Battery Check

S

Sailfree

Well-Known Member
Joined
18 Jan 2003
Messages
21,672
Location
Nazare Portugal
Visit site
I have 4 x 125AH batteries that were new in Jan 2005 when they came with the new Jeaneau.

They are sealed and i accept they owe me nothing. Boat is a charter boat (kept in marina) so in emergency all battery banks can be joined to start engine. No hint of trouble yet.

I was going to leave them over winter lift out for 3 weeks without charge and check voltage but boat is now going in after 1 week and I did not isolate batteries.

Is there a simple to check them? I don't want to buy 4 new ones for the sake of it.

To my simple mind I am thinking of waiting for a 2 week window with no bookings, disconnect the batteries and note voltage and leave isolated and check voltage again say after 1.5 to 2 wks. If any have dropped to say below 11V replace the lot.

Anyone with a better idea and no I am not going to discconnect them and lug them to a battery shop for load test - if I go to that bother I would replace them while they are out!!!
 
Sailfree said:
I have 4 x 125AH batteries that were new in Jan 2005 when they came with the new Jeaneau.

They are sealed and i accept they owe me nothing. Boat is a charter boat (kept in marina) so in emergency all battery banks can be joined to start engine. No hint of trouble yet.

I was going to leave them over winter lift out for 3 weeks without charge and check voltage but boat is now going in after 1 week and I did not isolate batteries.

Is there a simple to check them? I don't want to buy 4 new ones for the sake of it.

To my simple mind I am thinking of waiting for a 2 week window with no bookings, disconnect the batteries and note voltage and leave isolated and check voltage again say after 1.5 to 2 wks. If any have dropped to say below 11V replace the lot.

Anyone with a better idea and no I am not going to discconnect them and lug them to a battery shop for load test - if I go to that bother I would replace them while they are out!!!
Click to expand...

I would charge them (separately if possible in case a duff one is affecting the charge to the rest of the bank). Let them rest for 12 hours with no load and no further charging) Any that you cannot get above a rested figure of 12.7 volts are suspect.

Allow to stand for a couple of weeks with no loads and no charge and retest. Any that fall to below 12.5 are suspect . 11 volts = Dodo

It is a only a quick first check..... any that fail it are unlikely to be any good, but passing it does not guarantee that they are good.
Lugging them to the battery shop for proper testing is the only way to be sure.
 
You've done quite well if these are the original 2005 batteries. My Jeanneau supplied Tudor's went after 3 and a bit years. However, I was spending a lot of time on the boat and very little of that with shorepower.

Are you certain that they are sealed. Mine had long covers that were easy to lever off when topping up. I believe that most sealed, flooded batteries can be topped up. Often just a matter of removing a sticker to find the cover.

Might be worth checking if you are planning some heavy duty recharging, equalisation etc. to attempt a recovery.

You could run your own discharge tests in-situ but that tends to be time consuming. I brought my old ones home and ran capacity tests there. Just a matter of applying a suitable load and and monitoring the voltage. I did that, but plotted temperature, SG and voltage vs. time just to be a bit more thorough. This is better than taking it to someone for a car type load test. It also gives quite a good indication as an alternative to a professional battery test.
 
Last edited:
The cheap Amazon device really won't give you a valid indication of useful capacity for house batteries, nor will the ones used by garages. There is no substitute for a capacity check at a realistic discharge rate.
I would agree Mistroma's post in every respect.
 
Anyone made a capacity tester?

Shouldn't be too hard, thinking about it today. Ardiino and bits to measure but how would you get rid of the power? 12v coffee cup heater thing maybe? Feeling my cheap inverter would cut out at too high a voltage to use anything 240v.

And why is the capacity measured in Ah? Won't that change as the voltage drops, wouldn't Watt hours make more sense?
 
Conachair said:
Anyone made a capacity tester?

Shouldn't be too hard, thinking about it today. Ardiino and bits to measure but how would you get rid of the power? 12v coffee cup heater thing maybe? Feeling my cheap inverter would cut out at too high a voltage to use anything 240v.

And why is the capacity measured in Ah? Won't that change as the voltage drops, wouldn't Watt hours make more sense?
Click to expand...

If you look at battery testing equipment as used in the industry, the expensive part of it is the automatic control to maintain constant discharge current as the voltage drops, because capacity has traditionally been measured in Ah at constant current. Of course before the automatic kit you would have had Fred standing there watching the current and manually stepping the resistance loads to keep it fairly constant. It will be done at a known temperature too of course.
That's why you can only do it roughly with light bulbs etc. at home.
There has been a bit of a move towards rating in Wh for inverter UPS systems but it hasn't really taken off.
 
You must log in or register to reply here.

Other threads that may be of interest

W
Battery suicide
Replies
17
Views
570
Refueler
Refueler
P
Adding fuses to my batteries
2 3 4
Replies
61
Views
2K
AngusMcDoon
AngusMcDoon

Share this page

Top