Possible Battery Damage

[richardbrennan]

For reasons I will not bore you with, virtually everything electrical was switched on at once on the boat today including radar, the plotter, the all the nav lights and even the eberspacher. This resulted in a low voltage warning from the plotter which was perhaps not surprising, the batteries are AGM deep cycle domestics, there's a different high demand battery for engine starting.

My question is was the low voltage warning to be expected from these batteries under the circumstances, and might this sudden but short lived high demand have done any permanent damage?

 

[padge]

Very unlikely any damage was done .

even deep cycle batteries can safely produce V large current for a short time

The low voltage warning is normal

 

[halcyon]

For reasons I will not bore you with, virtually everything electrical was switched on at once on the boat today including radar, the plotter, the all the nav lights and even the eberspacher. This resulted in a low voltage warning from the plotter which was perhaps not surprising, the batteries are AGM deep cycle domestics, there's a different high demand battery for engine starting.

My question is was the low voltage warning to be expected from these batteries under the circumstances, and might this sudden but short lived high demand have done any permanent damage?

How long were they running before the alarm ? what size battery bank ? it sounds a bit like a charging problem producing low capacity, or just to small a battery bank.

Brian

 

[richardbrennan]

We have 200 amp hours domestic and 100 amp hour engine batteries, the load was reduced almost immediately. Our concern is that the charger may be faulty, it had been on continuously for well over a week with no loads so we were a bit surprised that we got the warning as the batteries should have been 100% charged.

 

[Mistroma]

Quite possible that battery voltage wasn't that low when the alarm went off. The plotter is likely to read voltage after battery connectors, cabling, isolation switches and various connections. Bad connections will result in a fair drop in Volts and it might be worth checking with a meter to see if this is happening.

Alarm on panel in my boat went off due to a poor contact inside battery isolation switches. However, Smartgauge showed much higher voltage at the batteries. I think the difference was around 0.6V and dropped to 0.1V after a temp fix to clean the contacts a bit (by flipping the isolators on/off rapidly a few times with everything turned off).

 

[halcyon]

We have 200 amp hours domestic and 100 amp hour engine batteries, the load was reduced almost immediately. Our concern is that the charger may be faulty, it had been on continuously for well over a week with no loads so we were a bit surprised that we got the warning as the batteries should have been 100% charged.

What you need to do is get some data, what voltages do you get at the battery charger, and at the batteries when on charge ( gives indication of bad connection ), before switching on load check voltage, then monitor load, the time and voltage to reach say 12.2 volt on load.

Gices a basic idea of the system.

Brian

 

[lpdsn]

For reasons I will not bore you with, virtually everything electrical was switched on at once on the boat today including radar, the plotter, the all the nav lights and even the eberspacher. This resulted in a low voltage warning from the plotter which was perhaps not surprising, the batteries are AGM deep cycle domestics, there's a different high demand battery for engine starting.

My question is was the low voltage warning to be expected from these batteries under the circumstances, and might this sudden but short lived high demand have done any permanent damage?

Assuming the battery was in good condition and fully charged when you switched everything on, my first suspicion would be an excessive voltage drop in the cabling.

Do you have a voltmeter/multimeter? Can you repeat the situation after charging the batteries again, then see what voltage there is at the batteries and what voltage there is at the chartplotter?

If there's quite a difference then the chief suspect is your cabling. Either it simply isn't beefy enough for the length of run, or you have a poor connection somewhere with higher resistance than it should have.

 

[richardbrennan]

The cabling could probably do with beefing up, we had to do this with the cabling from the engine battery when we had a new engine fitted so perhaps it's a job for the winter. However, we still have concerns about the charger which is supposedly of the "smart" variety and also serves as the mains distribution panel for the AC with switches for the ring main and the immersion heater. I'll take some readings as halcyon has suggested.