Houseboat build: Server rack w/ or w/out heat

[PlainJay]

First time posting and most likely several more to come. I am designing an off grid system for a large aluminum hull houseboat (located in Southern KY). I would like to use 48v server rack batteries matched with 2xEG4 6000xps. The storage location for the batteries will be in the front hatch. It will be dry, but not temperature controlled. The off-grid system will rarely be used when the air temperature is below freezing. Is it sufficient to use batteries with just low temperature protection? Or should I use batteries with heaters? If heaters, is there a preferred brand based on experience? Thanks, Jay

 

[IGBT]

Is it a pretty tight budget? I would consider the Epoch 48V marine battery, as it is on sale right now for $1799 - 10% = $1620. They have a built in heater and are quite water resistant. I am pretty sure they are made by Roypow for Epoch.

 

[HarryN]

Water craft are subject to a lot of vibration from waves.

Server batteries are designed for stationary / low vibration applications.

Most likely your main challenge will be keeping them cool enough vs warm enough.

 

[Suijkerbuijk]

Water craft are subject to a lot of vibration from waves.

Server batteries are designed for stationary / low vibration applications.

Most likely your main challenge will be keeping them cool enough vs warm enough.

Cool is not the problem.
Its more like how to warm them up for the winter use.

See attach files
Boat in side vs the spot ware the battery are.
Yes its my boat.

 

[SparkyGage]

Throwing this out to make sure the relevant points are addressed:

1) This sounds like a 60'+ flat hull house boat and probably weighs in excess of 28000lbs and a top speed under 10mph, so vibration will be minimal unless you run the motors wide open for an extended period, in which case you'll have hull damage before long. If you have enough vibration to damage the batteries in the nose, the motors are damaging their mounts. Putting your rack on rubber isolation would protect it from what limited vibration it would encounter. The sudden jar of a large wave hitting broadside would be my biggest fear but if you don't have a problem with things in your fridge and cabinets falling over, that's likely not a problem. (My dad had a 60' Stardust Cruiser for several years and a steel hull River Queen prior to that).

2) You are on a lake which is a big thermal battery:
- How often does the water at the slip/marina ice over?
- How often does ice or frost form on your covered areas above that hatch?
- Have you ever had liquids in that hold freeze or form ice crystals
- Has your fresh water tank ever had a problem with freezing?
- Does this area typically have sub 32F temps for more than 72 consecutive hours?

If the answers to all of questions in 2) are NO or ZERO you probably don't have to worry about freezing. Even with the air temps at freezing the thermal mass of the lake will radiate through the lower part of the hull and deck and keep the holds above freezing. (Dad's boat spent a week at or below 30F, getting down into single digits at night, and nothing in the holds froze.) You can probably find out from the the agency that manages the lake to learn what the lowest average water temp is. At your latitude, I doubt anything below the surface inch gets below 40F.

If the answers to any part of 2) is YES or NOT ZERO, you will probably need some means of heating that I'll let others address.

Hope this helps.

 

[PlainJay]

Wow, thanks for the great information! This boat will not have an issue with vibration (18x wide x 92 ft long, top speed ~7mph, aluminum hull, will spend 98% of its life not under power but rather in the dock or beached), but really appreciate the consideration to eliminate that variable. Batteries will be in a front hatch that is 18 feet wide by 14 feet long so plenty of air for cooling. Summer water temps are ~87 F and it will be well protected from direct sun.

For the heating questions, the lake temp rarely gets below 38-40 F. We have never had issues with liquids freezing in the holds. The air temp will drop below for 32 F for several days, but the thermal battery of the lake temperature seems to overpower that inside the aluminum hull.

If I do go without heat and the battery temps fall below 32 F for a few days AND they are not being used (on float charging), what is the problem you foresee? I assume the BMS will shut off charging until the temps rise (they do have temp protection). Thanks again, Jay

 

[chrisski]

If I do go without heat and the battery temps fall below 32 F for a few days AND they are not being used (on float charging), what is the problem you foresee? I assume the BMS will shut off charging until the temps rise (they do have temp protection). Thanks again, Jay

Assuming the BMS has temp sensors it would shut it off. Battery could discharge less than 32, depending on the battery maybe 15F, just can't charge. If the battery is used within those specs no problem. Just would need to warm up prior to use.