Which AGM (gel) battery to buy?

MedwaySailor

MedwaySailor

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When we bought our boat we knew we would have to replace the batteries. Delving deeper it transpires that the last owner had replaced the manufacturer's spec of Gel Batteries, 1 x 75Ah and 1 x 105Ah or higher with old fashioned lead acid with two 75Ah and it explains the boxes and strapping he used. I have found several brands, AGM technology, which are totally unfamiliar to me

75Ah (the starter battery)
Energy Expedition Plus/3 yr warranty/CCA60/can't find the number of cycles/ from alpha-batteries.co.uk £100 inc VAT and delivery
AGM Power Plus/5 yr warranty/CCA780/cycles?/from advancedbatterysupplies.co.uk £129 inc

105Ah (the house battery) or higher
Expedition 115Ah/4 yr warranty/can't find the CCA figure/700 cycles/from alpha £130 inc
Power Plus/5 yrs/CCA950/?cycles/from advancedbatterysuplied £210 in

They all fit the current housings

I am unfamiliar with both brands but would be pleased to hear about other people's experiences. I can get a silver calcium , fully sealed maintenance free battery, from Bosch which I would rather do; they fit and are fully sealed but not gel.

What to do?
 
Starter battery ah and cycles are irrelevant. CCA is all that matters. Nothing wrong with fitting lead acid, as such, but a single 75ah battery is too small for domestic use.

I wouldn't get hung up on AGM for the domestic battery, i fit a lot of these, good value and work well ; Hankook XL31 Dual Purpose Leisure Battery - Battery Megastore

I also wouldn't get carried away with the engine battery. No great need for it to be AGM and if it's working OK, i'd leave it alone. If you need to change it and want to go AGM, these are OK Hankook SA57020 AGM Starter Battery: Type 096 - Battery Megastore

Other sizes of engine battery on the same site, you don't give any info regarding the boat or engine though.
 
PaulRainbow said:
Starter battery ah and cycles are irrelevant. CCA is all that matters. Nothing wrong with fitting lead acid, as such, but a single 75ah battery is too small for domestic use.

I wouldn't get hung up on AGM for the domestic battery, i fit a lot of these, good value and work well ; Hankook XL31 Dual Purpose Leisure Battery - Battery Megastore

I also wouldn't get carried away with the engine battery. No great need for it to be AGM and if it's working OK, i'd leave it alone. If you need to change it and want to go AGM, these are OK Hankook SA57020 AGM Starter Battery: Type 096 - Battery Megastore

Other sizes of engine battery on the same site, you don't give any info regarding the boat or engine though.
Click to expand...
Thank you. It's a Delphia 29 (which no one has ever heard of ) with a Volvo Penta 20
 
Medway !
The most important thing...
Is that you change, all your batteries, to the same Amp capacity !
Otherwise, even the newest 6 stage chargers, will not work !
Imagine, connecting to one 85 amp battery, while the rest of your bank, is 200 ?
Then, yes , your 85 amp battery, might be fully charged, but your other 200 amp bats, also , only get charged to 85 amps !
That will cause battery failure & more expense, down the line !
Also, unlike Lead Acid & Water batteries, the AGM batteries, can be mounted on end or whatever !
Which might be easier , for you ? I had an AGM battery mounted on its side, on my motorbike, for years !
 
Last edited:
I upgraded my batteries during the winter, the main reason for moving away from wet acid is vibration, no risk of leaks and not having to top up with distilled water.

After I fair amount of searching I found these guys autocarpartrus on eBay and was able to get the physical sizes I needed as heights of batteries do vary. the other significant benefit was I found 3 * 130Ah batteries with the same dimensions as a 100Ah one giving me an extra nominal 90Ah and 1 * 75Ah starter battery - I have gone for all AGM as my charger has two settings, wet/AGM.

The service from Autocarpatrus was good, but so far I've not been able to complete the installation or use them due to CV-19.
 
Sandy said:
...I found 3 * 130Ah batteries with the same dimensions as a 100Ah one giving me an extra nominal 90Ah...
Click to expand...

To the OP, Unless you pay top dollar for some sort of Uber-Battery, I’d be very wary of batteries of similar dimensions (to lower output units) giving vastly more amp/hours. Amp/hours sell, and it’s not unheard of for battery manufacturers or sellers to get a bit carried away with their stats!
 
fredrussell said:
To the OP, Unless you pay top dollar for some sort of Uber-Battery, I’d be very wary of batteries of similar dimensions (to lower output units) giving vastly more amp/hours. Amp/hours sell, and it’s not unheard of for battery manufacturers or sellers to get a bit carried away with their stats!
Click to expand...
Hence the word nominal.

Space for me was an important design consideration.
 
STILL AFLOAT said:
Imagine, connecting to one 85 amp battery, while the rest of your bank, is 200 ?
Then, yes , your 85 amp battery, might be fully charged, but your other 200 amp bats, also , only get charged to 85 amps !
That will cause battery failure & more expense, down the line !
Click to expand...

Paralleling batteries of different Ah capacity in the same bank might not be best practice, but this warning seems exaggerated.
Think of how often a large domestic battery bank is paralleled with a small starter battery via a relay during charging – and everything charges up fine.
 
STILL AFLOAT said:
Medway !
The most important thing...
Is that you change, all your batteries, to the same Amp capacity !
Otherwise, even the newest 6 stage chargers, will not work !
Imagine, connecting to one 85 amp battery, while the rest of your bank, is 200 ?
Then, yes , your 85 amp battery, might be fully charged, but your other 200 amp bats, also , only get charged to 85 amps !
That will cause battery failure & more expense, down the line !
Click to expand...

This is absolute rubbish and can safely be ignored.
 
STILL AFLOAT said:
Medway !
The most important thing...
Is that you change, all your batteries, to the same Amp capacity !
Otherwise, even the newest 6 stage chargers, will not work !
Imagine, connecting to one 85 amp battery, while the rest of your bank, is 200 ?
Then, yes , your 85 amp battery, might be fully charged, but your other 200 amp bats, also , only get charged to 85 amps !
That will cause battery failure & more expense, down the line !
Click to expand...

This is all incorrect.

Batteries don't have "amp capacities".

The battery charger senses the voltage of the entire bank, not individual batteries. If one battery had a greater capacity than the other, the one with the greater capacity would accept charge quicker and both batteries would reach a state of full charge at the same time.
 
Hey OP!

I noticed your boat at MYC, welcome to cruising from the Medway.

I've not gone for AGM batteries, just new Exide lead acid batteries every 5 years or so works for me.

I'm sure you have done but if not you might want to think about how to keep these charged on a mooring if you're keeping the boat at MYC. Running the engine for a bit every now and then won't be enough. I use a 50 watt solar panel laid on the coach roof during the week, always back to full power by Friday night.
 
Hi Bev
We have had AGM batteries for the past 10 yrs , still in good condition , they are charged by 2 solar panels .
As Dave says If the boats on the MYC moorings , a solar charging panel of at least 80 watt will keep them topped up during the week .
 
STILL AFLOAT said:
Medway !
The most important thing...
Is that you change, all your batteries, to the same Amp capacity !
Otherwise, even the newest 6 stage chargers, will not work !
Imagine, connecting to one 85 amp battery, while the rest of your bank, is 200 ?
Then, yes , your 85 amp battery, might be fully charged, but your other 200 amp bats, also , only get charged to 85 amps !
That will cause battery failure & more expense, down the line !
Also, unlike Lead Acid & Water batteries, the AGM batteries, can be mounted on end or whatever !
Which might be easier , for you ? I had an AGM battery mounted on its side, on my motorbike, for years !
Click to expand...
"Which might be easier , for you ? I had an AGM battery mounted on its side, on my motorbike, for years !"

I'm not surprised. If you knew as much about motorbikes as you know about batteries I assume you kept falling off.
 
I am medway based . If your interested I have four of these, they are a couple of years old but not used, they were for a solar power system that never got installed. SWL3300FR
I have two on my boat and a 55w solar panel keeps them topped up, I use a split charger from the engine and a different controller for two banks from the solar as the engine battery is standard type. It all works well and they are all always fully charged.
They cost about £200 each but selling for £50 as I have no use for them.
 
Jmc1764 said:
I am medway based . If your interested I have four of these, they are a couple of years old but not used, they were for a solar power system that never got installed. SWL3300FR
I have two on my boat and a 55w solar panel keeps them topped up, I use a split charger from the engine and a different controller for two banks from the solar as the engine battery is standard type. It all works well and they are all always fully charged.
They cost about £200 each but selling for £50 as I have no use for them.
Click to expand...

Those are standby batteries, they're not designed to be cycled and will fail prematurely if they are.

http://news.yuasa.co.uk/wp-content/uploads/2016/05/LIT_038_Yuasa_Industrial_Range_Web_2017.pdf
 
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