lithium batteries

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skip1202
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lithium batteries

Post by skip1202 » Sun Dec 20, 2020 4:05 pm

Hi All
I currently run two AGM batteries in my camper (in parralell). One of these have died and i am contemplating changing to Lithium batteries. For ballance i would like to run two bateries however i've heard that some lithium batteries can not be connected together.
thoughts please.

Cheers, Peter

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robcaz
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Re: lithium batteries

Post by robcaz » Tue Dec 22, 2020 10:26 am

Hi Peter,

If for example you are running two 120 amp hour AGM batteries, in reality you only have 120 amp hours available if you apply the 50% discharge rule.

On the otherhand a Lithium battery can be discharged to 80% so a 120 amp hour battery has 96 amp hours available. A 150 amp hour Lithium battery will have 120 amp hours available, so perhaps two 75 amp hour lithiums would suit your situation.

A 150 amp hour Lithium battery weighs 20kg compared to two 120 amp hour AGM's weighing 70kg combined.

You will be up for a new charger as lithium batteries require a different charging criteria.

There are some good articles on the Enerdrive website https://enerdrive.com.au/

Hope this helps.
happy camping
Rob & Carol
Australian CamperTrailers Group co-owner


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We're just two lost souls swimming in a fish bowl, year after year

grsouthern
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Joined: Mon Feb 10, 2014 7:39 pm

Re: lithium batteries

Post by grsouthern » Tue Dec 22, 2020 8:46 pm

Please be aware lithium batteries vary in quality. I purchased a 120 amp and it was only 80 amp. Thank fully had only installed for a week and got my money reimbursed. Revolution Power Australia is an ethical supplier and a quick chat to John Freath will answer your queries. However my experience has made me readdress my requirement for lithium vs AGM.

Justme
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Re: lithium batteries

Post by Justme » Sat Mar 27, 2021 9:18 am

Well I replace 3 x 120 agms with 2 x 120 lithium Itech batteries. Saved around90kg in weight. Also gained about an extra 20+ available A/hs. They charge up in well under 1/2 the time of the agm,s. I can boil the kettle from them (if I want...but I dont) and they can put out some serious amperage without damaging the batteries. The price is quite good. You can get them for around $780 when on special. I,ve read nothing but good reviews on them. When price, power, weight, reliability and longevity are taken into account they are well ahead of installing new agm batteries.

Justme
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Re: lithium batteries

Post by Justme » Thu Apr 01, 2021 5:14 pm

I also bought the Itech 120x Lithiums. Saved over75 kg replacing my 3 x 120 amp agms. Love the way they charge up way faster than agm. the agms gave me around 180A/h of useable power. The 2 x 120 lithiums are good for 210 A/h of power....Wont be boiling any kettles either...thats what gas is for.

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robcaz
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Re: lithium batteries

Post by robcaz » Fri Apr 02, 2021 5:57 pm

Hi Justme,

Please let us know how you go withy these batteries.
happy camping
Rob & Carol
Australian CamperTrailers Group co-owner


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We're just two lost souls swimming in a fish bowl, year after year

Justme
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Re: lithium batteries

Post by Justme » Thu Apr 22, 2021 4:51 pm

robcaz wrote:
Fri Apr 02, 2021 5:57 pm
Hi Justme,

Please let us know how you go withy these batteries.
Will do. Heading off very soon for a weeks camping..

StormCamper
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Re: lithium batteries

Post by StormCamper » Mon May 24, 2021 12:59 am

Some confusion here.

One of the main if not only reasons to stick with the 50% rule is so you have some reserve in those sticky situations, not because of cycle life, the same logic holds true for lithium so yes you can take them right down to 100% but it's not a smart way to go in alot of cases. This closes the gap between agm and lithium. For example my lithium was sized so come early morning it was at 90% but if the clouds rolled in I had very little buffer to come up with plan b. Now it's a bit bigger so come 10am to 12noon with weak solar it's at 90%DOD and this gives much better time to come up with plan b. :P

@Justme

Reliability is far in favor of an agm, obviously some agms are used by the armed forces. lithium have internal electronics which is a major potential failure point, those reviews tell you nothing. Lifepo4 has a working life of up to 10years so please wait until the smoke settles...
How can they be well ahead of an agm if reliability is questionable? You also clearly dont understand what cold temps and age does to performance. :lol:

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robcaz
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Re: lithium batteries

Post by robcaz » Tue Jun 08, 2021 9:39 am

The depth of discharge effects the life of an AGM battery, just as much as incomplete fully charging.

An AGM battery regularly discharged only 20% will last a lot only than one that is regularly discharged to 80%.

Image

We had 9 years from two Ritar 120 amp hour AGM's using the 50% rule & 100% charging.

The depth of discharge also has a bearing on the life of a Lithium battery.

For example let's say we use 30 amp hours over 24 hours. With a 240 amp hours AGM battery capacity we have 120 amp hours available keeping to the 50% rule. This gives us around 4 days usage with no sun.

A good rule of thumb for battery charging is to set up a solar panel so the battery is fully recharged by after lunch or in 5 hours. 30 amp hours divided by 5 hours = 6 amps. You need a solar panel that delivers 6 amps an hour. 18 volt solar panel output x 6 amps = 108 watt panel. Of course this is a very rough calc not taking into consideration any voltage drop of the wiring & panel output effected by heat. This can result is a 30% loss. So it would be fair to say a 150 watt panel is needed.
happy camping
Rob & Carol
Australian CamperTrailers Group co-owner


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We're just two lost souls swimming in a fish bowl, year after year

ColHut
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Joined: Wed Mar 27, 2019 12:18 am

Re: lithium batteries

Post by ColHut » Mon Jun 14, 2021 1:46 am

Some of this hugely depends on the use case. For weekend a month say 30 days a year, the battery will take 70% discharge and still only use 300 of its nominal 600 cycles in 10 years. If you live in the thing then lucky to get 2 years.

No doubt though that 50% reserve capacity is good for the unexpected though as it will get you through the odd extra rainy day :D

Not much you can do if the Lithium battery is down to 20%.

Ideally perhaps you would have as much Lithium as you had AGM.

Regards

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