Topping up batteries

[DeepBass9]

For those of us with Trojan lead acid batteries that need topping up with water from time to time, do you think these auto filling system are worthwhile? Like this? http://www.trojanbattery.com/products/hydrolink-watering-system/ Is anyone using one?

Not that it is a big job mind you. I check mine (T1275 150Ah ) once a month and usually have to put in maybe 50ml per cell or less. When it was very hot over summer I noticed that the cells dropped quicker, and in winter not so much, so a large part of the water loss must be plain evaporation. 

[Guest]

Interesting. If you have to top up per month. Batts are working hard?

Reason I ask is because the only time that the batts lose water, is during charging.

Those kits are about, was, R 2 600.00 for 48v system. Just need to top up the reservoir.

[DeepBass9]

Quote

the only time that the batts lose water, is during charging.

Are you sure about that? There is evaporation as well I'm sure. R2600 is quite a lot though to save on 15mins work per month.

[Guest]

Jip, that is why I put the price up that I got a while ago. 

Am I sure, that is what the Trojan supplier told me. When batteries are charging, you can hear them bubble, that is when the evaporation takes place.

For years now I check the water levels every couple of months. Seldom do I need to add water, unless I have been charging hard and long, then there is a noticeable increase in frequency.

EDIT: There is a fine line between softly bubbling and bubble during charging.

[DeepBass9]

During charging, that is electrolysis, not evaporation. Evaporation with bubbling is called boiling. Good to know when a salesman knows his product!

[Guest]

Let me quote Trojan: 
3. Is it normal for my flooded batteries to lose water?
It is completely normal for flooded batteries to lose water. They lose water because of the gassing that they go through with every charge. Gassing is an important part of the recharge process. The gassing allows the electrolyte to mix well and helps the battery get back to a fully charged state at the end of the charge process. Unfortunately, the gassing also causes water to be lost. The addition of water should be only be done once the batteries are fully charged as the electrolyte levels vary as a function of state of charge and are highest once the batteries are fully charged. The correct electrolyte level is about 1/8th of an inch below the bottom of the vent well. Please use distilled water only.

http://www.trojanbattery.com/tech-support/faq/

 

[edmundp]

Technically the process of electrolysis causes the breakdown of h2o in electrolyte into h2 and o2. Hence water dissappearing. Hence evaporation.

Edit. Trojans are all fitted with vent caps reducing traditional evaporation to a minimum. The only form in which liquid can escape is if converted to a gas. In small quantities that is unless there is a presence of excessive gas formed due to electrolysis due to charging.

Sent from my SM-N900 using Tapatalk

[DeepBass9]

Nevertheless, not the same thing.

[Chris Hobson]

4 hours ago, DeepBass9 said:

When it was very hot over summer I noticed that the cells dropped quicker, and in winter not so much

Part of that loss is gassing and gassing voltage is higher the cooler it gets so at any given charge rate less electrolyte losses in winter. For this reason I bring my charge rate down when battery temperatures approach 30^oC.

 

[Guest]

2 hours ago, DeepBass9 said:

Nevertheless, not the same thing.

DB9, what do you mean, maybe we are missing a point?

 

The batteries must bubble in order to mix the acid and water during charging versus equalizing, where they bubble distinctly more, to helps stir the sediment off the bottom.

One day at peak charge, or after a equalise, open the cap next to the pole where the inverter is connected, for best result. You will see the water is brownish. Do NOT do this whilst they are charging, acid in your eye is alallegedly quite uncomfortable when you peak in and a bubble pops right at the moment.

Then when the batts are at rest, check again, the water is clear or clearer. Sediment has settled again.

So I am worried because you fill up with a lot of water, with Trojan's having caps that limit evaporation as much as possible, that you may be overcharging them. It would be a good idea to go and listen to the batteries when they are on peak charge. You should here them bubble every now and then. If you don't hear anything, that is not good. If they sound like water starting to boil, extremely bad.

Max charge amps should not be above 13% of your battery AH (you will hear them bubble, but not 'boiling'). 10% is good (you will also hear them bubble ever so often) and 8% is for weekend use, i.e, batts take days to recharge fully (you may not hear them at all).

I once had a controller that got stuck on 24v and it charged the 12v Trojans for a day. They where in my office at the time, a test, and I could see water being forced out of the caps. Could also smell something, probably hydrogen. When I listened to them, ear close, they sounded like they where coming to a boil. Aaaah, extreme equalizing day I see, and promptly sorted the controller.

 

FWIW: I have been told that battery manufacturers can determine if batts where overused, under or over charged at their labs, if there is a dispute. I also saw on a overseas site, that if their is a warranty claim, that the manufacturers may ask for up to 3 months of charging records.

[DeepBass9]

My point is people are using the terms 'evaporation' interchangably with 'gassing' and 'bubbling' which is electrolysis and a different process, although it may produce the same result.

[DeepBass9]

Anyway, I just checked the last date I topped up water which was 25 May (so much for the once a month). I put about 1.5 litres into the bank, so that is about 180ml per battery and so 30ml per cell. None of the plates were exposed, so that doesn't seem excessive to me?  

[Guest]

Just be be 100% sure, make a note of how frequently you fill them with water?

And what are the max amps you charge them at?
Setting on inverter and what is actually recorded by the BMV going into them. 

EDIT: I am really very interested.

[DeepBass9]

Max amps from the MPPT must be about 40A, similar from my generator. As I said, I don't top them up more frequently than once a month. I bought 5l of water at the beginning of the year and still have some left.

[Guest]

@DeepBass9, let me just make sure, if I may?

You have 4 x 12v T1275 150ah batteries, connected for a 48v bank: So you have a 150Ah?
Or 8 x 12v T1275 150ah batteries, connected for a 48v bank: 300ah bank?

EDIT: How long have you had this setup?

[DeepBass9]

8x

[Guest]

Cool. 

You are charging 300ah battery bank at 40amps, just over 13%, so you are at the top end. 13% is good for off-grid fast charging.

Set it to rather to 10%, 30amps, and see if you use less water.

[DeepBass9]

Where do you get that figure from? 13% of what?

[Mark]

10% of 300ah is 30A charging max.  Try not to go above this value...slower is better so if you had enough sunlight time and your DOD wasn't that low then 20A woud be better - a slow charge means less time for batteries to go out of balance.

[Chris Hobson]

16 minutes ago, DeepBass9 said:

Where do you get that figure from? 13% of what?

13% of battery bank capacity expressed as a charging rate 40A/300Ah. The other way of expressing a charging rate is 1C where you charge the capacity of the battery bank in 1 hour. Recommendation is C/10  or in an off grid situation where you have limited charge hours 13% (between C/7 and C/8).  C/10 can also be expresses as 0.1C  C/8 as 0.125C, C/7 as 0.143C and so on.  Some AGM batteries can be charged at C/5,  an advantage in an off-grid situation.   

[Guest]

Put it another way to Chris, what I have been taught by off-grid people.

Charging amps of 8% of C20 battery ah is perfect for a small array for the weekends use. Takes 5 days to fully re-charge.
Charging amps of 10% of C20 battery ah is what we all tend to do, for that is good for daily cycling if recharged in 5.5 hours of good sunlight.
Charging amps of 13% of C20 battery ah is what you do in off-grid situations where you have to charged quickly, you will use more water.

If it was me, I would lower the amps to 10% of C20 battery ah. Best of both worlds.

Below 8% and above 13% you are damaging the batteries over time.

 

 

[Weasel]

On 7/27/2016 at 5:49 PM, The Terrible Triplett said:

Those kits are about, was, R 2 600.00 for 48v system. Just need to top up the reservoir.

just to note a refill kit is to refill more easily, its not to have the process automated. you still have to wait for the batteries to be fully charged before you open the tap and have the system fill.