When is it time to buy new habitation batteries

[wp1234]

I have two 100ah gel habitation batteries and they are now coming up to 3.5 years old. My question is when do you change them out or do you wait until they basically die ?
Also what make of gel batteries would you recommend ?
thanks in advance

 

[funflair]

Gel batteries seem quite reliable and long lived so I would not start worrying about them unless the performance has deteriorated. Exide or Sonnenschein both good names.

 

[Bounty Hunter]

Our 4 Gel batteries were 10 years old in July and still performing well. If your batteries are performing as they have always done keep them

John

 

[Gaston aires]

They last ages, no need to change until they start to die. However, if I was going on a long tour to Morocco say, I might get them checked.
Phil

 

[Lenny HB]

As said your Gels have only just been born they have another 5 to 10 years life in them yet. All lead batteries will lose 2.5% of their capacity a year apart from that I doubt if there is anything wrong with them.
I have 2 x 5½ year old & one 4½ year old gels all performing like new apart from expected losses.

If you want to check them it's best to use the slow discharge method like this:-

First charge the battery fully and leave it to settle for an hour then:-

For example, if it's a 100a/h battery load it with a 5 amp load and run for 5 hours, this will represent a 25% discharge. (adjust load/time to suit the size of the battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeat the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged.

Always best to test each battery individually if in any doubt.

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[wp1234]

Thanks Lenny very useful table

 

[wp1234]

Thanks Lenny very useful table

 

[autorouter]

To answer the question, if I were hiring a motorhome from a rental company, I would expect them to fit new batteries if the existing ones lost more than 20% of their capacity, ie down to 80% of their capacity when new. If it was my own motorhome I would probably let them carry on until they were a lot less, maybe 50% capacity.

The next question is, how do you measure the capacity? Lenny HB describes a procedure to do this. If you discharge 25% of the nominal capacity (5A for 5hours in this example) then the battery should be down to the 75% level: 12.65V if it's a Gel.

If the actual measured voltage is 12.35V, then it's at the 50% level. That means the 5A drain for 5 hours has used up 50% of the capacity, not the 25% you were expecting. The total battery capacity has reduced to 50% of the value when it was new. Time for a new battery.

 

[The Wino]

We've got ordinary lead acid now 7 1/2 years old still does the job although I am thinking I might replace just due to the age.

 

[wp1234]

For example, if it's a 100a/h battery load it with a 5 amp load and run for 5 hours, this will represent a 25% discharge. (adjust load/time to suit the size of the battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeat the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged.

Always best to test each battery individually if in any doubt.

View attachment 536606

Hi Lenny quick question and I’m sure it’s a stupid one …how do you actually load your battery with. 5Amp load ?

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[mofurt]

Easiest way is with a bulb.
Power = Volts * Amps, so 12v * 5A = 60W - put a 60W automotive (not household 240V) bulb on it and you'll draw 5A. If your battery is at 13V, that's 65W you'd need.
But the precise current doesn't really matter, use a 55W headlight bulb and you'll get about 4.5A load. Or three 21W bulbs in parallel to give you a 63W load.

 

[The Wino]

Having proudly said that our original lead acid hab battery is still going strong after 7 1/2 years guess what!

 

[Stumbleweed]

I used a spare trailer board, removed the plug and connected the 4x21W bulbs, (stop lights + indicators), to give 84W / 7A to test my 140 Ah batteries in turn at the 20-hour rate. Other combinations can be used for different size batteries.