Mains Charger For Leisure Battery Advice Please!

[aandncaravan]

mac74 - 2019-04-03 8:28 PM

 

Hello all, i have finally decided to go for the - Victron Energy Blue Smart IP65 15amp Charger - I hope this will give my 2 new yuasa L36-EFB 100ah batts a longer life than my current ctek 5amp charger? time will tell i guess. Going to order it tomorrow, cheapest ive found is ebay @ £137 ish delivered, from battery megastore, i just want to check its a connect and forget type. Sorry ive been going on about this for a while, (allan has probably still got his head in his hands) but genuinely many thanks to all, for your input on it, as its been really helpful to me.

 

Best Regards To All

 

Malcolm

 

Malcolm, not been great lately that was the only reason for not replying.

Glad you have a resolution.

 

Can I suggest that you regard 12.8v as a fully charged Yuasa L36-EFB and 12.3v/50% Depth Of Discharge as the lowest you let it drain before recharging.

If you can recharge every day and keep the voltage above 12.5v (resting/no load) it will make a big difference to battery life

 

[mac74]

 

 

Malcolm, not been great lately that was the only reason for not replying.

Glad you have a resolution.

 

Can I suggest that you regard 12.8v as a fully charged Yuasa L36-EFB and 12.3v/50% Depth Of Discharge as the lowest you let it drain before recharging.

If you can recharge every day and keep the voltage above 12.5v (resting/no load) it will make a big difference to battery life

 

 

Hello allan, for info: i got the new victron IP65 15amp today, and wanted to try it, so i disconnected one of my EFB's that i had on the ctek since yesterday, fully charged, and on float - I then immediately connected the victron, and it went straight to absorption charge state, and it was on for the next 1hr and 15mins with current @ 0.2a (30mins) then 0.1a until it went to float. So it has put more power in i think but not a huge amount?

[mac74]

Ive also just put my 2nd EFB on vic charge about 40mins ago (which had very little use 2day, 2hrs max) and the iphone monitor tells me in went straight to absorption @ 15amp going down bit by bit to to 3amps - but now its telling me its on float charge 13.8v ok, BUT 2.6 amp current? shouldn't the FLOAT charge, have hardly any current/amps going in at all??? compared to my above findings?? I wonder if my unit is faulty?? now after 1hr or so its still 13.8v but the current is slowly dropping, now @ 1.8/2.0amp - It looks like it still in absorption stage, given that its still taking amps in, BUT it says float, which the manual says its ready at this point, but how can it be if its still taking a charge? WTF This driving my mad! Help please m

[mac74]

Ive just disconnected it and put it back on, and it now says absoption charge (for the last 10 mins that ive re put on) 14.4v and 3.4a current, i think this unit is faulty, bo**ocks! ill call them tomorrow. Thanks m

[mac74]

Hello all, i re-wired all my van work equipment today, i.e Battery to controller then to pump - plus new batt clamps, wire bullet joiners and install thicker gauge wire, (ive just got to fit the watt meters shortly) Wow what a difference in pump performance! I Put a fresh efb batt in, and it dosen't drop lower than 12.2v under load GREAT!, as b4 it was 11.4v :'( . This is probably a combination of the re-wire and the better charge up from the victron maybe? Taking of the victron IP65 15amp charger, i have since noticed that i have to unplug it, every time i do a new cycle charge, for it to start from its first test cycle phase? i couldn't get through to the company where i bought it from to ask them today, but, IS THIS NORMAL ANYONE? As the ctek i have, i don't have to unplug it from mains to re-start it, i just take the croc clips off one batt, and put them on the next battery for charge, and the cycle starts from the beginning again. Thanks again all, (hope your feeling better allan)

 

Best Regards

 

Malcolm

[spirou]

Victron have awesome support and I'd suggest you ask directly rathe than whatever company you got it from

https://community.victronenergy.com/index.html

[mac74]

spirou - 2019-04-07 6:09 AM

 

Victron have awesome support and I'd suggest you ask directly rathe than whatever company you got it from

https://community.victronenergy.com/index.html

 

Good idea, ive just registered on there now, ive also wired in my watt meters today so i will have a accurate reading on how much power i draw! many thanks all. m

[mac74]

Hello all, i done my first watt meter reading today, from my setup of one 100psi shurflo pump and a spring electronic flow controller wired from a fully charged L36-EFB 100AH battery. The results below was after a 3.5hr constant on/off blast, with hardly any split charge relay use today.

 

12.4v

 

93.6wh (watt hrs?)

 

6.13ap (peak amps?)

 

11.42vm (max volts?)

 

70.8wp (peak watts?)

 

7.949ah (amp hours used?)

 

 

Im not sure how my 3.5hr solid on/off usage would stack up against the 20hr discharge rule? and does it mean i only drained out 7.949amps? give or take say10% for a cheap chinese meter?

 

Many Thanks

 

Malcolm

[aandncaravan]

Yes the 6 amps (probably on initial start-up before the Spring takes control) is a peak and the 7.9Ah indicates total Ah draw from the battery.

 

A resting voltage of 12.4v either indicates that the battery still has some load on it or it wasn't fully charged at the start of the day, I would have expected about 12.6v on a new battery that has still got to reach full potential.

 

But as you say that assumes the meter is 100% accurate.

 

Have you had both batteries on charge for at least 24 hours before first use?

 

 

[mac74]

Sorry allan, i should have said that today's experiment was x 2, as i asked a friend to help me test this out (it was difficult but i found a way) and both meters were fairly identical on all accounts. I just thought i would say one reading to make it simpler for all, and i would just double it? thanks allan for your help. m

[mac74]

Does anyone know how the 20hr 100ah battery use calculation would convert to a 5hr use, is it just 3x less?

[aandncaravan]

Not sure I understand the question, but at higher current draws there may be more heat generated and other efficiency loss so a battery being asked to deliver high currents for long periods will end up delivering less than their 100Ah capacity.

I have a graph somewhere of a Varta LA95 delivering just 67Ah of it's 95Ah capacity at over 150amps draw on an Inverter.

 

The lower the current draw, the closer you will get to the battery capacity. The more current you draw the more that will be 'lost'.

 

A battery that delivers 100Ah at the C20 rate should deliver 5 amps over a 20hour period, but obviously if you did discharge a battery right down flat to 100% Depth Of Discharge then the battery life would be severely shortened, so the reality is that just 50Ah will be available, 5amps for 10hours is the 'recommended' C20 rate.

 

While there can be a big difference in reduced capacity at 100+amps current, the difference between a 5amp draw and a 3amp draw is unlikely to be measurable.

 

 

It is important to recharge a Lead Acid battery as soon as possible after any reasonable discharge, leaving it for only a few days can still result in lost capacity through Sulphation.

 

In your case, recharging the battery overnight after each days use would be important for decent life.

 

[plwsm2000]

Malcolm, Most batteries are rated at their "C/20" (capacity over 20 hours) discharge rate. i.e. a 100Ahr battery when discharged at 5Amps will last for about 20 hours before it is totally flat.

 

If you draw more current that the C/20 rate, the battery will appear to have a lower capacity that its normal rating and if drawing less current, the battery will appear to have a higher capacity.

The effects are quite substantial, and to give some examples - If you only draw 0.5 Amp from a 100Ahr Gel battery, it will last around about 280 hours (it behaves as a 140Ahr battery). Drawing 20 Amps from the same battery will only give about 4 hours (80Ahr capacity)

 

A German scientist Wilhelm Peukert back in 1897 studied this effect and produced a mathmatical equation that predicted the apparent capacity at different discharge rates. He came up with something now called "peukert's coefficient" that can be used to predict capacity for different battery types and discharge rates.

 

There is a simple Excel spreadsheet at - that will allow you to easily calculate your battery's effective capacity at different discharge currents. (I have no connection with this site and have no experience of their products but there is quite a lot of technical stuff on their site as well [url=] http://www.smartgauge.co.uk/technical1.html that I also found quite interesting).

 

If you use the above spreadsheet, set the puekert's coefficient to 1.1 for AGM, 1.15 for Gel and 1.2 for wet batteries. Unfortunately the value changes (increases) as the battery ages and is also temperature dependant so it is only a guide. (obviously you should not totally discharge the battery in any case).

 

Using this to answer your question (I think!), if you have a bank of 2x100Ahr wet batteries, discharging at 32Amps will last about 5 hours before they are totally flat (100% DOD). They would appear as a 160Ahr bank. Finally, don't just look at individual batteries - treat them as a single 200Ahr one.