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Post by kris on Mar 16, 2021 16:14:09 GMT
This is a question for Nick really, I remember you talking about reinvigorating trojans with a charging regime. There’s a boater moored where I am now who could do with doing it . Would you mind explaining it again please?
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Post by Telemachus on Mar 16, 2021 18:19:26 GMT
This is a question for Nick really, I remember you talking about reinvigorating trojans with a charging regime. There’s a boater moored where I am now who could do with doing it . Would you mind explaining it again please? Presume we are talking about open wet cells? (Trojan do AGM as well) Well it depends on what is wrong with them. The first thing to do is to fully charge and then check the specific gravity, should be 1.277 after compensating for temperature. If not they need equalising, ie charging at around 15.5-16v for several hours, until the sg stops increasing (taking care they have plenty of water). If they are just a bit lazy then giving them a fairly deep cycle can wake them up. Take down to about 20% SoC (11.7v rested open circuit voltage) and recharge fairly slowly, say C/10.
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Post by kris on Mar 16, 2021 18:26:45 GMT
Thanks very much, I’ll pass the information on.
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Post by Deleted on Mar 16, 2021 18:30:58 GMT
An idiot question if you'll forgive me.
I know AGM stands for absorbed glass mat ... but have no idea what it means.
Are these AGM batteries interchangeable with lead acid batteries ... simply replace LA batteries with AGM ?
How do they work ?
Do they charge exactly the same as LA batteries ?
Thanks
Rog
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Post by kris on Mar 16, 2021 18:38:08 GMT
They are what they say Rog they have glass mats in between the lead plates rather than just having acid between lead plates. They are the same chemistry as lead acid. The idea of glass mats is too prolong life because they help the plates deteriorate slower than lead plates on their own. If I remember right they need higher voltages to charge. But most mppt controllers and battery chargers have Agm settings. Obviously a very old adult will be along to correct me shortly.
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Post by Telemachus on Mar 16, 2021 22:03:36 GMT
They are what they say Rog they have glass mats in between the lead plates rather than just having acid between lead plates. They are the same chemistry as lead acid. The idea of glass mats is too prolong life because they help the plates deteriorate slower than lead plates on their own. If I remember right they need higher voltages to charge. But most mppt controllers and battery chargers have Agm settings. Obviously a very old adult will be along to correct me shortly. Yes I think that’s about it. They are sealed and without much spare electrolyte so overcharging can kill them quick. But they are less prone to sulphation, ie less need to fully charge. Personally I think wet Trojans are a better bet in terms of life, provided you charge them properly. And then of course there is lithium...
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Post by kris on Mar 16, 2021 22:07:33 GMT
They are what they say Rog they have glass mats in between the lead plates rather than just having acid between lead plates. They are the same chemistry as lead acid. The idea of glass mats is too prolong life because they help the plates deteriorate slower than lead plates on their own. If I remember right they need higher voltages to charge. But most mppt controllers and battery chargers have Agm settings. Obviously a very old adult will be along to correct me shortly. Yes I think that’s about it. They are sealed and without much spare electrolyte so overcharging can kill them quick. But they are less prone to sulphation, ie less need to fully charge. Personally I think Trojans are a better bet in terms of life, provided you charge them properly. And then of course there is lithium... To be honest at the moment, if you are prepared to buy direct from China and buy a cheaper brand Eve I believe are okay. Then lithium’s are cheaper than agms. So no competition in my opinion, I’m beginning to really like these lithium’s.
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Post by ianali on Mar 23, 2021 7:02:08 GMT
Do people using lithium batteries take any/extra fire precautions? I ask as my neighbour is an engineer at MIRA,(motor research facility) and recently they had a large fire caused by a rogue battery. Maybe they are a different animal?
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Post by Telemachus on Mar 23, 2021 7:22:11 GMT
Do people using lithium batteries take any/extra fire precautions? I ask as my neighbour is an engineer at MIRA,(motor research facility) and recently they had a large fire caused by a rogue battery. Maybe they are a different animal? No. But there are wide variations of risk according to the wide variations of battery chemistry. Lithium polymer has the highest energy density (wh per kg) but is also the most likely to spontaneously combust if abused. When it does go on fire, it provides its own oxygen so isn’t extinguished by smothering. By contrast LiFePO4 has much less energy density but is really hard to ignite, and when it does burn, does not produce enough oxygen to self-sustain. I think it probably is possible to get it to burn but this is one reason for high voltage disconnects and battery temperature monitoring. A lead acid battery can be made to explode and spray boiling acid everywhere.
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