Battery question

[Robmac]

During a week long trip recently, I noticed that the batteries on my van weren't performing as they should. I have 2 x Trojan T125's, 240A each and 6V - wired in Series to produce 12V and 240A.

We were on EHU with the built in (cheap) battery charger connected but after a couple of hours I noticed that the reading was 12.0 volt. The compressor fridge was in use at the time. I checked the electrolyte and noticed that one was at the same level as I topped them up to about a month before and the other was way down below the level of the plates. My granddaughter was with us at the time and had a charger in her car so I attached this directly to the batteries having topped up the electrolyte on the low level battery first.

After a few hours charging the batteries were still only reading 12.6 )It's a fairly weak 4A charger!) and as soon as the battery was disconnected they quickly dropped to 12.0. At the end of the week we drove home and even with all of that alternator input the batteries only went up to 12.6. Now, a week or so later I checked this morning and the batteries were reading 13.1 which is purely from being charged by Solar on the drive.

I just connected them to my 7 stage, 20A smart charger and they immediately showed 14.3V and it went through the 7 stages (including recondition) in no time at all and is now on the trickle charge showing 13.7 so I've switched the charger off and the fridge on to see how long it takes to drop. It has dropped to 13.3 pretty quickly. Just looked again 10 minutes later and now 12.8.

This is pretty much confirming my suspicions that at least one of the batteries is goosed. They are 6 years old and to be honest have been brilliant so not too bad an innings. I shall monitor the batteries over the next couple of hours and if they drop right down I shall order 2 more of the same.

One question though, if one of them is faulty, why didn't the charger go through the recon stage which usually takes a couple of hours? Thanks in advance.

 

[Robmac]

...Still 12.8

 

[trevskoda]

Dropping to 12.7 is normal, but they way you say may be prof one is goosed, why not go for lead carbon next time, more cycles.
Many sizes to get.

 

[1 Cup]

Just get a lithium bms and wire it to all battery and your see all cell / battery voltage by Bluetooth. Pics of 12v but if you power by 24 volts the other four work

!this one has a 2amp balancer built in and 24v is just to power the unit not the output of battery pack. ,.

 

[Robmac]

Dropping to 12.7 is normal, but they way you say may be prof one is goosed, why not go for lead carbon next time, more cycles.
Many sizes to get.View attachment 122812View attachment 122813View attachment 122814View attachment 122815View attachment 122816

To be honest Trev, I've been really impressed by the Trojans, and they can discharge to 80%.

Being 6V they charge up more quickly too.

 

[Robmac]

Just get a lithium bms and wire it to all battery and your see all cell / battery voltage by Bluetooth. Pics of 12v but if you power by 24 volts the other four work View attachment 122817!this one has a 2amp balancer built in and 24v is just to power the unit not the output of battery pack. ,.

I'm a simple bloke Jeff. Can't be bothered with all that tech these days!

I just prefer to look at the volt meter and if it's reading high 12's or more that'll do for me.

 

[Robmac]

...now 12.9 so the solar must have kicked in between the compressor cycles. Even if it is overcast at the moment.

 

[1 Cup]

Think of it as a simple upgrade to find a poor or unhealthy battery in your 6v pack at a glance.
People just say its complicated so they can charge more.£££"
If there smoke in Herefordshire later today ignore my last sentence

live and a temp fit for the early offended.

 

[wildebus]

To be honest Trev, I've been really impressed by the Trojans, and they can discharge to 80%.

Being 6V they charge up more quickly too.

Don't see why they should charge more quickly because they are 6V batteries?
I think at least one is knackered if the voltage jumped to 14.3V virtually as soon as you plugged in a 20A charger.

Trojan 6V Traction Batteris used to be a very popular option but there are a lot better solutions now, and without changing to Lithium.
Wet cells with the need to top them up is one thing against them (you can get auto-fillers for the trojans, btw though, if you really want to keep that style).
Want a battery you can discharge to 80%? get a lead-carbon and you can use it until it's dead if you really want to and then recharge. The Lead Carbon technology also support a PSOC (partial state of charge) situation, where you can leave the battery partially charged for periods (conventional lead acid batteries should be kept fully charged when possible and recharged immediately after use for best life).

Get two more trojans and you will be in a good situation. but you can do better for sure.

 

[Robmac]

Don't see why they should charge more quickly because they are 6V batteries?
I think at least one is knackered if the voltage jumped to 14.3V virtually as soon as you plugged in a 20A charger.

Trojan 6V Traction Batteris used to be a very popular option but there are a lot better solutions now, and without changing to Lithium.
Wet cells with the need to top them up is one thing against them (you can get auto-fillers for the trojans, btw though, if you really want to keep that style).
Want a battery you can discharge to 80%? get a lead-carbon and you can use it until it's dead if you really want to and then recharge. The Lead Carbon technology also support a PSOC (partial state of charge) situation, where you can leave the battery partially charged for periods (conventional lead acid batteries should be kept fully charged when possible and recharged immediately after use for best life).

Get two more trojans and you will be in a good situation. but you can do better for sure.

I don't know why 6V would be quicker either David to be honest but I did read it somewhere (on here I think).

But as said, I am more than happy with the Trojans and all of my wiring is suited to wiring in Series at 6V - I know I could re-do it but I'm lazy and if it ain't broke (which it might be ), don't fix it.

OK, I will have a look at the lead carbons.

Up to 13.1V now so I may not have to bother just yet!

 

[Robmac]

12.7

 

[Robmac]

13.1V

I suspect that to do a proper test I should really cover up the solar panel to simulate how quickly it will drop overnight.

 

[Robmac]

12.7 now with the solar panel covered.

I'm wondering if my compressor fridge has a low voltage cut out and so is never getting down to temperature and the compressor has been cutting in every time the solar brought it up to power.

 

[barryd]

When they are charging either by solar or ehu then they will show high voltage like 13.x or 14.x

That's a false reading though I think. They will quickly drop to 12.7 once you have no charge input at all and you put them under load (TV lights etc). The test is how long it takes them to drop to 12.6 - 12.5 etc once there is no charge input.

If they stay around 12.7 - 12.6 for say an evenings use I would guess nothing wrong with them. If they drop to 12.0 fooked!

 

[Robmac]

When they are charging either by solar or ehu then they will show high voltage like 13.x or 14.x

That's a false reading though I think. They will quickly drop to 12.7 once you have no charge input at all and you put them under load (TV lights etc). The test is how long it takes them to drop to 12.6 - 12.5 etc once there is no charge input.

If they stay around 12.7 - 12.6 for say an evenings use I would guess nothing wrong with them. If they drop to 12.0 fooked!

That's the thing though Barry. Whilst on EHU in Cornwall they were only showing 12.6 and falling - same when driving back as well.

I think they are kerfooked!

 

[wildebus]

Stop the charges, put on a known current load.
For your 220Ah 12V system, try and do a 10A constant load - around 120W (so if you have an Inverter, run a couple of old-fashioned lightbulbs) and see what the voltage is after a few hours. If the batteries are good, after 10 hours at 10A, the battery should be at over 12V after the load is removed.

 

[Robmac]

Stop the charges, put on a known current load.
For your 220Ah 12V system, try and do a 10A constant load - around 120W (so if you have an Inverter, run a couple of old-fashioned lightbulbs) and see what the voltage is after a few hours. If the batteries are good, after 10 hours at 10A, the battery should be at over 12V after the load is removed.

Unfortunately I don't have an inverter David.

I did disconnect all chargers (Mains and Solar) about 2 hours ago and it seems to be holding a constant 12.6 - 12.7 at the moment.

All that is switched on is the 'fridge which consumes 40W at about 3.3A at 12V.

 

[wildebus]

Unfortunately I don't have an inverter David.

I did disconnect all chargers (Mains and Solar) about 2 hours ago and it seems to be holding a constant 12.6 - 12.7 at the moment.

All that is switched on is the 'fridge which consumes 40W at about 3.3A at 12V.

you need some kind of load to 'stress' the battery.
I remember my VW LT starter battery used to sit at 12.7V no bother and it recharged really fast - 'coz it was knackered and had a tiny capacity left
When I turned the key to start the engine, it would drop to under 11V and not recover. a voltage reading is not actually a real indication of a batteries health.

 

[trevskoda]

To be honest Trev, I've been really impressed by the Trojans, and they can discharge to 80%.

Being 6V they charge up more quickly too.

Should charge the same as 12v when wired in series, problem with them is low cycles and plates fussing up, lead carbon will be better.

 

[Robmac]

you need some kind of load to 'stress' the battery.
I remember my VW LT starter battery used to sit at 12.7V no bother and it recharged really fast - 'coz it was knackered and had a tiny capacity left
When I turned the key to start the engine, it would drop to under 11V and not recover. a voltage reading is not actually a real indication of a batteries health.

Not sure what I could do to put such a load on the battery without an inverter. (I may buy one though).

I'll see how it gets on for the rest of the day, the fridge is doing it's job (very cold!). I have an upcoming trip to Norfolk in a couple of weeks and as long as I get through that with no problems I will have a re-think. I will be on EHU so I don't think I will really know until I'm next off grid.

I'm still a bit puzzled why the alternator didn't put the voltage right up though on a 7 hour trip back from Cornwall? The deeper points of leccy are a complete mystery to me though!