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AGM versus Gel batteries


Cloudinspector

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I’ll soon be looking to replace our battery bank which is 3 x 200ah Victron AGM batteries. The current batteries are about 10 years old and for the last 3 1/2 years we’ve been off grid. Our charging regime consists of a built in 9kva generator, 300w solar and 140amp engine mounted alternator. The inverter/charger is a Victron multiplus 3000/120. The inverter is on 24/7 as it powers a 240v AAA rated fridge and a diesel fired range which provides cooking, heating and hot water.

I’m more than happy with how the Victron batteries have performed and would be happy to replace like for like. However the Gel version are slightly more expensive and according to the Victron figures would give a longer service life. Could anyone tell me which is likely to be more suitable given my circumstances?

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The Gels are likely to give a somewhat longer service life as a true deep cycle battery but are less well suited to heavy discharges. Looking at your OP you don’t list any heavy mains consumers such as microwave, hair dryer etc which would suggest that the gels would be fine for you. However, their service life isn’t THAT much greater than the AGMs so if there’s much of a price difference I’d stick to what’s worked for you for the last 10 years. 

In another 10 years I think that lithium-ion (or its replacement) will be a no-brainer but for now I’d stick with what you know works. 

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1 hour ago, WotEver said:

In another 10 years I think that lithium-ion (or its replacement) will be a no-brainer but for now I’d stick with what you know works. 

 

I very much agree with this. At the moment there is only the tiniest userbase of Lithium batteries on the cut so there will be drawbacks not widely known and understood amongst narrowboaters. For a 'mission critical' purchase such as yours it sounds to me as though you don't have the resilience to cope should they turn out to be a Big Mistake for reasons no-one is here predicting. 

Being an early adoptor of fringe technology is great when it doesn't matter that much if it works as expected or not, but as a liveaboard relying heavily on batteries that work, I suggest trailing edge technology is the safe bet you need. 

Buy the AGMs!

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I think you're gaining nothing tangible by going for Gel, so save money and buy the more common, and therefore cheaper, AGMs. They're a bit more forgiving about charging rates too but, since you've had 10 years from the last set, your charging sources must be well matched.

.

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Changing to gel may buy you 12 years life instead of 10 for AGM but is that worth it?  Changing to lithium will mean replacing or upgrading your chargers because they have different requirements, so extra cost.  In 10 years time when you are next changing things will be different, the boat will be older, you may have to change the engine due to new regulations, much of the boats electronics may have been upgraded etc.

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2 hours ago, Detling said:

Changing to gel may buy you 12 years life instead of 10 for AGM but is that worth it?  Changing to lithium will mean replacing or upgrading your chargers because they have different requirements, so extra cost.  In 10 years time when you are next changing things will be different, the boat will be older, you may have to change the engine due to new regulations, much of the boats electronics may have been upgraded etc.

LiFePO4 uses same charging voltage as AGM so no need to upgrade your chargers (The OP has a Victron combi so is more than fine).   If going down the LiFePO4 route you will need a BMS and as the OP has Victron stuff already I would personally use Victron batteries and BMS.  (I'm going down this route).   With the Victron BMS it has external relays and cables to disable loads and turn off charging equipment, the Combi is directly controlled via the RJ45 cable.

The biggest advantage with LiFePO4 bar the 3000-5000 cycle count is that you don't need to fully charge, the batteries will be able to take the full bulk of the charger to nearly 100% SoC and at a better charging efficiency (98-99%).  This reduces the charging time which is good news when charging via genny. 

Edited by Robbo
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1 hour ago, Robbo said:

LiFePO4 uses same charging voltage as AGM so no need to upgrade your chargers (The OP has a Victron combi so is more than fine).   If going down the LiFePO4 route you will need a BMS and as the OP has Victron stuff already I would personally use Victron batteries and BMS.  (I'm going down this route).   With the Victron BMS it has external relays and cables to disable loads and turn off charging equipment, the Combi is directly controlled via the RJ45 cable.

How is the alternator protected from damage when the last BMS disconnects?

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I would stick with the same as you already have. Li po batteries have been known to catch fire on thousands of occasions :mellow: so why take the risk. A canadian company have come up with a fix for this so I read a couple of days ago, it also increases the range by x3 when used in cars so when this happens I would maybe think about them but they are seriously expensive so it is a very large gamble

1 minute ago, Robbo said:

It's connected to the starter battery.

Not if its a separate alternator

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Just now, peterboat said:

I would stick with the same as you already have. Li po batteries have been known to catch fire on thousands of occasions :mellow: so why take the risk. A canadian company have come up with a fix for this so I read a couple of days ago, it also increases the range by x3 when used in cars so when this happens I would maybe think about them but they are seriously expensive so it is a very large gamble

Not LiFoPO4 batteries tho.  You can abuse them without issue.

2 minutes ago, peterboat said:

Not if its a separate alternator

Can still be connected to starter battery tho.

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53 minutes ago, Robbo said:

Can still be connected to starter battery tho.

Which is strictly advised against by Relion due to the different resting voltages. 

1 hour ago, Meanderingviking said:

If it's any help I have recently replaced our 10 year old AGMS with more AGMS,  if it ain't broke don't fix it ...........:D

Spot on for now. Maybe in another 10 years time whatever has replaced lithium will be a good idea. 

1 hour ago, Robbo said:

It's connected to the starter battery.

Typical layout...

Cyrix-Li-ion-Diagram.jpg

Typical according to whom? Relion specifically say not to do so. 

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2 hours ago, WotEver said:

Typical according to whom? Relion specifically say not to do so. 

That layout is for the Victron BMS, the BMS we have been talking about.   I’ve not seen that recommendation from Relion, link?  The Cyrix-Li-ct relay in the diagram is voltage sensing so disconnects at resting voltage.

Edited by Robbo
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10 minutes ago, Robbo said:

I’ve not seen that recommendation from Relion, link?

You’d have to join the 12V Boat Electrics closed FB group to see the email from their support dept. Alternatively you could write to them yourself and ask the question I guess. 

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The more I read up on lithiums, the less I like them. Can't charge when temp below 0 C. Wouldn't have been much use this week then! Not sure which Li batteries this is. Is it all of them? My son drives a BMW 330e ( I think that is the model) with the additional plug in electric drive hybridy thingymajig. He says on a cold morning (less than 0C) it doesn't run on electric until it is ' conditioned' i.e. Warmed up. So you can't charge them and you cant use them if it's below freezing. I guess you need a lead acid one to start up and  heat the Lithium ones. Maybe all of that is a load of c**p but I know the efficiency of lithiums suffers the lower the temp.

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2 minutes ago, Dr Bob said:

The more I read up on lithiums, the less I like them. Can't charge when temp below 0 C. Wouldn't have been much use this week then! Not sure which Li batteries this is. Is it all of them? My son drives a BMW 330e ( I think that is the model) with the additional plug in electric drive hybridy thingymajig. He says on a cold morning (less than 0C) it doesn't run on electric until it is ' conditioned' i.e. Warmed up. So you can't charge them and you cant use them if it's below freezing. I guess you need a lead acid one to start up and  heat the Lithium ones. Maybe all of that is a load of c**p but I know the efficiency of lithiums suffers the lower the temp.

Be Patient Bob , it Cannot be Too long till the 97 Horse power Jalapeno-Ecofan Infinity Drive appears on the open Market ,Power will be in abundance , Trust me ,like I trusted you Re the Duck....

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8 minutes ago, cereal tiller said:

Be Patient Bob , it Cannot be Too long till the 97 Horse power Jalapeno-Ecofan Infinity Drive appears on the open Market ,Power will be in abundance , Trust me ,like I trusted you Re the Duck....

Defo worth a greenie, but sadly mine have expired for the day. Run out of them. It is a shame about the duck. Didn't you see it coming? What thread are we on? ....not the Infra red flooring then?

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42 minutes ago, Dr Bob said:

The more I read up on lithiums, the less I like them. Can't charge when temp below 0 C. Wouldn't have been much use this week then! Not sure which Li batteries this is. Is it all of them? My son drives a BMW 330e ( I think that is the model) with the additional plug in electric drive hybridy thingymajig. He says on a cold morning (less than 0C) it doesn't run on electric until it is ' conditioned' i.e. Warmed up. So you can't charge them and you cant use them if it's below freezing. I guess you need a lead acid one to start up and  heat the Lithium ones. Maybe all of that is a load of c**p but I know the efficiency of lithiums suffers the lower the temp.

Yes they aren’t too good at low temperature, but then since they don’t emit nasty acidic or explosive hydrogen fumes, you could install them in a heated part of the boat.

Edited by nicknorman
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On 15/12/2017 at 00:27, nicknorman said:

Yes they aren’t too good at low temperature, but then since they don’t emit nasty acidic or explosive hydrogen fumes, you could install them in a heated part of the boat.

 

I bet they have other hidden traps too that are only discovered once purchased and installed.

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