Hydrometer readings

[Umpa]

I have a question regarding flooded lead acid batteries if I may.

I have a small solar shed setup, and I recently decided to get a hydrometer to test the batteries. The charge controller regularly shows its in float mode, however the hydrometer shows that most of the cells the cells require charging and are in the red zone and are all slightly different.

The built in magic eye is showing green, so I don't know how reliable that is.

Here is my set up :-

600 Watts of solar, 6 panels of 100w 12v in parallel.
30 amp PWM Charge Controller
2x 70AH 12v FLA in parallel
1000 watt inverter,

I realise my battery bank is lacking in size, and they are second hand batteries, but it only powers an 80w 1990's midi hifi, some led lights and every now and a gain a small bench pillar drill an a small soldering iron.

I don't have an issue with available solar power - just the fact the charge controller only ever shows bulk - and float, along with my recent SG which suggest otherwise.

The charge controller is this one :- https://www.amazon.co.uk/Esky-Intell.../dp/B013HK2OOE

Its no longer available, its was a cheap and nasty job. I have only posted a link to it so you can see what it actually is.

[Xplode]

What is the actual gravity reading you get when checking the batteries. And have you taken a voltage measurement first thing in the morning? (Let it charge up the day before and don't use any power from the battery overnight)

How old are your batteries?

[Mike90250]

> The built in magic eye is showing green

The built in magic eye only indicates fluid level, seldom state of charge

[inetdog]

> The built in magic eye is showing green

The built in magic eye only indicates fluid level, seldom state of charge

Actually, the typical Magic Eye (TM) setup uses float(s) of calibrated specific gravity, and so as long as the electrolyte level is above the minimum required will give a crude go/no-go indication at that one SG value. But the "reading" is a compromise value and is not temperature compensated. Therefore it is of little value to the off grid PV system operator.

[Umpa]

Thanks for the help guys,
Just went up to the shed this morning 8:00am - the voltage was reading 13.6v. The weather lately here grim and grey, its been chucking it down for the last two days.
Charge controller was reporting 'bulk charge' but there is hardly any light. I did use a fair amount of power last night for lighting whilst I put some shelves up.

The batteries are 3 years old, I have had them about a year - they were gifted to me when they came out of warranty.

Now if I am reading this hydrometer right - it is split in to 3 zones - red, white and green.
The instructions say the red zone is 1100 - 1205 discharge - white zone 1205-1260 low charge - green zone 1260-1300 fully charged.

battery 1:- 4 in the red 2 in the white

1100
1103
1102
1250
1200
1100

battery 2:- all in the red.

1100
1152
1100
1100
1100
1101

Ok so this says the batteries are flat ?

They are still in the red but a bit higher, when the charge controller reports float charge too when the sun is out and burning a hole in my eyes.
FWIW my lights are in a split configuration 2-1, when all on they draw 4.1A and when just one is on its about 1.2A. I can power these light for quite a while before the system shuts them off.

When the sun is out and the controller is in float mode, it usually charges at 3 or so amp. When I am using power for the drill, lights, hi-fi - soldering iron on etc (basically a full load on) the controller will push 25 amps in to the batteries so i think that part is working OK.

I have been toying with taking a battery off, and charging it on a mains charger - the last time I did this, the green light came on straight away to say it was fully charged - but I did not have the hydrometer then.

[Matrix]

Perhaps charge them on the "main charger" independent of each other until the SG stops rising. See if it will come up into range. Do you have a way to charge at an Equalization Charge voltage? Or can you set the charge controller voltage higher? Something in the range of 2.65v + per cell would be an EQ voltage depending on manufacture. But if you can EQ the batteries, it may take several hours and careful monitoring.

[Umpa]

Hi, I have to report my above post is wrong - sorry

Please disregard all my SG readings they are not correct for 2 reasons.

1) It was two early for me, and I read them wrong - when I posted 1103 what I meant to post was 1130
2) With the above said they were not right either because at 12pm this afternoon, after it had brightened up a fair bit I checked again, this time the voltage was 14.5v but the SG was the same, it turned out to be a stopper with some holes in it under the squeeze bulb preventing the float rising up enough - so all my readings are wrong.

So after checking all the cells, the results are that they are all the same at 1250. So they are registering low charge according to the instructions, but not as low as I originally thought. I have tried to get more charge in to each one with a battery charger, but it puts a green light on and says they are fully charged.

Also it was only 'float' charging them at C0.3A as soon as I turned the lights on it jumped up to C4.4A, so that would suggest the charge controller is doing its job and could provide more power. So do you think the batteries are on their last legs ?

FWIW I have never seen this controller do a EQ charge, and I don't think its user programmable.

[Umpa]

With the charge controller going in to float charge with a battery back that seems to be at a low start of charge (hydrometer wise) - does anyone know what this means ?

Are the batteries duff - or do I need to start looking at another charge controller ?

[Umpa]

Perhaps charge them on the "main charger" independent of each other until the SG stops rising. See if it will come up into range. Do you have a way to charge at an Equalization Charge voltage? Or can you set the charge controller voltage higher? Something in the range of 2.65v + per cell would be an EQ voltage depending on manufacture. But if you can EQ the batteries, it may take several hours and careful monitoring.

The only battery charger I have is a fully automatic job, it has trickle - heavy and start settings. Heavy charge might give the voltage, I would have to put a multimeter on it and see. I guess I am looking for heavy gassing of the cells during this process ?

What do you think of the charge controller ?, should I get a better one, or put the money in to more FLA batteries, as I am pretty sure I am wasting solar charge power with just the 2x 70AH FLA. I guess if I did the latter, it would prove or disprove duff batteries at least, and its not like I will have wasted the money, unlike replacing a good controller.

That said of course if the charge controller is going in to float to early and not fully charging them, then the new batteries will sulphate and i'll bugger them up too. Oooo decisions - decisions lol.

[Matrix]

Yes you are looking to get to a charge voltage that produces gassing. I would definately start by trying to charge the batteries up fully before considering replacing them. This will require some kind of controlled over charge like an EQ charge and gassing voltage. Monitor the temps closely (with a thermal heat device or some other method) and stop charge if the temps get too hi. charge at gassing voltage until the SG stops rising in all cells. I would do this before I got new batteries

Cant really say about the Controller. Perhaps if this is just a small system for powering a shed or small lighting etc, you could continue on with this controller, but use your AC battery charger for doing balancing / EQ charges as needed.

But it seems you are suffering from surface charging right now and this is why the Controller is going into float so quickly.

[Umpa]

I looked up surface charging, the solution seems to be to discharge the battery a bit. I do this anyway when using the power, and it goes to bulk charging, eventually returning to float. Never seen an equalising charge. Even when the sun is strong and I am not using the shed.

I'll sort it eventually.

[Mike90250]

Do you still have the manual for the charge controller ? The amazon page lists it as a full function PWM controller

Have you needed to add water to the cells at all ? Normal charging would require adding water every 2-3 months, heavy charging = monthly water.

• TECHNICALS: Max 30A 12V/24V 360W/720W, power rate adjustable with dual USB ports; 4-Stage(EQU, Bulk, ABS, Float) charge management and 3-Stage PWM charge
• EASY TO USE: Comes with a 30x50cm LCD display that can clearly indicate the status and data, it can be conveniently switched modes and parameter configuration etc.

[Umpa]

No I have never had to top them up. I might have the instructions somewhere, but from memory it just told me what it did. I don't seem to be able to actually change any setting, although I could be wrong. I'll see if I can find them or get a pdf and report back.

edit:
I think this is it (or at least a clone of it) https://manblan-a.akamaihd.net/ibloc...082b8030ca.pdf

If I am reading it correct, it seems the only user options are to the load part of the controller, and in my case it just powers a few led lights.

[Umpa]

Another update, its very sunny here right now, so I decided to take another hydrometer reading - still no change they are all in the low charge to fair portion 1200 - 1250 range not in the green fully charged section. So I disconnected one of the batteries and stuck it on the charger. The charge complete led lit up, and it started charging at 2 amps (pulsing).

The only way I could get a boil on it was to put the charger in engine start mode, and even then it only pulled 9 amps at 17volts, after about 30 mins rising to 12 amps and dropping to 16.6 volts. This boil is more like a gentle simmer, its not exactly going for it still.

I took another reading but this time the acid has gone a very slight brown colour - more a haze than anything else!!! the hydrometer has risen a little more towards the green section. Battery is still cool not even slightly warm.

[Xplode]

My guess on the that colour ishe sediment from plate degradation is getting stirred up into the electrolyte. But I'm not sure and in curious to see what the more experienced players say.

The fact that the charging voltage dropped but the amperage increased leads me to believe you're breaking up some of the surface sulfation on the plates. I'd keep going a bit longer but since the charging voltage is higher than I've seen recommended, id just keep a close eye on it.