Battery advice

Steveandjulie

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We was hoping to get it sorted before the Hereford meet in October. Would one 110 lithium battery give me the same output then as two AGM batteries we are going to fit around 300 watts of solar to run compressor fridge and watch TV what are your thoughts
 

wildebus

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We was hoping to get it sorted before the Hereford meet in October. Would one 110 lithium battery give me the same output then as two AGM batteries we are going to fit around 300 watts of solar to run compressor fridge and watch TV what are your thoughts
A lithium battery that allows 100% discharge should give same output as a pair of AGMs taken down to 50%, yes.

In fact, it will be slightly better, as as the voltage of a battery drops, more current (amps) is drawn from the battery to deliver the same power (watts) - and while Lead Acid batteries drop in voltage as energy is used up, that effect is minimal on a Lithium until right at the end.
300W will run the compressor fridge no bother in the Summer. Come Autumn ... should be ok if not overcast all day :)
 

in h

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Be aware that if 100Ah doesn't prove to be enough storage (two or maybe three overcast days) you can't just add a second 100Ah lithium battery in parallel, unless you bought the more expensive sort that have BMS designed for linking.
 

wildebus

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Be aware that if 100Ah doesn't prove to be enough storage (two or maybe three overcast days) you can't just add a second 100Ah lithium battery in parallel, unless you bought the more expensive sort that have BMS designed for linking.
This point well made, and not just models with linked BMSes
I think it is worth futureproofing by choosing a battery that will allow expansion. (so for example, the two I mentioned before - BASE and INFI - I would pay the extra for the INFI model for that reason)

(some smaller campers will either not have the room, or very little likely need of more power, and for them, a non-parallel capable battery would be fine)
 

Steveandjulie

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A lithium battery that allows 100% discharge should give same output as a pair of AGMs taken down to 50%, yes.

In fact, it will be slightly better, as as the voltage of a battery drops, more current (amps) is drawn from the battery to deliver the same power (watts) - and while Lead Acid batteries drop in voltage as energy is used up, that effect is minimal on a Lithium until right at the end.
300W will run the compressor fridge no bother in the Summer. Come Autumn ... should be ok if not overcast all day :)
Thanks for your reply very much appreciated still undecided as this camper isn't a forever van only till we retire then upgrade to a larger van.so would I be better off with the 2 AGM would they provide enough power for our needs
 

wildebus

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Thanks for your reply very much appreciated still undecided as this camper isn't a forever van only till we retire then upgrade to a larger van.so would I be better off with the 2 AGM would they provide enough power for our needs
you know, it could be worth going lithium still potentially, as in terms of service life, they could well outlive you (I think a new one will outlive me!) and you could take them with you to your new van, and you could drop in a brand new Lead Battery into the current van for the sale, which could be a good selling point?

AGMs are still good batteries to use regardless of course and I still fit way way more AGMs than Lithiums due to the price difference.
 

snapster

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Before you buy AGM batteries, make sure your charger has an AGM setting and alternator has enough output. They require a higher charge rate than lead acid batteries.
Our van came with AGM batteries and an AGM charger, but I had read many reports of AGM batteries failing if they weren't charged properly and the consensus ( from people that had them) is that they had a much shorter life than lead acid or gel.
I change mine for good quality lead acid batteries. ( Varta LFD90)
 

in h

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748
Before you buy AGM batteries, make sure your charger has an AGM setting and alternator has enough output. They require a higher charge rate than lead acid batteries.
Our van came with AGM batteries and an AGM charger, but I had read many reports of AGM batteries failing if they weren't charged properly and the consensus ( from people that had them) is that they had a much shorter life than lead acid or gel.
I change mine for good quality lead acid batteries. ( Varta LFD90)
That's a rather inaccurate description of the problem. Yes, the charge profile of an AGM battery is different and yes you can shorten its life dramatically by charging it wrongly. But it's utterly untrue to say that they require a higher charge rate. You can trickle-charge an AGM battery with impunity.
 

wildebus

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If a battery was damaged by having a low charge into it then using Solar would be a death knell for thousands of batteries in campers and motorhomes.
 

nabsim

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I purposely went for Lifepo4 that could only be solo or paired as I could afford two of them and at that time they were almost half the retail cost of an RB100. I worked on the theory if I did need more I would set up a separate bank and have them switchable. Not a big deal to set up solo banks just need to do it differently 👍
Of course you also have the cost of monitoring Lifepo4 but if doing it now I would get the headless monitor as I never use the readout,only bluetooth
 

Molly 3

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Hang around for a couple of months as alpha batterys are starting a new range of lifepo4 batterys about half the price of relion . Not that much more than 2 good agm batterys . In winter their will be times when 300 w won't be enough .you . did not mention heating .2 agm battery would weigh about 60 klg .lithiam less than 15 klg .
 

snapster

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That's a rather inaccurate description of the problem. Yes, the charge profile of an AGM battery is different and yes you can shorten its life dramatically by charging it wrongly. But it's utterly untrue to say that they require a higher charge rate. You can trickle-charge an AGM battery with impunity.
I was reliably informed by a company that makes AGM batteries that they require a higher charge rate than lead acid, I assume that’s why many chargers now have an AGM profile. Solar charging and long slow charging will work fine, but unless you regularly charge the battery fully, you will shorten its life.
The handbook in my van ( with AGM profile on the charger and high output alternator) states that to ensure long life of the batteries, they should be fully charged after every trip using the built in charger.
My solar charger shows AGM batteries reach the absorption stage at 14.7v whereas lead acid only need to achieve 14.4v before the absorption stage starts.
 

nabsim

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Hang around for a couple of months as alpha batterys are starting a new range of lifepo4 batterys about half the price of relion . Not that much more than 2 good agm batterys . In winter their will be times when 300 w won't be enough .you . did not mention heating .2 agm battery would weigh about 60 klg .lithiam less than 15 klg .
My 100ah are 13kg each Baz, pair together are the weight of one of the Bosch 90ah they replaced. Gave me a nice 52kg weight saving 👍
 

wildebus

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I was reliably informed by a company that makes AGM batteries that they require a higher charge rate than lead acid, I assume that’s why many chargers now have an AGM profile. Solar charging and long slow charging will work fine, but unless you regularly charge the battery fully, you will shorten its life.
The handbook in my van ( with AGM profile on the charger and high output alternator) states that to ensure long life of the batteries, they should be fully charged after every trip using the built in charger.
My solar charger shows AGM batteries reach the absorption stage at 14.7v whereas lead acid only need to achieve 14.4v before the absorption stage starts.
Ref ensuring long life by fully charging as soon as possible ... that is true of the large majority of lead acid batteries, not just AGM.

There are some Lead Acid batteries that don't really care about getting charged ASAP - the ones I have for example don't require that (" NorthStar AGM thin plate lead carbon technology delivers ultra fast recharge times and more than three times as many cycles as standard AGMs, thanks to its PSOC compatibility" - PSOC = Partial State of Charge)
Ref the voltages, you are generally correct in saying that different battery technologies tend to need different charge voltages - AGM usually need more then SLA, and that is often more than Wet Cell fillables. Calcium Batteries would need more than AGM, so a charger that is designed only for 'standard' Lead Acid SLA/Wet batteries might not be optimized for AGM Lead Acid batteries (just to make one think clear .... AGM Batteries ARE Lead Acid batteries).
Again, those voltage values are not a hard and fast rule. 14.7V would be like a fast charge for a battery, but 14.4V for AGM is perfectly acceptable and is better for the battery. Personally, I would not use 14.7V for AGM (and taking my own Lead Acid GM Carbon batteries, I have my mains and B2B chargers set to 14.1V, with Solar at 14.2V to finish the job - they like 14.2V more than 14.4 and would never use 14.7 on them for any length of time)

All the above is only for Lead Acid. Lithium is different and actually likes to be left in a PSOC for longer life.
 

Steveandjulie

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We have a sterling b2b charger and a smart charger from Aldi for when on hook up so both should work for lithium so seriously thinking of waiting for alpha to get the cheap lithium battery. Would one 100 amp be enough or best get 2?
We are hoping to fit a diesel heater soon as well as running a compressor fridge and a 12 volt TV in the evening
 

wildebus

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We have a sterling b2b charger and a smart charger from Aldi for when on hook up so both should work for lithium so seriously thinking of waiting for alpha to get the cheap lithium battery. Would one 100 amp be enough or best get 2?
We are hoping to fit a diesel heater soon as well as running a compressor fridge and a 12 volt TV in the evening
diesel heater ... assume 1.5Ah/per hour running x how many hours? 6? 8? you decide. Lets say 6 hours as an example.
fridge ... assume 2Ah/Hour on average (pessimistic) x 24 Hours a day
TV and lights ... depends on TV - maybe 4Ah (50W) an Hour x Hours? say 4 hours?

so Heater = 9Ah; Fridge = 48Ah (Fridge is always the biggy); TV and lights = 16Ah. Total for the day = 73Ah.
If you have solar, that will provide some recharging of course - but really only in summer. Autumn reduced, Winter - regard solar charge as a surprise bonus if it happens.

having 100Ah usable is close to what you will use - I'd want to go for 200Ah useable TBH to cover bad weather days unless you are on the move most days or on sites with EHU often.
 

jagmanx

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Yes winter is the problem..Plan for ZERO solar in December..Yes ZERO

as above
so Heater = 9Ah; Fridge = 48Ah (Fridge is always the biggy); TV and lights = 16Ah. Total for the day = 73Ah.
If you have solar, that will provide some recharging of course - but really only in summer. Autumn reduced, Winter - regard solar charge as a surprise bonus if it happens.
Even with 2 batteries without engine or EHU seriously depleted in a few days because of limited re-charging
 

wildebus

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The key factor is the seasons really.
The time you need more more (heating on, lights on for longer, more likely to be inside due to cold = more TV) is the time of year when solar is decorative. In the summer, solar likely gives you more recharging on a single battery then you would need.
So first thing to determine really is if you are a fair weather camper or all-year-rounder?
 

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