AGM Batteries.. replace as before… or?

[BabaYaga]

Some of the comments to this thread may give the impression that all AGM batteries have similar caracteristics. This is not the case. There are those designed for starting and other high current uses, as well as those aimed at deep cycling, typical service battery use. Some AGMs are dual purpose.
With the OP’s size of battery bank, I would consider different types of AGMs for starting and service use.

 

[Kukri]

Decision. The starter batteries are fine, holding 12.1v after 18 months of neglect (why, you ask, are there two Rolls 128s to start a fifty horsepower Yanmar? Because there used to be a plumbed in generator, as well). The six house batteries will be reduced to four, a diesel stove will go where the other two were, when we get round to the electric windlass it will get its own batteries, and we will get round to fitting some solar panels. Thank you, Paul Rainbow.

 

[Rhylsailer99]

I think I should have got agm batteries , I got normal leisure batteries and have found when the kids are charging their phones the volts start to get low fast.

 

[KompetentKrew]

I think I should have got agm batteries , I got normal leisure batteries and have found when the kids are charging their phones the volts start to get low fast.

I'd have thought the draw of a phone would be so small to be unnoticeable on most boats' banks, but you might consider a big 20000mAh or 30000mAh power bank to be on the safe side. The model I have seems unavailable, but this one seems like a bargain.

 

[PaulRainbow]

I think I should have got agm batteries , I got normal leisure batteries and have found when the kids are charging their phones the volts start to get low fast.

If phone chargers are making the "volts get low fast", you either have a hell of a lot of kids, a pitiful amount of batteries, or something isn't right.

 

[CFG98]

Nope.



Don't listen to gossip

Was I thinking of gel batteries? Do they need a different charging system?

 

[PaulRainbow]

Was I thinking of gel batteries? Do they need a different charging system?

There are some slight differences between lead acid, SLA, Gel, AGM etc, but the ones that has some significant differences are Lithium, you might have been thinking of those.

 

[Rhylsailer99]

If phone chargers are making the "volts get low fast", you either have a hell of a lot of kids, a pitiful amount of batteries, or something isn't right.

5 kids all plugged into usb ports charging

 

[blampied]

If it was me replacing batteries this year, I’d go for the cheapest lead acid types.
On the assumption they will last at least 5 years, with Lithium batteries fast improving and at same time dropping in price (maybe even solid state Lithium could become a reality) in 5 or so years you will want to change to the lighter, bigger capacity that Lithium offers.

 

[Kukri]

If it was me replacing batteries this year, I’d go for the cheapest lead acid types.
On the assumption they will last at least 5 years, with Lithium batteries fast improving and at same time dropping in price (maybe even solid state Lithium could become a reality) in 5 or so years you will want to change to the lighter, bigger capacity that Lithium offers.

That’s an interesting point.

On the other hand (and I may be saying this as I have just bought four Rolls 128s!?) the lithium batteries are bound to carry on getting better and cheaper because so many will be being used in cars, in the years to come, so ten years out of my new investment (if I live that long!) may not be so bad!

 

[Kelpie]

I priced up Trojans and ended up going DIY LiFePo4 instead. Cells+ BMS were £407, vs £690 for Trojans of equivalent capacity. Of course there are some additional costs (fuses, isolator, etc) but those would have been broadly similar regardless of the installation.

Caveat is that I haven't actually finished installing the new system yet, so it could all turn out to be a dud...

 

[jwfrary]

I priced up Trojans and ended up going DIY LiFePo4 instead. Cells+ BMS were £407, vs £690 for Trojans of equivalent capacity. Of course there are some additional costs (fuses, isolator, etc) but those would have been broadly similar regardless of the installation.

Caveat is that I haven't actually finished installing the new system yet, so it could all turn out to be a dud...

Have you considered the alternator protection ?

 

[oldgit]

5 kids all plugged into usb ports charging

Huh ......that assumes that they only have one device each and that does not include a matching Ipad.

Try this .... Grandkids, 3 x Ipads, mum and dads phones/Ipads and Grandads phone/Ipad and ye olde laptop.
Ooops nearly forgot Nannies phone.
Amazed my boat can start sometimes.
Actually last week it did not...................

 

[Zing]

I’ve been through two sets of flooded Trojans and am now on my second set of home built lithium packs. I won’t go back. It’s a bit techy though, so you have to invest a good bit of time to learn how do it right. Done this way they are from the same price down to a lot cheaper than lead. Massively better in most ways. I wouldn’t probably buy an off the shelf lithium solution. They are either too expensive like from Mastervolt or for my needs don’t have the correct BMS and current protection. If sticking with lead I would consider the 2v units such as are standard in the fork lift truck industry. They are extremely tough.

 

[Kelpie]

Have you considered the alternator protection ?

Yes, I charge from solar.
My old lead acid bank remains in place but will only handle a small fraction of the loads, including the plotter etc.

(Ok in the interests of full disclosure, I've also got a B2B charger purchased secondhand, but total cost remains less than Trojans, and due to the way I am setting up the system it may turn out to be optional anyway. Just another example of how everybody has different usage requirements)