I can imagine it getting warm fast if under the bed.. me personally I like to sleep cool but want it summer-warm during the day...



im assuming all your water is also under the bed too? so you can essentially let the rest of the bus get as cold as it wants and you are still warm in bed? seems like a huge energy saver for sure

[Rucker]

Originally Posted by Rock-N-Ruth

Tom,
Getting 16 400W panels on the roof of your 37 foot bus might be a pretty interesting feat. The 327w panels we use are 61"×41". We have 12 on the roof. We can fit 2 more. If we wanted to get to 16, at least 2 of the panels would have to retract.
<snip>

Remember branches will most likely hit the passenger side of the bus so if you have anything mounted up there, might help to put a tattle or some kind of deflection.

[TaliaDPerkins]

Originally Posted by Rucker

Remember branches will most likely hit the passenger side of the bus so if you have anything mounted up there, might help to put a tattle or some kind of deflection.

As heavy a steel sheet as I can manage will be covering them while in transit, and a ramp to help things skip over them.



Thank you.

[john61ct]

Warming LFP batteries allows them to be charged

at all when ambient gets close to freezing, slow rates until they get up over 70°F

faster, say 0.4C if ambients are below that

1C even higher if you get them hot, maybe up to 110°

[cadillackid]

Originally Posted by john61ct

Warming LFP batteries allows them to be charged

at all when ambient gets close to freezing, slow rates until they get up over 70°F

faster, say 0.4C if ambients are below that

1C even higher if you get them hot, maybe up to 110°

Interesting .. I always noticed when I had my Chevy.volt that in cold winter it seemed to take forever to charge if it was outside and not in the garage . If I remembered to plug it in right after driving it then it charged fast but I usually forgot till I checked the app before bed and saw it wasn’t so I’d plug it ion and the “full “ reminder came at a longer time .. makes sense as that was some type of lithium pack

[john61ct]

Heating film in an insulated battery box is pretty much required for very cold locations.

And standard in higher end EVs.

Reduces range once off grid of course

[Rock-N-Ruth]

Originally Posted by cadillackid

does battery heat allow the packs to reach a higher SOC? or gives you more useable Watt hours if they are tempered?

The only thing battery heater does for the batteries is prevent the batteries from being damaged by being charged when they are at or below freezing.
We don't use low temperature cut off to prevent low temp charging, which will damage LFP batteries. Instead we just never let them get cold.

We placed the battery bank on a sheet of 2" XPS then laid a 45W underfloor heating pad. A 1/8" sheet of compressed hardboard, then batteries. We put 2" XPS around the batteries and left it open on the top.

The battery heater turns off if the underside of the bed reaches 80 degrees F. And turns back on at 50 degrees F.

During the warm months it is just off.

Also realize that the batteries themselves generate heat when they charge and discharge.

As for water under the bed, no room there. The battery bank is made up of 6 BYD 24V batteries that came from a commercial solar farm. Each battery is about 24" tall 21" wide and 9" deep. With the Insulation they occupy most of the space between the wheels.

[Rock-N-Ruth]

Originally Posted by Rucker

Remember branches will most likely hit the passenger side of the bus so if you have anything mounted up there, might help to put a tattle or some kind of deflection.

We have a bit more tha 12,000 miles with the current configurations. We haven't had any trouble with branches. Although we are aware and avoid residential neighborhoods.