How much water wet batteries loose unused?

[Tim Good]

Q:
How long do you think an unused, trickle charged, wet battery will last before needed to be topped up with water again?

Background:
I have 4 Trojan T105s in my boat. They’re kept topped up by solar. In September last year we had our first child and we laid the boat up and I haven’t been back since. Back then I topped the batteries up with water. We’ve been traveling around Europe for the last year so haven’t been able to check in the boat other than the yard visually checking the outside.

Do you think the batteries will have lost sufficient water to have damaged them in that time? I.e gone below the lead plates?

 

[William_H]

I would not worry too much. Especially if the cost to you to check or get them checked is great. I would imagine that if the water got too low it may damage that area of plate exposed. On the other hand it used to be normal to store and deliver LA batteries with no fluid so can't be harmful just sitting. Small trickle charge may affect that theory. Plus of course your lovely batteries will have got older any way. ol'will

 

[geem]

I would not worry too much. Especially if the cost to you to check or get them checked is great. I would imagine that if the water got too low it may damage that area of plate exposed. On the other hand it used to be normal to store and deliver LA batteries with no fluid so can't be harmful just sitting. Small trickle charge may affect that theory. Plus of course your lovely batteries will have got older any way. ol'will

My engine batteries are kept charged with solar and only need a water top up once a year. I would have thought now was a good time to do it

 

[Refueler]

William H mentions the dry batterys .....

They are charged fully before transportation. There is no charge current applied while in that state. Only after electrolyte is re-introduced by dealer can charge be applied.

 

[Aeolus]

My T105s are on solar charge most of the time and I think I've topped them up once in the four years that I've had them - and that time the plates were still fully immersed.

 

[Mistroma]

Depends on the charge regime, temperature, battery age etc. I left my new T105s on solar for 2 years in Greece.

I had marginally overfilled pre-Covid and they took 600mls per battery. Plates still just covered and taken to normal level.

My solar is set to T105 float +0.1V and does a short eq. charge on 28th of each month.

 

[Tim Good]

My T105s are on solar charge most of the time and I think I've topped them up once in the four years that I've had them - and that time the plates were still fully immersed.

When we’re using ours hard and living aboard then we need to top up perhaps every 4-6 months.

 

[VicS]

Q:
How long do you think an unused, trickle charged, wet battery will last before needed to be topped up with water again?
>
Do you think the batteries will have lost sufficient water to have damaged them in that time? I.e gone below the lead plates?

It depends on the current and the time actually charging.

 

[vas]

+1 on the current and general charging profile.
Have 4XT105RE on 600w solar in the Med via a Victtron MPPT configured exactly as per the Trojan specsheet
Summer months needed a 4lt bottle every couple of months

Now they are backup (in series) to a LifePO4 bank, so softer charging profile. Need some water once every couple of months.
so ymmv

EDIT to add that my Trojans are in the e/r (mobo) so when engines are on (and for the next 6h) temps are rather high. LifePO4 is in the salon, much cooler.

 

[Graham376]

When we’re using ours hard and living aboard then we need to top up perhaps every 4-6 months.

My 4 x T105 charged by 320w solar use about 4 litres of water over a year. When leaving the boat for 2-3 months, I top up to half-way up the slots in the fillers.

 

[Alex_Blackwood]

Afraid no one can answer that, not being funny but the only way to tell is by use of the MK1 eyeball.
Far too many variables in the equations, as has been touched upon in previous answers.