Lithium battery charging time (1 Viewer)

Sep 28, 2021
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Hi All,

I 've recently got my first ever van, we used it a bit feel we need to upgrade the battery for better of grid use.

I think I want to go for 2 x 100Ah lithium batteries. We intend to do a lot little hopes driving for an hour or two and then a stop over for a day or two.

The van comes with a Schaudt WA 121525 b2b boost charger which I believes charges at 25A.

Does that mean if we want to fully charge both batteries if they where flat it would take 200 / 25 so at least 8 hours of driving? I'm getting a little confused installers are saying opposite things, I'm trying to workout if I need to upgrade the B2B charger as well. I will have also some solar.

Thanks
 

Kannon Fodda

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Upgrading the B2B also depends on what an alternator can output, not being demanded by engine systems. But yes if B2B is 25A that is per hour so emptied min 8 hours to recharge a 200Ah of battery, assuming alternator has that spare capacity.
 
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GaryMo
Sep 28, 2021
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Upgrading the B2B also depends on what an alternator can output, not being demanded by engine systems. But yes if B2B is 25A that is per hour so emptied min 8 hours to recharge a 200Ah of battery, assuming alternator has that spare capacity.
Thanks for the reply, yes that's what I thought. I had been told by a installer that lithium battery would charge in a hour or two, I guess he must be referring for a top up. It's a new Fiat van with their standard mh alternator. We will also have some solar 200w ish, but you can't always count on the sun. So it seems a bigger b2b charger would be better, or should I just let the van tick offer when pitched?
 

bigtwin

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A LiFePO4 will, subject to its BMS limits and unlike a lead acid battery, charge as fast as you can feed it. Consequently, if you had a sufficiently large charge source you could indeed charge it as quickly as the installer suggested. However, if not, it will take as long as you’ve calculated.

Ian
 

suavecarve

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What is going to use 200 ah of electricity to make you think youre going to need to recharge that amount ?

Consideration of a singular 200 ah battery ?

How much solar you got to recharge it ?

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GaryMo
Sep 28, 2021
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A LiFePO4 will, subject to its BMS limits and unlike a lead acid battery, charge as fast as you can feed it. Consequently, if you had a sufficiently large charge source you could indeed charge it as quickly as the installer suggested. However, if not, it will take as long as you’ve calculated.

Ian
Thanks Ian,

Surly the fast as you can feed it will be the 25A output from the battery to battery charger, or am i missing somthing?
 
Sep 3, 2012
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I think with 200watts of solar and your b2b you should be OK. Dont forget you dont need to have both batteries 100% charged to use them..the solar will charge your batteries whilst its stood on your drive.
 

Lenny HB

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If it is a new van with a smart alternator the alternator could be anything between 110 amp up to 200amp. Best to find out what it is before upgrading the B2B. If its 160 amp or above you will be OK with a 60 amp B2B.
 

Kannon Fodda

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Yes lithium batteries can accept a high charge rate. In practice charge rate is dependent on source. Capacity of alternator (and other draws on it), resistance of wiring (size and length), B2B ( or other device) rating.

In my case whilst a 60A rated B2B is fitted, I suspect I max out at 45A over a couple of hours driving, with a single 120Ah lithium. And yes easy to take battery low enough for that if you recharge ebike battery plus use whilst off grid.
 
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GaryMo
Sep 28, 2021
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What is going to use 200 ah of electricity to make you think youre going to need to recharge that amount ?

Consideration of a singular 200 ah battery ?

How much solar you got to recharge it ?
Looking at the 12v fridge spec it indicates a 200ah batteries will be good for 2.5 days. We will have a 1200w Invertor and be charging 2 ebikes, slow cooker etc..

looking at option of either single or two batteries

We are also looking at solar options.

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suavecarve

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Looking at the 12v fridge spec it indicates a 200ah batteries will be good for 2.5 days. We will have a 1200w Invertor and be charging 2 ebikes, slow cooker etc..

looking at option of either single or two batteries

We are also looking at solar options.
Couple of hundred ah of lithium will easily resolve your cooking, ebikes and general usage but your fridge, wow.

Wondering if your money is better spent with an underslung gas tank than on lithium if you have a 3 way fridge
 
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GaryMo
Sep 28, 2021
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If it is a new van with a smart alternator the alternator could be anything between 110 amp up to 200amp. Best to find out what it is before upgrading the B2B. If its 160 amp or above you will be OK with a 60 amp B2B.
Thanks Lenny, so first check alternator, if okay go for something like a 60A B2B if I want faster charging. On one site it says about very easy installation, so I may stick with the factory fitted and upgrade if I can't charge it enough through normal driving and solar
 
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GaryMo
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Couple of hundred ah of lithium will easily resolve your cooking, ebikes and general usage but your fridge, wow.

Wondering if your money is better spent with an underslung gas tank than on lithium if you have a 3 way fridge
It's a Thetford fridge, I was told it super efficient, I think it can draw up to 4a in day mode and 2a in night mode and obviously it depends on how hot it is. I hoping the quoted 2.5 days was worst case

Silly me just had another read, (now that I know a little more), it's average usage is 28 ah/24, so is say 3-5 days, but that is based on acid/gel batteries so only used 50% of charge, for lithium it should be 6 -10 days, that's more like it
 
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Kannon Fodda

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Hmm look first at potential use to determine min capacity of your batteries and then look at how you will recharge.

Fridge if maxed out 4A, 24 hours, is 96 Ah. That's a big battery load by itself.

Ebike, don't know of yours but my Bosch 500 to recharge via inveter when at say 20% took some 40Ah plus out of the battery.

Your 2 x 100 lithium will be working hard for a two day stopover.

Once you have capacity think about how to recharge, B2B size, solar, even mains hook up.
 

Tombola

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I had 200ah..now have 400 .
It all rests on your fridge... use gas for it if you can they use very little on gas...leaves you loads for everything else.
I still run my fridge mostly on gas

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bigtwin

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Thanks Ian,

Surly the fast as you can feed it will be the 25A output from the battery to battery charger, or am i missing somthing?

Yes, if your charge source is limited to 25A then it’ll take as long as you calculated. As I said, if you had a large charge source (60/80/100A) then the batteries would suck all that current up and charge proportionately quicker. That would not be the case with lead acids; they will only accept a certain charge rate irrespective of the size of your charge source(s).

Ian
 

Hoovie

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The way the OP describes the fridge ....
It's a Thetford fridge, I was told it super efficient, I think it can draw up to 4a in day mode and 2a in night mode and obviously it depends on how hot it is. I hoping the quoted 2.5 days was worst case

Silly me just had another read, (now that I know a little more), it's average usage is 28 ah/24, so is say 3-5 days, but that is based on acid/gel batteries so only used 50% of charge, for lithium it should be 6 -10 days, that's more like it
says to me it is a 12V Compressor fridge, so it will neither run on gas or ever use 96Ah a day. I would say the 28Ah/Day is a bit optimistic. the numbers quoted won't take into account losses incurred when you open the door to put stuff in, take stuff out, etc. I found just the action of filling my Fridge/Freezer uses a few Ahs! I would say more likely close to 50Ah if it is a fridge/freezer and a bit less if just a Fridge.

Should you upgrade the B2B? depends on how much driving you do, how much solar you intend getting, when you are going to use the camper (summer? all year?), how much power you will actually use a day and how long you are spending off-grid.
In other words, impossible to say either "yes" or "no" with any degree of reason without more information. I would just see how you go with what you have and then you will have some information to work from.
 
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Not long enough!
200Ah of LiFePo4 will be easily enough. This is like 400Ah of LeadAcid as it is all usable. The WA booster works well enough. I would add the Lithium (change setting on WA booster also) and nothing else and try it out before changing too much.
If you have 200W solar, in good weather you should be comfortably fine.

(We had an Adria Twin with compressor fridge. It also had the 100Ah lead acid and the Schaudt WA booster.) No solar at the start. The 100Ah lead (50Ah usable) was not enough to cope with a compressor fridge, but I added a second lead battery and 150w solar and it coped well, so you should be golden as you will have a lot more capacity than I did.
 
Jul 13, 2021
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I have a schaudt 25, 300w solar, 200Ah Lithium, Thetford compressor fridge. Winter with no sun and static in a field using Whale heating on gas, laptop, phone, router, TV - 4 days before a charge is required. If the sun comes out and I have a short drive I can last forever.
If only there wasn't a need to do 1s and 2s and have an abundance of water on tap (pun excused).
 
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You may want to look at the Fogstar Drift batteries as they are a drop in replacement for lead acid batteries.
One 230AH would be better than 2 x 110AH due to the way the BMS works.

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Mar 12, 2021
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We have 2x 100 AH KS. Energy lithiums. 30 amp BtB and 2Kw invertor.
We are very seldom on sites, battery’s run all the usual stuff + kettle, toaster, microwave,
But fridge and heating on gas we can stay off grid easily for 7 days without starting the engine.
K S Energy 10% funsters discount.
I would get your drop in lithium’s which you won’t regret and see how it goes from there.😀
 

Garry - June

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I had 200ah..now have 400 .
It all rests on your fridge... use gas for it if you can they use very little on gas...leaves you loads for everything else.
I still run my fridge mostly on gas
I upgraded my old RMD 3 way fridge to a new RCD 10.5 compressor model last summer.... by far the best upgrade I have made to my van...the difference in power consumption is huge and it now purrs away nicely wired to my 2x KS Energy Lithiums.. not cheap I admit but we fulltime so I can justify it.
 

Tombola

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I upgraded my old RMD 3 way fridge to a new RCD 10.5 compressor model last summer.... by far the best upgrade I have made to my van...the difference in power consumption is huge and it now purrs away nicely wired to my 2x KS Energy Lithiums.. not cheap I admit but we fulltime so I can justify it.
Im on the same lithiums from KS, they do well.

How many ah per day do you think it uses ? Garry - June
 

brynric

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I think the key to this is knowing your daily usage.
We are very frugal users. We don’t have a tv in the van, when we’re off grid gas takes care of cooking, heating and fridge. Our main uses are lighting and recharging of devices like phones, kindles and hair dryer. Our daily us is often around 25ah which is replaced by the 140w solar on a good day.
I’m sure we will upgrade our charging at some point but it’s not a priority yet.
 

Hoovie

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I think the key to this is knowing your daily usage.
We are very frugal users. We don’t have a tv in the van, when we’re off grid gas takes care of cooking, heating and fridge. Our main uses are lighting and recharging of devices like phones, kindles and hair dryer. Our daily us is often around 25ah which is replaced by the 140w solar on a good day.
I’m sure we will upgrade our charging at some point but it’s not a priority yet.
This is indeed key :)
For some folk, a 100Ah battery is more than enough. For others, that wouldn't even touch the sides :D.
take the 25Ah that brynic uses in a day? in my setup, I use more than 25Ah a day just to MONITOR the electrical system (how ironic is that!).
 
Jul 13, 2021
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FYI - I have two vehicles with Lithium. One is using Renogy batteries and the other Fogstar. Not only is the Fogstar cheaper amp for amp but its BMS, in my opinion, is superior. In addition, Fogstar Lithium are heated. Both have bluetooth.
The wait for the Fogstar was longer than Renogy but they will talk to you as well as issuing a full charging specification. Renogy on the other hand do not respond to technical emails and to date, have failed to issue their recommended charging parameters and I'm not the only one who has been asking them.
So for me: Renogy 7/10 and Fogstar 9/10
 
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GaryMo
Sep 28, 2021
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FYI - I have two vehicles with Lithium. One is using Renogy batteries and the other Fogstar. Not only is the Fogstar cheaper amp for amp but its BMS, in my opinion, is superior. In addition, Fogstar Lithium are heated. Both have bluetooth.
The wait for the Fogstar was longer than Renogy but they will talk to you as well as issuing a full charging specification. Renogy on the other hand do not respond to technical emails and to date, have failed to issue their recommended charging parameters and I'm not the only one who has been asking them.
So for me: Renogy 7/10 and Fogstar 9/10
Thanks for the info. I need to find a n installer who with do the batteries but also fit inverters and solar plus a few other bits at a sensible price. One possible installer, Rhino, do Eco Tree and KS Energy batteries, can anyone else recommend installers for fogstar?
 
Jul 13, 2021
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FYI - I have two vehicles with Lithium. One is using Renogy batteries and the other Fogstar. Not only is the Fogstar cheaper amp for amp but its BMS, in my opinion, is superior. In addition, Fogstar Lithium are heated. Both have bluetooth.
The wait for the Fogstar was longer than Renogy but they will talk to you as well as issuing a full charging specification. Renogy on the other hand do not respond to technical emails and to date, have failed to issue their recommended charging parameters and I'm not the only one who has been asking them.
So for me: Renogy 7/10 and Fogstar 9/10

Thanks for the info. I need to find a n installer who with do the batteries but also fit inverters and solar plus a few other bits at a sensible price. One possible installer, Rhino, do Eco Tree and KS Energy batteries, can anyone else recommend installers for fogstar?
If you are not confident to fit your own system then I would be purchasing my own Fogstar battery or batteries and asking an installer to fit them. You would save yourself an awful lot of money.

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