Your thoughts please - you Leisure battery experts

[Phill D]

Some of you will have read that i am in the process of sourcing a replacement leisure battery. The current is an Exide G85 GEL ( 85 AH ) and is 9 years old.

we are not heavy usurers and generally in combination with our 140W solar panel it has seen us ok for around 5 / 6 days static ( no driving ) in UK summers. however, I have increasingly felt that it is dropping quicker and the 5/ 6 days has become more like 3 / 4 and at 9 years it has probably been around a long time for a leisure battery.

anyway to the point:

I decided that before I part with my hard earned cash for a New "Exide ES1300 120AH"; i would try to be a bit more scientific than just say its had its day move on...

So I decided to see if i could properly establish if the battery was on its last or not.
I fully charged the battery, removed from charge and disconnected it from everything to stand alone.

after 1 hour it was 14.2V - it charges at 14.4 max.
after 20 hours it was 13.65V - this seemed quite high.
i placed a steady load measured with my multi meter of 2.5 amps and left it for 4 hours, disconnected the load left settle for 30 minutes and recorded a Voltage of 12.7V.

The only info I can find suggests that 12.65V it is 75%. and unless I am missing something it appears to be about right for an 85AH battery after a 2.5A load for 4 hours.

Is this correct or have i missed something?? any of you battery whizkids got any useful pointers please?

 

[bigtwin]

I fully charged the battery, removed from charge and disconnected it from everything to stand alone.

Did you disconnect the solar? If not, you won‘t be able to undertake a meaningful test.

Ian

 

[Phill D]

Did you disconnect the solar? If not, you won‘t be able to undertake a meaningful test.

Ian

yes i did completely removed all sources of drain and charge after fully charging the battery ( bare terminals ) then attached the load.

 

[ManTheVan]

Sounds about right. 12.7v is pretty much full.

 

[Phill D]

Sounds about right. 12.7v is pretty much full.

yes it is on a wet battery but not sure it is on a GEL..... and thats why I am asking.

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[Phill D]

i have now left the battery standing no drain or solar or ehu, so will be interesting to see what the voltage reading is in the morning.

 

[Lenny HB]

5 amps is a bit light for a meaningful test 5 amps would give a more meaningful result.
.

State of Charge	Sealed or Flooded Lead Acid battery voltage	Gel battery voltage	AGM battery voltage
100%	12.70+	12.85+	12.80+
75%	12.40	12.65	12.60
50%	12.20	12.35	12.30
25%	12.00	12.00	12.00
0%	11.80	11.80	11.80

 

[Phill D]

5 amps is a bit light for a meaningful test 5 amps would give a more meaningful result.
.

State of Charge	Sealed or Flooded Lead Acid battery voltage	Gel battery voltage	AGM battery voltage
100%	12.70+	12.85+	12.80+
75%	12.40	12.65	12.60
50%	12.20	12.35	12.30
25%	12.00	12.00	12.00
0%	11.80	11.80	11.80

thats the chart I came up with also.
i will recharge overnight and try 5 amps, so do you rekon 5 amps for 4 hours or is that too long?

although the more i think about it i do want more available capacity and I think it is probably not a good idea to add a battery this existing one.

 

[bigtwin]

after 20 hours it was 13.65V - this seemed quite high

That does sound high/odd. I’d have expected the resting voltage to be around 12.7%

i placed a steady load measured with my multi meter of 2.5 amps and left it for 4 hours, disconnected the load left settle for 30 minutes and recorded a Voltage of 12.7V.

The only info I can find suggests that 12.65V it is 75%. and unless I am missing something it appears to be about right for an 85AH battery after a 2.5A load for 4 hours.

Ideally, you should try to apply a load equivalent to the C20 discharge rate. This would be a load drawing a little over 4A, a 55W/60W headlight dip/main headlight bulb using the dip element will give you about 4.4 A.

You can use the table in the image to determine the depth of discgarge from your test. For example, if you ran the bulb discharge test for 4hrs and hence had used 17.6Ah, this would represent a 20% discharge (17.6/85). In which case, the measured voltage (at least 1 hr after disconnecting the load) should be approx 12.42V. A voltage at or above this would suggest that the battery still has a good original capacity*; a voltage below this would suggest tgat the battery has a reduced capacity (e.g. if the measured voltage was 12.2V (representing a 60% discharge) then this would suggest that the battery has a capacity of only 29Ah (17.6/0.6).

* ideally you would repeat another period of discharge to bring the battery close to it’s 50% level of discharge and measure again to confirm, or otherwise, that the battery still has its design capacity.

Ian

Edit: looks as though Lenny HB has beaten me to it (and with a better table ).

 

[Phill D]

i have put it back on charge and will test again tomorrow and see where i am.

i am still a bit at odds with the resting voltage after 20 hours, but i checked it with 2 different meters because i was surprised.

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[Lenny HB]

thats the chart I came up with also.
i will recharge overnight and try 5 amps, so do you rekon 5 amps for 4 hours or is that too long?

although the more i think about it i do want more available capacity and I think it is probably not a good idea to add a battery this existing one.

I would load it with 5 amps and by the length of time

thats the chart I came up with also.
i will recharge overnight and try 5 amps, so do you rekon 5 amps for 4 hours or is that too long?

although the more i think about it i do want more available capacity and I think it is probably not a good idea to add a battery this existing one.

At 9 years old the battery capacity is probably down to 65 to 70 a/h lead acid batteries lose around 2.5% of their capacity per year, Gels seem to fair a bit better.

5 amps over 4 hours is 20 a/h so not far off 20% depending on actual battery capacity.
I would run it at that load rest it for ½ hour then check the voltage, then repeat after the 3rd time it should be down around 20%.

 

[Lenny HB]

i have put it back on charge and will test again tomorrow and see where i am.

i am still a bit at odds with the resting voltage after 20 hours, but i checked it with 2 different meters because i was surprised.

Gels often rest far higher than expected after a full charge.

 

[JJ]

Varta LFD 90 from Tayna batteries...

Job done.

JJ

 

[autorouter]

i am still a bit at odds with the resting voltage after 20 hours, but i checked it with 2 different meters because i was surprised.

Usually they are checked while still connected in the MH. The small permanent loads (frost protection valve, fridge control board etc) are enough to take the surface charge down, but not enough to greatly affect the resting voltage. If the battery is totally isolated on a bench it can take hours or days to reach the resting voltage.

 

[Phill D]

Usually they are checked while still connected in the MH. The small permanent loads (frost protection valve, fridge control board etc) are enough to take the surface charge down, but not enough to greatly affect the resting voltage. If the battery is totally isolated on a bench it can take hours or days to reach the resting voltage.

i did rest it for 2hours and check voltage while still attached to the van ( solar ) disconnected ) and it showed 14.3V. then disconnected left for an hour.
but, will give it another shot tomorrow and see where i am.

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[Phill D]

Quick update. Just went to put battery back on charge its been stood for 2 hours.
And its sitting at 13V. before reconnect of charging.
Now back on charge

 

[Phill D]

this battery is really surprising me for its age.

so recharged for around 14 hours. then rested. resting voltage after 1 hour 13.95V
loaded up with a smidge over 5 Amps. ( 5.1A to be precise )

after 1 hour load still on..... 12.7V
after 2 hours load still on ....12.55V then me thinks Aha got you!
after 3 hours load still on .... 12.5V... Ah perhaps not!

I had to stop there because of other stuff i needed to do. so removed load and left to rest for 30 minutes... 12.67V

the load was just a fraction over 15 AH in total
so according to Lenny HB chart a smidge over 75%

for a 9 year old battery that seems a good result.

So i know have a minor dilemma;
Do i keep this battery and add a duplicate Exide 85AH to it , total then 170AH perhaps. £199 + fittings and cables. £240ish
or
Do I just replace it with the New Exide 120AH and move on. £252

 

[Richard n Ann]

Keep it seems like it's working OK. I definitely wouldn't add a new one to it, you only pair up new batteries.

 

[bigtwin]

the load was just a fraction over 15 AH in total
so according to @Lenny HB chart a smidge over 75%

for a 9 year old battery that seems a good result.

So i know have a minor dilemma;
Do i keep this battery and add a duplicate Exide 85AH to it , total then 170AH

The above shows that you have a reduction in your capacity from 85Ah to 60Ah so your total will be 145Ah rather than your stated 170Ah.

However, I would continue your test for another couple of hrs to get a better/truer estimate of the available capacity.
In previous tests I’ve undertaken, I’ve seen the voltage collapse suddenly as you take more out of the battery such that the battery is incapable of providing the calculated capacity taken earlier in the test.
Your test thus far suggests that you have a capacity of 60Ah but if you continue the test you may find that you only actually have a capacity of, for example, 30Ah. Hopefully that isn’t the case but I think you need to discharge the battery further to find out.

Ian

 

[eddie]

Well it sounds like its good

Why not wait till it fails and then start with two new ones

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[Lenny HB]

At 9 years old I would carry on with the current or if you really need more power bite the bullet and fit 2 new batteries.

 

[Phill D]

Thanks guys, all the input helps a great deal.