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Leisure battery advice for mobile coffee van


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Hello all!

So sorry to ask what must be age old questions, but google searching is getting me very confused with conflicting results so I thought it better to ask experts that actually do this for a living.

I currently have a mobile coffee van and it can run either off mains or independently with a gas cylinder and 2 x 100ah leisure batteries connected together. After two years my leisure batteries finally failed and left me high and dry after a few minutes into a gig. Red faces all around! They were showing 12.6v after full charge so I knew they were tired, and then immediately they reducing to 12.2v as soon as I used them and quickly dipped to 11. something after that so I assumed they got sulphorcated with old age. I am looking at the inverter to see the voltage indication. So I've now replaced them like with like. They're both Superbat Silver 9000 12v 100ah. 

1) But now I'm wondering should I have replaced the 100ah with 110 ah as everyone else seems to use those? Is this okay to do, or can it cause problems if the ah is too high? i had the van built for me and the folks that made it installed 100ah. Do they last longer with a higher ah? (Apologies, as you can see I'm about as technically minded as a postage stamp!)

2) Now lock down is easing, events are opening up that require longer hours and sometimes plug in power is not available or simply too expensive to be viable on top of already crazy high pitch fees. So I was thinking I could take a spare set of batteries to swap out when my current ones get too low. In that case, what would be an ideal voltage to say "Yes, I need to swap them over now."? 12.4v? or is it okay to let them run lower just as long as I charge them fully when I get home to avoid sulphorcation? 

3) Final question. My batter charger has two settings, trickle charge and fast charge. I'm fairly certain that I read I should not trickle charge the leisure batteries. But when I fast charge them the fully charged light comes on after about 3 to 4 hours. Should I just leave them charging for longer as I've read they should initially be charged for at least 24 hours? Or is it better to unhook them from the charger as soon as the charger fully charge light indicates green?

Huge thanks to anyone who can help with any of these questions.

Jim.

Edited by Jim H
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The higher the Ah the longer the batteries will last. If you already have your new ones in place I wouldn’t worry too much about the 110, it won’t make a massive difference. 

2 x 100 should get you through a very busy event in my experience. 

It is my understanding that trickle charging is much better for batteries than fast charging. 

In all honesty I don’t think there are that many members that use this set up. It is 99% domestic users. There are lots of questions about it but it tends to be newbies looking to set up. I’d speak to some experts if I were you. There are plenty of companies that specialise in 12 volts gear.

Another tip - as you depend on this to make money, do not buy cheap Chinese off brand junk batteries, chargers or inverters.

Edited by davril
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As above changing to 110 amp would not make an appreciable difference, using higher amperage batteries will not harm installation.

Leisure batteries are different from other batteries as they are 'deep cycle' = they can be run quite low before recharging without damage.

How old were your previous batteries ?. Did you ever leave them in a discharged state ?. From your statement above , your charger sounds to be quite a basic charger ? Most batteries, particularly leisure types do not like boost / rapid charging.

Do the batteries lie idle in the winter ?

A good charger should sense the state of charge in the battery and adjust the charge to suit, tapering it off as the charge reaches full.

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Thank you guys!

@davril Thank you for the advice, that provider you mentioned has a super useful guide that has pointed out some of the mistakes I was making 👍

@El carajillo Yes, I think to my horror I made most of the mistakes you mentioned. The batteries were two years old when they failed and I'd been using them for a good year full time. My van has a split charger but I tend to drive only for about 40mins a day as my pitches are all local so the batteries weren't getting the boost they needed. And from time to time I was charging them with an RAC car battery charger on fast charge which I now understand was probably the wrong thing to do. I shall bite the bullet and invest in a proper leisure battery charger in the hope of not making the same mistake again. Though I've already been charging my new batters in the same way so I've likely damaged those too *face palm* xD

Thank you again folks, I really appreciate it : )

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@Jony

I have to admit, first time I removed them I was quite surprised by the weight, they're snuggled into a rather small space underneath my knockout draw and need to be dragged out across some fragile wires. I figured if stone age man could drag Stonehenge from Wales then I could find a way to extract my batteries from my rig. But I think 50kg each would probably kill me! xD

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 I posted a while ago some stuff you might find interesting in answer to a question about farmers markets and inverters. The bits about batteries should be of particular interest.

For lead acid batteries

  • batteries like to be trickle and float charged...in fact they love float charging
  • they don't like to be left in any state of discharge especially 50% or less, for any length of time
  • they don't have memory effect
  • They don't like high current draws when cold and a bit discharged (really don't like it)
  • depending on your dual battery setup, if one goes bad it might drag the other down with it fairly quickly
  • only bank on using 40% of the theoretical capacity before recharging (or they won't last very long)
  • recharge at every opportunity
  • don't fast charge unless you have to
  • if the electrolyte level is low and you can see it...even if the battery is SLA, see if you can open it and add distilled water

 

Sticks and Stones, sours…or rancid (horrible). Quakers hide until roasted, pick em out and flick them in the bin. Life is too short for bad coffee

 

 

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Hi Jim, I'd like to start with a caveat that I am not speaking from direct experience in your business and I may not be fully versed in the subleties between different battery types but I have worked around electrics, automotive, technology and engineering most of my life so I will still chirp in if I may.

1. Increasing amp-hours (ah) has no detrimental effect. It simply defines the 'capacity' of the battery to deliver charge. higher amp-hours means longer running. In my experience going as high as you can afford/make room for is never bad.

2. Although you can use volt drop to get an round-about idea of what's going on with your batteries, the problem you seem to have experienced is that an older 'tired' battery cannot sustain charge for as long. In effect the amp-hour rating drops as the battery reaches end of life, so just measuring voltage may not give you an accurate assessment. Even though some batteries last longer than others, it may not be a bad idea for you to keep a weekly/monthly running total of how many hours the batteries have been used to give you an idea of when they may be approaching end of life, replacing before they become to tired to work to requirements. Perhaps buy a new set of batteries a little before you need to replace and keep them on standby.

It used to be a thing in certain auto services to check the state of your battery with a volt-drop test. This usually involved a special meter or hoiking great big metal tongs put across the battery with a given resistance that would 'safely' fast drain the battery and assess how well it was able to hold charge. I always felt somehow this test wasn't good for the battery so I wouldn't recommend doing it weekly but perhaps you can find a friendly garage or test centre that will check your batteries for you every month or couple of months to give you an idea as to when they are beginning to lose their ability to hold charge.

3. Here I'm really not an expert so I will give an opinion based on personal experience and not specific technical knowledge so please do investigate yourself further. I am not aware of any battery that would prefer a fast charge to a trickle charge. Most batteries work (very approximated) through chemical reaction and electrolysis and recharging in effect reverses the effect through charge, returning the materials inside the container to their original pre-discharged state. Fast charge does this more aggresively and usely generates more heat and is less efficient and more strenuous on the battery. The rule of thumb used to be 'a fast charge doesn't hold charge', ie use it when you need it but it isn't the most efficient. A trickle charge is far less aggressive on the battery and tended to result in a better 'refreshed state', which loosely translated to a better recharged battery. My general advice would have been always trickle charge when possible and fast charge only when you must. I would echo some feedback from others here though that it is worth investing in a high quality charger. But again, I am perfectly happy to accept I may not be correct with specific batteries or applications so perhaps best get the advice from the experts.

A good place for advice is caravan and mobile home builders. They will have lots of experience regarding rating, selection and usage/charge/drain of leisure batteries.

I would also suggest finding the contact details of a reputable, or your preferred, battery manufacturer online, and contacting them directly. This is surprisingly easy and you can usually be transferred to someone in their technical department that can give you very specific and accurate answers.

 

I hope some of this was useful and I again apologise if some of the information may not be spot on for your particular application. Hope there's some food for thought there though.

 

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Oh and everything Dave just said 🙂

Something else maybe worth noting is that in my experience batteries don't like to be discharged HOT either (ie high current draw directly after a fast charge). They tend to discharge quicker and they tend to lose their efficiency faster. Better to let a battery come down in temp before discharging. Another good reason for trickle charging as this does not result in overheating.

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1 hour ago, Jim H said:

Thank you guys!

@davril Thank you for the advice, that provider you mentioned has a super useful guide that has pointed out some of the mistakes I was making 👍

@El carajillo Yes, I think to my horror I made most of the mistakes you mentioned. The batteries were two years old when they failed and I'd been using them for a good year full time. My van has a split charger but I tend to drive only for about 40mins a day as my pitches are all local so the batteries weren't getting the boost they needed. And from time to time I was charging them with an RAC car battery charger on fast charge which I now understand was probably the wrong thing to do. I shall bite the bullet and invest in a proper leisure battery charger in the hope of not making the same mistake again. Though I've already been charging my new batters in the same way so I've likely damaged those too *face palm* xD

Thank you again folks, I really appreciate it : )

Something to remember with basic  split charge system, when one of the batteries reaches full charge the system ceases to  charge can / may also apply if vehicle battery achieves full charge.

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