Specific battery / charger advice

[[3889]]

I'm looking at replacing my 2 x 70Ah oem house batteries with two of these, which are a good fit:

http://www.tayna.co.uk/EXV100-Enduroline-Leisure-Battery-P8705.html

I have ruled out AGM etc. as I cannot justify the extra cost.

I have been advised that my current Cristec 25A charger might struggle to fully charge a 200AH bank as the difference between float and boost (4 hours) is too low at 0.7V and this may cause early failure. I don't pretend to understand the details of this advice. The batteries will spend most of their time recharging from 100W regulated solar or engine, never on mains for more than 24 hours.

The charging options for the Cristec are:

Boost Float
15.1V 14.4
14.3 13.6
14.1 13.4
13.7 13.0

Will this set up be OK and if not, would it help to reduce the battery bank to 2 x 90AH or 2 x 70 AH? I don't want the extra hassle of a new charger.

 

[mersey]

For those lead acid you should be looking at around 10% of AH in amps.

So 2x100ah =200 10% = 20amp charger.

Thats the basic guidance.

 

[Pete7]

I think with those batteries you could go to 25% of the AH, so a 25AH battery charger is fine. However, it makes little difference in the real world as the batteries will only absorb what they want. We have a 40 AH charger on a 220 AH bank and yes on switching it on it does give 42AH, but only briefly then the AH slowly drops down so I do not get an hour at 40 AH, its much lower, probably mid 20s.

They don't quote the weight of those batteries which might be worth comparing with others. Also they appear to be sealed so you can't add water to them.

Pete

 

[VicS]

I think with those batteries you could go to 25% of the AH, so a 25AH battery charger is fine. However, it makes little difference in the real world as the batteries will only absorb what they want. We have a 40 AH charger on a 220 AH bank and yes on switching it on it does give 42AH, but only briefly then the AH slowly drops down so I do not get an hour at 40 AH, its much lower, probably mid 20s.

They don't quote the weight of those batteries which might be worth comparing with others. Also they appear to be sealed so you can't add water to them.

Pete

Ampere-hours (symbol Ah) are the units of capacity of a battery.

Current, eg the output of a battery charger, is measured in amps (an abbreviation for amperes), symbol A

 

[pvb]

The batteries will be fine with that charger. There are worse things to worry about (like terminology).

 

[[3889]]

Thanks for replies to date. To clarify, the issue is whether the charger is too small to fully charge batts: as the boost voltage switches off after 4 hours, dropping from 14.1V to 13.4V, will this prevent full charge for 200 Ah?

 

[KellysEye]

I've looked at the site and it doesn't say if they are CCA batteries for starting or deep cycle for house batteries which are what you need. Do you know which they are?

 

[macd]

I've looked at the site and it doesn't say if they are CCA batteries for starting or deep cycle for house batteries which are what you need. Do you know which they are?

As you probably noticed, it says they're 'leisure' which I daresay you know means almost nothing at all.

 

[sailinglegend420]

....However, it makes little difference in the real world as the batteries will only absorb what they want.....
Pete

Mr Sterling in his Advanced Battery Charging article managed to put 160 amps into a 100Ah battery at 14.8v that was only 50% charged. The current fell fairly quickly but it was only after 1 hour that the current acceptance of the battery had reached 25 amps. That would be the most current from a constant current charger that most battery manufacturers would recommend. For maximum life cycles Trojan recommend 10-13 amps for a 100Ah battery.

So a battery can take more than it needs if the charging source is too large. In the real world most boats don't have large chargers.

 

[[3889]]

I've looked at the site and it doesn't say if they are CCA batteries for starting or deep cycle for house batteries which are what you need. Do you know which they are?

CCA is 700A as opposed to 950A on the 100 Ah starter battery equivalent. I realise these are not true deep cycle batteries but would prefer the smaller up front investment than to pay 2 or 3 times more for Trojan or AGM which might fail from a charging mishap. I've bought expensive batteries in the past and don't feel they offer good value.

 

[Plevier]

It's not going to make any real difference whether you have 70, 90 or 100Ah batteries. None of them will take the full 25A charge for long it will soon drop.
I think the 25A Cristec I had boosted for 6 hours. 4 is a bit short. Is it adjustable?
Nonetheless if you set it to 14.3/13.6 along with your other charging sources you should be OK. It's not perfect but these are quite cheap batteries and are unlikely to have a long life anyway!
You could even set it to 15.1/14.4 if 24hrs on charge is not frequent, but watch out for increased water loss. You can probably remove the vent strip visible in the photo to top up, they are usually press fit not heat sealed.

 

[Pete7]

So a battery can take more than it needs if the charging source is too large. In the real world most boats don't have large chargers.

No, the battery will take what it wants, but as you say in the real world most boat don't have large chargers, so a 25 amp charger will do nicely.

Pete