swapping wet cells for gel..advice needed

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electricfarmer
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Joined: Sat Apr 26, 2014 4:39 pm

swapping wet cells for gel..advice needed

Postby electricfarmer » Sun Apr 27, 2014 4:53 pm

Hello Everyone,

I'm on the brink of swapping out a set of 8 Trojan T-105s for some gel EV batteries of similar capacity in my Tomberlin 4x4 electric mule. The wet cells are just too keen on leaking with the off-road driving and I'm starting to get some corrosion issues. I was looking at the Haze HZY-EV6-225 gel EV batteries but wondered if I need to also change the onboard charger to better suit gel batteries. Is this correct? If so, any suggestions on an on-board charging solution for 8x 6v 225Ah gel batteries in series. The current system charges from about 80% discharged to full in 8 hrs. Something similar would be fine.
Any help much appreciated
Tim

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timpootle
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Location: Chorlton-cum-Hardy, UK

Re: swapping wet cells for gel..advice needed

Postby timpootle » Sun Apr 27, 2014 7:30 pm

Hello Tim, and welcome.
My understanding was that the charging regime for all lead acid batteries is the same so you can keep your existing charger.

I hope someone with more experience of lead acid traction batteries will be along soon to confirm or correct my belief.
Tim Crumpton

electricfarmer
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Re: swapping wet cells for gel..advice needed

Postby electricfarmer » Mon Apr 28, 2014 7:09 am

Thanks Tim.
Will be relieved if you are correct. Fourteen hundred quid in batteries is painful enough without buying a new charger!
I wasn't sure if some form of temperature monitoring was needed for charging sealed batteries. The current charger seems fairly advanced with 5 charging stages and a float charge at the end. I will dig out the manual and check the details.

Grumpy-b
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Re: swapping wet cells for gel..advice needed

Postby Grumpy-b » Mon Apr 28, 2014 4:03 pm

I have just swapped out a set of Lead acid cells on an Elelctric Polaris Ranger, for a set of used 200 AH Thundersky cells. The cells dont use a BMS but have been bottom balanced as a pack, and are no where near to being fully charged by the std Lead acid charger. But thats absolutely fine we were not looking to get the ultimate performance, just a virtually sag free voltage and a weight loss of around 100+kg with a higher AH even if not fully charged. Its still going to hold more than the original approx 125ah though.
Do be careful with whatever cells you choose. Check the discharge rate as many of the cheaper sealed cells are not designed for traction use, and while it may have a lot of stored power in Ah, it cant give it out at the rate of discharge the electric vehicle requires, hence on the Polaris they use two parallel strings of 12v cells just to give the discharge rate required by the motor / controller.

Grumpy-b

glyndwr1998
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Re: swapping wet cells for gel..advice needed

Postby glyndwr1998 » Tue Apr 29, 2014 6:21 pm

Hi tim,

I'm assuming your £1400 spend is on batteries, and I'm assuming your target voltage is 48v.

Why not consider instead the purchase of a used set of thunder sky's lifepo4, you'd need 16 of them, not sure if grumpyb has any left from the stock he has acquired in the past, but I think that would be a better proposition.

Then charge using your current 48v charger, or a meanwell 48v power supply andl set that up to output your target voltage. This way you would have better voltage delivery with little sag, and a battery that will outlast the others many times over.

No need for a bms, just bottom balance, or use like I do a couple of cell loggers to monitor individual cell voltage, and also set up a trip relay for high and low voltage alarm.

In my opinion that would be a better solution.

Anthony.


electricfarmer wrote:Thanks Tim.
Will be relieved if you are correct. Fourteen hundred quid in batteries is painful enough without buying a new charger!
I wasn't sure if some form of temperature monitoring was needed for charging sealed batteries. The current charger seems fairly advanced with 5 charging stages and a float charge at the end. I will dig out the manual and check the details.

Gareth Covell
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Location: Hereford

Re: swapping wet cells for gel..advice needed

Postby Gareth Covell » Sun May 04, 2014 11:12 am

Wet lead acid batteries like the T105's need to have a gassing charge every few cycles.
Sealed lead acid's do not, so they will tend to dry out.
When I replaced the wet batteries on my city-el vehicle with Haze agm units I also replaced the charger with ones designed for sealed lead acid.
1999 City-el

jonathan jewkes
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Location: Bristol

Re: swapping wet cells for gel..advice needed

Postby jonathan jewkes » Sun May 04, 2014 8:24 pm

Are you able to adjust the settings of your existing charger? The important thing is to avoid gassing - this does not matter with wet cells (so long as you keep the water topped up) and as Gareth says this can even be good for wet cells. But if a sealed battery gasses it will be drying out, and there is no way you can put the water back in.
So you need to ensure that, as the cells come near to being fully charged, your charger limits the voltage at the correct level (check the manufacturer's spec). You may find that your existing settings are OK
Sealed batteries do have vents which open if the pressure inside rises, so if gassing does occur does you will hear a popping noise.
Jonathan Jewkes
Daily EV user for 10years - an enthusiast and also a realist

electricfarmer
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Re: swapping wet cells for gel..advice needed

Postby electricfarmer » Sun May 11, 2014 4:15 pm

thanks for all the help chaps.

The charger is a Delta-q QuiQ charger which does have 10 selectable charge profiles although I'm yet to find any information on what those charge profiles might be (or what I might need for 8x hzy-ev6-225 batteries). I shall have a go at contacting the manufacturer.

Would love to replace with Lithium batteries ( and would happily take 2/3 of the AH to do so) but just can't justify the cost right now. Hoping a set of good gel lead/acids will last long enough that Li (or whatever else the future holds) will be affordable when I next change the batteries.

Ta
Tim

Grumpy-b
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Re: swapping wet cells for gel..advice needed

Postby Grumpy-b » Sun May 11, 2014 7:21 pm

A number of these type of vehicles are set with the Delta Q charger effectively over charging the cells. Some might argue this is a way of selling batteries and has no value whatsoever in doing this. Some people set the charger at a lower charge rate and prolong thier battery life considerably. But its also the cause of the corrosion as the cells are excessively gassing for an excessive amount of time. So whatever cells you choose I would suggest you change the charger setting. I do have the data on how to do this somewhere. I will try and find it.

Grumpy-b

electricfarmer
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Re: swapping wet cells for gel..advice needed

Postby electricfarmer » Mon May 12, 2014 8:55 pm

I have the info on how to change the charger setting but my battery knowledge is somewhat limited so I'm struggling to know what settings to choose from the available options. The programmed algorithms only include one for gel batteries and that is for 105Ah batteries and I was looking at using 225Ah batteries. Not sure what the implications are. I would assume it will avoid gassing but not sure what the significantly larger Ah of my batteries would result in. There are numerous other settings but I'm really not expert enough to make a judgement.

I have a PDF with the 10 pre-programmed charge profile options but not sure how to post it on a forum.


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