Battery tilt

J

JimC

Well-Known Member
Joined
30 Aug 2001
Messages
1,570
Location
Lancashire
Visit site
Sorry to start yet another battery thread. Is there any problem with mounting sealed lead/acid batteries such that their base is not horizontal but tilted about 10 degrees to the horizontal both transversely and logitudinaly. Sitting my domestic battery directly on the bottom of the hull without a platform under it would allow me to use a bigger (taller) battery but would necessitate tilting it.
 
They must be able to cope with some tilt otherwise you would have to sail upright all the time.

Having a 10° tilt before the boat leans is going to mean you are in danger of spilling battery acid on one tack, the other tack will be extra safe though.

Just noticed it's a sealed battery, the above only applies for normal batteries like mine. You should be ok I think.
 
I measured the angle using my Trojan T-105s before fitting them. They are open flooded batteries and were over-filled if anything. I can't remember the angle when they came close to spilling with no caps inserted, but it was more than 45 degrees. I wasn't too worried as they would normally have a bit less acid in them and the caps should help reduce leakage from intermittent large heel angles (not that I'm planning to sail at 45 degrees).

Starting from 10 degrees only gives 35 degrees of heel on one tack. No problem for AGM but can't see too much of a problem if they are sealed leisure batteries. I suppose some of the plates will eventually be above the acid level and so capacity will drop more rapidly than a battery installed in upright position.
 
Last edited:
Mistroma said:
I measured the angle using my Trojan T-105s before fitting them. They are open flooded batteries and were over-filled if anything. I can't remember the angle when they came close to spilling with no caps inserted, but it was more than 45 degrees. I wasn't too worried as they would normally have a bit less acid in them and the caps should help reduce leakage from intermittent large heel angles (not that I'm planning to sail at 45 degrees).

Starting from 10 degrees onl gives 35 degrees of heel on one tack. No problem for AGM but can't see too much of a problem if they are sealed leisure batteries. I suppose some of the plates will eventually be above the acid level and so capacity will drop more rapidly than a battery installed in upright position.
Click to expand...

OR Always sail on the tack which ensures they're level!
 
As Mistroma says the plates will soon be above the electrolyte level which will damage them when charging or discharging. This can happen in any wet led acid battery if the battery is mounted fwd to aft, they should be mounted lengthways across the boat. This is all to do with the rectangular nature of each cell. Use an ice cream cartoon to see the effect of healing and how much more the plates will be exposed when they are inline with the boat.
 
JimC said:
Thanks for the link, just about says it all doesn't it.
Click to expand...

It's made me rethink new batteries for my little ship too. The duff one was mounted fore n aft, I may be better off with 2 or 3 smaller ones mounted sideways.
I don't think I could get 2 100 Amp hr ones in sideways. The battery tray will need modifying anyway so I could turn it through 90° at the same time. Damn, the locker lid would need altering too.

Nothing is ever easy is it.
 
ccscott49 said:
+1, look on Ebay, lots of AGM's 100ah, cheap, I have 15 of them!
Click to expand...
I'm surprised to hear you of all people suggesting people should buy cheap AGM batteries on ebay. Yes AGMs and Gels are a good idea to avoid the Tilt problem, but many AGMs being sold on ebay are Gels not AGMs - there is a very big difference - some are even being advertised as using "AGM" technology!

Not all AGMs are the same, they are either for starter or deep cycle use, but many of them are a Leisure AGM which is a compromise between the two.

True Deep Cycle AGMs are not so easy to source and they are now becoming more popular, but there are only a few designed for marine use,. Many cheaper ones are designed for Automotive, Telecoms or Solar standby use, not for mounting in a boat which often falls off 3 metre waves, so check very carefully with the manufacturer that they are rugged enough. AGMs main advantage is they can charge much faster and accept higher charging currents, but not all brands are made the same way, so may not even make these claims, so potential new buyers are often confused. Alternator and Shorepower chargers may need to be upgraded to take full advantage of AGMs fast charge capability to justify their extra cost over flooded wet lead acid batteries.

Buyer Beware!
 
You must log in or register to reply here.

Other threads that may be of interest

Y
The Seafarer 700 and NASA clipper sounders saga
Replies
10
Views
432
Dellquay13
Dellquay13

Share this page

Top