AGM battery and solar installation

**alouwtjie** · 2020/12/01, 08:15 AM

I currently have 2 x 74AH "High Cycle" lead-acid batteries (size 657) in my trailer. These have been in use since mid 2016 and have reached the end of there life so I'm looking to replace with some kind of "Deep Cycle". Best would of course be a proper 105AH deep cycle but due to restricted space in the trailer this will not fit.

I run 2 x National Luna fridges, a water pump and some LED lights off the setup.

While not traveling the trailer is on permanent power and trickle charging. When off-grid I have 3 x 100W solar panels with a 20A MPPT charger.

Speaking to dealers I have been getting conflicting advice. One dealer recommended the 652 AGM (same dimensions as the current batteries), the other says AGM is not recommended when using solar. I am aware that I could probably fit one of Victron's deep cycles but I am not willing to splash that much. I have read that GEL batteries can be used on its side, which means I would be able to fit a different size battery, but there are also conflicting views on this.

Any experts out there with recommendations / alternatives? Is AGM and solar really problematic?

**Dungbeetle** · 2020/12/01, 09:02 AM

Originally Posted by alouwtjie

.......replace with some kind of "Deep Cycle". Best would of course be a proper 105AH deep cycle but due to restricted space in the trailer this will not fit.....

For a cost effective and smaller dimensions alternative option see:
https://www.dixonbatteries.co.za/638...wh-240x172x220

**alouwtjie** · 2020/12/02, 07:16 PM

Originally Posted by Dungbeetle

For a cost effective and smaller dimensions alternative option see:
https://www.dixonbatteries.co.za/638...wh-240x172x220

Thanks Dungbeetle, unfortunately the battery compartment restricts the battery's height to 195mm max, the height of the 638 is 225mm.

**Dungbeetle** · 2020/12/03, 06:15 AM

Originally Posted by alouwtjie

Thanks Dungbeetle, unfortunately the battery compartment restricts the battery's height to 195mm max, the height of the 638 is 225mm.

Have a look at the Varta LFD75 Marine battery. Expensive but handles deep discharge cycles well.

Height is 179mm if I remember correctly.

(I am not aware of an AGM less than 220 high)

Which trailer do you have - I made changes to my Echo3 battery well to fit bigger batteries

**Die SwartKat** · 2020/12/03, 06:48 AM

Originally Posted by alouwtjie

I currently have 2 x 74AH "High Cycle" lead-acid batteries (size 657) in my trailer. These have been in use since mid 2016 and have reached the end of there life so I'm looking to replace with some kind of "Deep Cycle". Best would of course be a proper 105AH deep cycle but due to restricted space in the trailer this will not fit.

I run 2 x National Luna fridges, a water pump and some LED lights off the setup.

While not traveling the trailer is on permanent power and trickle charging. When off-grid I have 3 x 100W solar panels with a 20A MPPT charger.

Speaking to dealers I have been getting conflicting advice. One dealer recommended the 652 AGM (same dimensions as the current batteries), the other says AGM is not recommended when using solar. I am aware that I could probably fit one of Victron's deep cycles but I am not willing to splash that much. I have read that GEL batteries can be used on its side, which means I would be able to fit a different size battery, but there are also conflicting views on this.

Any experts out there with recommendations / alternatives? Is AGM and solar really problematic?

Not an expert, but AGM's / Gel batteries can definitely be used on its side, though it feels wrong to do it. They're classified as dry cell whereas normal lead acids are the flooded type - wet cell and will obviously leak when turned on its side.

Provided you have a proper solar regulator, it is rubbish that solar and AGM's don't work well together. In fact quite the opposite from what I've read.

I have 4 x 200Ah AGM's in use with my home solar system and from my BMV 712 battery monitor it is clear that they're quite happy to be charged by PV.

My 2 cents.

**GeoED** · 2020/12/03, 10:27 PM

	Have a look at the Omnipower 120ah. Dimensions: 33 × 18 × 22 cm,. and it will happily lie on its side. Gel/AGM Hybrid. High Cycle The AGM/Gel states it requires a cycle charge voltage of 14.4V, but tested and works just as well with 14.1V - 13.8V solar chargers, just charges a bit slower but it still charges. Using it with my setup 320W panels and 20A MPPT HCDP Panel.

**ekkekan** · 2020/12/04, 06:43 AM

The following AGMs are below 195 in height.
652. 658. 668

**alouwtjie** · 2020/12/04, 11:20 AM

Originally Posted by Dungbeetle

Have a look at the Varta LFD75 Marine battery. Expensive but handles deep discharge cycles well.

Height is 179mm if I remember correctly.

(I am not aware of an AGM less than 220 high)

Which trailer do you have - I made changes to my Echo3 battery well to fit bigger batteries

Will have a look at the Varta, thanks. I have a Echo4 trailer. I have raised the lid of the battery well a little to prevent accidental shorts but max safe height is 195.

**Dungbeetle** · 2020/12/04, 11:23 AM

Originally Posted by alouwtjie

Will have a look at the Varta, thanks. I have a Echo4 trailer. I have raised the lid of the battery well a little to prevent accidental shorts but max safe height is 195.

I made 2 trays from SS - see drawing in next post

Cut out sections in the bottom of the well and drop the trays in, sealed and bolted down - now regular 105Ah deep cycles fit easily