How long do you run your eberspacher off the batteries

[slipknot]

I dont have mains electric or generator at my mooring. Assuming you can get the thing started from the batteries, how long would you expect to be able to run it from a single 85ah battery? A couple of hours? overnight? couple of days?

Appreciate that this is one of those 'how long is a piece of string' questions but I would appreciate any words of wisom.

 

[cliff]

Overnight. unit draws 20A to start then around 3~4 amps running so I would expect around 10 hours running (overnight)

 

[flawed_logic]

What's the draw of the unit? You can then work it out, this might help
http://www.fridge-and-solar.net/amps.htm

 

[photodog]

Overnight. unit draws 20A to start then around 3~4 amps running so I would expect around 10 hours running (overnight)

We had 150 ah of domestic.... If I ran the heater overnight even at a low setting the battery was crapped out...

The problem is that there are usually other power draws... The battery may not be fully charged to start after a few hours sailing... Etc etc..

I simply do not in the heater now for any extended period unless we are on the mains...

I would be surprised if the op got more than 4 hours out of a 85ah battery in real life...

 

[TopDonkey]

I think you should be able to squeeze about 10 hours running out of it, possibly 12 if running on low, but if you turn the heater off after more than 4 hours running, i doubt you would have enough power to restart it as the start-up current causes a big sag in the voltage on a smaller battery and can make it cut out

 

[Pye_End]

Appreciate that this is one of those 'how long is a piece of string' questions but I would appreciate any words of wisom.

Mine takes 7A at start up and 2A max, but in anything but the middle of winter this gets turned down to 1A or less fairly quickly - less current than a pre-LED ticolour. So this could probably keep going for a whole night on a reasonably fresh battery without any problems, although really all you need is to go to bed warm, and maybe switch it on when you get up (plus a good thick sleeping bag).

So, yes, I agree, it depends...

 

[Mudisox]

I always run the engine on startup and then my bank of 190aH takes over. The heat is sufficient to want to turn it off after an hour or so. Alongside with shore power, use the fan heater.

 

[James_Calvert]

Overnight for one of my pair of 75Ah batteries. But at this time of year I'd want to have run the engine recently to make sure both were charged up.
No fridge or other major draws on the battery apart from occasional lighting.

 

[Dockhead]

It depends on how much volume you need to heat, what is the heat loss, outside temp, and, obviously capacity of your batts.

However, I would not run mine overnight in any case without charging in the morning.

An alternative to running it overnight is to sleep in a warm sleeping bag with it switched off, set the timer to come on an hour before you plan to get up.

 

[dunedin]

I always run the engine on startup and then my bank of 190aH takes over. The heat is sufficient to want to turn it off after an hour or so. Alongside with shore power, use the fan heater.

+1

I learnt this trick also from this forum. If the voltage is too low it simply fails to start, which could be chilly. Starting the engine first often sorts this, then switch off again when fully running. Thanks forum for keeping us warm

 

[BlueSkyNick]

As said, it depends on the size of the unit and level on the thermostat, but there are two other factors in my view.

- It is not good to discharge batteries to less than 50%, 30% at worst.
- I am paranoid about a major heat source on board, and dont leave the boat unattended while it is running, nor would we turn in for the night without turning it off at the last minute before bed.